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How to Handle Non-matching Resources

This example demonstrates how you can define a sequence to be invoked if the Micro Integrator is unable to find a matching resource definition for a specific API invocation. This sequence generates a response indicating an error when no matching resource definition is found.

Synapse configurations

Following is a sample REST API configuration and Sequence configuration that we can used to implement this scenario. See the instructions on how to build and run this example.

<api xmlns="http://ws.apache.org/ns/synapse" name="jaxrs" context="/jaxrs">
   <resource methods="GET" uri-template="/customers/{id}">
      <inSequence>
         <call>
            <endpoint key="CustomerService" />
         </call>
         <respond />
      </inSequence>
   </resource>
</api> 

<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>404</tp:code>
            <tp:type>Status report</tp:type>
            <tp:message>Not Found</tp:message>
            <tp:description>The requested resource (/$1) is not available.</tp:description>
         </tp:fault>
      </format>
      <args>
         <arg xmlns:ns="http://org.apache.synapse/xsd" expression="$axis2:REST_URL_POSTFIX"/>
      </args>
   </payloadFactory>
   <property name="RESPONSE" value="true" scope="default"/>
   <property name="NO_ENTITY_BODY" action="remove" scope="axis2"/>
   <property name="HTTP_SC" value="404" scope="axis2"/>
   <header name="To" action="remove"/>
   <send/>
</sequence>

<endpoint name="CustomerService" xmlns="http://ws.apache.org/ns/synapse">
   <address uri="http://localhost:8290/jaxrs_basic/services/customers/customerservice"/>
</endpoint>

Build and run

Create the artifacts:

  1. Launch Visual Studio Code with the Micro Integrator for VS Code extension (MI for VS Code) installed.

    Info

    Follow the Install Micro Integrator for VS Code documentation for a complete installation guide.

  2. Create an integration project..

  3. Create the rest API and mediation sequence with the configurations given above.
  4. Deploy the artifacts in your Micro Integrator.

Set up the back-end service:

  1. Download the back-end service.
  2. Extract the downloaded zip file.
  3. Open a terminal, navigate to the axis2Server/bin/ directory inside the extracted folder.

  4. Execute the following command to start the axis2server with the SimpleStockQuote back-end service:

    sh axis2server.sh

    axis2server.bat

Send an invalid request to the back end as follows:

curl -X GET http://localhost:8290/jaxrs/customers-wrong/123

You will get the following response:

<tp:fault xmlns:tp="http://test.com">
<tp:code>404</tp:code>
<tp:type>Status report</tp:type>
<tp:message>Not Found</tp:message>
<tp:description>The requested resource (//customers-wrong/123) is not available.</tp:description>
</tp:fault>