Saga-Pattern-Orchestration-Eventual-Consistency

The aim of this project is to process the Eventual Consistency by following the best practices with Saga Pattern Orchestration on NETCore.

Eventual Consistency - Saga Pattern

A transaction management pattern used in distributed systems and microservices architectures.
Other systems come into play in sequence based on the success status.
There is no atomic state.
In case of possible errors, Compensable Transaction will be activated, and all operations will be rolled back.
- This ensures data consistency.
What is the purpose of Saga?
- To introduce a model for managing long-lived and complex transactions in distributed systems and microservices.
- Aims to make the system more modular and scalable.
There may be short delays between services.
There are two different approaches: Events/Choreography and Command/Orchestration.

Distributed transactions between services are coordinated with a central controller.
This controller is referred to as Saga State Machine or alternatively as Saga Orchestrator.
Saga Orchestrator manages all transactions between services and dictates which operations to perform based on events.
Saga State Machine keeps track of the application state related to user requests, interprets it, and applies compensatory operations when necessary.
Easily applicable in systems with multiple services.
Provides centralized control.
No need for services to be aware of any information about each other.

The class that provides us with the structure of the state machine. It plays a central role in determining states, events, and specific behaviors.
Manages distributed transactions.
To be a state machine class, it needs to implement the MassTransitStateMachine<T> interface.
The generic T specified is an instance of a State.

A class representing the data of a State Machine.
For example, each order request with different data will be stored as a state instance in the database.
To be a state instance, it needs to implement the SagaStateMachineInstance interface.
The CorrelationId is used to distinguish between these two requests.

The context object that manages the database where State Machine data is stored.
Derives from the abstract class SagaDbContext.

The class that allows for validation settings of properties in the saved State Instance in the database.
Derives from the abstract class SagaClassMap<T>.
Generic parameter T is a State Instance.

Triggering Event
- An event that triggers the corresponding service.
Successful Event
- An event indicating that the operation has been successfully completed.
Failure Event
- An event indicating that the operation has failed.
Compensable Event
- An event indicating the reversal of the performed operation.