The Barracuda EventHandler (WebSocket) Plugin

The Barracuda EventHandler plugin or EH for short is a protocol stack that enables real-time data exchange between a client application and the Barracuda Embedded Web Server. The protocol stack is implemented in C code for the server side and JavaScript code for the client side.

How it works

The EventHandler uses a number of techniques under the hood for maintaining a persistent connection. Techniques used are the standard server side push technologies such as pushlet and long polling. In addition, the WebSocket protocol is automatically used when the EventHandler client detects a browser that supports this new technology.

The protocol is typically used when a user interface requires real time responses from a server, such as alarm notifications. A browser based user interface can be designed using HTML and JavaScript. The HTML and JavaScript code is initially loaded from the server and once loaded, the JavaScript code opens a persistent, full duplex, bi-directional communication channel with the server.

The JavaScript code uses various technologies for keeping a persistent connection with the server. The client stack detects the browser capabilities at startup and uses the best technology for communicating with the server. We also provide a Java client implementation that can be used by standalone Java programs. A Java application using the Java version of the client stack can also be made to load via the server or be installed separately on a client computer.

Fast Track Your WebSocket Development


As WebSockets are gaining momentum, more companies are discovering the benefits of keeping a persistent server connection over HTTP(S) for real time device management. Our EventHandler includes WebSocket support and can be found in many Barracuda Server powered industrial products dating as far back as 2005.

Fast track your WebSocket development by downloading our combined demo and tutorial, which lets you start developing your WebSocket applications today.