> this chapter give the reader a general and comperhencevie overview on the clean acrchitecture and some DDD principles.
### General Into to CA & DDD
Clean Architecture and Domain-Driven Design (DDD) are both pivotal methodologies in modern software development that focus on creating robust, maintainable, and scalable systems.
**Clean Architecture**, popularized by Robert C. Martin, emphasizes the separation of concerns within an application. It organizes code into distinct layers, each with its own responsibility, such as the domain, application, interface, and infrastructure layers. This separation ensures that business logic remains independent of external factors like UI frameworks and data storage mechanisms. By adhering to this structure, Clean Architecture promotes code that is easier to test, maintain, and evolve over time, as changes in one layer have minimal impact on others.
**Domain-Driven Design (DDD)**, introduced by Eric Evans, centers on modeling complex business domains and aligning the software design closely with business needs. DDD advocates for creating a shared language between developers and domain experts, focusing on the core domain and its interactions. It involves defining bounded contexts, which are distinct areas of the domain with their own models and rules, ensuring that different parts of the system communicate effectively while preserving their own integrity. By focusing on the domain model and its entities, DDD helps in developing software that is more aligned with business objectives and adaptable to changing requirements.
When combined, Clean Architecture and DDD provide a powerful framework for building software that is not only well-organized and maintainable but also deeply aligned with business logic, facilitating clearer communication between technical and non-technical stakeholders and fostering a more responsive and agile development process.
In the context of ASP.NET Core, Clean Architecture and Domain-Driven Design (DDD) can significantly enhance the maintainability and scalability of applications. These methodologies, along with Command Query Responsibility Segregation (CQRS), provide a structured approach to organizing code and managing complex business requirements.
### **Clean Architecture in ASP.NET Core**
**Clean Architecture** focuses on creating a well-organized, decoupled system by separating concerns into distinct layers. In ASP.NET Core, Clean Architecture can be implemented as follows:
1.**Core Layer (Domain Layer)**:
-**Entities**: Represents the core business objects or models.
-**Value Objects**: Immutable objects that represent descriptive aspects of the domain.
-**Aggregates and Aggregate Roots**: Groups of related entities that are treated as a single unit for data changes.
-**Interfaces**: Define contracts for repositories and services that interact with the domain.
2.**Application Layer**:
-**Use Cases**: Contains application-specific business logic and orchestrates the flow of data between the domain and presentation layers.
-**DTOs (Data Transfer Objects)**: Simplified data structures used for communication between the layers.
3.**Infrastructure Layer**:
-**Repositories**: Implement data access logic and interact with the database or other external storage.
-**Services**: Implement services like file storage, email sending, etc.
4.**Presentation Layer**:
-**Controllers**: Handle HTTP requests, interact with the application layer, and return HTTP responses.
-**Views**: Define the user interface (in web applications) and handle user input.
By adhering to this layered architecture, ASP.NET Core applications can achieve:
-**Separation of Concerns**: Each layer has a clear responsibility, making the system easier to understand and maintain.
-**Testability**: Core business logic is isolated from infrastructure concerns, allowing for easier unit testing.
-**Flexibility**: Changes in one layer (e.g., switching from SQL Server to MongoDB) have minimal impact on other layers.
### **Domain-Driven Design (DDD) in ASP.NET Core**
**Domain-Driven Design (DDD)** emphasizes building software based on the core business domain and its logic. In ASP.NET Core, DDD is applied through:
1.**Domain Models**: Represent the core business concepts and rules. Entities, value objects, and aggregates are designed to reflect the real-world domain.
2.**Bounded Contexts**: Define distinct areas of the domain with clear boundaries. Each bounded context has its own domain model and language, ensuring that different parts of the system do not interfere with each other.
3.**Ubiquitous Language**: A common vocabulary shared by developers and domain experts to ensure clarity and alignment throughout the project.
4.**Repositories**: Repositories handle data acces, ensuring that domain rules are maintained when data is persisted.By offer a Contract for store and retreive data independ of the data store approach
5.**Domain Events**: Represent significant changes or actions within the domain. They can trigger processes or updates across different parts of the system.
### **Command Query Responsibility Segregation (CQRS) in ASP.NET Core**
**CQRS** is a pattern that separates the read and write operations of a system into distinct models, each optimized for its specific task:
1.**Commands**: Represent actions that change the state of the system. These are handled by command handlers, which process the command, perform the necessary business logic, and update the state.
2.**Queries**: Represent requests for data without changing the state. These are handled by query handlers, which retrieve data from read models optimized for querying.
In ASP.NET Core, CQRS is implemented as follows:
-**Command Handlers**: Manage the execution of commands, interacting with the domain and possibly updating the state in the database.
-**Query Handlers**: Fetch and return data based on queries, often using specialized read models that are optimized for performance.
**Benefits**:
-**Maintainability**: Clear separation of concerns and well-defined boundaries make the system easier to maintain and evolve.
-**Scalability**: CQRS allows for scalable read and write operations, handling complex queries and high-throughput scenarios efficiently.
-**Alignment with Business Goals**: DDD ensures that the software remains aligned with business needs and processes.
By applying these methodologies in ASP.NET Core, developers can build applications that are well-structured, flexible, and capable of adapting to changing business requirements.
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## Solution Components
### General Overview
### Soltuion Architecture
the solution to achive the requirement has 8 projects
and one prpject for teting the architecture as shown below in the figure
2. Applciation Layer achived by applciation project
3. Shared kernell Layer achived by shard kernell project
4. Presentaion Layer achived by presentaion and api and contracts projects
5. Infrastructure Layer achived by Persistence and Services projects
6. Architecture Tests achived by architecture tests project
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## Shared Kernel Layer
As its defined by " a concept from Domain-Driven Design (DDD) that refers to a part of the domain model that is shared across multiple bounded contexts within a system. It serves as a common area where multiple parts of the system agree on certain domain concepts and implementations, ensuring consistency and reducing duplication".
in our solution we use it to put our absttraction in its.
which represent the abstracion and base of the cmmands and queries by those interfaces
ICommand and ILoggable Command
IQuery and ILoaggableQuery
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2. Domain Events:
contain the abstraction of events and there handlers by the interfaces IDomainEvent & IDomainEventHandler
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3. Domain Errors:
the base of the errors
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4. Repository :
the base of repository
and so on for the rest.
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## Domain Layer
this layer and as we mention in the System Design Chapeter in the report in the paragraph **1.7 Design Principles** we have 7 domains which is as the follow :
1. Projects Domain
2. Projects Types Domain
3. Customers Domain
4. Employees Domain
5. Tracking Domain
6. Steps Domain
7. Financial Spends
so in the domain layer we have 7 folders one for each domain and we have a folder for the identity domain
the service layer conatin a real implementation for the integration of the employee data
and contain only dummy implementation of bringing the data.
its also contain cron job for sync the data
its call the (sync data service for sync)
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## Presentaion Layer
the presentaion layer contain three projects
one for contract and has no dependency on ay project, its conatin the request and response for the API Endpoints
one for API config and middlewares sets
its responsibile for inject the deoendencies and chose the infrastructure layer.
and one for presentation its contain the controllers and mappers from request to commands and from DTO's to Response.
contracts project
Presentation proejct
API Dependency Config in its project
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## Architecture Tests
**Architecture Testing for Clean Architecture** is a practice that ensures the adherence to architectural principles and patterns defined in the Clean Architecture approach. In Clean Architecture, the primary goal is to achieve a separation of concerns where business logic is independent of frameworks, UI, and external systems. Architecture tests verify that the dependencies between layers are correctly enforced — for example, ensuring that the application layer does not directly reference the infrastructure layer. They also ensure that use cases and domain logic remain isolated from external frameworks.
**Naming Convention Tests for CQRS and Events** (Command Query Responsibility Segregation) are designed to enforce consistency and clarity in naming commands, queries, handlers, and other components associated with the CQRS pattern.
Naming convention tests ensure that commands and queries are named descriptively and according to predefined standards (e.g., suffixing with `Command` or `Query`), which helps maintain clarity and understanding of their responsibilities.and the smae for events.
## for dependency test (layer test)
we do the test that shown in the image and its success
