How to generate a custom Error Message with Custom HTTP Status Code for unavailable Resources in WSO2 ESB

WSO2 ESB 4.8.1  does not throw any exception or error message when an API defined is access with incorrect HTTP method and it will just respond with 202.  In this blog post , i am explaining on how we can get a custom HTTP status code for the above.


In order to get a custom error message , you need to add following sequence to ESB which is not there by default.

<?xml version="1.0" encoding="UTF-8"?>
<sequence xmlns="http://ws.apache.org/ns/synapse" name="_resource_mismatch_handler_">
   <payloadFactory media-type="xml">
      <format>
         <tp:fault xmlns:tp="http://test.com">
            <tp:code>405</tp:code>
            <tp:type>Status report</tp:type>
            <tp:message>Method not allowed</tp:message>
            <tp:description>The requested HTTP method for resource (/$1) is not allowed.</tp:description>
         </tp:fault>
      </format>
      <args>
         <arg xmlns:ns="http://org.apache.synapse/xsd"
              xmlns:ns3="http://org.apache.synapse/xsd"
              evaluator="xml"
              expression="$axis2:REST_URL_POSTFIX"/>
      </args>
   </payloadFactory>
   <property name="NO_ENTITY_BODY" scope="axis2" action="remove"/>
   <property name="HTTP_SC" value="405" scope="axis2"/>
   <respond/>
   <drop/>
</sequence>

In ESB documentation [1] , it has explained that in order to handle non-matching resources, it is needed to define this sequence _resource_mismatch_handler_


[1] https://docs.wso2.com/display/ESB481/Configuring+Specific+Use+Cases#ConfiguringSpecificUseCases-Handlingnon-matchingresources