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Event Sourcing

Event Store Persistent Subscriptions

One of the really nice features of Event Store is the Persistent Subscriptions that were implemented in v3.2.0.  I was previously using catch-up subscriptions but needed the ability to have many worker processes handle events from the same stream. First lets take a look at couple of the subscription models Event Store suports. Catch Up Subscriptions As mentioned, I previously would use catch-up subscriptions for various use cases.  One of them would be for sending emails on specific events occurring in the system. A worker process would subscribe to the $all event stream and handle incoming messages accordingly. The issue is that catch… Read More »Event Store Persistent Subscriptions

Event Stream as a Message Queue

I was recently having a discussion around a system being built using Microsoft Azure.  Some concepts being discussed for this system where CQRS, Event Sourcing and Message Queue. The diagram below is fairly typical when discussing CQRS and Event Sourcing. One of the first things that stood out to me was the use of the Message Queue and Azure Service Bus. For this blog post, I want to focus on the Service bus, which is used for publish-subscribe pattern.  The domain will emit events that are stored to the event stream and then will be published to the Service Bus.  Subscribers, such as… Read More »Event Stream as a Message Queue