Overview

The Rating domain is responsible for collecting and managing customer feedback for books in the BookWorm ecosystem. As a core domain, it implements Domain-Driven Design principles with a well-defined bounded context focused on the feedback lifecycle. This domain enables customers to share their experiences and ratings, helping other users make informed purchasing decisions.

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1 services are in this domain

This service publishes domain events to other bounded contexts

Domain Model

Domain Events

The domain publishes events to notify other parts of the system about feedback changes:

• FeedbackCreatedEvent: Triggered when a new feedback is submitted
• FeedbackDeletedEvent: Triggered when a feedback is removed

Value Objects

• Rating: An integer value between 0 and 5, representing the customer’s satisfaction level

Domain Rules

• Ratings must be between 0 and 5 stars
• Each feedback is associated with a specific book
• Feedback can include optional comments and customer information

Strategic Design

Bounded Context

The Rating domain maintains a clear boundary around feedback management, with well-defined interfaces to other domains:

• Catalog Context: Receives book rating updates to display on product pages
• Customer Context: Provides customer information for feedback attribution

Context Mapping

• Partnership with Catalog domain: Bidirectional relationship where ratings affect book visibility and popularity
• Customer-Supplier with Identity domain: Consumes user information to associate with feedback

Tactical Design

Application Services

The domain implements CQRS pattern with distinct commands and queries:

• Commands:

  • CreateFeedbackCommand: Adds a new feedback for a book
  • DeleteFeedbackCommand: Removes an existing feedback

• Queries:

  • ListFeedbackQuery: Retrieves feedback for a specific book
  • GetAverageRatingQuery: Calculates the average rating for a book

Repository Pattern

The IFeedbackRepository provides an abstraction over the persistence mechanism:

• AddAsync: Persists new feedback
• GetByIdAsync: Retrieves feedback by ID
• ListAsync: Retrieves feedback based on specifications
• CountAsync: Counts feedback matching specifications
• Delete: Removes feedback

Integration Events

The domain publishes integration events to notify other bounded contexts:

• FeedbackCreatedIntegrationEvent: Notifies the Catalog service about new ratings
• FeedbackDeletedIntegrationEvent: Notifies the Catalog service about removed ratings

Architecture diagram

Messages for this domain

Sends messages (2)

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Events (2)

Name	Version	Type	Summary
Created Feedback	v1.0.0	event	Represents a successful integration event when creating a feedback in the system
Deleted Feedback	v1.0.0	event	Represents a successful integration event when deleting a feedback in the system

Receives messages (4)

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Events (1)Queries (1)Commands (2)

Name	Version	Type	Summary
Updated Book Rating Fail	v1.0.0	event	Represents a failed integration event when updating a book's rating in the system
List Feedbacks	v1.0.0	query	Get feedbacks for a book
Create Feedback	v1.0.0	command	Create feedback for a book
Delete Feedback	v1.0.0	command	Delete feedback for a book in the Rating Service

Technical Implementation

The Rating domain is implemented using:

• Aggregate Pattern: Encapsulates business rules and invariants
• Domain Events: For internal communication within the bounded context
• Integration Events: For cross-bounded context communication
• CQRS: Separating read and write operations
• Specification Pattern: For flexible query composition