WSO2 Micro Integrator Validate Mediator fails with Unsupported Operation - wso2

Question

Working with Integration Studio in Windows 10.
When I try Validate my Payload from REST API body with Sequence with Validate Mediator I get an Error.
Error:
[2020-03-10 11:07:29,295] INFO {TRACE_LOGGER} - Building message. Sequence <SequenceMediator> is content aware
[2020-03-10 11:07:29,309] ERROR {org.apache.synapse.mediators.base.SequenceMediator} - Unsupported Operation org.apache.axiom.om.OMException: Unsupported Operation
at org.apache.axiom.om.impl.llom.OMTextImpl.getInputStream(OMTextImpl.java:422)
at org.apache.synapse.mediators.builtin.ValidateMediator.mediate(ValidateMediator.java:231)
at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:109)
at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:71)
at org.apache.synapse.mediators.base.SequenceMediator.mediate(SequenceMediator.java:158)
at org.apache.synapse.mediators.base.SequenceMediator.mediate(SequenceMediator.java:214)
at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:109)
at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:71)
at org.apache.synapse.config.xml.AnonymousListMediator.mediate(AnonymousListMediator.java:37)
at org.apache.synapse.config.xml.SwitchCase.mediate(SwitchCase.java:69)
at org.apache.synapse.mediators.filters.SwitchMediator.mediate(SwitchMediator.java:134)
at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:109)
at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:71)
at org.apache.synapse.mediators.base.SequenceMediator.mediate(SequenceMediator.java:158)
at org.apache.synapse.rest.Resource.process(Resource.java:331)
at org.apache.synapse.rest.API.process(API.java:440)
at org.apache.synapse.rest.RESTRequestHandler.apiProcessNonDefaultStrategy(RESTRequestHandler.java:149)
at org.apache.synapse.rest.RESTRequestHandler.dispatchToAPI(RESTRequestHandler.java:95)
at org.apache.synapse.rest.RESTRequestHandler.process(RESTRequestHandler.java:71)
at org.apache.synapse.core.axis2.Axis2SynapseEnvironment.injectMessage(Axis2SynapseEnvironment.java:325)
at org.apache.synapse.core.axis2.SynapseMessageReceiver.receive(SynapseMessageReceiver.java:98)
at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:180)
at org.apache.synapse.transport.passthru.ServerWorker.processNonEntityEnclosingRESTHandler(ServerWorker.java:367)
at org.apache.synapse.transport.passthru.ServerWorker.processEntityEnclosingRequest(ServerWorker.java:412)
at org.apache.synapse.transport.passthru.ServerWorker.run(ServerWorker.java:181)
at org.apache.axis2.transport.base.threads.NativeWorkerPool$1.run(NativeWorkerPool.java:172)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Then I try to validate from it:
<?xml version="1.0" encoding="UTF-8"?>
<sequence name="Reserves" statistics="enable" trace="enable" xmlns="http://ws.apache.org/ns/synapse">
<validate cache-schema="false" source="json-eval($)">
<schema key="conf:/schemas/ReservesRoot.json"/>
<on-fail>
<payloadFactory media-type="json">
<format>{"Error":$1"}</format>
<args>
<arg evaluator="xml" expression="$ctx:ERROR_MESSAGE"/>
</args>
</payloadFactory>
<property name="HTTP_SC" scope="axis2" type="STRING" value="500"/>
<respond/>
</on-fail>
</validate>
</sequence>
JSON Schema:
{
"$schema": "http://json-schema.org/draft-04/schema#",
"type": "object",
"properties": {
"Type": {
"type": "string"
}
},
"required": [
"Type"
]
}
When I get the schema in property I see the schema's string.
<property value="get-property('registry', 'conf:/schemas/ReservesRoot.json')" name="ReservesSchema"/>
<log>
<property expression="get-property('ReservesSchema')" name="JSON_P"/>
</log>

Answer 1

This issue occurs when the JSON-schema saved in the registry does not have the correct media-type (must be application/json). Could you please double-check this in Integration studio Resources Editor view.
You can access the resources editor view by right click on registry resource project -> Registry resource editor

Answer 2

This issue occurs with Micro integrator. Micro integrator does not have rdbms registry artifacts. Hence we cannot specify the media type. The work around is to add local entry file with the validation json schema and refer it in synapse.
<validate cache-schema="false">
<schema key="createotpvalidate"/>
<on-fail>
<payloadFactory media-type="json">
<format>{"Error":$1"}</format>
<args>
<arg evaluator="xml" expression="$ctx:ERROR_MESSAGE"/>
</args>
</payloadFactory>
<property name="HTTP_SC" scope="axis2" type="STRING" value="500"/>
<respond/>
<!-- <schema key="conf:/schema/CreateOTPSchema.json"/> -->
</on-fail>
</validate>
Local Entry file:
<?xml version="1.0" encoding="UTF-8"?>
<localEntry key="createotpvalidate" xmlns="http://ws.apache.org/ns/synapse"><![CDATA[{ "$schema": "http://json-schema.org/draft-04/schema#", "type": "object", "properties": { "request_type": { "type": "string" },"mobile": { "type": "string" },"otp": { "type": "string" } }, "required": [ "request_type","mobile","otp" ] }]]></localEntry>