Adding error sequence to a custom sequence

In my previous posi i explained how to call an endpoint using the call mediator. Usually when errors are thrown from the call mediator we can handle them using a custom sequence. When call mediators fails the execution stops hence handling errors is very essential.

For this post I will be modifying the same sequence which i created in the blog post [1]

The change which we need to do is we need to modify the sequence definition to map with the error sequence as shown below. You can find the modified sequence here.


<sequence xmlns="http://ws.apache.org/ns/synapse" name="countrySequenceWithError" onError="countryErrorSequence">
<property name="uri.var.countryCode" expression="$url:countryCode"/>
<property name="REST_URL_POSTFIX" scope="axis2" action="remove"/>
    <call blocking="true">
        <endpoint>
            <http method="get" uri-template="http://www.mocky.io/v2/597058891000001b0471d8fc/countryCode/{uri.var.countryCode}"/>
        </endpoint>
    </call>
<property name="uri.var.country" expression="json-eval($.country)"/>
<property name="uri.var.isfulltext" expression="json-eval($.fullText)"/>
<log level="full"/>
</sequence>


Then we need to create the sequence countryErrorSequence. Save the content in this link in a file and save it as countryErrorSequence.xml. You can modify the highlighted section with any error message which you like.


<?xml version="1.0" encoding="ISO-8859-1"?>
<sequence xmlns="http://ws.apache.org/ns/synapse" name="countrySequence">
    <log level="custom">
        <property name="STATUS" value="Executing default 'fault' sequence"/>
        <property name="ERROR_CODE" expression="get-property('ERROR_CODE')"/>
        <property name="ERROR_MESSAGE" expression="get-property('ERROR_MESSAGE')"/>
    </log>
    <filter source="get-property('MESSAGE_FORMAT')" regex="soap1[1-2]">
        <then>
            <property name="SOAP_FAULT_CODE" value="Server"/>
            <makefault>
                <code expression="$ctx:SOAP_FAULT_CODE"/>
                <reason expression="$ctx:ERROR_MESSAGE"/>
            </makefault>
        </then>
        <else>
            <payloadFactory>
                <format>
                    <CountryDetailsError>
                        <code>$1</code>
                        <type>Error Encountered</type>
                        <message>An error occurred when trying to get the details of the requested country</message>
                    </CountryDetailsError>
                </format>
                <args>
                    <arg expression="$ctx:ERROR_CODE"/>
                </args>
            </payloadFactory>
                <property name="messageType" value="application/json" scope="axis2"/>
        </else>
    </filter>


After saving the file you need to copy this file into the location wso2am-2.1.0/repository/deployment/server/synapse-configs/default/sequences/ if you are creating this API in the tenant mode then you need to copy this sequence to the location

wso2am-2.1.0/repository/tenants/{tenant_id}/synapse-configs/default/sequences

Further more you can handle custom error codes and provide different messages for them as well. The error codes returned can be found here.