Masterarbeit/Versuche/Versuch 02/Ergenisse/software/SwRS_DataModel.md

Software Data Model Specification

Centron Enterprise Application - Data Architecture and Implementation

Document Control

• Project: Centron Enterprise Application
• Version: 1.0
• Date: 2025-09-30
• Standard: ISO/IEC/IEEE 29148:2018
• Classification: Software Data Model and Schema Documentation

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Table of Contents

1. Data Model Overview
2. Entity Framework Architecture
3. Domain Entity Categories
4. Database Schema Implementation
5. NHibernate Mapping Configuration
6. Data Relationships and Constraints
7. Data Validation and Business Rules
8. Data Flow and Transformation

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1. Data Model Overview

1.1 Data Architecture Statistics

• Total Entity Files: 1,145 entity classes
• NHibernate Mappings: 956 FluentNHibernate mapping files
• Domain Categories: 268 business domain categories
• Database Tables: Estimated 800+ tables
• Entity Relationships: Complex web of one-to-many, many-to-many associations

1.2 Data Architecture Principles

SW-DATA-ARCH-001: The software SHALL implement domain-driven design principles

• Entity Aggregates: Related entities grouped into aggregate roots
• Bounded Contexts: Clear separation between business domains
• Value Objects: Immutable objects representing domain concepts

SW-DATA-ARCH-002: The software SHALL use standardized entity base classes

• Base Entity: BaseEntity with primary key I3D
• Persisted Entity: PersistedEntity with audit trail fields
• Soft Delete Pattern: IsDeleted flag for logical deletion

1.3 Data Storage Technologies

Technology	Purpose	Implementation Location
SQL Server	Primary database	Production and development
NHibernate	ORM Framework	src/backend/Centron.DAO/
FluentNHibernate	Mapping Configuration	src/backend/Centron.DAO/Mappings/
Entity Framework	Limited use	Some specialized components

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2. Entity Framework Architecture

2.1 Base Entity Hierarchy

SW-ENT-001: Base Entity Structure

// File: src/backend/Centron.Entities/BaseEntity.cs
public abstract class BaseEntity
{
    public virtual int I3D { get; set; } // Primary Key
}

// File: src/backend/Centron.Entities/PersistedEntity.cs
public class PersistedEntity : BaseEntity
{
    public virtual DateTime? CreatedDate { get; set; }
    public virtual DateTime? ChangedDate { get; set; }
    public virtual int? CreatedByI3D { get; set; }
    public virtual int? ChangedByI3D { get; set; }
    public virtual bool IsDeleted { get; set; }
    public virtual DateTime? DeletedDate { get; set; }
    public virtual int? DeletedByI3D { get; set; }
}

Design Requirements:

• SW-ENT-001.1: All entities MUST inherit from BaseEntity
• SW-ENT-001.2: Business entities SHOULD inherit from PersistedEntity
• SW-ENT-001.3: Primary keys MUST use I3D naming convention
• SW-ENT-001.4: Foreign keys MUST end with I3D suffix

2.2 Entity Naming Conventions

SW-ENT-002: Naming Standard Implementation

• Entity Classes: PascalCase (e.g., Account, AccountAddress)
• Properties: PascalCase (e.g., Name, CreatedDate)
• Foreign Keys: EntityNameI3D (e.g., AccountI3D, EmployeeI3D)
• Collection Properties: Plural names (e.g., Addresses, AccountTypes)

File Organization:

• Entities: src/backend/Centron.Entities/Entities/{Domain}/{EntityName}.cs
• Mappings: src/backend/Centron.DAO/Mappings/{Domain}/{EntityName}Maps.cs

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3. Domain Entity Categories

3.1 Account Management Domain

SW-DOM-001: Account Entity Model

• Root Entity: Account (src/backend/Centron.Entities/Entities/Accounts/Account.cs)
• Related Entities: 45+ account-related entity classes

Core Account Entities:

// Account aggregate root
public class Account : BaseEntity, IAccount
{
    public virtual int Number { get; set; }
    public virtual string Name { get; set; }
    public virtual string Matchcode { get; set; }
    public virtual string Email { get; set; }
    public virtual bool IsActive { get; set; }
    public virtual bool IsLocked { get; set; }

    // Navigation properties
    public virtual IList<AccountAddress> Addresses { get; set; }
    public virtual IList<AccountTypeToAccount> AccountTypes { get; set; }
}

// Account address value object
public class AccountAddress : PersistedEntity
{
    public virtual int AccountI3D { get; set; }
    public virtual string Street { get; set; }
    public virtual string PostalCode { get; set; }
    public virtual string City { get; set; }
    public virtual int? CountryI3D { get; set; }
    public virtual bool IsMainAddress { get; set; }

    // Navigation properties
    public virtual Account Account { get; set; }
    public virtual IList<AccountAddressContact> Contacts { get; set; }
}

Account Domain Entities:

Entity	Purpose	Key Relationships
Account	Core account data	→ AccountAddress, AccountType
AccountAddress	Address information	→ Account, Country, Contacts
AccountAddressContact	Contact persons	→ AccountAddress, Employee
AccountContract	Service contracts	→ Account, ContractKind
AccountType	Account classification	← AccountTypeToAccount
AccountActivity	Activity logging	→ Account, Employee

3.2 Sales and Receipt Domain

SW-DOM-002: Receipt Entity Model

• Entity Count: 150+ receipt-related entities
• Root Entities: Receipt types (Offer, Order, Invoice, DeliveryList)
• Complex Hierarchy: Receipt → ReceiptItem → ReceiptItemArticle

Receipt Entity Hierarchy:

// Abstract receipt base
public abstract class ReceiptBase : PersistedEntity, IReceiptBase
{
    public virtual int Number { get; set; }
    public virtual DateTime? CreatedAt { get; set; }
    public virtual decimal CurrencyFactor { get; set; }
    public virtual string Comment { get; set; }
    public virtual ReceiptState State { get; set; }

    // Customer relationship
    public virtual int? CustomerI3D { get; set; }
    public virtual Customer Customer { get; set; }

    // Receipt items
    public virtual IList<ReceiptItemBase> Items { get; set; }
}

// Specific receipt types
public class Offer : ReceiptBase
{
    public virtual DateTime? ValidUntil { get; set; }
    public virtual bool IsConverted { get; set; }
}

public class Order : ReceiptBase
{
    public virtual DateTime? DesiredDeliveryDate { get; set; }
    public virtual bool IsUrgent { get; set; }
}

public class Invoice : ReceiptBase
{
    public virtual DateTime? DueDate { get; set; }
    public virtual decimal TotalAmount { get; set; }
    public virtual InvoiceType Type { get; set; }
}

Receipt Domain Statistics:

• Receipt Types: 8 main types (Offer, Order, Invoice, etc.)
• Receipt Items: 20+ item-related entities
• Article Integration: Links to merchandise management
• Price Calculation: Complex pricing entity relationships

3.3 Customer Asset Domain

SW-DOM-003: Asset Management Entities

• Entity Count: 80+ asset-related entities
• Asset Lifecycle: Purchase → Installation → Service → Disposal
• Service Integration: Links to helpdesk and support systems

Core Asset Entities:

public class CustomerAsset : PersistedEntity
{
    public virtual int CustomerI3D { get; set; }
    public virtual int ArticleI3D { get; set; }
    public virtual string SerialNumber { get; set; }
    public virtual DateTime? PurchaseDate { get; set; }
    public virtual DateTime? WarrantyEndDate { get; set; }
    public virtual AssetCondition Condition { get; set; }
    public virtual decimal PurchasePrice { get; set; }
    public virtual string Location { get; set; }

    // Navigation properties
    public virtual Customer Customer { get; set; }
    public virtual Article Article { get; set; }
    public virtual IList<ServiceOrder> ServiceOrders { get; set; }
    public virtual IList<AssetContract> Contracts { get; set; }
}

3.4 Administration Domain

SW-DOM-004: System Administration Entities

• Entity Count: 200+ administration entities
• Categories: Users, Rights, Settings, Company, Logging
• Security Model: Role-based access control implementation

Key Administration Entities:

Entity Category	Entity Count	Key Entities
User Management	25+	Employee, User, UserLogin, UserRights
Company Structure	30+	Mandator, Branch, CompanyGroup
System Settings	40+	ApplicationSetting, SystemConfiguration
Document Management	35+	Document, Directory, FileReference
Audit and Logging	20+	AuditLog, SystemLog, ChangeTracking

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4. Database Schema Implementation

4.1 Primary Key Strategy

SW-SCHEMA-001: Primary Key Implementation

• Column Name: I3D (Integer 3 Digits, legacy naming)
• Data Type: INT IDENTITY(1,1) NOT NULL
• Clustering: Clustered primary key on I3D

SQL Schema Pattern:

CREATE TABLE [dbo].[Accounts] (
    [I3D] INT IDENTITY(1,1) NOT NULL,
    [Number] INT NOT NULL,
    [Name] NVARCHAR(255) NOT NULL,
    [Matchcode] NVARCHAR(64) NULL,
    [Email] NVARCHAR(255) NULL,
    [IsActive] BIT NOT NULL DEFAULT(1),
    [CreatedDate] DATETIME2(2) NULL,
    [ChangedDate] DATETIME2(2) NULL,
    [CreatedByI3D] INT NULL,
    [ChangedByI3D] INT NULL,
    [IsDeleted] BIT NOT NULL DEFAULT(0),

    CONSTRAINT [PK_Accounts] PRIMARY KEY CLUSTERED ([I3D])
);

4.2 Foreign Key Conventions

SW-SCHEMA-002: Foreign Key Implementation

• Naming: {ReferencedEntity}I3D
• Nullable: Most foreign keys nullable to support partial data
• Constraints: Declarative referential integrity

Foreign Key Examples:

-- Account to Employee reference
ALTER TABLE [Accounts] ADD CONSTRAINT [FK_Accounts_CreatedBy]
    FOREIGN KEY ([CreatedByI3D]) REFERENCES [Employees]([I3D]);

-- Account Address to Account reference
ALTER TABLE [AccountAddresses] ADD CONSTRAINT [FK_AccountAddresses_Account]
    FOREIGN KEY ([AccountI3D]) REFERENCES [Accounts]([I3D]);

4.3 Audit Trail Implementation

SW-SCHEMA-003: Audit Field Standard

• Creation: CreatedDate, CreatedByI3D, CreatedVersion
• Modification: ChangedDate, ChangedByI3D, ChangedVersion
• Deletion: IsDeleted, DeletedDate, DeletedByI3D

Audit Trigger Pattern (Implemented where needed):

CREATE TRIGGER [TR_Accounts_Audit] ON [Accounts]
AFTER INSERT, UPDATE
AS
BEGIN
    UPDATE a SET
        ChangedDate = GETUTCDATE(),
        ChangedByI3D = SYSTEM_USER
    FROM [Accounts] a
    INNER JOIN inserted i ON a.I3D = i.I3D
END

---

5. NHibernate Mapping Configuration

5.1 FluentNHibernate Mapping Pattern

SW-MAP-001: Standard Mapping Implementation

• Location: src/backend/Centron.DAO/Mappings/{Domain}/{Entity}Maps.cs
• Pattern: ClassMap inheritance
• Configuration: Table name, column mappings, relationships

Example Mapping Implementation:

// File: src/backend/Centron.DAO/Mappings/Accounts/AccountMaps.cs
public class AccountMaps : ClassMap<Account>
{
    public AccountMaps()
    {
        // Table mapping
        Table("Accounts");

        // Primary key
        Id(m => m.I3D).Column("I3D");

        // Simple properties
        Map(m => m.Number).Column("Number").Not.Nullable();
        Map(m => m.Name).Column("Name").Length(255);
        Map(m => m.Email).Column("Email").Length(255).Nullable();
        Map(m => m.IsActive).Column("IsActive");

        // Audit fields
        Map(m => m.CreatedDate).Column("CreatedDate").Nullable();
        Map(m => m.CreatedByI3D).Column("CreatedByI3D").Nullable();
        Map(m => m.ChangedDate).Column("ChangedDate").Nullable();
        Map(m => m.ChangedByI3D).Column("ChangedByI3D").Nullable();

        // One-to-many relationships
        HasMany(m => m.Addresses)
            .KeyColumn("AccountI3D")
            .Cascade.All()
            .Lazy();

        HasMany(m => m.AccountTypes)
            .KeyColumn("AccountI3D")
            .Cascade.All()
            .Lazy();
    }
}

5.2 Relationship Mapping Patterns

SW-MAP-002: Association Mapping Strategy

• One-to-Many: HasMany() with KeyColumn
• Many-to-One: References() with Column
• Many-to-Many: HasManyToMany() with intermediate table
• Component: Component() for value objects

Complex Relationship Example:

public class ReceiptMaps : ClassMap<Receipt>
{
    public ReceiptMaps()
    {
        Table("Receipts");
        Id(m => m.I3D).Column("I3D");

        // Many-to-one customer reference
        References(m => m.Customer)
            .Column("CustomerI3D")
            .Nullable()
            .Lazy();

        // One-to-many receipt items
        HasMany(m => m.Items)
            .KeyColumn("ReceiptI3D")
            .Cascade.AllDeleteOrphan()
            .Lazy();

        // Component mapping for value object
        Component(m => m.DeliveryAddress, address =>
        {
            address.Map(a => a.Street).Column("DeliveryStreet");
            address.Map(a => a.City).Column("DeliveryCity");
            address.Map(a => a.PostalCode).Column("DeliveryPostalCode");
        });
    }
}

5.3 Lazy Loading Configuration

SW-MAP-003: Performance Optimization Strategy

• Default: Lazy loading enabled for collections
• Eager Loading: Fetch joins for frequently accessed associations
• Batch Size: Configured batch sizes for N+1 query prevention

Lazy Loading Implementation:

// Lazy loading (default)
HasMany(m => m.Items).Lazy();

// Eager loading for critical paths
HasMany(m => m.Items)
    .Fetch.Join()
    .BatchSize(50);

// No lazy loading for small datasets
HasMany(m => m.StatusHistory)
    .Not.LazyLoad()
    .Cascade.All();

---

6. Data Relationships and Constraints

6.1 Domain Model Relationships

SW-REL-001: Core Business Relationships

erDiagram
    ACCOUNT ||--o{ ACCOUNT_ADDRESS : has
    ACCOUNT_ADDRESS ||--o{ ACCOUNT_ADDRESS_CONTACT : has
    ACCOUNT ||--o{ RECEIPT : creates
    RECEIPT ||--o{ RECEIPT_ITEM : contains
    RECEIPT_ITEM }o--|| ARTICLE : references
    CUSTOMER_ASSET }o--|| CUSTOMER : belongs_to
    CUSTOMER_ASSET }o--|| ARTICLE : is_instance_of
    CUSTOMER_ASSET ||--o{ SERVICE_ORDER : requires

Key Relationship Patterns:

1. Account Hierarchy: Account → Address → Contact
2. Receipt Processing: Customer → Receipt → Item → Article
3. Asset Management: Customer → Asset → Service → Contract
4. User Management: Employee → User → Rights → Functions

6.2 Referential Integrity

SW-REL-002: Database Constraint Implementation

• Primary Keys: Enforced at database level
• Foreign Keys: Declarative constraints with appropriate actions
• Check Constraints: Business rule enforcement
• Unique Constraints: Data uniqueness requirements

Constraint Examples:

-- Unique account number constraint
ALTER TABLE [Accounts] ADD CONSTRAINT [UQ_Accounts_Number]
    UNIQUE ([Number]);

-- Check constraint for valid email format
ALTER TABLE [Accounts] ADD CONSTRAINT [CK_Accounts_Email]
    CHECK ([Email] LIKE '%_@_%.__%' OR [Email] IS NULL);

-- Foreign key with cascade delete
ALTER TABLE [AccountAddresses] ADD CONSTRAINT [FK_AccountAddresses_Account]
    FOREIGN KEY ([AccountI3D]) REFERENCES [Accounts]([I3D])
    ON DELETE CASCADE;

6.3 Data Consistency Rules

SW-REL-003: Business Rule Enforcement

• Account Status: Active accounts cannot be deleted, only deactivated
• Receipt Workflow: State transitions must follow defined workflow
• Financial Integrity: Invoice totals must match item sum plus tax
• Asset Tracking: Assets must have valid customer and article references

---

7. Data Validation and Business Rules

7.1 Entity Validation Framework

SW-VAL-001: Validation Implementation

• Level 1: Property-level validation in entity setters
• Level 2: Entity-level validation in business logic
• Level 3: Cross-entity validation in aggregates
• Level 4: Database constraint validation

Validation Pattern Example:

public class Account : BaseEntity, IValidatableObject
{
    private string _name;
    public virtual string Name
    {
        get => _name;
        set
        {
            if (string.IsNullOrWhiteSpace(value))
                throw new ArgumentException("Account name cannot be empty");
            if (value.Length > 255)
                throw new ArgumentException("Account name too long");
            _name = value;
        }
    }

    public IEnumerable<ValidationResult> Validate(ValidationContext context)
    {
        var results = new List<ValidationResult>();

        // Email validation
        if (!string.IsNullOrEmpty(Email) && !IsValidEmail(Email))
        {
            results.Add(new ValidationResult("Invalid email format",
                new[] { nameof(Email) }));
        }

        // Account number validation
        if (Number <= 0)
        {
            results.Add(new ValidationResult("Account number must be positive",
                new[] { nameof(Number) }));
        }

        return results;
    }
}

7.2 Business Rule Implementation

SW-VAL-002: Domain-Specific Validation Rules

• Account Management: Name uniqueness, valid contact information
• Receipt Processing: State transition validation, price consistency
• Asset Management: Serial number uniqueness, warranty date logic
• Financial: Tax calculation correctness, currency constraints

Business Rule Examples:

public class AccountBusinessRules
{
    public Result<bool> ValidateAccountCreation(Account account)
    {
        // Rule 1: Account name must be unique within mandator
        if (IsAccountNameDuplicate(account.Name, account.MandatorI3D))
        {
            return Result.Error("Account name already exists in this mandator");
        }

        // Rule 2: At least one address must be marked as main address
        if (account.Addresses?.Any(a => a.IsMainAddress) != true)
        {
            return Result.Error("Account must have at least one main address");
        }

        // Rule 3: Customer accounts must have valid tax number if required
        if (account.AccountTypes.Any(t => t.Type.RequiresTaxNumber) &&
            string.IsNullOrEmpty(account.TaxNumber))
        {
            return Result.Error("Tax number required for this account type");
        }

        return Result.Success(true);
    }
}

---

8. Data Flow and Transformation

8.1 Entity-DTO Transformation Pipeline

SW-FLOW-001: Data Transformation Architecture

• Inbound: DTO → Entity conversion for API requests
• Outbound: Entity → DTO conversion for API responses
• Validation: Data validation at transformation boundaries
• Security: Sensitive field filtering during transformation

Transformation Pipeline:

public class AccountDataTransformer
{
    public Account ConvertDTOToEntity(AccountDTO dto)
    {
        // 1. Create entity instance
        var entity = new Account();

        // 2. Map simple properties
        entity.Number = dto.Number;
        entity.Name = dto.Name;
        entity.Email = dto.Email;

        // 3. Handle complex properties
        entity.Addresses = dto.Addresses?
            .Select(ConvertAddressDTO)
            .ToList() ?? new List<AccountAddress>();

        // 4. Apply business rules during conversion
        ValidateAndApplyBusinessRules(entity);

        return entity;
    }

    public AccountDTO ConvertEntityToDTO(Account entity)
    {
        // 1. Ensure entity is not connected to NHibernate session
        NHibernateUtil.Initialize(entity);

        // 2. Use ObjectMapper for conversion
        var dto = ObjectMapper.Map<AccountDTO>(entity);

        // 3. Filter sensitive information
        FilterSensitiveFields(dto);

        return dto;
    }
}

8.2 Data Synchronization Patterns

SW-FLOW-002: Multi-Source Data Management

• External APIs: Sync product data from suppliers
• Legacy Systems: Import existing customer data
• Web Services: Real-time data exchange with client applications
• Batch Processing: Nightly data consolidation and cleanup

Synchronization Example:

public class DataSynchronizationService
{
    public async Task<Result<bool>> SynchronizeCustomerData()
    {
        // 1. Load pending sync items
        var pendingSyncs = await LoadPendingSynchronizations();

        // 2. Process each sync item
        foreach (var sync in pendingSyncs)
        {
            try
            {
                // 3. Transform external data format
                var entity = await TransformExternalData(sync.ExternalData);

                // 4. Validate and merge with existing data
                var mergeResult = await MergeWithExistingEntity(entity);
                if (!mergeResult.IsSuccess) continue;

                // 5. Save changes and mark sync complete
                await SaveEntity(mergeResult.Value);
                await MarkSyncComplete(sync.I3D);
            }
            catch (Exception ex)
            {
                await LogSyncError(sync.I3D, ex);
            }
        }

        return Result.Success(true);
    }
}

8.3 Change Tracking Implementation

SW-FLOW-003: Entity Change Detection

• NHibernate Events: Automatic change detection via interceptors
• Audit Logging: Complete audit trail of all entity modifications
• Version Control: Optimistic locking with version stamps
• Change Notifications: Event publishing for interested subscribers

Change Tracking Pattern:

public class EntityChangeTracker : IInterceptor
{
    public bool OnSave(object entity, object id, object[] state,
        string[] propertyNames, IType[] types)
    {
        if (entity is PersistedEntity persistedEntity)
        {
            // Set audit fields for new entities
            var now = DateTime.UtcNow;
            var userId = GetCurrentUserId();

            persistedEntity.CreatedDate = now;
            persistedEntity.CreatedByI3D = userId;

            // Log entity creation
            LogEntityChange("CREATE", entity.GetType().Name, id, state);
        }

        return false;
    }

    public bool OnFlushDirty(object entity, object id, object[] currentState,
        object[] previousState, string[] propertyNames, IType[] types)
    {
        if (entity is PersistedEntity persistedEntity)
        {
            // Set audit fields for modified entities
            persistedEntity.ChangedDate = DateTime.UtcNow;
            persistedEntity.ChangedByI3D = GetCurrentUserId();

            // Log detailed field changes
            LogFieldChanges(entity.GetType().Name, id, propertyNames,
                previousState, currentState);
        }

        return false;
    }
}

---

Performance and Scalability

Database Performance Optimization

Indexing Strategy:

• Primary Keys: Clustered indexes on I3D columns
• Foreign Keys: Non-clustered indexes on all FK columns
• Search Fields: Composite indexes on frequently searched combinations
• Query Optimization: Index hints and query plan analysis

Sample Index Strategy:

-- Primary key (clustered)
CREATE CLUSTERED INDEX [PK_Accounts] ON [Accounts]([I3D]);

-- Foreign key indexes
CREATE NONCLUSTERED INDEX [IX_Accounts_CreatedBy]
    ON [Accounts]([CreatedByI3D]);

-- Search optimization indexes
CREATE NONCLUSTERED INDEX [IX_Accounts_Search]
    ON [Accounts]([Name], [Matchcode], [Email])
    INCLUDE ([Number], [IsActive]);

-- Date range queries
CREATE NONCLUSTERED INDEX [IX_Accounts_DateRange]
    ON [Accounts]([CreatedDate], [ChangedDate])
    WHERE [IsDeleted] = 0;

Memory and Session Management

NHibernate Performance:

• Session Scope: Session-per-request pattern
• Lazy Loading: Optimized lazy loading configuration
• Batch Processing: Batch sizes configured for large datasets
• Cache Strategy: Second-level cache for reference data

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Document Approval

• Database Architect: Schema design and constraints verified
• Data Modeler: Entity relationships and mappings validated
• Performance Engineer: Query optimization and indexing approved
• Security Officer: Data protection and audit requirements confirmed
• Date: 2025-09-30
• Version Control: Committed to repository requirements/software/