Crate cqrs_es2

cqrs-es2

A lightweight, opinionated CQRS and event sourcing framework targeting serverless architectures.

Installation

cqrs-es2 is available from Crates.io or Github.

[dependencies]
cqrs-es2 = "0.2.1"

Usage

Documentation is available here along with an introduction to CQRS and event sourcing.

A demo application is available here.

Todos

• Event upcasters.
• Event serialization uses the event type as the root node of the JSON tree. This simplifies deserialization but is non-standard.
• A persistence implementation for DynamoDb.
• A persistence implementation for MySql.

Modules

test

Test provides a test framework for building a resilient test base around aggregates. A TestFramework should be used to build a comprehensive set of aggregate tests to verify your application logic (aka business rules).

Structs

CqrsFramework

This is the base framework for applying commands to produce events.

EventEnvelope

EventEnvelope is a data structure that encapsulates an event with along with it’s pertinent information. All of the associated data will be transported and persisted together.

MemoryStore

Simple memory store only useful for testing purposes

MemoryStoreAggregateContext

Holds context for a pure event store implementation for MemoryStore

Enums

AggregateError

The base error for the framework.

Traits

Aggregate

In CQRS (and Domain Driven Design) an Aggregate is the fundamental component that encapsulates the state and application logic (aka business rules) for the application. An Aggregate is always an entity along with all objects associated with it.

AggregateContext

Returns the aggregate and context around it that is needed when committing events

DomainEvent

A DomainEvent represents any business change in the state of an Aggregate. DomainEvents are immutable and with event sourcing they are the source of truth.

EventStore

The abstract central source for loading past events and committing new events.

Query

A Query is a read element in a CQRS system. As events are emitted multiple downstream queries are updated to reflect the current state of the system. A query may also be referred to as a ‘view’, the concepts are identical but ‘query’ is used here to conform with CQRS nomenclature.

QueryProcessor

Each CQRS platform should have one or more QueryProcessors where it will distribute committed events, it is the responsibility of the QueryProcessor to update any interested queries.