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Level 2 - Detailed Service Decomposition

Here we zoom into the most important building blocks from Level 1, showing their internal structure and components based on the actual implementation. We focus on the core business services that represent the most complexity and business value.

Catalog Service - Internal Structure​

The Catalog Service manages product catalog, AI-powered search, and file storage with sophisticated AI integration.

Catalog Endpoints​

Purpose/Responsibility Exposes HTTP REST endpoints for catalog operations including book management, search, and metadata operations.

Interface(s)

  • REST API for book CRUD operations
  • Search and filtering endpoints
  • File upload/download endpoints

Catalog Facade​

Purpose/Responsibility Core business logic coordinator that orchestrates operations across storage, vector, and LLM services.

Interface(s)

  • Business operation coordination
  • Transaction management
  • Domain rule enforcement

Vector Service​

Purpose/Responsibility Manages vector embeddings for semantic search capabilities using AI models.

Interface(s)

  • Vector embedding generation
  • Similarity search operations
  • Index management

Storage Service​

Purpose/Responsibility Manages book files and metadata storage in Azure Blob Storage.

Interface(s)

  • File upload/download operations
  • Metadata management
  • Storage optimization

LLM Service​

Purpose/Responsibility Provides AI-powered recommendations and chat interactions using large language models.

Interface(s)

  • AI recommendation generation
  • Chat model integration
  • Vector database queries

Order Service - Internal Structure​

The Order Service handles order lifecycle management with event-driven architecture.

Order Endpoints​

Purpose/Responsibility REST API endpoints for order management including creation, updates, queries, and buyer management.

Interface(s)

  • Order CRUD operations
  • Buyer management endpoints
  • Order status tracking
  • Real-time order streaming

Order Facade​

Purpose/Responsibility Core business logic for order processing, state management, and business rule enforcement.

Interface(s)

  • Order lifecycle management
  • Business rule validation
  • Integration with external services

Event Publisher​

Purpose/Responsibility Publishes domain events for order state changes to notify other services.

Interface(s)

  • Event publishing to message bus
  • Event subscription handling
  • Message routing and delivery

Finance Service - Internal Structure​

The Finance Service implements saga orchestration for distributed transaction management.

Finance Endpoints​

Purpose/Responsibility Provides API endpoints for retrieving state machine information and financial operation status.

Interface(s)

  • State machine query endpoints
  • Transaction status queries
  • Financial reporting APIs

Saga Orchestrator​

Purpose/Responsibility Coordinates distributed transactions across multiple services using the Saga pattern for order processing.

Interface(s)

  • Saga workflow coordination
  • Distributed transaction management
  • Compensation action handling
  • State persistence and recovery

Chat Service - Internal Structure​

The Chat Service provides AI-powered conversational capabilities with advanced model integration.

Chat Endpoints​

Purpose/Responsibility REST API endpoints for chat session management and real-time conversation handling.

Interface(s)

  • Chat session CRUD operations
  • Real-time chat streaming
  • Chat history retrieval

Chat Facade​

Purpose/Responsibility Core business logic for chat management, session handling, and conversation flow control.

Interface(s)

  • Chat session orchestration
  • Business rule enforcement
  • Integration coordination

LLM Service​

Purpose/Responsibility Handles AI-powered conversations using large language models with tool integration capabilities.

Interface(s)

  • AI conversation processing
  • Model Context Protocol (MCP) integration
  • Chat model interaction
  • Context management and persistence

Supporting Services​

Basket Service​

Rating Service​

Notification Service​

API Layer​

Purpose/Responsibility Exposes HTTP REST endpoints for catalog operations including product browsing, search, and catalog management.

Interface(s)

  • HTTP REST API for external clients
  • OpenAPI/Swagger documentation
  • JWT authentication integration

Quality/Performance Characteristics

  • Response caching for read operations
  • Rate limiting and throttling
  • Input validation and sanitization

gRPC Service​

Purpose/Responsibility Provides high-performance internal API for other services to retrieve product information.

Interface(s)

  • gRPC protocol buffers interface
  • Service discovery integration
  • Load balancing support

Quality/Performance Characteristics

  • Low-latency communication
  • Binary serialization
  • Connection pooling

Search Engine​

Purpose/Responsibility Implements AI-powered semantic search using vector embeddings for intelligent product discovery.

Interface(s)

  • Vector similarity search
  • Text search with ranking
  • Filter and faceting capabilities

Quality/Performance Characteristics

  • Sub-second search response times
  • Relevance scoring and ranking
  • Real-time index updates

Inventory Manager​

Purpose/Responsibility Manages product stock levels, availability, and inventory operations.

Interface(s)

  • Stock level queries
  • Inventory reservation and release
  • Stock movement tracking

Quality/Performance Characteristics

  • ACID transactions for stock operations
  • Optimistic concurrency control
  • Real-time stock updates

Order Service - Internal Structure​

The Order Service orchestrates the complex order fulfillment process across multiple services.

Order API​

Purpose/Responsibility Provides RESTful endpoints for order creation, modification, tracking, and management.

Interface(s)

  • CRUD operations for orders
  • Order status tracking
  • Order history and reporting

Quality/Performance Characteristics

  • Idempotent operations
  • Request validation
  • Audit logging

Order Workflow​

Purpose/Responsibility Manages the order state machine and lifecycle from creation to completion.

Interface(s)

  • State transition management
  • Business rule enforcement
  • Workflow persistence

Quality/Performance Characteristics

  • Reliable state transitions
  • Compensation actions
  • Recovery from failures

Saga Orchestrator​

Purpose/Responsibility Coordinates distributed transactions across multiple services using the Saga pattern.

Interface(s)

  • Saga definition and execution
  • Compensation transaction handling
  • Cross-service coordination

Quality/Performance Characteristics

  • Eventually consistent transactions
  • Failure isolation
  • Automatic retry and compensation