Implement Model Refactoring

<UserStory> 1955: Model Refactoring</UserStory>

UserStory #1955

<Changes>
1. Replaced CSV-based serialization and deserialization in ComboPackage, JobCard, Service, and ServiceBooking models with fixed-size SerializedRecord structures for shared memory storage.
2. Implemented serialize() methods to convert objects into SerializedComboPackage, SerializedJobCard, SerializedService, and SerializedServiceBooking records.
3. Implemented deserialize() methods to reconstruct objects directly from SerializedRecord types instead of parsing CSV strings.
4. Updated model class interfaces to use SerializedRecord types, removing legacy CSV serialization APIs and header generation functions.
5. Added SerializedRecords.h dependencies and forward declarations for Serialized structures across affected models.
</Changes>

<Test>
N/A
</Test>

<Review>
Sreeja Reghukumar, please review
</Review>

.gitignore

@@ -427,5 +427,5 @@ FodyWeavers.xsd
 *.msm
 *.msp
 
-# DAT Files
+# CSV Files
-*.dat
+*.csv

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem.vcxproj

@@ -140,6 +140,7 @@
     <ClCompile Include="models\User.cpp" />
     <ClCompile Include="services\AuthenticationManagementService.cpp" />
     <ClCompile Include="services\InventoryManagementService.cpp" />
+    <ClCompile Include="services\NotificationManagementService.cpp" />
     <ClCompile Include="services\PaymentManagementService.cpp" />
     <ClCompile Include="services\ServiceManagementService.cpp" />
     <ClCompile Include="services\UserManagementService.cpp" />
@@ -156,7 +157,6 @@
     <ClInclude Include="core\patterns\Observer.h" />
     <ClInclude Include="core\patterns\Subject.h" />
     <ClInclude Include="datastores\DataStore.h" />
-    <ClInclude Include="datastores\DataStoreLockGuard.h" />
     <ClInclude Include="datastores\sharedmemory\FileHeader.h" />
     <ClInclude Include="datastores\sharedmemory\MappingInfo.h" />
     <ClInclude Include="datastores\sharedmemory\RecordState.h" />
@@ -181,6 +181,7 @@
     <ClInclude Include="utilities\Config.h" />
     <ClInclude Include="utilities\Enums.h" />
     <ClInclude Include="utilities\FileHelper.h" />
+    <ClInclude Include="utilities\FileManager.h" />
     <ClInclude Include="utilities\InputHelper.h" />
     <ClInclude Include="utilities\Map.h" />
     <ClInclude Include="utilities\OutputHelper.h" />

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem.vcxproj.filters

@@ -114,6 +114,9 @@
     <ClCompile Include="datastores\DataStore.cpp">
       <Filter>Source Files\DataStores</Filter>
     </ClCompile>
+    <ClCompile Include="services\NotificationManagementService.cpp">
+      <Filter>Source Files\Services</Filter>
+    </ClCompile>
     <ClCompile Include="core\patterns\Observer.cpp">
       <Filter>Source Files\Core\Patterns</Filter>
     </ClCompile>
@@ -242,6 +245,9 @@
     <ClInclude Include="utilities\Config.h">
       <Filter>Header Files\Utilities</Filter>
     </ClInclude>
+    <ClInclude Include="utilities\FileManager.h">
+      <Filter>Header Files\Utilities</Filter>
+    </ClInclude>
     <ClInclude Include="utilities\StringHelper.h">
       <Filter>Header Files\Utilities</Filter>
     </ClInclude>
@@ -272,8 +278,5 @@
     <ClInclude Include="datastores\sharedmemory\SharedMemory.h">
       <Filter>Header Files\DataStores\SharedMemory</Filter>
     </ClInclude>
-    <ClInclude Include="datastores\DataStoreLockGuard.h">
-      <Filter>Header Files\DataStores</Filter>
-    </ClInclude>
   </ItemGroup>
 </Project>

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/controllers/Controller.cpp

@@ -588,37 +588,63 @@ void Controller::configureNotifications(bool paymentNotifications, bool serviceN
 }
 
 /*
-Function: initialize
+Function: loadSystemData
-Description: Initializes the system and run system checks to ensure critical configurations, such as verifying admin existence.
+Description: Loads all system data from persistent storage into memory.
-Parameters:
+             Invokes the respective management services to load users, inventory items, services,
-    - None
+             combo packages, service bookings, job cards, invoices, and observers.
-Returns:
-    - bool
-*/
-bool Controller::initialize()
-{
-    auto& dataStore = DataStore::getInstance();
-
-    if (!dataStore.initialize())
-    {
-        return false;
-    }
-    m_userManagementService.ensureAdminExists();
-    m_inventoryManagementService.sendLowStockAlerts();
-    m_paymentManagementService.sendPaymentReminders();
-    return true;
-}
-
-/*
-Function: shutdown
-Description: Shutdown the system, and do necessary cleanups
 Parameters:
     - None
 Returns:
     - void
 */
-void Controller::shutdown()
+void Controller::loadSystemData()
 {
-    auto& dataStore = DataStore::getInstance();
+    m_userManagementService.loadUsers();
-    dataStore.shutdown();
+    m_inventoryManagementService.loadInventoryItems();
+    m_serviceManagementService.loadServices();
+    m_serviceManagementService.loadComboPackages();
+    m_serviceManagementService.loadServiceBookings();
+    m_serviceManagementService.loadJobCards();
+    m_paymentManagementService.loadInvoices();
+    m_serviceManagementService.loadObservers();
+    m_paymentManagementService.loadObservers();
+    m_inventoryManagementService.loadObservers();
 }
+
+/*
+Function: saveSystemData
+Description: Saves all system data from memory back to persistent storage.
+             Invokes the respective management services to save users, inventory items, services,
+             combo packages, service bookings, job cards, invoices, and observers.
+Parameters:
+    - None
+Returns:
+    - void
+*/
+void Controller::saveSystemData()
+{
+    m_userManagementService.saveUsers();
+    m_inventoryManagementService.saveInventoryItems();
+    m_serviceManagementService.saveServices();
+    m_serviceManagementService.saveComboPackages();
+    m_serviceManagementService.saveServiceBookings();
+    m_serviceManagementService.saveJobCards();
+    m_paymentManagementService.saveInvoices();
+    m_serviceManagementService.saveObservers();
+    m_paymentManagementService.saveObservers();
+    m_inventoryManagementService.saveObservers();
+}
+
+/*
+Function: runSystemChecks
+Description: Runs system checks to ensure critical configurations, such as verifying admin existence.
+Parameter: None
+Return type: void
+*/
+void Controller::runSystemChecks()
+{
+    m_userManagementService.ensureAdminExists();
+    m_inventoryManagementService.sendLowStockAlerts();
+    m_paymentManagementService.sendPaymentReminders();
+}
+

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/controllers/Controller.h

@@ -70,6 +70,7 @@ public:
     util::Vector<const Notification*> getNotifications();
     void deleteNotification(const std::string& notificationID);
     void configureNotifications(bool paymentNotifications, bool serviceNotifications);
-    bool initialize();
+    void loadSystemData();
-    void shutdown();
+    void saveSystemData();
+    void runSystemChecks();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/core/patterns/Observer.h

@@ -7,8 +7,11 @@ Date: 19-May-2026
 
 #pragma once
 
+class Notification;
+
 class Observer
 {
 public:
     virtual ~Observer() = default;
+    virtual void addNotification(Notification* notification) = 0;
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/datastores/DataStore.cpp

@@ -12,8 +12,6 @@ Date: 19-May-2026
 #include "Config.h"
 #include "SerializedRecords.h"
 #include "FileHelper.h"
-#include "ServiceBooking.h"
-#include "JobCard.h"
 
 /*
 Function: DataStore
@@ -146,6 +144,11 @@ bool DataStore::initialize()
             success = false;
             break;
         }
+        if (!SharedMemory::createOrOpenMapping(m_payments))
+        {
+            success = false;
+            break;
+        }
         if (!SharedMemory::createOrOpenMapping(m_serviceManagementObservers))
         {
             success = false;
@@ -190,6 +193,7 @@ void DataStore::shutdown()
     SharedMemory::closeMapping(m_serviceBookings);
     SharedMemory::closeMapping(m_jobCards);
     SharedMemory::closeMapping(m_invoices);
+    SharedMemory::closeMapping(m_payments);
     SharedMemory::closeMapping(m_serviceManagementObservers);
     SharedMemory::closeMapping(m_paymentManagementObservers);
     SharedMemory::closeMapping(m_inventoryManagementObservers);
@@ -224,8 +228,6 @@ Returns:
 */
 util::Map<std::string, TrackedRecord<User>>& DataStore::getUsers()
 {
-    auto users = loadRecords<User, SerializedUser>(m_users);
-    refreshCache(m_userCache, users);
     return m_userCache;
 }
 
@@ -239,8 +241,6 @@ Returns:
 */
 util::Map<std::string, TrackedRecord<Notification>>& DataStore::getNotifications()
 {
-    auto notifications = loadRecords<Notification, SerializedNotification>(m_notifications);
-    refreshCache(m_notificationCache, notifications);
     return m_notificationCache;
 }
 
@@ -254,28 +254,6 @@ Returns:
 */
 util::Map<std::string, TrackedRecord<Service>>& DataStore::getServices()
 {
-    util::Map<std::string, TrackedRecord<Service>> services = loadRecords<Service, SerializedService>(m_services);
-    refreshCache(m_serviceCache, services);
-    util::Map<std::string, TrackedRecord<InventoryItem>>& inventoryItems = getInventoryItems();
-    size_t numberOfServices = m_serviceCache.getSize();
-    for (int iteratorOne =0; iteratorOne < numberOfServices; iteratorOne++)
-    {
-        Service* currentService = m_serviceCache.getValueAt(iteratorOne).data;
-        util::Map<std::string, InventoryItem*> inventoryItemMap;
-        util::Vector<std::string> currentServiceInventoryItem = currentService->getRequiredInventoryItemIDs();
-        for (int iteratorTwo = 0; iteratorTwo < currentServiceInventoryItem.getSize(); iteratorTwo++)
-        {
-            const std::string& currentInventoryItemId = currentServiceInventoryItem[iteratorTwo];
-            int currentInventoryItemIndex = inventoryItems.find(currentInventoryItemId);
-            if (currentInventoryItemIndex == -1)
-            {
-                throw std::runtime_error("Invalid inventory item ID");
-            }
-            InventoryItem* currentItem = inventoryItems.getValueAt(currentInventoryItemIndex).data;
-            inventoryItemMap[currentInventoryItemId] = currentItem;
-        }
-        currentService->setRequiredInventoryItems(inventoryItemMap);
-    }
     return m_serviceCache;
 }
 
@@ -289,28 +267,6 @@ Returns:
 */
 util::Map<std::string, TrackedRecord<ComboPackage>>& DataStore::getComboPackages()
 {
-    util::Map<std::string, TrackedRecord<ComboPackage>> comboPackages = loadRecords<ComboPackage, SerializedComboPackage>(m_comboPackages);
-    refreshCache(m_comboPackageCache, comboPackages);
-    util::Map<std::string, TrackedRecord<Service>>& services = getServices();
-    size_t numberOfComboPackages = m_comboPackageCache.getSize();
-    for (int iteratorOne = 0; iteratorOne < numberOfComboPackages; iteratorOne++)
-    {
-        ComboPackage* currentComboPackage =  m_comboPackageCache.getValueAt(iteratorOne).data;
-        util::Vector<std::string> currentServiceIds = currentComboPackage->getServiceIDs();
-        util::Map<std::string, Service*> currentComboPackageServices;
-        for (int iteratorTwo = 0; iteratorTwo < currentServiceIds.getSize(); iteratorTwo++)
-        {
-            const std::string& currentServiceId = currentServiceIds[iteratorTwo];
-            int serviceIndex = services.find(currentServiceId);
-            if (serviceIndex == -1)
-            {
-                throw std::runtime_error("Invalid service ID");
-            }
-            Service* currentService = services.getValueAt(serviceIndex).data;
-            currentComboPackageServices[currentServiceId] = currentService;
-        }
-        currentComboPackage->setServices(currentComboPackageServices);
-    }
     return m_comboPackageCache;
 }
 
@@ -337,49 +293,6 @@ Returns:
 */
 util::Map<std::string, TrackedRecord<ServiceBooking>>& DataStore::getServiceBookings()
 {
-    util::Map<std::string, TrackedRecord<ServiceBooking>> serviceBookings = loadRecords<ServiceBooking, SerializedServiceBooking>(m_serviceBookings);
-    refreshCache(m_serviceBookingCache, serviceBookings);
-    auto& users = getUsers();
-    auto& services = getServices();
-    size_t numberOfServiceBookings = m_serviceBookingCache.getSize();
-    for (int iteratorOne = 0; iteratorOne < numberOfServiceBookings; iteratorOne++)
-    {
-        ServiceBooking* serviceBooking = m_serviceBookingCache.getValueAt(iteratorOne).data;
-        auto& serviceIds = serviceBooking->getServiceIDs();
-        util::Map<std::string, Service*> servicesInBooking;
-        for (int iteratorTwo = 0; iteratorTwo < serviceIds.getSize(); iteratorTwo++)
-        {
-            const std::string& currentServiceId = serviceIds[iteratorTwo];
-            int serviceIndex = services.find(currentServiceId);
-            if (serviceIndex == -1)
-            {
-                throw std::runtime_error("Invalid service index.");
-            }
-            auto currentService = services.getValueAt(serviceIndex);
-            servicesInBooking[currentServiceId] = currentService.data;
-        }
-        serviceBooking->setServices(servicesInBooking);
-        if (!serviceBooking->getCustomerId().empty())
-        {
-            int userIndex = users.find(serviceBooking->getCustomerId());
-            if (userIndex == -1)
-            {
-                throw std::runtime_error("Invalid user index.");
-            }
-            auto customer = users.getValueAt(userIndex);
-            serviceBooking->setCustomer(customer.data);
-        }
-        if (!serviceBooking->getAssignedTechnicianId().empty())
-        {
-            int technicianIndex = users.find(serviceBooking->getAssignedTechnicianId());
-            if (technicianIndex == -1)
-            {
-                throw std::runtime_error("Invalid technician index.");
-            }
-            auto technician = users.getValueAt(technicianIndex);
-            serviceBooking->setAssignedTechnician(technician.data);
-        }
-    }
     return m_serviceBookingCache;
 }
 
@@ -393,51 +306,9 @@ Returns:
 */
 util::Map<std::string, TrackedRecord<JobCard>>& DataStore::getJobCards()
 {
-    util::Map<std::string, TrackedRecord<JobCard>> jobCards = loadRecords<JobCard, SerializedJobCard>(m_jobCards);
-    refreshCache(m_jobCardCache, jobCards);
-    auto& serviceBookings = getServiceBookings();
-    auto& services = getServices();
-    auto& users = getUsers();
-    int numberOfJobCards = m_jobCardCache.getSize();
-    for (int iterator = 0; iterator < numberOfJobCards; iterator++)
-    {
-        JobCard* jobCard = m_jobCardCache.getValueAt(iterator).data;
-        if (!jobCard)
-        {
-            continue;
-        }
-        const std::string& bookingId = jobCard->getBookingId();
-        int bookingIndex = serviceBookings.find(bookingId);
-        if (bookingIndex == -1)
-        {
-            throw std::runtime_error("Invalid booking ID: " + bookingId);
-        }
-        auto trackedBooking = serviceBookings.getValueAt(bookingIndex);
-        jobCard->setBooking(trackedBooking.data);
-        const std::string& serviceId = jobCard->getServiceId();
-        int serviceIndex = services.find(serviceId);
-        if (serviceIndex == -1)
-        {
-            throw std::runtime_error("Invalid service ID: " + serviceId);
-        }
-        auto trackedService = services.getValueAt(serviceIndex);
-        jobCard->setService(trackedService.data);
-        const std::string& technicianId = jobCard->getTechnicianId();
-        if (!technicianId.empty())
-        {
-            int technicianIndex = users.find(technicianId);
-            if (technicianIndex == -1)
-            {
-                throw std::runtime_error("Invalid technician ID: " + technicianId);
-            }
-            auto trackedTechnician = users.getValueAt(technicianIndex);
-            jobCard->setTechnician(trackedTechnician.data);
-        }
-    }
     return m_jobCardCache;
 }
 
-
 /*
 Function: getInvoices
 Description: Retrieves all invoice records from the datastore.
@@ -451,37 +322,6 @@ util::Map<std::string, TrackedRecord<Invoice>>& DataStore::getInvoices()
     return m_invoiceCache;
 }
 
-/*
-Function: getObservers
-Description: Retrieves observer records from the specified observer mapping
-             and resolves them to User objects.
-Parameters:
-    - mapping: Observer mapping to read from
-Returns:
-    - util::Map<std::string, User*>: Collection of observer records
-Throws:
-    - std::runtime_error if an observer references an invalid user ID
-*/
-util::Map<std::string, User*> DataStore::getObservers(MappingInfo& mapping)
-{
-    auto& users = getUsers();
-    util::Map<std::string, User*> observers;
-    SharedMemory::ensureLatestMapping(mapping);
-    size_t recordCount = SharedMemory::getRecordCount(mapping);
-    for (size_t index = 0; index < recordCount; index++)
-    {
-        const SerializedObserver* observer = static_cast<SerializedObserver*>(SharedMemory::getRecordAddress(mapping, index));
-        int userIndex = users.find(observer->id);
-        if (userIndex == -1)
-        {
-            throw std::runtime_error("Invalid observer user ID");
-        }
-        User* user = users.getValueAt(userIndex).data;
-        observers.insert(user->getId(), user);
-    }
-    return observers;
-}
-
 /*
 Function: getServiceManagementObservers
 Description: Retrieves all service management observer records from the datastore.
@@ -492,7 +332,7 @@ Returns:
 */
 util::Map<std::string, User*> DataStore::getServiceManagementObservers()
 {
-    return getObservers(m_serviceManagementObservers);
+    return util::Map<std::string, User*>();
 }
 
 /*
@@ -505,7 +345,7 @@ Returns:
 */
 util::Map<std::string, User*> DataStore::getPaymentManagementObservers()
 {
-    return getObservers(m_paymentManagementObservers);
+    return util::Map<std::string, User*>();
 }
 
 /*
@@ -518,7 +358,7 @@ Returns:
 */
 util::Map<std::string, User*> DataStore::getInventoryManagementObservers()
 {
-    return getObservers(m_inventoryManagementObservers);
+    return util::Map<std::string, User*>();
 }
 
 /*
@@ -531,7 +371,6 @@ Returns:
 */
 void DataStore::saveUsers()
 {
-    saveRecords<User, SerializedUser>(m_users, m_userCache);
 }
 
 /*
@@ -544,7 +383,6 @@ Returns:
 */
 void DataStore::saveNotifications()
 {
-    saveRecords<Notification, SerializedNotification>(m_notifications, m_notificationCache);
 }
 
 /*
@@ -557,7 +395,6 @@ Returns:
 */
 void DataStore::saveServices()
 {
-    saveRecords<Service, SerializedService>(m_services, m_serviceCache);
 }
 
 /*
@@ -570,7 +407,6 @@ Returns:
 */
 void DataStore::saveComboPackages()
 {
-    saveRecords<ComboPackage, SerializedComboPackage>(m_comboPackages, m_comboPackageCache);
 }
 
 /*
@@ -595,7 +431,6 @@ Returns:
 */
 void DataStore::saveServiceBookings()
 {
-    saveRecords<ServiceBooking, SerializedServiceBooking>(m_serviceBookings, m_serviceBookingCache);
 }
 
 /*
@@ -608,7 +443,6 @@ Returns:
 */
 void DataStore::saveJobCards()
 {
-    saveRecords<JobCard, SerializedJobCard>(m_jobCards, m_jobCardCache);
 }
 
 /*
@@ -623,49 +457,16 @@ void DataStore::saveInvoices()
 {
 }
 
-/*
-Function: saveObservers
-Description: Persists observer records to the specified observer mapping.
-Parameters:
-    - mapping: MappingInfo&, observer mapping to save to
-    - observers: util::Map<std::string, User*>&, collection of observer records
-Returns:
-    - None
-*/
-void DataStore::saveObservers(MappingInfo& mapping, util::Map<std::string, User*>& observers)
-{
-    size_t observerCount = static_cast<size_t>(observers.getSize());
-    size_t capacity = config::file::INITIAL_CAPACITY;
-    while (capacity < observerCount)
-    {
-        capacity *= config::file::GROWTH_FACTOR;
-    }
-    if (!SharedMemory::resizeMapping(mapping, capacity))
-    {
-        throw std::runtime_error("Failed to resize observer mapping");
-    }
-    SharedMemory::setRecordCount(mapping, observerCount);
-    for (size_t index = 0; index < observerCount; index++)
-    {
-        SerializedObserver serializedObserver;
-        User* user = observers.getValueAt(static_cast<int>(index));
-        strcpy_s(serializedObserver.id, sizeof(serializedObserver.id), user->getId().c_str());
-        SerializedObserver* destination = static_cast<SerializedObserver*>(SharedMemory::getRecordAddress(mapping, index));
-        *destination = serializedObserver;
-    }
-}
-
 /*
 Function: saveServiceManagementObservers
 Description: Persists all service management observer records to the datastore.
 Parameters:
-    - observers: util::Map<std::string, User*>&, collection of observer records
+    - observers: util::Map<std::string, TrackedRecord<std::string>>&, collection of observer records
 Returns:
     - None
 */
 void DataStore::saveServiceManagementObservers(util::Map<std::string, User*>& observers)
 {
-    saveObservers(m_serviceManagementObservers, observers);
 }
 
 /*
@@ -678,7 +479,6 @@ Returns:
 */
 void DataStore::savePaymentManagementObservers(util::Map<std::string, User*>& observers)
 {
-    saveObservers(m_paymentManagementObservers, observers);
 }
 
 /*
@@ -691,7 +491,32 @@ Returns:
 */
 void DataStore::saveInventoryManagementObservers(util::Map<std::string, User*>& observers)
 {
-    saveObservers(m_inventoryManagementObservers, observers);
+}
+
+/*
+Function: lockDataStore
+Description: Acquires exclusive access to the datastore.
+Parameters:
+    - None
+Returns:
+    - bool: True if the datastore was successfully locked, otherwise false
+*/
+bool DataStore::lockDataStore()
+{
+    return false;
+}
+
+/*
+Function: unlockDataStore
+Description: Releases exclusive access to the datastore.
+Parameters:
+    - None
+Returns:
+    - bool: True if the datastore was successfully unlocked, otherwise false
+*/
+bool DataStore::unlockDataStore()
+{
+    return false;
 }
 
 /*

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/datastores/DataStore.h

@@ -11,16 +11,15 @@ Date: 19-May-2026
 #include "Map.h"
 #include "MappingInfo.h"
 #include "TrackedRecord.h"
-#include "SerializedRecords.h"
 #include "SharedMemory.h"
-#include "User.h"
+class User;
-#include "Notification.h"
+class Notification;
-#include "Service.h"
+class Service;
-#include "ComboPackage.h"
+class ComboPackage;
-#include "InventoryItem.h"
+class InventoryItem;
-#include "ServiceBooking.h"
+class ServiceBooking;
-#include "JobCard.h"
+class JobCard;
-#include "Invoice.h"
+class Invoice;
 
 class DataStore
 {
@@ -40,6 +39,7 @@ private:
     MappingInfo m_serviceBookings;
     MappingInfo m_jobCards;
     MappingInfo m_invoices;
+    MappingInfo m_payments;
     MappingInfo m_serviceManagementObservers;
     MappingInfo m_paymentManagementObservers;
     MappingInfo m_inventoryManagementObservers;
@@ -86,8 +86,6 @@ private:
     void saveRecords(MappingInfo& mapping, util::Map<std::string, TrackedRecord<TObject>>& records);
     template<typename TObject> void clearCache(util::Map<std::string, TrackedRecord<TObject>>&cache);
     template<typename TObject> void refreshCache(util::Map<std::string, TrackedRecord<TObject>>&cache, util::Map<std::string, TrackedRecord<TObject>>&refreshedCache);
-    util::Map<std::string, User*> getObservers(MappingInfo& mapping);
-    void saveObservers(MappingInfo& mapping, util::Map<std::string, User*>& observers);
 };
 
 /*
@@ -197,10 +195,10 @@ void DataStore::clearCache(util::Map<std::string, TrackedRecord<TObject>>&cache)
 
 /*
 Function: refreshCache
-Description: Refreshes the cache while preserving object addresses
+Description: Replaces the contents of an existing cache
-             for records that already exist. Existing objects are
+             with a newly loaded cache. Existing cached
-             updated in-place so that pointers held elsewhere remain
+             objects are destroyed before ownership of
-             valid after the refresh.
+             the new cache contents is transferred.
 Parameters:
     - cache: Existing cache to refresh.
     - refreshedCache: Newly loaded cache contents.
@@ -208,40 +206,8 @@ Returns:
     - None
 */
 template<typename TObject>
-void DataStore::refreshCache(util::Map<std::string, TrackedRecord<TObject>>& cache, util::Map<std::string, TrackedRecord<TObject>>& refreshedCache)
+void DataStore::refreshCache(util::Map<std::string, TrackedRecord<TObject>>&cache, util::Map<std::string, TrackedRecord<TObject>>&refreshedCache)
 {
-    util::Map<std::string, TrackedRecord<TObject>> oldCache = cache;
+    clearCache(cache);
-    cache.clear();
+    cache = refreshedCache;
-    for (int index = 0; index < refreshedCache.getSize(); ++index)
-    {
-        const std::string& id = refreshedCache.getKeyAt(index);
-        TrackedRecord<TObject>& refreshedRecord = refreshedCache.getValueAt(index);
-        int oldIndex = oldCache.find(id);
-        if (oldIndex != -1)
-        {
-            TrackedRecord<TObject>& oldRecord = oldCache.getValueAt(oldIndex);
-            *oldRecord.data = *refreshedRecord.data;
-            oldRecord.slotIndex = refreshedRecord.slotIndex;
-            oldRecord.state = refreshedRecord.state;
-            delete refreshedRecord.data;
-            refreshedRecord.data = oldRecord.data;
-        }
-        cache.insert(id, refreshedRecord);
-    }
-    for (int index = 0; index < oldCache.getSize(); ++index)
-    {
-        const std::string& id = oldCache.getKeyAt(index);
-        const TrackedRecord<TObject>& localTrackedRecord = oldCache.getValueAt(index);
-        if (cache.find(id) == -1)
-        {
-            if (localTrackedRecord.state == RecordState::NEW_RECORD)
-            {
-                cache.insert(id, localTrackedRecord);
-            }
-            else
-            {
-                delete localTrackedRecord.data;
-            }
-        }
-    }
 }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/datastores/DataStoreLockGuard.h

@@ -1,28 +0,0 @@
-/*
-File: DataStoreLockGuard.h
-Description: Defines the DataStoreLockGuard class used to manage DataStore
-             locking and unlocking automatically within a scope.
-Author: Trenser
-Date: 12-June-2026
-*/
-
-#pragma once
-#include "DataStore.h"
-
-class DataStoreLockGuard
-{
-public:
-    explicit DataStoreLockGuard(DataStore& dataStore)
-        : m_dataStore(dataStore)
-    {
-        m_dataStore.lockDataStore();
-    }
-    ~DataStoreLockGuard()
-    {
-        m_dataStore.unlockDataStore();
-    }
-    DataStoreLockGuard(const DataStoreLockGuard&) = delete;
-    DataStoreLockGuard& operator=(const DataStoreLockGuard&) = delete;
-private:
-    DataStore& m_dataStore;
-};

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/datastores/sharedmemory/SharedMemory.cpp

@@ -10,7 +10,6 @@ Created: 11-June-2026
 */
 
 #include "SharedMemory.h"
-#include "Windows.h"
 #include "Config.h"
 
 /*
@@ -320,7 +319,7 @@ bool SharedMemory::ensureCapacityForInsert(MappingInfo& mapping)
     {
         return true;
     }
-    return resizeMapping(mapping, capacity * config::file::GROWTH_FACTOR);
+    return resizeMapping(mapping, capacity * 2);
 }
 
 /*

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/models/ComboPackage.h

@@ -12,7 +12,7 @@ Date: 19-May-2026
 #include "Enums.h"
 
 class Service;
-struct SerializedComboPackage;
+class SerializedComboPackage;
 
 class ComboPackage
 {

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/models/Notification.cpp

@@ -1,13 +1,12 @@
 /*
 File: Notification.cpp
 Description: Implements the Notification class which represents system notifications in the Vehicle Service Management System.
-             Provides constructors, accessors, and mutators for notification details such as ID, recipientID, title, message, and timestamp.
+             Provides constructors, accessors, and mutators for notification details such as ID, recipient, title, message, and timestamp.
 Author: Trenser
 Date: 19-May-2026
 */
 
 #include <sstream>
-#include "SerializedRecords.h"
 #include "Notification.h"
 #include "StringHelper.h"
 #include "Factory.h"
@@ -23,8 +22,8 @@ Returns:
     - A new Notification object.
 */
 Notification::Notification()
-    : m_id("NOT" + std::to_string(++m_uid)), 
+    : m_id("NOT" + std::to_string(++m_uid)),
-    m_state(util::State::ACTIVE) {}
+    m_recipient(nullptr) {}
 
 /*
 Function: Notification
@@ -38,14 +37,13 @@ Parameters:
 Returns:
     - A new Notification object.
 */
-Notification::Notification(const std::string& recipientUserId, const std::string& title, const std::string& message, const util::Timestamp& createdAt)
+Notification::Notification(const std::string& recipientUserId, User* recipient, const std::string& title, const std::string& message, const util::Timestamp& createdAt)
     : m_id("NOT" + std::to_string(++m_uid)),
     m_recipientUserId(recipientUserId),
+    m_recipient(recipient),
     m_title(title),
     m_message(message),
-    m_state(util::State::ACTIVE),
+    m_createdAt(createdAt) {}
-    m_createdAt(createdAt) {
-}
 
 /*
 Function: Notification (parameterized constructor with ID)
@@ -60,13 +58,13 @@ Parameters:
 Returns:
     - A new Notification object
 */
-Notification::Notification(const std::string& id, const std::string& recipientUserId, const std::string& title, const std::string& message, const util::Timestamp& createdAt, const util::State& state)
+Notification::Notification(const std::string& id, const std::string& recipientUserId, const std::string& title, const std::string& message, const util::Timestamp& createdAt)
     : m_id(id),
     m_recipientUserId(recipientUserId),
+    m_recipient(nullptr),
     m_title(title),
     m_message(message),
-    m_createdAt(createdAt),
+    m_createdAt(createdAt) 
-    m_state(state)
 {
     int idNumber = util::extractNumber(m_id);
     if (idNumber > m_uid)
@@ -81,7 +79,7 @@ Description: Retrieves the unique ID of the notification.
 Returns:
     - const std::string& representing the notification ID.
 */
-const std::string& Notification::getId() const
+const std::string& Notification::getId() const 
 {
     return m_id;
 }
@@ -97,6 +95,17 @@ const std::string& Notification::getRecipientUserId() const
     return m_recipientUserId;
 }
 
+/*
+Function: getRecipient
+Description: Retrieves the pointer to the recipient user.
+Returns:
+    - User* representing the recipient.
+*/
+User* Notification::getRecipient() const
+{
+    return m_recipient;
+}
+
 /*
 Function: getTitle
 Description: Retrieves the title of the notification.
@@ -130,17 +139,6 @@ const util::Timestamp& Notification::getCreatedAt() const
     return m_createdAt;
 }
 
-/*
-Function: getState
-Description: Retrieves the Notification state
-Returns:
-    - const util::Timestamp& representing the creation timestamp.
-*/
-util::State Notification::getState() const
-{
-    return m_state;
-}
-
 /*
 Function: setId
 Description: Sets the unique ID of the notification.
@@ -167,6 +165,19 @@ void Notification::setRecipientUserId(const std::string& recipientUserId)
     m_recipientUserId = recipientUserId;
 }
 
+/*
+Function: setRecipient
+Description: Sets the recipient user pointer for the notification.
+Parameters:
+    - recipient: Pointer to the User object.
+Returns:
+    - void
+*/
+void Notification::setRecipient(User* recipient)
+{
+    m_recipient = recipient;
+}
+
 /*
 Function: setTitle
 Description: Sets the title of the notification.
@@ -206,54 +217,71 @@ void Notification::setCreatedAt(const util::Timestamp& createdAt)
     m_createdAt = createdAt;
 }
 
-/*
-Function: setState
-Description: Sets the Notification state.
-Parameters:
-    - state: Notification state value.
-Returns:
-    - void
-*/
-void Notification::setState(util::State state)
-{
-    m_state = state;
-}
-
 /*
 Function: serialize
-Description: Serializes the Notification object into a SerializedNotification record.
+Description: Serializes the notification into a CSV-formatted string.
 Parameters:
     - None
 Returns:
-    - SerializedNotification: Serialized representation of the notification
+    - std::string: Serialized notification record
 */
-SerializedNotification Notification::serialize() const
+std::string Notification::serialize() const
 {
-    SerializedNotification serialized = {};
+    std::ostringstream serializedNotification;
-    strcpy_s(serialized.id, sizeof(serialized.id), m_id.c_str());
+    serializedNotification << m_id << ','
-    strcpy_s(serialized.recipientUserId, sizeof(serialized.recipientUserId), m_recipientUserId.c_str());
+        << m_recipientUserId << ','
-    strcpy_s(serialized.title, sizeof(serialized.title), m_title.c_str());
+        << m_title << ','
-    strcpy_s(serialized.message, sizeof(serialized.message), m_message.c_str());
+        << m_message << ','
-    serialized.createdAt = m_createdAt;
+        << m_createdAt.toString();
-    serialized.state = m_state;
+    return serializedNotification.str();
-    return serialized;
 }
 
 /*
 Function: deserialize
-Description: Deserializes a SerializedNotification record into a Notification object.
+Description: Deserializes a CSV-formatted string into a Notification object.
 Parameters:
-    - serializedNotification: const SerializedNotification&, serialized notification record
+    - record: const std::string&, serialized notification record
 Returns:
     - Notification*: Pointer to the deserialized Notification object
+Throws:
+    - std::runtime_error if timestamp parsing fails
 */
-Notification* Notification::deserialize(const SerializedNotification& serializedNotification)
+Notification* Notification::deserialize(const std::string& record)
 {
+    std::string id, recipientUserId, title, message, createdAtTimestampString;
+    std::istringstream serializedNotification(record);
+    getline(serializedNotification, id, ',');
+    getline(serializedNotification, recipientUserId, ',');
+    getline(serializedNotification, title, ',');
+    getline(serializedNotification, message, ',');
+    getline(serializedNotification, createdAtTimestampString, ',');
+    util::Timestamp createdAtTimestamp;
+    try
+    {
+        createdAtTimestamp = util::Timestamp::fromString(createdAtTimestampString);
+    }
+    catch (...)
+    {
+        throw std::runtime_error("Invalid createdAt timestamp");
+    }
     return Factory::getObject<Notification>(
-        serializedNotification.id,
+        id,
-        serializedNotification.recipientUserId,
+        recipientUserId,
-        serializedNotification.title,
+        title,
-        serializedNotification.message,
+        message,
-        serializedNotification.createdAt,
+        createdAtTimestamp
-        serializedNotification.state);
+    );
+}
+
+/*
+Function: getHeaders
+Description: Retrieves the CSV headers for notification serialization.
+Parameters:
+    - None
+Returns:
+    - std::string: Header string ("ID,RecipientID,Title,Message,Timestamp")
+*/
+std::string Notification::getHeaders()
+{
+    return "ID,RecipientID,Title,Message,Timestamp";
 }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/models/Notification.h

@@ -9,10 +9,8 @@ Date: 19-May-2026
 #pragma once
 #include <string>
 #include "Timestamp.h"
-#include "Enums.h"
 
 class User;
-struct SerializedNotification;
 
 class Notification
 {
@@ -20,26 +18,27 @@ private:
     static int m_uid;
     std::string m_id;
     std::string m_recipientUserId;
+    User* m_recipient;
     std::string m_title;
     std::string m_message;
     util::Timestamp m_createdAt;
-    util::State m_state;
 public:
     Notification();
-    Notification(const std::string& recipientUserId, const std::string& title, const std::string& message, const util::Timestamp& createdAt);
+    Notification(const std::string& recipientUserId, User* recipient, const std::string& title, const std::string& message, const util::Timestamp& createdAt);
-    Notification(const std::string& id, const std::string& recipientUserId, const std::string& title, const std::string& message, const util::Timestamp& createdAt, const util::State& state);
+    Notification(const std::string& id, const std::string& recipientUserId, const std::string& title, const std::string& message, const util::Timestamp& createdAt);
     const std::string& getId() const;
     const std::string& getRecipientUserId() const;
+    User* getRecipient() const;
     const std::string& getTitle() const;
     const std::string& getMessage() const;
     const util::Timestamp& getCreatedAt() const;
     void setId(const std::string& id);
     void setRecipientUserId(const std::string& recipientUserId);
+    void setRecipient(User* recipient);
     void setTitle(const std::string& title);
     void setMessage(const std::string& message);
     void setCreatedAt(const util::Timestamp& createdAt);
-    util::State getState() const;
+    std::string serialize() const;
-    void setState(util::State state);
+    static Notification* deserialize(const std::string&);
-    SerializedNotification serialize() const;
+    static std::string getHeaders();
-    static Notification* deserialize(const SerializedNotification&);
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/models/User.cpp

@@ -8,7 +8,6 @@ Date: 19-May-2026
 */
 
 #include <sstream>
-#include "SerializedRecords.h"
 #include "User.h"
 #include "Notification.h"
 #include "Enums.h"
@@ -29,8 +28,7 @@ Returns:
 User::User()
     : m_id("USR" + std::to_string(++m_uid)),
     m_type(util::UserType::CUSTOMER),
-    m_status(util::State::ACTIVE) {
+    m_status(util::State::ACTIVE) {}
-}
 
 /*
 Function: User
@@ -53,8 +51,7 @@ User::User(const std::string& userName, const std::string& password, const std::
     m_phone(phone),
     m_email(email),
     m_type(role),
-    m_status(util::State::ACTIVE) {
+    m_status(util::State::ACTIVE) {}
-}
 
 /*
 Function: User (parameterized constructor with ID)
@@ -89,6 +86,23 @@ User::User(const std::string& userId, const std::string& userName, const std::st
     }
 }
 
+/*
+Function: ~User
+Description: Destructor that cleans up dynamically allocated notifications associated with the user.
+Parameters:
+    - None
+Returns:
+    - void
+*/
+User::~User()
+{
+    auto values = m_notifications.getValues();
+    for (int index = 0; index < values.getSize(); index++)
+    {
+        delete values[index];
+    }
+}
+
 /*
 Function: getId
 Description: Retrieves the unique ID of the user.
@@ -155,6 +169,17 @@ const std::string& User::getEmail() const
     return m_email;
 }
 
+/*
+Function: getNotifications
+Description: Retrieves the map of notifications associated with the user.
+Returns:
+    - util::Map<std::string, Notification*>& representing the notifications.
+*/
+util::Map<std::string, Notification*>& User::getNotifications()
+{
+    return m_notifications;
+}
+
 /*
 Function: getUserType
 Description: Retrieves the role of the user.
@@ -255,6 +280,22 @@ void User::setEmail(const std::string& email)
     m_email = email;
 }
 
+/*
+Function: addNotification
+Description: Adds a new notification to the user’s notification map.
+Parameters:
+    - notification: Pointer to the Notification object.
+Returns:
+    - void
+*/
+void User::addNotification(Notification* notification)
+{
+    if (notification)
+    {
+        m_notifications.insert(notification->getId(), notification);
+    }
+}
+
 /*
 Function: setRole
 Description: Sets the role of the user.
@@ -283,43 +324,68 @@ void User::setState(util::State status)
 
 /*
 Function: serialize
-Description: Serializes the User object into a SerializedUser record.
+Description: Serializes the user into a CSV-formatted string.
 Parameters:
     - None
 Returns:
-    - SerializedUser: Serialized representation of the user
+    - std::string: Serialized user record
 */
-SerializedUser User::serialize() const
+std::string User::serialize() const
 {
-    SerializedUser serialized = {};
+    std::ostringstream serializedUser;
-    strcpy_s(serialized.id, sizeof(serialized.id), m_id.c_str());
+    serializedUser << m_id << ','
-    strcpy_s(serialized.username, sizeof(serialized.username), m_userName.c_str());
+        << m_userName << ','
-    strcpy_s(serialized.password, sizeof(serialized.password), m_password.c_str());
+        << m_password << ','
-    strcpy_s(serialized.name, sizeof(serialized.name), m_name.c_str());
+        << m_name << ','
-    strcpy_s(serialized.phone, sizeof(serialized.phone), m_phone.c_str());
+        << m_phone << ','
-    strcpy_s(serialized.email, sizeof(serialized.email), m_email.c_str());
+        << m_email << ','
-    serialized.userType = m_type;
+        << util::getUserTypeString(m_type) << ','
-    serialized.status = m_status;
+        << util::getStateString(m_status);
-    return serialized;
+    return serializedUser.str();
 }
 
 /*
 Function: deserialize
-Description: Deserializes a SerializedUser record into a User object.
+Description: Deserializes a CSV-formatted string into a User object.
 Parameters:
-    - serializedUser: const SerializedUser&, serialized user record
+    - record: const std::string&, serialized user record
 Returns:
     - User*: Pointer to the deserialized User object
 */
-User* User::deserialize(const SerializedUser& serializedUser)
+User* User::deserialize(const std::string& record)
 {
-    return Factory::getObject<User>(
+    std::string id, name, username, phone, password, email;
-        serializedUser.id,
+    std::string userTypeString, stateString;
-        serializedUser.username,
+    std::istringstream serializedUser(record);
-        serializedUser.password,
+    getline(serializedUser, id, ',');
-        serializedUser.name,
+    getline(serializedUser, username, ',');
-        serializedUser.phone,
+    getline(serializedUser, password, ',');
-        serializedUser.email,
+    getline(serializedUser, name, ',');
-        serializedUser.userType,
+    getline(serializedUser, phone, ',');
-        serializedUser.status);
+    getline(serializedUser, email, ',');
+    getline(serializedUser, userTypeString, ',');
+    getline(serializedUser, stateString);
+    util::UserType userType = util::getUserType(userTypeString);
+    util::State status = util::getState(stateString);
+    return Factory::getObject<User>(id,
+        username,
+        password,
+        name,
+        phone,
+        email,
+        userType,
+        status);
+}
+
+/*
+Function: getHeaders
+Description: Retrieves the CSV headers for user serialization.
+Parameters:
+    - None
+Returns:
+    - std::string: Header string ("ID,Username,Password,Name,Phone,Email,UserType,UserStatus")
+*/
+std::string User::getHeaders()
+{
+    return "ID,Username,Password,Name,Phone,Email,UserType,UserStatus";
 }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/models/User.h

@@ -14,7 +14,6 @@ Date: 19-May-2026
 #include "Enums.h"
 
 class Notification;
-struct SerializedUser;
 
 class User : public Observer
 {
@@ -26,19 +25,21 @@ private:
     std::string m_name;
     std::string m_phone;
     std::string m_email;
+    util::Map<std::string, Notification*> m_notifications;
     util::UserType m_type;
     util::State m_status;
 public:
     User();
     User(const std::string& userName, const std::string& password, const std::string& name, const std::string& phone, const std::string& email, util::UserType role);
     User(const std::string& userId, const std::string& userName, const std::string& password, const std::string& name, const std::string& phone, const std::string& email, util::UserType role, util::State status);
-    ~User() = default;
+    ~User();
     const std::string& getId() const;
     const std::string& getUserName() const;
     const std::string& getPassword() const;
     const std::string& getName() const;
     const std::string& getPhone() const;
     const std::string& getEmail() const;
+    util::Map<std::string, Notification*>& getNotifications();
     util::UserType getUserType() const;
     util::State getState() const;
     void setId(const std::string& id);
@@ -47,8 +48,10 @@ public:
     void setName(const std::string& name);
     void setPhone(const std::string& phone);
     void setEmail(const std::string& email);
+    void addNotification(Notification* notification) override;
     void setRole(util::UserType role);
     void setState(util::State status);
-    SerializedUser serialize() const;
+    std::string serialize() const;
-    static User* deserialize(const SerializedUser& serializedUser);
+    static User* deserialize(const std::string&);
+    static std::string getHeaders();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/AuthenticationManagementService.cpp

@@ -10,8 +10,6 @@ Date:19-May-2026
 #include <stdexcept>
 #include "AuthenticationManagementService.h"
 #include "User.h"
-#include "Utility.h"
-#include "DataStoreLockGuard.h"
 
 User* AuthenticationManagementService::m_authenticatedUser = nullptr;
 
@@ -26,12 +24,11 @@ Return type: bool - true if login successful, false otherwise
 */
 bool AuthenticationManagementService::login(const std::string& username, const std::string& password)
 {
-	DataStoreLockGuard lock(m_dataStore);
+	util::Map<std::string, User*> users = m_dataStore.getUsers();
-	auto& trackedUserMap = m_dataStore.getUsers();
+	int usersMapSize = users.getSize();
-	int trackedUserMapSize = trackedUserMap.getSize();
+	for (int index = 0; index < usersMapSize; index++)
-	for (int index = 0; index < trackedUserMapSize; index++)
 	{
-		User* user = trackedUserMap.getValueAt(index).data;
+		User* user = users.getValueAt(index);
 		if (username == user->getUserName())
 		{
 			if (password == user->getPassword())
@@ -77,18 +74,9 @@ Return type: void
 */
 void AuthenticationManagementService::changePassword(const std::string& newPassword)
 {
-	DataStoreLockGuard lock(m_dataStore);
-	auto& trackedUsersMap = m_dataStore.getUsers();
 	if (m_authenticatedUser == nullptr)
 	{
 		throw std::runtime_error("There is no user currently logged in!");
 	}
-	int index = trackedUsersMap.find(m_authenticatedUser->getId());
-	if (index == -1)
-	{
-		throw std::runtime_error("User does not exist!\n");
-	}
 	m_authenticatedUser->setPassword(newPassword);
-	trackedUsersMap.getValueAt(index).state = RecordState::MODIFIED;
-	m_dataStore.saveUsers();
 }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/InventoryManagementService.cpp

@@ -12,13 +12,14 @@ Date: 22-May-2026
 #include "Config.h"
 #include "Enums.h"
 #include "Factory.h"
+#include "FileManager.h"
 #include "InventoryItem.h"
 #include "InventoryManagementService.h"
 #include "Timestamp.h"
 #include "User.h"
 #include "Utility.h"
 #include "Vector.h"
-#include "DataStoreLockGuard.h"
+
 
 util::Map<std::string, User*> InventoryManagementService::m_observers{};
 
@@ -89,6 +90,95 @@ void InventoryManagementService::sendLowStockAlerts()
 	}
 }
 
+/*
+Function: getObserverIDs
+Description: Retrieves the IDs of all observers currently attached to the
+			 InventoryManagementService.
+Parameters:
+	- None
+Returns:
+	- util::Vector<std::string>: Vector of observer user IDs
+*/
+util::Vector<std::string> InventoryManagementService::getObserverIDs()
+{
+	util::Vector<std::string> observerIDs;
+	int numberOfObservers = m_observers.getSize();
+	for (int index = 0; index < numberOfObservers; index++)
+	{
+		User* observer = m_observers.getValueAt(index);
+		if (observer)
+		{
+			observerIDs.push_back(observer->getId());
+		}
+	}
+	return observerIDs;
+}
+
+/*
+Function: loadInventoryItems
+Description: Loads inventory items from persistent storage into the datastore.
+			 Uses FileManager to deserialize inventory items from the configured file.
+Parameters:
+	- None
+Returns:
+	- void
+*/
+void InventoryManagementService::loadInventoryItems()
+{
+	util::FileManager<InventoryItem> inventoryItemFileManager(config::file::INVENTORYITEM_FILE);
+	auto& inventoryItems = m_dataStore.getInventoryItems();
+	auto inventoryItemsMap = inventoryItemFileManager.load();
+	int numberOfInventoryItems = inventoryItemsMap.getSize();
+	for (int index = 0; index < numberOfInventoryItems; index++)
+	{
+		inventoryItems[inventoryItemsMap.getKeyAt(index)] = inventoryItemsMap.getValueAt(index);
+	}
+}
+
+/*
+Function: saveInventoryItems
+Description: Saves inventory items from the datastore to persistent storage.
+			 Uses FileManager to serialize inventory items into the configured file.
+Parameters:
+	- None
+Returns:
+	- void
+*/
+void InventoryManagementService::saveInventoryItems()
+{
+	util::FileManager<InventoryItem> inventoryItemFileManager(config::file::INVENTORYITEM_FILE);
+	auto& inventoryItems = m_dataStore.getInventoryItems();
+	inventoryItemFileManager.save(inventoryItems);
+}
+
+/*
+Function: loadObservers
+Description: Loads observer IDs from persistent storage and attaches corresponding
+			 users as observers to the InventoryManagementService.
+Parameters:
+	- None
+Returns:
+	- void
+*/
+void InventoryManagementService::loadObservers()
+{
+	util::loadObservers(config::file::INVENTORYMANAGEMENTOBSERVERS, this, m_dataStore);
+}
+
+/*
+Function: saveObservers
+Description: Saves the current observer IDs of the InventoryManagementService
+			 to persistent storage for future retrieval.
+Parameters:
+	- None
+Returns:
+	- void
+*/
+void InventoryManagementService::saveObservers()
+{
+	util::saveObservers(config::file::INVENTORYMANAGEMENTOBSERVERS, this);
+}
+
 /*
 Function: addInventoryItem
 Description: Creates a new inventory item using the Factory and inserts it
@@ -181,9 +271,6 @@ Returns:
 */
 void InventoryManagementService::attach(User* user)
 {
-	DataStoreLockGuard lock(m_dataStore);
-	m_observers.clear();
-	m_observers = m_dataStore.getInventoryManagementObservers();
 	if (user)
 	{
 		const std::string& userID = user->getId();
@@ -192,7 +279,6 @@ void InventoryManagementService::attach(User* user)
 			m_observers[userID] = user;
 		}
 	}
-	m_dataStore.saveInventoryManagementObservers(m_observers);
 }
 
 /*
@@ -205,9 +291,6 @@ Returns:
 */
 void InventoryManagementService::detach(User* user)
 {
-	DataStoreLockGuard lock(m_dataStore);
-	m_observers.clear();
-	m_observers = m_dataStore.getInventoryManagementObservers();
 	if (user)
 	{
 		const std::string& userID = user->getId();
@@ -216,7 +299,6 @@ void InventoryManagementService::detach(User* user)
 			m_observers.remove(userID);
 		}
 	}
-	m_dataStore.saveInventoryManagementObservers(m_observers);
 }
 
 /*
@@ -233,27 +315,27 @@ Throws:
 */
 void InventoryManagementService::sendNotification(User* user, const std::string& title, const std::string& message)
 {
-	if (!user)
+	if (user)
 	{
-		return;
+		if (m_observers.find(user->getId()) != -1)
+		{
+			Notification* notification =
+				Factory::getObject<Notification>(
+					user->getId(),
+					user,
+					title,
+					message,
+					util::Timestamp()
+				);
+			if (notification)
+			{
+				user->addNotification(notification);
+			}
+			else
+			{
+				throw std::runtime_error("Failed to create notification");
+			}
+		}
 	}
-	DataStoreLockGuard lock(m_dataStore);
-	m_observers = m_dataStore.getInventoryManagementObservers();
-	if (m_observers.find(user->getId()) == -1)
-	{
-		return;
-	}
-	Notification* notification = Factory::getObject<Notification>(
-		user->getId(),
-		title,
-		message,
-		util::Timestamp());
-	if (!notification)
-	{
-		throw std::runtime_error("Failed to create notification");
-	}
-	auto& trackedNotificationsMap = m_dataStore.getNotifications();
-	trackedNotificationsMap.insert(notification->getId(), util::createNewRecord(notification));
-	m_dataStore.saveNotifications();
 }
 

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/InventoryManagementService.h

@@ -21,6 +21,7 @@ class InventoryManagementService : public NotificationManagementService
 private:
     DataStore& m_dataStore;
     static util::Map<std::string, User*> m_observers;
+    util::Vector<std::string> getObserverIDs() override;
 public:
     InventoryManagementService() : m_dataStore(DataStore::getInstance()) {}
     util::Map<std::string, InventoryItem*> getInventoryItems();
@@ -32,4 +33,8 @@ public:
     void sendNotification(User* user, const std::string& title, const std::string& message) override;
     void attach(User* user) override;
     void detach(User* user) override;
+    void loadInventoryItems();
+    void saveInventoryItems();
+    void loadObservers();
+    void saveObservers();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/NotificationManagementService.cpp

@@ -0,0 +1 @@
+#include "NotificationManagementService.h"

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/NotificationManagementService.h

@@ -19,4 +19,5 @@ public:
 	virtual void sendNotification(User* recipient, const std::string& title, const std::string& message) = 0;
 	virtual void attach(User* user) = 0;
 	virtual void detach(User* user) = 0;
+	virtual util::Vector<std::string> getObserverIDs() = 0;
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/PaymentManagementService.cpp

@@ -11,6 +11,7 @@ Date: 20-May-2026
 #include "Config.h"
 #include "Enums.h"
 #include "Factory.h"
+#include "FileManager.h"
 #include "InventoryItem.h"
 #include "Invoice.h"
 #include "JobCard.h"
@@ -20,7 +21,6 @@ Date: 20-May-2026
 #include "Timestamp.h"
 #include "User.h"
 #include "Utility.h"
-#include "DataStoreLockGuard.h"
 
 util::Map<std::string, User*> PaymentManagementService::m_observers{};
 
@@ -34,9 +34,6 @@ Returns:
 */
 void PaymentManagementService::attach(User* user)
 {
-	DataStoreLockGuard lock(m_dataStore);
-	m_observers.clear();
-	m_observers = m_dataStore.getPaymentManagementObservers();
 	if (user)
 	{
 		const std::string& userID = user->getId();
@@ -45,7 +42,6 @@ void PaymentManagementService::attach(User* user)
 			m_observers[userID] = user;
 		}
 	}
-	m_dataStore.savePaymentManagementObservers(m_observers);
 }
 
 /*
@@ -58,9 +54,6 @@ Returns:
 */
 void PaymentManagementService::detach(User* user)
 {
-	DataStoreLockGuard lock(m_dataStore);
-	m_observers.clear();
-	m_observers = m_dataStore.getPaymentManagementObservers();
 	if (user)
 	{
 		const std::string& userID = user->getId();
@@ -69,7 +62,6 @@ void PaymentManagementService::detach(User* user)
 			m_observers.remove(userID);
 		}
 	}
-	m_dataStore.savePaymentManagementObservers(m_observers);
 }
 
 /*
@@ -86,28 +78,28 @@ Throws:
 */
 void PaymentManagementService::sendNotification(User* user, const std::string& title, const std::string& message)
 {
-	if (!user)
+	if (user)
 	{
-		return;
+		if (m_observers.find(user->getId()) != -1)
+		{
+			Notification* notification =
+				Factory::getObject<Notification>(
+					user->getId(),
+					user,
+					title,
+					message,
+					util::Timestamp()
+				);
+			if (notification)
+			{
+				user->addNotification(notification);
+			}
+			else
+			{
+				throw std::runtime_error("Failed to create notification");
+			}
+		}
 	}
-	DataStoreLockGuard lock(m_dataStore);
-	m_observers = m_dataStore.getPaymentManagementObservers();
-	if (m_observers.find(user->getId()) == -1)
-	{
-		return;
-	}
-	Notification* notification = Factory::getObject<Notification>(
-		user->getId(),
-		title,
-		message,
-		util::Timestamp());
-	if (!notification)
-	{
-		throw std::runtime_error("Failed to create notification");
-	}
-	auto& trackedNotificationsMap = m_dataStore.getNotifications();
-	trackedNotificationsMap.insert(notification->getId(), util::createNewRecord(notification));
-	m_dataStore.saveNotifications();
 }
 
 /*
@@ -148,6 +140,123 @@ void PaymentManagementService::sendPaymentReminders()
 	}
 }
 
+/*
+Function: getObserverIDs
+Description: Retrieves the IDs of all observers currently attached to the
+             PaymentManagementService.
+Parameters:
+    - None
+Returns:
+    - util::Vector<std::string>: Vector of observer user IDs
+*/
+util::Vector<std::string> PaymentManagementService::getObserverIDs()
+{
+	util::Vector<std::string> observerIDs;
+	int numberOfObservers = m_observers.getSize();
+	for (int index = 0; index < numberOfObservers; index++)
+	{
+		User* observer = m_observers.getValueAt(index);
+		if (observer)
+		{
+			observerIDs.push_back(observer->getId());
+		}
+	}
+	return observerIDs;
+}
+
+/*
+Function: loadInvoices
+Description: Loads invoices from persistent storage into the datastore.
+             Validates associated service bookings and inventory parts before
+             attaching them to each invoice. Throws exceptions if invalid IDs
+             are encountered.
+Parameters:
+    - None
+Returns:
+    - void
+Throws:
+    - std::runtime_error if a booking ID or part ID is invalid
+*/
+void PaymentManagementService::loadInvoices()
+{
+    util::FileManager<Invoice> invoiceFileManager(config::file::INVOICE_FILE);
+    auto& invoices = m_dataStore.getInvoices();
+    auto& serviceBookings = m_dataStore.getServiceBookings();
+    auto& inventoryItems = m_dataStore.getInventoryItems();
+    auto invoicesMap = invoiceFileManager.load();
+    for (int invoiceIndex = 0; invoiceIndex < invoicesMap.getSize(); invoiceIndex++)
+    {
+        Invoice* invoice = invoicesMap.getValueAt(invoiceIndex);
+        int bookingIndex = serviceBookings.find(invoice->getBookingId());
+        if (bookingIndex == -1)
+        {
+            throw std::runtime_error("Invalid Booking ID");
+        }
+        ServiceBooking* booking = serviceBookings.getValueAt(bookingIndex);
+        invoice->setBooking(booking);
+        util::Map<std::string, InventoryItem*> invoiceParts;
+        auto& partIDs = invoice->getPartIDs();
+        for (int partIndex = 0; partIndex < partIDs.getSize(); partIndex++)
+        {
+            const std::string& partID = partIDs[partIndex];
+            int inventoryIndex = inventoryItems.find(partID);
+            if (inventoryIndex == -1)
+            {
+                throw std::runtime_error("Invalid Part ID");
+            }
+            invoiceParts[partID] = inventoryItems.getValueAt(inventoryIndex);
+        }
+        invoice->setParts(invoiceParts);
+        invoices[invoice->getId()] = invoice;
+    }
+}
+
+/*
+Function: saveInvoices
+Description: Saves invoices from the datastore to persistent storage.
+             Uses FileManager to serialize invoices into the configured file.
+Parameters:
+    - None
+Returns:
+    - void
+*/
+void PaymentManagementService::saveInvoices()
+{
+    util::FileManager<Invoice> invoiceFileManager(config::file::INVOICE_FILE);
+    auto& invoices = m_dataStore.getInvoices();
+    invoiceFileManager.save(invoices);
+}
+
+/*
+Function: loadObservers
+Description: Loads observer IDs from persistent storage and attaches corresponding
+             users as observers to the PaymentManagementService.
+Parameters:
+    - None
+Returns:
+    - void
+Throws:
+    - std::runtime_error if an observer ID is invalid (not found in datastore)
+*/
+void PaymentManagementService::loadObservers()
+{
+    util::loadObservers(config::file::PAYMENTMANAGEMENTOBSERVERS, this, m_dataStore);
+}
+
+/*
+Function: saveObservers
+Description: Saves the current observer IDs of the PaymentManagementService
+             to persistent storage for future retrieval.
+Parameters:
+    - None
+Returns:
+    - void
+*/
+void PaymentManagementService::saveObservers()
+{
+    util::saveObservers(config::file::PAYMENTMANAGEMENTOBSERVERS, this);
+}
+
 /*
 Function: createInventoryItemsMap (static helper)
 Description: Builds a map of inventory items required for a given service and adds them to the booking’s inventory map.

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/PaymentManagementService.h

@@ -22,6 +22,7 @@ class PaymentManagementService : public NotificationManagementService
 private:
     DataStore& m_dataStore;
     static util::Map<std::string, User*> m_observers;
+    util::Vector<std::string> getObserverIDs() override;
 public:
     PaymentManagementService() : m_dataStore(DataStore::getInstance()) {}
     void generateInvoice(ServiceBooking* booking);
@@ -33,4 +34,8 @@ public:
     void sendNotification(User* user, const std::string& title, const std::string& message) override;
     void attach(User* user) override;
     void detach(User* user) override;
+    void loadInvoices();
+    void saveInvoices();
+    void loadObservers();
+    void saveObservers();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/ServiceManagementService.cpp

@@ -14,6 +14,7 @@ Date:19-May-2026
 #include "DataStore.h"
 #include "Enums.h"
 #include "Factory.h"
+#include "FileManager.h"
 #include "InventoryItem.h"
 #include "JobCard.h"
 #include "NotificationManagementService.h"
@@ -24,9 +25,7 @@ Date:19-May-2026
 #include "Timestamp.h"
 #include "User.h"
 #include "UserManagementService.h"
-#include "DataStoreLockGuard.h"
 #include "Utility.h"
-#include "DataStoreLockGuard.h"
 
 /*
 Function: purchaseService
@@ -47,19 +46,18 @@ void ServiceManagementService::purchaseService(const util::Vector<std::string>&
 	{
 		throw std::runtime_error("No user is currently logged in!");
 	}
-    DataStoreLockGuard lock(m_dataStore);
+	auto& servicesMap = m_dataStore.getServices();
-	auto& trackedServicesMap = m_dataStore.getServices();
+	auto& serviceBookingMap = m_dataStore.getServiceBookings();
-	auto& trackedServiceBookingMap = m_dataStore.getServiceBookings();
 	util::Map<std::string, Service*> selectedServices;
 	int selectedServicesCount = serviceIDs.getSize();
 	for (int index = 0; index < selectedServicesCount; index++)
 	{
-		int serviceIndex = trackedServicesMap.find(serviceIDs[index]);
+		int serviceIndex = servicesMap.find(serviceIDs[index]);
 		if (serviceIndex == -1)
 		{
 			throw std::runtime_error("Service not found!");
 		}
-		Service* service = trackedServicesMap.getValueAt(serviceIndex).data;
+		Service* service = servicesMap.getValueAt(serviceIndex);
 		selectedServices[service->getId()] = service;
 	}
 	ServiceBooking* serviceBooking = Factory::getObject<ServiceBooking>(util::ServiceJobStatus::PENDING, selectedServices, authenticatedUser->getId(), authenticatedUser, vehicleNumber, vehicleBrand, vehicleModel, 0);
@@ -67,7 +65,7 @@ void ServiceManagementService::purchaseService(const util::Vector<std::string>&
 	{
 		throw std::runtime_error("Failed to create service booking");
 	}
-	trackedServiceBookingMap[serviceBooking->getId()] =  util::createNewRecord(serviceBooking);
+	serviceBookingMap[serviceBooking->getId()] = serviceBooking;
     std::string title = "Service Booking succeeded";
     std::string message = "Your service booking has been successfully placed with ID " + serviceBooking->getId();
     sendNotification(authenticatedUser, title, message);
@@ -92,22 +90,21 @@ void ServiceManagementService::purchaseComboPackage(const std::string& comboPack
 	{
 		throw std::runtime_error("No user is currently logged in!");
 	}
-    DataStoreLockGuard lock(m_dataStore);
+	auto& comboPackagesMap = m_dataStore.getComboPackages();
-	auto& trackedComboPackagesMap = m_dataStore.getComboPackages();
+	auto& serviceBookingMap = m_dataStore.getServiceBookings();
-	auto& trackedServiceBookingMap = m_dataStore.getServiceBookings();
+	int comboPackageIndex = comboPackagesMap.find(comboPackageID);
-	int comboPackageIndex = trackedComboPackagesMap.find(comboPackageID);
 	if (comboPackageIndex == -1)
 	{
 		throw std::runtime_error("Combo Package not found!");
 	}
-	const ComboPackage* comboPackage = trackedComboPackagesMap[comboPackageID].data;
+	const ComboPackage* comboPackage = comboPackagesMap[comboPackageID];
 	util::Map<std::string, Service*> selectedServices = comboPackage->getServices();
 	ServiceBooking* serviceBooking = Factory::getObject<ServiceBooking>(util::ServiceJobStatus::PENDING, selectedServices, authenticatedUser->getId(), authenticatedUser, vehicleNumber, vehicleBrand, vehicleModel, comboPackage->getDiscountPercentage());
 	if (serviceBooking == nullptr)
 	{
 		throw std::runtime_error("Failed to create combo package service booking");
 	}
-	trackedServiceBookingMap[serviceBooking->getId()] = util::createNewRecord(serviceBooking);
+	serviceBookingMap[serviceBooking->getId()] = serviceBooking;
     std::string title = "Combo Package Service Booking succeeded";
     std::string message = "Your service booking for the combo package has been successfully placed with ID " + serviceBooking->getId();
     sendNotification(authenticatedUser, title, message);
@@ -125,9 +122,6 @@ Returns:
 */
 void ServiceManagementService::attach(User* user)
 {
-    DataStoreLockGuard lock(m_dataStore);
-    m_observers.clear();
-    m_observers = m_dataStore.getServiceManagementObservers();
 	if (user)
 	{
 		const std::string& userID = user->getId();
@@ -136,7 +130,6 @@ void ServiceManagementService::attach(User* user)
 			m_observers[userID] = user;
 		}
 	}
-    m_dataStore.saveServiceManagementObservers(m_observers);
 }
 
 /*
@@ -149,9 +142,6 @@ Returns:
 */
 void ServiceManagementService::detach(User* user)
 {
-    DataStoreLockGuard lock(m_dataStore);
-    m_observers.clear();
-    m_observers = m_dataStore.getServiceManagementObservers();
 	if (user)
 	{
 		const std::string& userID = user->getId();
@@ -160,7 +150,6 @@ void ServiceManagementService::detach(User* user)
 			m_observers.remove(userID);
 		}
 	}
-    m_dataStore.saveServiceManagementObservers(m_observers);
 }
 
 /*
@@ -177,28 +166,345 @@ Throws:
 */
 void ServiceManagementService::sendNotification(User* user, const std::string& title, const std::string& message)
 {
-    if (!user)
+	if (user)
+	{
+		if (m_observers.find(user->getId()) != -1)
+		{
+			Notification* notification =
+				Factory::getObject<Notification>(
+					user->getId(),
+					user,
+					title,
+					message,
+					util::Timestamp()
+				);
+			if (notification)
+			{
+				user->addNotification(notification);
+			}
+			else
+			{
+				throw std::runtime_error("Failed to create notification");
+			}
+		}
+	}
+}
+
+/*
+Function: getObserverIDs
+Description: Retrieves the IDs of all observers currently attached to the
+             ServiceManagementService.
+Parameters:
+    - None
+Returns:
+    - util::Vector<std::string>: Vector of observer user IDs
+*/
+util::Vector<std::string> ServiceManagementService::getObserverIDs()
+{
+	util::Vector<std::string> observerIDs;
+	int numberOfObservers = m_observers.getSize();
+	for (int index = 0; index < numberOfObservers; index++)
+	{
+		User* observer = m_observers.getValueAt(index);
+		if (observer)
+		{
+			observerIDs.push_back(observer->getId());
+		}
+	}
+	return observerIDs;
+}
+
+/*
+Function: loadServices
+Description: Loads services from persistent storage into the datastore.
+             Validates required inventory items and attaches them to each service.
+Parameters:
+    - None
+Returns:
+    - void
+Throws:
+    - std::runtime_error if an inventory item ID is invalid
+*/
+void ServiceManagementService::loadServices()
+{
+    util::FileManager<Service> serviceFileManager(config::file::SERVICE_FILE);
+    auto& services = m_dataStore.getServices();
+    auto& inventoryItems = m_dataStore.getInventoryItems();
+    auto servicesMap = serviceFileManager.load();
+    for (int serviceIndex = 0; serviceIndex < servicesMap.getSize(); serviceIndex++)
     {
-        return;
+        Service* service = servicesMap.getValueAt(serviceIndex);
+        services[service->getId()] = service;
+        util::Map<std::string, InventoryItem*> inventoryItemsMap;
+        auto& inventoryItemIDs = service->getRequiredInventoryItemIDs();
+        for (int inventoryItemIndex = 0; inventoryItemIndex < inventoryItemIDs.getSize(); inventoryItemIndex++)
+        {
+            const std::string& inventoryItemID = inventoryItemIDs[inventoryItemIndex];
+            int index = inventoryItems.find(inventoryItemID);
+            if (index == -1)
+            {
+                throw std::runtime_error("Invalid Inventory Item ID");
+            }
+            inventoryItemsMap[inventoryItemID] = inventoryItems.getValueAt(index);
+        }
+        service->setRequiredInventoryItems(inventoryItemsMap);
     }
-    DataStoreLockGuard lock(m_dataStore);
+}
-    m_observers = m_dataStore.getServiceManagementObservers();
+
-    if (m_observers.find(user->getId()) == -1)
+/*
+Function: saveServices
+Description: Saves services from the datastore to persistent storage.
+             Uses FileManager to serialize services into the configured file.
+Parameters:
+    - None
+Returns:
+    - void
+*/
+void ServiceManagementService::saveServices()
+{
+	util::FileManager<Service> serviceFileManager(config::file::SERVICE_FILE);
+	auto& services = m_dataStore.getServices();
+	serviceFileManager.save(services);
+}
+
+/*
+Function: loadComboPackages
+Description: Loads combo packages from persistent storage into the datastore.
+             Validates associated services and attaches them to each package.
+Parameters:
+    - None
+Returns:
+    - void
+Throws:
+    - std::runtime_error if a service ID is invalid
+*/
+void ServiceManagementService::loadComboPackages()
+{
+    util::FileManager<ComboPackage> comboPackageFileManager(config::file::COMBOPACKAGE_FILE);
+    auto& comboPackages = m_dataStore.getComboPackages();
+    auto& services = m_dataStore.getServices();
+    auto comboPackagesMap = comboPackageFileManager.load();
+    for (int packageIndex = 0; packageIndex < comboPackagesMap.getSize(); packageIndex++)
     {
-        return;
+        ComboPackage* comboPackage = comboPackagesMap.getValueAt(packageIndex);
+        util::Map<std::string, Service*> packageServices;
+        auto& serviceIDs = comboPackage->getServiceIDs();
+        for (int serviceIndex = 0; serviceIndex < serviceIDs.getSize(); serviceIndex++)
+        {
+            const std::string& serviceID = serviceIDs[serviceIndex];
+            int serviceMapIndex = services.find(serviceID);
+            if (serviceMapIndex == -1)
+            {
+                throw std::runtime_error("Invalid Service ID");
+            }
+            packageServices[serviceID] = services.getValueAt(serviceMapIndex);
+        }
+        comboPackage->setServices(packageServices);
+        comboPackages[comboPackage->getId()] = comboPackage;
     }
-    Notification* notification = Factory::getObject<Notification>(
+}
-        user->getId(),
+
-        title,
+/*
-        message,
+Function: saveComboPackages
-        util::Timestamp());
+Description: Saves combo packages from the datastore to persistent storage.
-    if (!notification)
+             Uses FileManager to serialize combo packages into the configured file.
+Parameters:
+    - None
+Returns:
+    - void
+*/
+void ServiceManagementService::saveComboPackages()
+{
+    util::FileManager<ComboPackage> comboPackageFileManager(config::file::COMBOPACKAGE_FILE);
+    auto& comboPackages = m_dataStore.getComboPackages();
+    comboPackageFileManager.save(comboPackages);
+}
+
+/*
+Function: loadServiceBookings
+Description: Loads service bookings from persistent storage into the datastore.
+             Validates associated services, customers, and technicians before
+             attaching them to each booking.
+Parameters:
+    - None
+Returns:
+    - void
+Throws:
+    - std::runtime_error if a service ID, customer ID, or technician ID is invalid
+    - std::runtime_error if a user is not of the expected type (customer/technician)
+*/
+void ServiceManagementService::loadServiceBookings()
+{
+    util::FileManager<ServiceBooking> bookingFileManager(config::file::SERVICEBOOKING_FILE);
+    auto& serviceBookings = m_dataStore.getServiceBookings();
+    auto& services = m_dataStore.getServices();
+    auto& users = m_dataStore.getUsers();
+    auto bookingsMap = bookingFileManager.load();
+    for (int bookingIndex = 0; bookingIndex < bookingsMap.getSize(); bookingIndex++)
     {
-        throw std::runtime_error("Failed to create notification");
+        ServiceBooking* booking = bookingsMap.getValueAt(bookingIndex);
+        util::Map<std::string, Service*> bookingServices;
+        auto& serviceIDs = booking->getServiceIDs();
+        for (int serviceIndex = 0; serviceIndex < serviceIDs.getSize(); serviceIndex++)
+        {
+            const std::string& serviceID = serviceIDs[serviceIndex];
+            int serviceMapIndex = services.find(serviceID);
+            if (serviceMapIndex == -1)
+            {
+                throw std::runtime_error("Invalid Service ID");
+            }
+
+            bookingServices[serviceID] = services.getValueAt(serviceMapIndex);
+        }
+        booking->setServices(bookingServices);
+        int customerIndex = users.find(booking->getCustomerId());
+        if (customerIndex == -1)
+        {
+            throw std::runtime_error("Invalid Customer ID");
+        }
+        User* customer = users.getValueAt(customerIndex);
+        if (customer->getUserType() != util::UserType::CUSTOMER)
+        {
+            throw std::runtime_error("User is not a customer");
+        }
+        booking->setCustomer(customer);
+        const std::string& technicianId = booking->getAssignedTechnicianId();
+        if (!technicianId.empty())
+        {
+            int technicianIndex = users.find(technicianId);
+            if (technicianIndex == -1)
+            {
+                throw std::runtime_error("Invalid Technician ID");
+            }
+            User* technician = users.getValueAt(technicianIndex);
+            if (technician->getUserType() != util::UserType::TECHNICIAN)
+            {
+                throw std::runtime_error("User is not a technician");
+            }
+            booking->setAssignedTechnician(technician);
+        }
+        serviceBookings[booking->getId()] = booking;
     }
-    auto& trackedNotificationsMap = m_dataStore.getNotifications();
+}
-    trackedNotificationsMap.insert(notification->getId(), util::createNewRecord(notification));
+
-    m_dataStore.saveNotifications();
+/*
+Function: saveServiceBookings
+Description: Saves service bookings from the datastore to persistent storage.
+             Uses FileManager to serialize bookings into the configured file.
+Parameters:
+    - None
+Returns:
+    - void
+*/
+void ServiceManagementService::saveServiceBookings()
+{
+    util::FileManager<ServiceBooking> bookingFileManager(config::file::SERVICEBOOKING_FILE);
+    auto& serviceBookings = m_dataStore.getServiceBookings();
+    bookingFileManager.save(serviceBookings);
+}
+
+/*
+Function: loadJobCards
+Description: Loads job cards from persistent storage into the datastore.
+             Validates associated bookings, services, and technicians before
+             attaching them to each job card.
+Parameters:
+    - None
+Returns:
+    - void
+Throws:
+    - std::runtime_error if a booking ID, service ID, or technician ID is invalid
+    - std::runtime_error if a service does not belong to the booking
+    - std::runtime_error if a user is not a technician
+*/
+void ServiceManagementService::loadJobCards()
+{
+    util::FileManager<JobCard> jobCardFileManager(config::file::JOBCARD_FILE);
+    auto& jobCards = m_dataStore.getJobCards();
+    auto& serviceBookings = m_dataStore.getServiceBookings();
+    auto& services = m_dataStore.getServices();
+    auto& users = m_dataStore.getUsers();
+    auto jobCardsMap = jobCardFileManager.load();
+    for (int jobCardIndex = 0; jobCardIndex < jobCardsMap.getSize(); jobCardIndex++)
+    {
+        JobCard* jobCard = jobCardsMap.getValueAt(jobCardIndex);
+        int bookingIndex = serviceBookings.find(jobCard->getBookingId());
+        if (bookingIndex == -1)
+        {
+            throw std::runtime_error("Invalid Booking ID");
+        }
+        ServiceBooking* booking = serviceBookings.getValueAt(bookingIndex);
+        jobCard->setBooking(booking);
+        int serviceIndex = services.find(jobCard->getServiceId());
+        if (serviceIndex == -1)
+        {
+            throw std::runtime_error("Invalid Service ID");
+        }
+        Service* service = services.getValueAt(serviceIndex);
+        if (booking->getServices().find(jobCard->getServiceId()) == -1)
+        {
+            throw std::runtime_error("Service does not belong to booking");
+        }
+        jobCard->setService(service);
+        int technicianIndex = users.find(jobCard->getTechnicianId());
+        if (technicianIndex == -1)
+        {
+            throw std::runtime_error("Invalid Technician ID");
+        }
+        User* technician = users.getValueAt(technicianIndex);
+        if (technician->getUserType() != util::UserType::TECHNICIAN)
+        {
+            throw std::runtime_error("User is not a technician");
+        }
+        jobCard->setTechnician(technician);
+        jobCards[jobCard->getId()] = jobCard;
+    }
+}
+
+/*
+Function: saveJobCards
+Description: Saves job cards from the datastore to persistent storage.
+             Uses FileManager to serialize job cards into the configured file.
+Parameters:
+    - None
+Returns:
+    - void
+*/
+void ServiceManagementService::saveJobCards()
+{
+    util::FileManager<JobCard> jobCardFileManager(config::file::JOBCARD_FILE);
+    auto& jobCards = m_dataStore.getJobCards();
+    jobCardFileManager.save(jobCards);
+}
+
+/*
+Function: loadObservers
+Description: Loads observer IDs from persistent storage and attaches corresponding
+             users as observers to the ServiceManagementService.
+Parameters:
+    - None
+Returns:
+    - void
+Throws:
+    - std::runtime_error if an observer ID is invalid (not found in datastore)
+*/
+void ServiceManagementService::loadObservers()
+{
+    util::loadObservers(config::file::SERVICEMANAGEMENTOBSERVERS, this, m_dataStore);
+}
+
+/*
+Function: saveObservers
+Description: Saves the current observer IDs of the ServiceManagementService
+             to persistent storage for future retrieval.
+Parameters:
+    - None
+Returns:
+    - void
+*/
+void ServiceManagementService::saveObservers()
+{
+    util::saveObservers(config::file::SERVICEMANAGEMENTOBSERVERS, this);
 }
 
 /*
@@ -208,7 +514,7 @@ Description: Restores inventory quantities for all required items in the service
 Parameter: ServiceBooking* booking - Pointer to the booking whose inventory items need to be restored
 Return type: void
 */
-static void restoreInventory(ServiceBooking* booking, util::Map<std::string, TrackedRecord<InventoryItem>>& trackedInventoryItems)
+static void restoreInventory(ServiceBooking* booking)
 {
     const int INCREMENT_VALUE = 1;
     if (!booking) 
@@ -227,17 +533,9 @@ static void restoreInventory(ServiceBooking* booking, util::Map<std::string, Tra
         for (int InventoryIterator = 0; InventoryIterator < items.getSize(); ++InventoryIterator)
         {
             InventoryItem* item = items.getValueAt(InventoryIterator);
-            const std::string& currentItemId = item->getId();
-            int itemIndex = trackedInventoryItems.find(currentItemId);
-            if (itemIndex == -1)
-            {
-                continue;
-            }
-            auto& currentTrackedInventoryItem = trackedInventoryItems.getValueAt(itemIndex);
             if (item)
             {
                 item->setQuantity(item->getQuantity() + INCREMENT_VALUE);
-                currentTrackedInventoryItem.state = RecordState::MODIFIED;
             }
         }
     }
@@ -255,28 +553,23 @@ Parameters:
     util::UserType userType - Type of user initiating cancellation (CUSTOMER or TECHNICIAN)
 Return type: void
 */
-static void processBookingCancellation(TrackedRecord<ServiceBooking>& trackedBooking,
+static void processBookingCancellation(ServiceBooking* booking,
-    util::Map<std::string, TrackedRecord<JobCard>>& jobs,
+    util::Map<std::string, JobCard*>& jobs,
     ServiceManagementService& currentService,
-    util::UserType userType,
+    util::UserType userType)
-    util::Map<std::string, TrackedRecord<InventoryItem>>& trackedInventoryItems)
 {
-    ServiceBooking* booking = trackedBooking.data;
     if (!booking)
     {
         return;
     }
-    const std::string& bookingId = booking->getId();
     for (int jobIterator = 0; jobIterator < jobs.getSize(); ++jobIterator)
     {
-        auto& trackedJobCard = jobs.getValueAt(jobIterator);
+        JobCard* jobCard = jobs.getValueAt(jobIterator);
-        JobCard* jobCard = trackedJobCard.data;
         if (!jobCard || jobCard->getBookingId() != booking->getId() || jobCard->getStatus() == util::ServiceJobStatus::CANCELLED)
         {
             continue;
         }
         jobCard->setStatus(util::ServiceJobStatus::CANCELLED);
-        trackedJobCard.state = RecordState::MODIFIED;
         if (userType == util::UserType::CUSTOMER)
         {
             if (User* technician = booking->getAssignedTechnician())
@@ -309,8 +602,7 @@ static void processBookingCancellation(TrackedRecord<ServiceBooking>& trackedBoo
     }
     booking->setAssignedTechnician(nullptr);
     booking->setAssignedTechnicianId("");
-    trackedBooking.state = RecordState::MODIFIED;
+    restoreInventory(booking);
-    restoreInventory(booking, trackedInventoryItems);
 }
 
 /*
@@ -323,25 +615,22 @@ Return type: void
 */
 void ServiceManagementService::cancelCustomerServiceBookings(const std::string& customerID)
 {
-    DataStoreLockGuard lock(m_dataStore);
+    auto& users = m_dataStore.getUsers();
-    auto& trackedUsers = m_dataStore.getUsers();
+    int userIndex = users.find(customerID);
-    int userIndex = trackedUsers.find(customerID);
     if (userIndex == -1)
     {
         throw std::runtime_error("User not found: " + customerID);
     }
-    User* customer = trackedUsers.getValueAt(userIndex).data;
+    User* customer = users.getValueAt(userIndex);
     if (!customer)
     {
         throw std::runtime_error("User not found: " + customerID);
     }
-    auto& trackedBookings = m_dataStore.getServiceBookings();
+    auto& bookings = m_dataStore.getServiceBookings();
-    auto& trackedJobs = m_dataStore.getJobCards();
+    auto& jobs = m_dataStore.getJobCards();
-    auto& trackedInventoryItems = m_dataStore.getInventoryItems();
+    for (int iteratorOne = 0; iteratorOne < bookings.getSize(); iteratorOne++)
-    for (int iteratorOne = 0; iteratorOne < trackedBookings.getSize(); iteratorOne++)
     {
-        auto& trackedBooking = trackedBookings.getValueAt(iteratorOne);
+        ServiceBooking* booking = bookings.getValueAt(iteratorOne);
-        ServiceBooking* booking = trackedBooking.data;
         if (!booking)
         {
             continue;
@@ -356,12 +645,8 @@ void ServiceManagementService::cancelCustomerServiceBookings(const std::string&
         {
             continue;
         }
-        processBookingCancellation(trackedBooking, trackedJobs, *this, util::UserType::CUSTOMER, trackedInventoryItems);
+        processBookingCancellation(booking, jobs, *this, util::UserType::CUSTOMER);
     }
-    m_dataStore.saveUsers();
-    m_dataStore.saveServiceBookings();
-    m_dataStore.saveJobCards();
-    m_dataStore.saveInventoryItems();
 }
 
 /*
@@ -373,25 +658,22 @@ Return type: void
 */
 void ServiceManagementService::cancelTechnicianJobs(const std::string& technicianID)
 {
-    DataStoreLockGuard lock(m_dataStore);
+    auto& users = m_dataStore.getUsers();
-    auto& trackedUsers = m_dataStore.getUsers();
+    int userIndex = users.find(technicianID);
-    int userIndex = trackedUsers.find(technicianID);
     if (userIndex == -1)
     {
         throw std::runtime_error("User not found: " + technicianID);
     }
-    User* technician = trackedUsers.getValueAt(userIndex).data;
+    User* technician = users.getValueAt(userIndex);
     if (!technician)
     {
         throw std::runtime_error("User not found: " + technicianID);
     }
-    auto& trackedBookings = m_dataStore.getServiceBookings();
+    auto& bookings = m_dataStore.getServiceBookings();
-    auto& trackedJobs = m_dataStore.getJobCards();
+    auto& jobs = m_dataStore.getJobCards();
-    auto& trackedInventoryItems = m_dataStore.getInventoryItems();
+    for (int iteratorOne = 0; iteratorOne < bookings.getSize(); iteratorOne++)
-    for (int iteratorOne = 0; iteratorOne < trackedBookings.getSize(); iteratorOne++)
     {
-        auto& trackedBooking = trackedBookings.getValueAt(iteratorOne);
+        ServiceBooking* booking = bookings.getValueAt(iteratorOne);
-        ServiceBooking* booking = trackedBooking.data;
         if (!booking)
         {
             continue;
@@ -412,12 +694,8 @@ void ServiceManagementService::cancelTechnicianJobs(const std::string& technicia
         {
             continue;
         }
-        processBookingCancellation(trackedBooking, trackedJobs, *this, util::UserType::TECHNICIAN, trackedInventoryItems);
+        processBookingCancellation(booking, jobs, *this, util::UserType::TECHNICIAN);
     }
-    m_dataStore.saveUsers();
-    m_dataStore.saveInventoryItems();
-    m_dataStore.saveServiceBookings();
-    m_dataStore.saveJobCards();
 }
 
 /*
@@ -431,7 +709,6 @@ Return type: void
 */
 void ServiceManagementService::createComboPackage(const std::string& packageName, const util::Vector<std::string>& serviceIDsInNewCombo, double discountPercentage)
 {
-    DataStoreLockGuard lock(m_dataStore);
     if (packageName.empty())
     {
         throw std::invalid_argument("The Combo Package Name cannot be empty.\n");
@@ -444,19 +721,19 @@ void ServiceManagementService::createComboPackage(const std::string& packageName
     {
         throw std::invalid_argument("Discount percentage must be between 0 and 100.");
     }
-    auto& trackedServicesMap = m_dataStore.getServices();
+    auto& servicesMap = m_dataStore.getServices();
     for (int index = 0; index < serviceIDsInNewCombo.getSize(); index++)
     {
-        const std::string& serviceid = serviceIDsInNewCombo[index];
+        const std::string serviceid = serviceIDsInNewCombo[index];
-        if (trackedServicesMap.find(serviceid) == -1)
+        if (servicesMap.find(serviceid) == -1)
         {
             throw std::runtime_error("Service ID not found: " + serviceid);
         }
     }
-    auto& trackedComboPackageMap = m_dataStore.getComboPackages();
+    auto& comboPackageMap = m_dataStore.getComboPackages();
-    for (int iterator = 0; iterator < trackedComboPackageMap.getSize(); iterator++)
+    for (int iterator = 0; iterator < comboPackageMap.getSize(); iterator++)
     {
-        ComboPackage* existingCombos = trackedComboPackageMap.getValueAt(iterator).data;
+        ComboPackage* existingCombos = comboPackageMap.getValueAt(iterator);
         const util::Map<std::string, Service*>& servicesInsideExistingCombos = existingCombos->getServices();
         if (servicesInsideExistingCombos.getSize() == serviceIDsInNewCombo.getSize())
         {
@@ -480,16 +757,15 @@ void ServiceManagementService::createComboPackage(const std::string& packageName
     for (int iteratorOne = 0; iteratorOne < serviceIDsInNewCombo.getSize(); iteratorOne++)
     {
         const std::string& serviceId = serviceIDsInNewCombo[iteratorOne];
-        int serviceIndex = trackedServicesMap.find(serviceId);
+        int serviceIndex = servicesMap.find(serviceId);
         if (serviceIndex == -1)
         {
             throw std::runtime_error("Service ID not found: " + serviceId);
         }
-        selectedServices.insert(serviceId, trackedServicesMap.getValueAt(serviceIndex).data);
+        selectedServices.insert(serviceId, servicesMap.getValueAt(serviceIndex));
     }
     ComboPackage* newComboPackage = Factory::getObject<ComboPackage>(packageName, discountPercentage, selectedServices);
-    trackedComboPackageMap.insert(newComboPackage->getId(), util::createNewRecord(newComboPackage));
+    comboPackageMap.insert(newComboPackage->getId(), newComboPackage);
-    m_dataStore.saveComboPackages();
 }
 
 /*
@@ -500,10 +776,7 @@ Return type: util::Map<std::string, ComboPackage*>
 */
 util::Map<std::string, ComboPackage*> ServiceManagementService::getComboPackages()
 {
-    DataStoreLockGuard lock(m_dataStore);
+    return m_dataStore.getComboPackages();
-    util::Map<std::string, ComboPackage*> comboPackages;
-    comboPackages = util::getObjects(m_dataStore.getComboPackages());
-    return comboPackages;
 }
 
 /*
@@ -514,17 +787,14 @@ Return type: void
 */
 void ServiceManagementService::removeComboPackage(const std::string& comboPackageID)
 {
-    DataStoreLockGuard lock(m_dataStore);
     bool removed = false;
-    auto& trackedComboPackages = m_dataStore.getComboPackages();
+    util::Map<std::string, ComboPackage*>& currentComboPackages = m_dataStore.getComboPackages();
-    for (int iterator = 0; iterator < trackedComboPackages.getSize(); iterator++)
+    for (int iterator = 0; iterator < currentComboPackages.getSize(); iterator++)
     {
-        auto& comboPackage = trackedComboPackages.getValueAt(iterator);
+        ComboPackage* currentComboPackage = currentComboPackages.getValueAt(iterator);
-        ComboPackage* currentComboPackage = comboPackage.data;
         if (currentComboPackage && currentComboPackage->getId() == comboPackageID)
         {
             currentComboPackage->setState(util::State::INACTIVE);
-            comboPackage.state = RecordState::MODIFIED;
             removed = true;
             break;
         }
@@ -533,7 +803,6 @@ void ServiceManagementService::removeComboPackage(const std::string& comboPackag
     {
         throw std::runtime_error("Combo package with ID '" + comboPackageID + "' not found.");
     }
-    m_dataStore.saveComboPackages();
 }
 
 /*
@@ -546,10 +815,7 @@ Returns:
 */
 util::Map<std::string, ServiceBooking*> ServiceManagementService::getServiceBookings()
 {
-    DataStoreLockGuard lock(m_dataStore);
+	return m_dataStore.getServiceBookings();
-    util::Map<std::string, ServiceBooking*> serviceBookings;
-    serviceBookings = util::getObjects(m_dataStore.getServiceBookings());
-    return serviceBookings;
 }
 
 /*
@@ -588,10 +854,9 @@ Throws:
 */
 void ServiceManagementService::createJobCard(const std::string& bookingID, const std::string& technicianID, const std::string& serviceID)
 {
-    DataStoreLockGuard lock(m_dataStore);
 	UserManagementService m_userManagementService;
 	ServiceBooking* currentBooking = getServiceBooking(bookingID);
-	auto& currentTrackedJobCards = m_dataStore.getJobCards();
+	auto& currentJobCards = m_dataStore.getJobCards();
 	if (currentBooking == nullptr)
 	{
 		throw std::runtime_error("Service Booking not available");
@@ -637,7 +902,7 @@ void ServiceManagementService::createJobCard(const std::string& bookingID, const
 	JobCard* jobCard = Factory::getObject<JobCard>(bookingID, currentBooking, currentService, serviceID, technicianID, selectedTechnician, util::Timestamp(), util::ServiceJobStatus::STARTED, util::Timestamp());
 	if (jobCard)
 	{
-		currentTrackedJobCards.insert(jobCard->getId(), util::createNewRecord(jobCard));
+		currentJobCards.insert(jobCard->getId(), jobCard);
 		sendNotification(selectedTechnician, title, message);
 	}
 	else
@@ -647,7 +912,6 @@ void ServiceManagementService::createJobCard(const std::string& bookingID, const
     title = "Technician assigned";
     message = "A technician has been assigned to your Service Booking with ID " + bookingID;
     sendNotification(currentBooking->getCustomer(), title, message);
-    m_dataStore.saveJobCards();
 }
 
 /*
@@ -665,17 +929,15 @@ Throws:
 */
 void ServiceManagementService::createService(const std::string& name, const util::Vector<std::string>& inventoryItemIDs, double laborCost)
 {
-    DataStoreLockGuard lock(m_dataStore);
 	util::Map<std::string, InventoryItem*> currentServiceInventoryItems;
-	auto& trackedInventoryItems = m_dataStore.getInventoryItems();
+	auto inventoryItems = m_dataStore.getInventoryItems();
-    auto& currentServices = m_dataStore.getServices();
 	for (int iteratorOne =0; iteratorOne < inventoryItemIDs.getSize(); iteratorOne++)
 	{
 		std::string currentItemID = inventoryItemIDs[iteratorOne];
 		bool itemFound = false;
-		for (int iteratorTwo = 0; iteratorTwo < trackedInventoryItems.getSize(); iteratorTwo++)
+		for (int iteratorTwo = 0; iteratorTwo < inventoryItems.getSize(); iteratorTwo++)
 		{
-			InventoryItem* currentInventoryItem = trackedInventoryItems.getValueAt(iteratorTwo).data;
+			InventoryItem* currentInventoryItem = inventoryItems.getValueAt(iteratorTwo);
 			if (currentInventoryItem && currentInventoryItem->getId() == currentItemID)
 			{
 				itemFound = true;
@@ -693,12 +955,12 @@ void ServiceManagementService::createService(const std::string& name, const util
 	{
 		throw std::runtime_error("Unable to create new service.");
 	}
+	util::Map<std::string, Service*>& currentServices = m_dataStore.getServices();
 	if (currentServices.find(newService->getId()) != -1)
 	{
 		throw std::runtime_error("Service with this ID Already exists.");
 	}
-	currentServices.insert(newService->getId(), util::createNewRecord(newService));
+	currentServices.insert(newService->getId(), newService);
-    m_dataStore.saveServices();
 }
 
 /*
@@ -711,10 +973,7 @@ Returns:
 */
 util::Map<std::string, Service*> ServiceManagementService::getServices()
 {
-    DataStoreLockGuard lock(m_dataStore);
+	return m_dataStore.getServices();
-    util::Map<std::string, Service*> services;
-    services = util::getObjects(m_dataStore.getServices());
-    return services;
 }
 
 /*
@@ -729,19 +988,14 @@ Throws:
 */
 void ServiceManagementService::removeService(const std::string& serviceID)
 {
-    DataStoreLockGuard lock(m_dataStore);
+	util::Map<std::string, Service*>& currentServices = m_dataStore.getServices();
-	auto& currentTrackedServices = m_dataStore.getServices();
+    util::Map<std::string, ComboPackage*>& currentComboPackages =  m_dataStore.getComboPackages();
-    auto& currentTrackedComboPackages =  m_dataStore.getComboPackages();
+	if (currentServices.find(serviceID) != -1)
-	if (currentTrackedServices.find(serviceID) != -1)
 	{
-        int serviceIndex, comboPackageIndex;
+		currentServices.getValueAt(currentServices.find(serviceID))->setState(util::State::INACTIVE);
-        serviceIndex = currentTrackedServices.find(serviceID);
+        for (int iterator = 0; iterator < currentComboPackages.getSize(); iterator++)
-		currentTrackedServices.getValueAt(serviceIndex).data->setState(util::State::INACTIVE);
-        currentTrackedServices.getValueAt(serviceIndex).state = RecordState::MODIFIED;
-        for (int iterator = 0; iterator < currentTrackedComboPackages.getSize(); iterator++)
         {
-            comboPackageIndex = iterator;
+            ComboPackage* currentComboPackage = currentComboPackages.getValueAt(iterator);
-            ComboPackage* currentComboPackage = currentTrackedComboPackages.getValueAt(iterator).data;
             if (currentComboPackage && currentComboPackage->getState() == util::State::ACTIVE)
             {
                 util::Map<std::string, Service*> currentServices = currentComboPackage->getServices();
@@ -751,7 +1005,6 @@ void ServiceManagementService::removeService(const std::string& serviceID)
                     if (currentService->getId() == serviceID)
                     {
                         currentComboPackage->setState(util::State::INACTIVE);
-                        currentTrackedComboPackages.getValueAt(comboPackageIndex).state = RecordState::MODIFIED;
                         break;
                     }
                 }
@@ -762,8 +1015,6 @@ void ServiceManagementService::removeService(const std::string& serviceID)
 	{
 		throw std::runtime_error("Service not found.");
 	}
-    m_dataStore.saveServices();
-    m_dataStore.saveComboPackages();
 }
 
 /*
@@ -802,12 +1053,11 @@ Returns:
 */
 util::Map<std::string, JobCard*> ServiceManagementService::getJobCards(const std::string& technicianID)
 {
-    DataStoreLockGuard lock(m_dataStore);
+	util::Map<std::string, JobCard*> jobCards = m_dataStore.getJobCards();
-	auto& trackedJobCards = m_dataStore.getJobCards();
 	util::Map<std::string, JobCard*> technicianJobCards;
-	for (int iterator = 0; iterator < trackedJobCards.getSize(); iterator++)
+	for (int iterator = 0; iterator < jobCards.getSize(); iterator++)
 	{
-		JobCard* currentJobCard = trackedJobCards.getValueAt(iterator).data;
+		JobCard* currentJobCard = jobCards.getValueAt(iterator);
 		if (currentJobCard->getTechnicianId() == technicianID)
 		{
 			technicianJobCards.insert(currentJobCard->getId(), currentJobCard);
@@ -856,7 +1106,6 @@ Returns:
 */
 void ServiceManagementService::updateJobStatus(const std::string& jobID)
 {
-    DataStoreLockGuard lock(m_dataStore);
 	AuthenticationManagementService authenticationManagementService;
 	PaymentManagementService paymentManagementService;
 	bool jobStatusUpdated = false, serviceBookingCompleted;
@@ -871,15 +1120,8 @@ void ServiceManagementService::updateJobStatus(const std::string& jobID)
 	{
 		throw std::runtime_error("No job cards assigned to the technician.");
 	}
-    auto& trackedJobCards = m_dataStore.getJobCards();
-    auto& trackedServiceBookings = m_dataStore.getServiceBookings();
 	if (currentAssignedJobs.find(jobID) != -1)
 	{
-        int jobIndex = trackedJobCards.find(jobID);
-        if (jobIndex == -1)
-        {
-            throw std::runtime_error("Unable to fetch current job.");
-        }
 		currentJob = currentAssignedJobs.getValueAt(currentAssignedJobs.find(jobID));
 		if (currentJob == nullptr)
 		{
@@ -888,20 +1130,16 @@ void ServiceManagementService::updateJobStatus(const std::string& jobID)
 		if (currentJob->getStatus() == util::ServiceJobStatus::STARTED)
 		{
 			currentJob->setStatus(util::ServiceJobStatus::IN_PROGRESS);
-            trackedJobCards.getValueAt(jobIndex).state = RecordState::MODIFIED;
 			jobStatusUpdated = true;
 		}
         else if (currentJob->getStatus() == util::ServiceJobStatus::IN_PROGRESS)
         {
             currentJob->setStatus(util::ServiceJobStatus::COMPLETED);
-            trackedJobCards.getValueAt(jobIndex).state = RecordState::MODIFIED;
             jobStatusUpdated = true;
             serviceBookingCompleted = hasCompletedAllJobs(currentJob->getBookingId(), currentAssignedJobs);
             if (serviceBookingCompleted)
             {
-                const std::string& bookingId = currentJob->getBookingId();
                 currentJob->getBooking()->setStatus(util::ServiceJobStatus::COMPLETED);
-                trackedServiceBookings.getValueAt(trackedServiceBookings.find(bookingId)).state = RecordState::MODIFIED;
                 paymentManagementService.generateInvoice(currentJob->getBooking());
                 std::string title = "Service Booking completed. Invoice Generated.";
                 std::string message = "Services completed for the booking and invoice generated.";
@@ -917,6 +1155,4 @@ void ServiceManagementService::updateJobStatus(const std::string& jobID)
 	{
 		throw std::runtime_error("Failed to update job status. Job may already be completed.");
 	}
-    m_dataStore.saveJobCards();
-    m_dataStore.saveServiceBookings();
 }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/ServiceManagementService.h

@@ -23,6 +23,7 @@ class ServiceManagementService : public NotificationManagementService
 private:
     DataStore& m_dataStore;
     static util::Map<std::string, User*> m_observers;
+    util::Vector<std::string> getObserverIDs() override;
 public:
     ServiceManagementService() : m_dataStore(DataStore::getInstance()) {}
     util::Map<std::string, Service*> getServices();
@@ -44,4 +45,14 @@ public:
     void sendNotification(User* user, const std::string& title, const std::string& message) override;
     void attach(User* user) override;
     void detach(User* user) override;
+    void loadServices();
+    void saveServices();
+    void loadComboPackages();
+    void saveComboPackages();
+    void loadServiceBookings();
+    void saveServiceBookings();
+    void loadJobCards();
+    void saveJobCards();
+    void loadObservers();
+    void saveObservers();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/UserManagementService.cpp

@@ -11,6 +11,7 @@ Date:19-May-2026
 #include "Config.h"
 #include "Enums.h"
 #include "Factory.h"
+#include "FileManager.h"
 #include "InventoryManagementService.h"
 #include "Notification.h"
 #include "PaymentManagementService.h"
@@ -19,9 +20,6 @@ Date:19-May-2026
 #include "UserManagementService.h"
 #include "Vector.h"
 #include "Validator.h"
-#include "Utility.h"
-#include "TrackedRecord.h"
-#include "DataStoreLockGuard.h"
 
 /*
 Function: ensureAdminExists
@@ -33,13 +31,12 @@ Return type: void
 */
 void UserManagementService::ensureAdminExists()
 {
-	DataStoreLockGuard lock(m_dataStore);
 	auto& usersMap = m_dataStore.getUsers();
 	int usersMapSize = usersMap.getSize();
 	bool isAdminFound = false;
 	for (int index = 0; index < usersMapSize; index++)
 	{
-		User* user = usersMap.getValueAt(index).data;
+		User* user = usersMap.getValueAt(index);
 		if (user && user->getUserType() == util::UserType::ADMIN)
 		{
 			isAdminFound = true;
@@ -76,9 +73,7 @@ void UserManagementService::createUser(const std::string& username, const std::s
 	InventoryManagementService inventoryManagementService;
 	PaymentManagementService paymentManagementService;
 	ServiceManagementService serviceManagementService;
-	DataStoreLockGuard lock(m_dataStore);
+	auto& usersMap = m_dataStore.getUsers();
-	auto& trackedUsersMap = m_dataStore.getUsers();
-	auto usersMap = util::getObjects(trackedUsersMap);
 	if (util::isUsernameDuplicate(username, usersMap))
 	{
 		throw std::runtime_error("Username already exists");
@@ -92,14 +87,13 @@ void UserManagementService::createUser(const std::string& username, const std::s
 		throw std::runtime_error("Phone already exists");
 	}
 	User* newUser = Factory::getObject<User>(username, password, name, phone, email, type);
-	trackedUsersMap.insert(newUser->getId(), util::createNewRecord(newUser));
+	usersMap.insert(newUser->getId(), newUser);
 	paymentManagementService.attach(newUser);
 	serviceManagementService.attach(newUser);
 	if (newUser->getUserType() == util::UserType::ADMIN)
 	{
 		inventoryManagementService.attach(newUser);
 	}
-	m_dataStore.saveUsers();
 }
 
 /*
@@ -113,24 +107,19 @@ Return type: void
 */
 void UserManagementService::updateUserDetails(const std::string& userID, const std::string& email, const std::string& phone)
 {
-	DataStoreLockGuard lock(m_dataStore);
+	auto& usersMap = m_dataStore.getUsers();
-	auto& trackedUsersMap = m_dataStore.getUsers();
+	int index = usersMap.find(userID);
-	auto usersMap = util::getObjects(trackedUsersMap);
-	int index = trackedUsersMap.find(userID);
 	if (index == -1)
 	{
 		throw std::runtime_error("User does not exist!\n");
 	}
-	User* user = trackedUsersMap.getValueAt(index).data;
+	User* user = usersMap.getValueAt(index);
-	bool isModified = false;
 	if (email != user->getEmail())
 	{
 		if (util::isEmailDuplicate(email, usersMap))
 		{
 			throw std::runtime_error("Email already exists!\n");
 		}
-		user->setEmail(email);
-		isModified = true;
 	}
 	if (phone != user->getPhone())
 	{
@@ -138,14 +127,9 @@ void UserManagementService::updateUserDetails(const std::string& userID, const s
 		{
 			throw std::runtime_error("Phone number already exists!\n");
 		}
-		user->setPhone(phone);
-		isModified = true;
-	}
-	if (isModified)
-	{
-		trackedUsersMap.getValueAt(index).state = RecordState::MODIFIED;
-		m_dataStore.saveUsers();
 	}
+	user->setEmail(email);
+	user->setPhone(phone);
 }
 
 /*
@@ -160,25 +144,20 @@ Throws:
 */
 util::Vector<Notification*> UserManagementService::getUserNotifications(const std::string& userID)
 {
-	DataStoreLockGuard lock(m_dataStore);
+	auto& usersMap = m_dataStore.getUsers();
-	auto& trackedUsersMap = m_dataStore.getUsers(); 
+	if (usersMap.find(userID) == -1)
-	if (trackedUsersMap.find(userID) == -1)
 	{
 		throw std::runtime_error("No user found with given UserID");
 	}
-	User* user = trackedUsersMap[userID].data;
+	User* user = usersMap[userID];
 	if (user)
 	{
-		auto& trackedNotificationMap = m_dataStore.getNotifications();
+		auto& notifications = user->getNotifications();
-		int numberOfNotifications = trackedNotificationMap.getSize();
+		int numberOfNotifications = notifications.getSize();
 		util::Vector<Notification*> notificationsVector;
 		for (int index = 0; index < numberOfNotifications; index++)
 		{
-			Notification* notification = trackedNotificationMap.getValueAt(index).data;
+		    notificationsVector.push_back(notifications.getValueAt(index));
-			if (notification->getRecipientUserId() == userID && notification->getState() == util::State::ACTIVE)
-			{
-				notificationsVector.push_back(notification);
-			}
 		}
 		return notificationsVector;
 	}
@@ -190,39 +169,97 @@ util::Vector<Notification*> UserManagementService::getUserNotifications(const st
 
 /*
 Function: deleteNotification
-Description: Marks a specific notification associated with a given user
+Description: Deletes a specific notification associated with a given user ID.
-			 as inactive.
 Parameters:
 	- notificationID: The unique ID of the notification to be deleted.
 	- userID: The unique ID of the user whose notification is to be deleted.
 Returns:
 	- void
 Throws:
-	- std::runtime_error if no user is found with the given UserID or
+	- std::runtime_error if no user is found with the given UserID or if no notification is found with the given NotificationID.
-	  if no notification is found with the given NotificationID.
 */
 void UserManagementService::deleteNotification(const std::string& notificationID, const std::string& userID)
 {
-	DataStoreLockGuard lock(m_dataStore);
+	auto& usersMap = m_dataStore.getUsers();
-	auto& trackedUsersMap = m_dataStore.getUsers();
+	if (usersMap.find(userID) == -1)
-	auto& trackedNotificationsMap = m_dataStore.getNotifications();
-	int userIndex = trackedUsersMap.find(userID);
-	if (userIndex == -1)
 	{
 		throw std::runtime_error("No user found with given UserID");
 	}
-	int notificationIndex = trackedNotificationsMap.find(notificationID);
+	User* user = usersMap[userID];
-	if (notificationIndex == -1)
+	auto& notifications = user->getNotifications();
+	if (notifications.find(notificationID) == -1)
 	{
 		throw std::runtime_error("No notification found with given NotificationID");
 	}
-	Notification* notification = trackedNotificationsMap.getValueAt(notificationIndex).data;
+	notifications.remove(notificationID);
-	if (notification->getRecipientUserId() == userID)
+}
-	{
+
-		notification->setState(util::State::INACTIVE);
+/*
-		trackedNotificationsMap.getValueAt(notificationIndex).state = RecordState::MODIFIED;
+Function: loadUsers
-		m_dataStore.saveNotifications();
+Description: Loads users and notifications from persistent storage into the datastore.
-	}
+             Validates that each notification’s recipient exists and attaches the
+             notification to the corresponding user.
+Parameters:
+    - None
+Returns:
+    - void
+Throws:
+    - std::runtime_error if a notification recipient user ID is invalid
+*/
+void UserManagementService::loadUsers()
+{
+    util::FileManager<User> userFileManager(config::file::USER_FILE);
+    util::FileManager<Notification> notificationFileManager(config::file::NOTIFICATION_FILE);
+    auto& users = m_dataStore.getUsers();
+    auto usersMap = userFileManager.load();
+    auto notificationsMap = notificationFileManager.load();
+    int numberOfUsers = usersMap.getSize();
+    int numberOfNotifications = notificationsMap.getSize();
+    for (int index = 0; index < numberOfUsers; index++)
+    {
+        users[usersMap.getKeyAt(index)] = usersMap.getValueAt(index);
+    }
+    for (int index = 0; index < numberOfNotifications; index++)
+    {
+        Notification* notification = notificationsMap.getValueAt(index);
+        const std::string& recipientUserId = notification->getRecipientUserId();
+        int userIndex = users.find(recipientUserId);
+        if (userIndex == -1)
+        {
+            throw std::runtime_error("Invalid recipient user ID");
+        }
+        User* user = users.getValueAt(userIndex);
+        user->addNotification(notification);
+    }
+}
+
+/*
+Function: saveUsers
+Description: Saves users and their notifications from the datastore to persistent storage.
+             Collects notifications from all users into a single map before saving.
+Parameters:
+    - None
+Returns:
+    - void
+*/
+void UserManagementService::saveUsers()
+{
+    util::FileManager<User> userFileManager(config::file::USER_FILE);
+    util::FileManager<Notification> notificationFileManager(config::file::NOTIFICATION_FILE);
+    auto& users = m_dataStore.getUsers();
+    util::Map<std::string, Notification*> notifications;
+    for (int userIndex = 0; userIndex < users.getSize(); userIndex++)
+    {
+        User* user = users.getValueAt(userIndex);
+        auto& userNotifications = user->getNotifications();
+        for (int notificationIndex = 0; notificationIndex < userNotifications.getSize(); notificationIndex++)
+        {
+            notifications[userNotifications.getKeyAt(notificationIndex)] =
+                userNotifications.getValueAt(notificationIndex);
+        }
+    }
+    userFileManager.save(users);
+    notificationFileManager.save(notifications);
 }
 
 /*
@@ -233,9 +270,7 @@ Return type: util::Map<std::string, User*>
 */
 util::Map<std::string, User*> UserManagementService::getUsers()
 {
-	DataStoreLockGuard lock(m_dataStore);
+	return m_dataStore.getUsers();
-	auto users = util::getObjects(m_dataStore.getUsers());
-	return users;
 }
 
 /*
@@ -246,12 +281,10 @@ Return type: User*
 */
 User* UserManagementService::getUser(const std::string& userID)
 {
-	DataStoreLockGuard lock(m_dataStore);
+	int index = m_dataStore.getUsers().find(userID);
-	auto& trackedUsersMap = m_dataStore.getUsers();
-	int index = trackedUsersMap.find(userID);
 	if (index != -1)
 	{
-		return trackedUsersMap.getValueAt(index).data;
+		return m_dataStore.getUsers().getValueAt(index);
 	}
 	return nullptr;
 }
@@ -267,53 +300,35 @@ void UserManagementService::removeUser(const std::string& userID)
 	InventoryManagementService inventoryManagementService;
 	PaymentManagementService paymentManagementService;
 	ServiceManagementService serviceManagementService;
-	DataStoreLockGuard lock(m_dataStore);
+	int index = m_dataStore.getUsers().find(userID);
-	auto& trackedUsersMap = m_dataStore.getUsers();
-	int index = trackedUsersMap.find(userID);
 	if (index != -1)
 	{
-		User* user = trackedUsersMap.getValueAt(index).data;
+		User* user = m_dataStore.getUsers().getValueAt(index);
 		if (user != nullptr)
 		{
 			if (user->getUserType() == util::UserType::CUSTOMER)
 			{
-				serviceManagementService.cancelCustomerServiceBookings(userID);
+				serviceManagementService.cancelCustomerServiceBookings(userID);	
 			}
 			if (user->getUserType() == util::UserType::TECHNICIAN)
 			{
 				serviceManagementService.cancelTechnicianJobs(userID);
 			}
+			user->setState(util::State::INACTIVE);
 			inventoryManagementService.detach(user);
 			paymentManagementService.detach(user);
 			serviceManagementService.detach(user);
-			user->setState(util::State::INACTIVE);
-			trackedUsersMap.getValueAt(index).state = RecordState::MODIFIED;
-			m_dataStore.saveUsers();
 		}
 	}
 }
 
-/*
+util::Map<std::string, User*> UserManagementService::getUsers(util::UserType type)
-Function: getUsers
-Description: Retrieves all active users of the specified type from
-			 the DataStore.
-Parameters:
-	- type: The user type to filter by
-			(ADMIN, CUSTOMER, or TECHNICIAN).
-Returns:
-	- util::Map<std::string, User*>:
-	  Collection of active users matching the specified type,
-	  keyed by user ID.
-*/
-util::Map<std::string, User*> UserManagementService::getUsers(util::UserType type) 
 {
-	DataStoreLockGuard lock(m_dataStore);
+	util::Map<std::string, User*>& currentUsers = m_dataStore.getUsers();
-	auto& trackedUsersMap = m_dataStore.getUsers();
-	util::Map<std::string, User*> currentUsers = util::getObjects(trackedUsersMap);
 	util::Map<std::string, User*> filteredUsersMap;
-	for (int index = 0; index < currentUsers.getSize(); index++)
+	for (int iterator = 0; iterator < currentUsers.getSize(); iterator++)
 	{
-		User* currentUser = currentUsers.getValueAt(index);
+		User* currentUser = currentUsers.getValueAt(iterator);
 		if (currentUser && currentUser->getState() == util::State::ACTIVE && currentUser->getUserType() == type)
 		{
 			filteredUsersMap.insert(currentUser->getId(), currentUser);

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/UserManagementService.h

@@ -31,4 +31,6 @@ public:
     util::Vector<Notification*> getUserNotifications(const std::string& userID);
     void deleteNotification(const std::string& notificationID, const std::string& userID);
     void ensureAdminExists();
+    void loadUsers();
+    void saveUsers();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/utilities/Config.h

@@ -29,7 +29,6 @@ namespace config
 	namespace file
 	{
 		const size_t INITIAL_CAPACITY = 100;
-		const size_t GROWTH_FACTOR = 2;
 		constexpr const char* DIRECTORY = "files/";
 		constexpr const char* INVENTORYITEM_FILE = "files/InventoryItem.dat";
 		constexpr const char* USER_FILE = "files/User.dat";

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/utilities/FileHelper.h

@@ -43,4 +43,67 @@ namespace util
             position++;
         }
     }
+
+    /*
+    Function: loadRecords
+    Description: Loads records from a given file path into a vector of strings.
+                 Skips the header line if present. Creates the file if it does not exist.
+    Parameters:
+        - filePath: const std::string&, path to the file
+    Returns:
+        - util::Vector<std::string>: Vector containing all records (excluding header)
+    Throws:
+        - None (creates file if missing)
+    */
+    inline util::Vector<std::string> loadRecords(const std::string& filePath)
+    {
+        util::Vector<std::string> records;
+        std::ifstream file(filePath);
+        if (!file.is_open())
+        {
+            ensureDirectoryExists(filePath);
+            std::ofstream newFile(filePath);
+            newFile.close();
+            file.open(filePath);
+        }
+        std::string line;
+        bool isHeader = true;
+        while (std::getline(file, line))
+        {
+            if (isHeader)
+            {
+                isHeader = false;
+                continue;
+            }
+            records.push_back(line);
+        }
+        return records;
+    }
+
+    /*
+    Function: saveRecords
+    Description: Saves records to a given file path. Overwrites existing content
+                 and writes a header line followed by all records.
+    Parameters:
+        - filePath: const std::string&, path to the file
+        - records: const util::Vector<std::string>&, vector of records to save
+    Returns:
+        - void
+    Throws:
+        - std::runtime_error if the file cannot be opened for writing
+    */
+    inline void saveRecords(const std::string& filePath, const util::Vector<std::string>& records)
+    {
+        std::ofstream file(filePath, std::ios::trunc);
+        if (!file.is_open())
+        {
+            throw std::runtime_error("Failed to open file " + filePath);
+        }
+        file << "Values" << '\n';
+        int numberOfRecords = records.getSize();
+        for (int index = 0; index < numberOfRecords; index++)
+        {
+            file << records[index] << '\n';
+        }
+    }
 }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/utilities/FileManager.h

@@ -0,0 +1,119 @@
+/*
+File: FileManager.h
+Description: Declares and implements a generic FileManager template class for
+			 loading and saving objects to and from files. Uses serialization
+			 and deserialization methods defined in the object type T.
+			 Provides persistence support for system entities such as Users,
+			 Services, InventoryItems, etc.
+Author: Trenser
+Date: 22-May-2026
+*/
+
+#pragma once
+#include <stdexcept>
+#include <string>
+#include <fstream>
+#include "Vector.h"
+#include "Map.h"
+#include "FileHelper.h"
+
+namespace util
+{
+	template <typename T> using objects = util::Map<std::string, T*>;
+
+	template <typename T>
+	class FileManager
+	{
+	private:
+		std::string m_filePath;
+	public:
+		FileManager() : m_filePath("") {}
+		FileManager(const std::string& filePath) : m_filePath(filePath) {}
+		objects<T> load();
+		void save(const objects<T>&);
+	};
+
+	/*
+	Function: load
+	Description: Loads records from the file into a map of objects.
+				 Skips the header line, deserializes each record into an object of type T,
+				 and stores them in a map keyed by object ID.
+	Parameters:
+		- None
+	Returns:
+		- util::Map<std::string, T*> containing deserialized objects
+	Throws:
+		- std::runtime_error if deserialization fails for any record
+	*/
+	template <typename T>
+	objects<T> FileManager<T>::load()
+	{
+		objects<T> records;
+		std::ifstream file(m_filePath);
+		if (!file.is_open())
+		{
+			ensureDirectoryExists(m_filePath);
+			std::ofstream newFile(m_filePath);
+			newFile.close();
+			file.open(m_filePath);
+		}
+		util::Vector<std::string> lines;
+		std::string line;
+		while (std::getline(file, line))
+		{
+			lines.push_back(line);
+		}
+		int numberOfLines = lines.getSize();
+		bool isHeader = true;
+		for (int lineIndex = 0; lineIndex < numberOfLines; lineIndex++)
+		{
+			const auto& record = lines[lineIndex];
+			if (isHeader)
+			{
+				isHeader = false;
+				continue;
+			}
+			auto object = T::deserialize(record);
+			if (!object)
+			{
+				throw std::runtime_error("Failed to deserialize record");
+			}
+			records[object->getId()] = object;
+		}
+		return records;
+	}
+
+	/*
+	Function: save
+	Description: Saves records to the file. Serializes each object of type T into a string,
+				 writes a header line, and then writes all serialized records to the file.
+	Parameters:
+		- records: const util::Map<std::string, T*>&, map of objects to save
+	Returns:
+		- void
+	Throws:
+		- std::runtime_error if the file cannot be opened for writing
+	*/
+	template <typename T>
+	void FileManager<T>::save(const objects<T>& records)
+	{
+		util::Vector<std::string> lines;
+		lines.push_back(T::getHeaders());
+		int numberOfRecords = records.getSize();
+		for (int recordIndex = 0; recordIndex < numberOfRecords; recordIndex++)
+		{
+			const auto& record = records.getValueAt(recordIndex);
+			lines.push_back(record->serialize());
+		}
+		std::ofstream file(m_filePath, std::ios::trunc);
+		if (!file.is_open())
+		{
+			throw std::runtime_error("Failed to open file " + m_filePath);
+		}
+		int numberOfLines = lines.getSize();
+		for (int lineIndex = 0; lineIndex < numberOfLines; lineIndex++)
+		{
+			file << lines[lineIndex] << '\n';
+		}
+	}
+}

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/utilities/InputHelper.h

@@ -28,7 +28,7 @@ namespace util
         if (!(std::cin >> value))
         {
             std::cin.clear();
-            std::cin.ignore((std::numeric_limits<std::streamsize>::max)(), '\n');
+            std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
             throw std::runtime_error("Invalid console input");
         }
     }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/utilities/Utility.h

@@ -54,79 +54,49 @@ namespace util
         return cost;
     }
 
-    template<typename TObject>
+    /*
-    Map<std::string, TObject*> getObjects(const Map<std::string, TrackedRecord<TObject>>& trackedRecords);
+    Function: loadObservers
-
+    Description: Loads observer IDs from a file and attaches the corresponding users
-    template<typename TObject>
+                 to the notification management service. Validates that each observer ID
-    Map<std::string, const TObject*> getConstObjects(const Map<std::string, TrackedRecord<TObject>>& trackedRecords);
+                 exists in the datastore before attaching.
-
+    Parameters:
-    template<typename TObject>
+        - filePath: const std::string&, path to the file containing observer IDs
-    TrackedRecord<TObject> createNewRecord(TObject* object);
+        - service: NotificationManagementService*, pointer to the notification service
-}
+        - dataStore: DataStore&, reference to the datastore containing users
-
+    Returns:
-/*
+        - void
-Function: getObjects
+    Throws:
-Description: Extracts the object pointers from a tracked-record
+        - std::runtime_error if an observer ID is invalid (not found in datastore)
-             collection and returns them as a map keyed by the
+    */
-             same identifiers.
+    inline void loadObservers(const std::string& filePath, NotificationManagementService* service, DataStore& dataStore)
-Parameters:
-    - trackedRecords: Collection of tracked records.
-Returns:
-    - Map<std::string, TObject*>: Collection of object pointers.
-*/
-template<typename TObject>
-util::Map<std::string, TObject*> util::getObjects(const util::Map<std::string, TrackedRecord<TObject>>& trackedRecords)
-{
-    util::Map<std::string, TObject*> objects;
-    for (int index = 0; index < trackedRecords.getSize(); ++index)
     {
-        const std::string& key = trackedRecords.getKeyAt(index);
+        auto observerIDs = util::loadRecords(filePath);
-        TObject* object = trackedRecords.getValueAt(index).data;
+        auto& users = dataStore.getUsers();
-        objects.insert(key, object);
+        for (int index = 0; index < observerIDs.getSize(); index++)
+        {
+            const std::string& observerID = observerIDs[index];
+            int userIndex = users.find(observerID);
+            if (userIndex == -1)
+            {
+                throw std::runtime_error("Invalid Observer ID");
+            }
+            service->attach(users.getValueAt(userIndex));
+        }
     }
-    return objects;
-}
 
-/*
+    /*
-Function: getConstObjects
+    Function: saveObservers
-Description: Extracts the object pointers from a tracked-record
+    Description: Saves the current observer IDs from the notification management service
-             collection and returns them as a read-only map
+                 to a file for persistence.
-             keyed by the same identifiers.
+    Parameters:
-Parameters:
+        - filePath: const std::string&, path to the file where observer IDs will be saved
-    - trackedRecords: Collection of tracked records.
+        - service: NotificationManagementService*, pointer to the notification service
-Returns:
+    Returns:
-    - Map<std::string, const TObject*>:
+        - void
-      Collection of read-only object pointers.
+    */
-*/
+    inline void saveObservers(const std::string& filePath, NotificationManagementService* service)
-template<typename TObject>
-util::Map<std::string, const TObject*> util::getConstObjects(
-    const util::Map<std::string, TrackedRecord<TObject>>& trackedRecords)
-{
-    util::Map<std::string, const TObject*> objects;
-    for (int index = 0; index < trackedRecords.getSize(); ++index)
     {
-        const std::string& key = trackedRecords.getKeyAt(index);
+        auto observerIDs = service->getObserverIDs();
-        const TObject* object = trackedRecords.getValueAt(index).data;
+        util::saveRecords(filePath, observerIDs);
-        objects.insert(key, object);
     }
-    return objects;
-}
-
-/*
-Function: createNewRecord
-Description: Creates a tracked record for a newly created
-             object. The record is initialized with
-             NEW_RECORD state.
-Parameters:
-    - object: Pointer to the newly created object.
-Returns:
-    - TrackedRecord<TObject>: Initialized tracked record.
-*/
-template<typename TObject>
-TrackedRecord<TObject> util::createNewRecord(TObject* object)
-{
-    TrackedRecord<TObject> record;
-    record.data = object;
-    record.state = RecordState::NEW_RECORD;
-    return record;
 }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/views/UserInterface.cpp

@@ -27,11 +27,8 @@ void UserInterface::run()
 {
 	try
 	{
-		if (!m_controller.initialize())
+		m_controller.loadSystemData();
-		{
+		m_controller.runSystemChecks();
-			std::cout << "Error: Failed to initialize the system!";
-			return;
-		}
 		bool isMenuActive = true;
 		while (isMenuActive)
 		{
@@ -52,7 +49,7 @@ void UserInterface::run()
 				util::pressEnter();
 			}
 		}
-		m_controller.shutdown();
+		m_controller.saveSystemData();
 	}
 	catch (const std::invalid_argument& exception)
 	{