Architecting Modern Java EE Applications

Synchronous execution

For a typical use case triggered by a HTTP request and involving a database query this works as follows. The request thread handles the request that goes into the boundary; for example, a JAX-RS UsersResource, by the inversion of control principle, the JAX-RS resource method is called by the container. The resource injects and uses a UserManagement EJB, which is also invoked indirectly by the container. All operations executed by the proxies happen in synchronous terms. The EJB will use an entity manager to store a new User entity and as soon as the business method that initiated the currently active transaction returns, the container will try to commit the transaction to the database. Depending on the transaction result, ...