Hexalith.EventStores.Abstractions 1.0.0

Hexalith.EventStores.Abstractions

This package defines the core abstractions and interfaces for the Hexalith.EventStores library, providing a contract for event store implementations.

Core Components

IEventStore

The IEventStore interface is the primary contract for event stores, defining methods for:

• Adding events to a stream
• Retrieving events with or without snapshots
• Creating and managing snapshots
• Managing store lifecycle (open/close)
• Handling versioning

public interface IEventStore
{
    Task<long> AddAsync(IEnumerable<EventMessage> items, CancellationToken cancellationToken);
    Task<IEnumerable<EventMessage>> GetAsync(CancellationToken cancellationToken);
    Task<IEnumerable<EventMessage>> GetAsync(bool useSnapshot, CancellationToken cancellationToken);
    Task<IEnumerable<EventMessage>> GetAsync(long version, bool useSnapshot, CancellationToken cancellationToken);
    Task SnapshotAsync(long version, EventMessage snapshot, CancellationToken cancellationToken);
    Task<long> VersionAsync(CancellationToken cancellationToken);
    Task OpenAsync(CancellationToken cancellationToken);
    void Close();
    // Additional methods...
}

IEventStoreProvider

The IEventStoreProvider interface defines the contract for event store factory services:

public interface IEventStoreProvider
{
    Task<IEventStore> GetOrCreateStoreAsync(string id, CancellationToken cancellationToken);
    Task<bool> StoreExistsAsync(string id, CancellationToken cancellationToken);
    Task DeleteStoreAsync(string id, CancellationToken cancellationToken);
    // Additional methods...
}

EventMessage

The EventMessage record encapsulates the core data structure for events:

public record EventMessage(
    object Data,
    Metadata Metadata)
{
    // Methods and properties...
}

EventStoreHelper

The EventStoreHelper class provides utility methods for working with event stores:

• Converting between event streams and domain objects
• Managing event metadata
• Helper methods for common event store operations

Configurations

The configurations namespace contains classes for configuring event stores:

• Connection settings
• Performance options
• Feature toggles

Exceptions

Custom exceptions for error handling in event store operations:

• EventStoreException: Base exception for all event store errors
• StoreVersionMismatchException: Thrown when event sequence numbers don't match
• StoreNotOpenException: Thrown when operations are attempted on a closed store
• InvalidStoreSessionException: Thrown when session validation fails
• Additional specialized exceptions

Using the Abstractions

These abstractions can be used to:

1. Implement custom event store providers for different storage technologies
2. Create mock implementations for testing
3. Build higher-level abstractions for specific domain scenarios
4. Create adapters for third-party event store technologies

Design Principles

The abstractions follow these design principles:

• Separation of Concerns: Clear distinction between storage and domain logic
• Interface Segregation: Focused interfaces with specific responsibilities
• Dependency Inversion: High-level modules depend on abstractions
• Asynchronous First: All long-running operations are async with cancellation support
• Immutability: Events are immutable records