CQRS & Application Layer

The Alert.CA.Admin.API.Application project implements the Command Query Responsibility Segregation (CQRS) pattern using MediatR. Every API request flows through this layer — controllers never access repositories or services directly.

Request Pipeline

Module Organization

The application layer is organized by domain module. Each module contains its own commands, queries, and handlers:

Alert.CA.Admin.API.Application/
├── DeviceConfig/
│   ├── Commands/
│   │   ├── CreateDeviceConfigCommand.cs
│   │   ├── UpdateDeviceConfigCommand.cs
│   │   └── DeleteDeviceConfigCommand.cs
│   └── Queries/
│       ├── GetAllDeviceConfigsQuery.cs
│       └── GetDeviceConfigByIdQuery.cs
├── ImageAcquisition/
│   ├── Commands/
│   └── Queries/
├── AxisCamera/
│   ├── Commands/
│   └── Queries/
├── UserAgencyCamera/
│   ├── Commands/
│   └── Queries/
├── Users/
├── Locations/
├── FeatureFlags/
├── ActivityLog/
└── EsriMapSync/
    ├── Commands/
    │   ├── ConvertToArcgisJsonCommand.cs
    │   ├── QueryEsriObjectIdsCommand.cs
    │   ├── DeleteEsriFeaturesCommand.cs
    │   ├── UploadEsriFeaturesCommand.cs
    │   └── FullEsriMapSyncCommand.cs
    ├── Queries/
    │   ├── GetEsriSyncConfigQuery.cs
    │   ├── GetEsriCameraDataQuery.cs
    │   └── GetEsriTokenQuery.cs
    └── Models/

Audit Behavior

The AuditBehavior<TRequest, TResponse> is a MediatR pipeline behavior that automatically logs audit records for any command implementing IAuditCommand:

What Gets Audited

• Who — User identity from JWT claims
• What — Command type and parameters
• When — Timestamp
• Result — Success or failure

This ensures every write operation has a traceable audit trail without requiring individual handlers to implement logging.

Registered Services

The DependencyInjection class registers all application-layer services:

Service	Interface	Purpose
Onboarding Service	IOnboardingService	Multi-step camera onboarding workflow
Bulk Operations Service	IBulkOperationsService	Batch camera operations
Location File Service	ILocationFileService	Location data file parsing and import
Durable Entity Service	IDurableEntityService	Interaction with Durable Functions entities
Feature Layer Service	IFeatureLayerService	ESRI feature layer updates
UCSD Client	IUCSDClient	UCSD Metadata API integration
ESRI Client	IESRIClient	ESRI GIS service integration
ESRI Map Sync Service	IEsriMapSyncService	Full ESRI map layer sync workflow

Adding a New Feature

To add a new feature to the Admin API:

1. Create a command or query in the appropriate module under Alert.CA.Admin.API.Application
2. Create a handler implementing IRequestHandler<TRequest, TResponse>
3. If the command modifies data, implement IAuditCommand to get automatic audit logging
4. Add a controller action in Alert.CA.Admin.API that calls _mediator.Send(command)
5. MediatR auto-discovers handlers — no manual registration needed