JSON (JavaScript Object Notation) is an open and text-based data exchange format, that provides a standardized data exchange format better suited for Ajax style web applications. You can find more information about JSON from www.json.org WSO2 SOA middleware platform supports sending and receiving JSON messages. This post takes you through the steps to deploy a simple web service in WSO2 Application Server and write a client using Axis2 ServiceClient API to invoke the service by sending JSON message. Pre-requisites: Download and install WSO2 Application Server 4.0.0 or later Step 1 We are using a simple web service, which echo's user input as follows. public class EchoService { public OMElement echo(OMElement element) { return element; } } You can download the service archive (EchoService.aar) from here and deploy on WSO2 Application Server. Step 2 Have a look at CARBON_HOME/repository/conf/axis2.xml (CARBON_HOME is the root directory of WSO2 Application Server).