Posts tagged jms

This month, In have been delving into Push architectures for the Web, looking into WebSockets among several other things. WebSockets, a fairly new standard (!) evolved along with HTML 5, specifies a communication protocol that provides an alternative to classic HTTP communication. WebSocket based interaction has lower overhead and – more importantly – is bi-directional which means that push from server to client is really supported (and not just emulated through poll, long poll or streaming responses as is currently the case in comet push style frameworks).

All modern browsers provide support for the WebSocket specification – meaning they can communicate based on the WebSocket protocol (ws:// and wss:// in addition to http:// and https://) and they implement the WebSocket client side (JavaScript) APIs. These API are well defined – http://dev.w3.org/html5/websockets/ – and seem to be truly standard across all browsers.

The WebSocket server side is at this moment not very well defined. Other than the fact that the communication over ws:// and wss:// should be handled by a server, not much has been decided about the server side of WebSockets. Currently, WebSockets is not supported in classic JEE servers although such support seems imminent with JEE 7 through the Servlet 3.1 specification (JSR 340, http://jcp.org/en/jsr/summary?id=340; also read http://antwerkz.com/websockets-and-java-ee/ on how WebSockets my be included in the Servlet API). Initial support for WebSockets has been shown in Jetty and GlassFish, with other JEE containers undoubtedly following suit in next 18 months or so. In the meanwhile, several stand alone WebSocket servers have been released, including Kaazing (a commercial offering which I mentioned in two earlier articles: http://technology.amis.nl/blog/14755/get-going-with-kaazing-websocket-gateway-html5-edition-installing-locally-and-running-demos and http://technology.amis.nl/blog/14777/push-based-synchronized-slideshow-web-application-implemented-using-websockets-and-kaazing-websocket-gateway) and jWebSocket (an open source offering – http://jwebsocket.org/), that I will introduce in this article.

These WebSocket servers are capable of handling WebSocket interaction with a variety of clients – well, the server should not have to care about the type of client but only about the communication. How the WebSocket server should relay WebSocket messages received from a client to a back end service is not well defined, at least not in a standardized way. Vice versa: how back end services can deliver their push messages and events – chat message, JMS message, mail reception, RSS entry, Tweet, database update, business event … – to the WebSocket server for onward routing to interested clients is not covered by an existing standard either. Even integration of WebSocket interaction into regular JEE Web Applications is very much in question. Kaazing spokesmen even suggested that perhaps WebSocket communication provides the foundation for a whole new type of application in which traditional JEE application servers are no longer needed (see: http://www.businesswire.com/news/home/20111019005426/en).

Well, before going to deep into these discussions, let’s take a look at how we can get the jWebSocket server going to at least run a few demo application on our local machine (or at least my local environment).

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