Invoking a RESTful service via WSO2ESB

In the ESB, when we define a proxy, it is not a must to provide the service wsdl, unless if you want to hide/add a new elements in your service contract.
Lets check a  very simple basic proxy to process a HTTP GET request

• Get wso2esb binary distribution.
• Deploy the simplestockquote service and start the sample axis2server.
• Start ESB.

Create the following proxy;

<proxy name="RestProxy" transports="https http" startOnLoad="true" trace="disable">         <target>               <endpoint>               <address uri="http://localhost:9000/services/SimpleStockQuoteService"/>             </endpoint>                          <outSequence>                 <send/>             </outSequence>         </target>     </proxy>

Execute the following GETrequest url in your browser;
http://localhost:8280/services/RestProxy/getSimpleQuote?symbol=IBM

Now you will see the response in your browser. If you place the tcpmon between client and ESB, you can check your http 'get' request,

GET /services/RestProxy/getSimpleQuote?symbol=IBM HTTP/1.1

Host: 127.0.0.1:5555

User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.24) Gecko/20111103 Firefox/3.6.24

Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8

Accept-Language: en-us,en;q=0.5

Accept-Encoding: gzip,deflate

Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7

Keep-Alive: 115

Connection: keep-alive

Cookie: region1_configure_menu=; region3_registry_menu=visible; region4_monitor_menu=;

In the above sample client sends the 'symbol=IBM' as the parameter for the operation "getSimpleQuote"..Say in the mediation logic user may need to change the parameter as 'SUN'.(ie:symbol=SUN)..For that he/she can use "REST_URL_POSTFIX" property ..Which basically adds the suffix for the REST service endpoint.
eg:
   <property name="REST_URL_POSTFIX" value="/getSimpleQuote?symbol=SUN" scope="axis2"/>

So, the insequence would be;

    <inSequence>

                <property name="REST_URL_POSTFIX" value="/getSimpleQuote?symbol=SUN" scope="axis2"/>

                <send>

                    <endpoint>

                        <address uri="http://localhost:9000/services/SimpleStockQuoteService"/>

                    </endpoint>

                </send>

    </inSequence>

User could add your own mediation logic with whatever the mediators within the sequence..

Related post;
REST support in WSO2ESB - Introduction
REST Support in WSO2ESB - Handling JSON messages