A real-time application framework

Cettia is a real-time application framework that allows you to focus on event handling itself. It provides reliable full duplex connection which frees you from the pitfalls of traditional real-time programming and elegant patterns which eliminates the boilerplate code involved with full duplex connection. Besides, it's designed to work well with any transport technology, any I/O framework, and any scaling methods, which is critical for modern enterprise applications.

Explore the Cettia subprojects:

flowersinthesand flowersinthesand wrote Cettia JavaScript Client 1.0.0-Beta2 released on January 7, 2017.


The most important thing is not managing connections or writing boilerplate code, but what you are trying to achieve in real-time.

// When a socket is created
server.onsocket(socket -> {});
// Runs for every socket in the server
server.all(socket -> {});
// When a socket sends some event
socket.on("echo", data -> {});

Here is a summary of key features in Cettia overall:

  • Automatic fallback - In the real world, it has turned out that WebSocket has many issues with coporate proxies, firewalls, antivirus softwares, cloud platforms, and so on. But, Cettia has automatic fallback mechanisms which works pretty well even in Internet Explorer 9.
  • I/O framework agnostic - Your application can run on almost any platform on the Java Virtual Machine seamlessly. Now Atmosphere, Grizzly, Java WebSocket API, Netty, Servlet and Vert.x are supported. Although your favorite platform is not supported, you can bridge your application to the platform with only a little bit of effort.
  • Scalable - A publish-subscribe messaging system is enough to scale your application horizontally. Because servers don't share any data, you can scale application horizontally with ease as well as don't need to prepare for key-value caches, NoSQL solutions or in-memory data grids.
  • Transport agnostic - Any transport technology besides WebSocket and HTTP can be used to bridge client and server as long as it meets requirements of Cettia transport. In this manner, you can build real-time applications optimized for Internet of Things at least in theory.
  • Event-based - From the semantic point of view, the unit of data to be sent and received is event associated with a customizable type. You don't need to write the boilerplate code to implement event system with plain text and JSON to organize your business logic.
  • Remote Procedure Call - It also allows to handle the result of the remote event processing through callback like Ajax. It's useful where request-response model is more suited than notification model like acknowledgement.
  • Entity handling - Socket is not appropriate to represent a specific entity. To give you a way to model a specific entity in the real world, Cettia provides Tag as an identifier of a group of sockets. For example, you can use it to model a user (entity) logged in using multiple devices (sockets).
  • Offline application - It is pretty important to make applications relying on full-duplex connection functional while offline. This feature enables you to handle socket as stateless object by providing various events to deal with disconnection.
  • Binary support - It enables you to exchange any arbitrary object including binary as well as text in an efficient way without binary-to-text conversion. Never mind what type of data is being sent.
  • 100% open source - All projects are distributed under the Apache Software License 2.0 which is one of the most flexible open source licenses.