❷ The output to the console: HTTP server is started and listens on port 5000 Now that we’ve verified that the project builds correctly, it’s time to talk about what it does. In the next section we’ll start with the build file and then look at the resources, and of course the actual code for the services.
We don’t have to learn anything new; it’s just sending and receiving messages. Changes kept as a sequence of events All changes are kept as a sequence of events, in this case MessageAdded events. The current state of the conversation can be rebuilt by replaying the events that occurred to the in-memory conversation, so it can continue where it left off. This type of database is often called a journal, and the technique is known as event sourcing. There is more to event sourcing but for now this definition will do.
Akka in Action by Raymond Roestenburg