The REST endpoints receive HTTP requests in order to perform a few different "use cases:

• PushMessage Send-Request to deliver messages to the particular networks (GCM, APNs, simplePush)

Currently the HTTP endpoints are (somewhat) directly performing the storage of the information. Helpers/Services classes are performing the work, but this is all "blocking IO".

Ideally, the HTTP endpoints are just receiving the HTTP requests, quickly publish a Message to a "Message Broker" and immediately return (if possible).

The actual work (of storing, via JPA etc) should be then done in a Consumer of a Topic/Queue of the Message broker;

Attached are two simple diagrams, to show the idea...