How to use POST_TO_URI property in WSO2 ESB

Until recently I had some doubts about using POST_TO_URI property within WSO2 ESB configuration. Finally, I think I understood the true purpose of it and used it correctly.

According to WSO2 ESB parameters catelog, POST_TO_URI property makes the outgoing URL of the ESB a complete URL and it is important when sending the messages through a proxy server.
Lets see how this property can be used in message mediation when a HTTP proxy server is used.

Step 1

As I explained in a previous post, you are supposed to configure WSO2 ESB to forward messages through a HTTP proxy server.

Step 2

Now, add the following sequence (or any message pass through sequence). (I used a service called "Axis2Sesrvice" which is deployed on WSO2 WSAS as the endpoint and I used Apache server as the proxy)

<sequence xmlns="http://ws.apache.org/ns/synapse" name="main">
<in>
<send>
<endpoint name="endpoint_urn_uuid_1286CEB97BC8A170468445150995919829308689">
<address uri="http://localhost:9764/services/Axis2Service/" />
</endpoint>
</send>
</in>
<out>
<send />
</out>
</sequence>

Step 3

Send a message to ESB using a client. You will notice that the message transmission is failed. If you look at the apache server log, you will notice something similar to the below.

127.0.0.1 - - [19/Jul/2010:14:19:30 +0530] "POST /services/Axis2Service/ HTTP/1.1" 404 220

Here, you can see that, POST message does not contain the full service URL hence the proxy server is unable to forward the message to the endpoint.

Step 4

Now update the above sequence with including POST_TO_URI property as follows.

<sequence xmlns="http://ws.apache.org/ns/synapse" name="main">
<in>
<property name="POST_TO_URI" value="true" scope="axis2" type="STRING" />
<send>
<endpoint name="endpoint_urn_uuid_1286CEB97BC8A170468445150995919829308689">
<address uri="http://localhost:9764/services/Axis2Service/" />
</endpoint>
</send>
</in>
<out>
<send />
</out>
</sequence>

Send a message again. This time, the message transmission will be successful. You will find the following entry in apache log. This proves that the message is correctly forwarded to the endpoint through the proxy server.

127.0.0.1 - - [19/Jul/2010:14:57:25 +0530] "POST http://localhost:9764/services/Axis2Service/