Implementing projections

Now it is time to start writing some code. We will use the final code of Chapter 9, CQRS - The Read Side, as the starting point. The final code for this chapter is located in the GitHub repository, in the Chapter11 folder.

We will go step by step and start by implementing one subscription just to see how subscriptions work in the Event Store. Then, we will create a few real read models using both RavenDB and PostgreSQL.

Catch-up subscriptions

In fact, to start making projections, we don't need any databases. I will show you a simple trick that allows you to go on with the initial development quickly, without any thoughts about the database engine that will be used to store read models. Very often...