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Aggregates.NET is a library to facilitate integration between NServiceBus and EventStore. It provides a framework to define entities, value objects, command and event handlers, and many other domain driven design and CQRS principles. The framework should take all the tediousness of dealing with event streams and message queues out of your consideration and give you a solid base to build a solid event sourced application.
Aggregates.NET uses Microsoft's standard DI and logging module - and I've removed direct support for StructureMap, SimpleInjector and LibLog which supported many different logging modules. I did this simply to reduce the headache for myself going forward to v1.0 - if you want to use one of these other libraries fear not! Each of them should have adaptors for Microsoft's DI and Logging.
All of the samples and examples are Microsoft Hosting setup so likely this won't affect your projects especially if you're new. But if you are upgrading Agg.net something to be aware of!
Take the following example
class Handler :
IHandleMessages<Send>
{
public async Task Handle(Send command, IMessageHandlerContext ctx)
{
var entity = await ctx.For<EchoEntity>().TryGet("default");
if (entity == null)
entity = await ctx.For<EchoEntity>().New("default");
entity.Echo(command.Message);
}
}
Users of NSB should immediately notice the IHandleMessages convention - everything inside the message handler is provided by Aggregates.NET. The special extension methods are using entity definitions to retreive streams from the eventstore. Once loaded the entity executes a method which generates an event which Aggregates.NET will save to the eventstore.
All of the complicated stream writing / reading details are handled internally by Aggregates.NET leaving you free to design your contexts and business objects without caring about the transport or storage.
More features of Aggregates.NET include -
- Children entities of entities (infinite parenthood)
- Snapshotting
- Sagas (similar to but easier to define than NSB's)
- Queries
- Unit of Work management for application storage (MongoDB, eventstore, etc)
v1.0 is coming soontm! As of March 2022 I just completed a very big overhaul of Aggregates.NET replacing the many container implementations and logging with Microsoft's standard libraries. I also cleaned up some more complicated bits of code to streamline the purpose the library over needless features.
I expect v1.0 to come sometime over the next year and with that a stable API which I will do my very best to maintain.
This is however a solo project so I make no guarantees that somethings may break over time. Maintaining backwards compatibility is not at the top of my priorities but if you are using Aggregates.NET and wish to contract my work for maintenance or development feel free to contact me via email!
This is a one man project so documentation is lacking - sorry about that. If you have any questions about using Aggregates.NET feel free to contact me via email.