CODEWITHSUNDEEP
springspring-integration
Cisco Java
Cisco Java

Reputation: 233

Using Publish Subscribe channel in Spring Integration

We have the below XML configuration for a rest service and Oracle Stored Proc. The use case is about handling Oracle SP errors.

When the Oracle SP throws error, we need to achieve 2 things:

  1. we need to send a json response back to the client in the format {"status": false,"message": "Oracle SP error payload"}

  2. Send an email out.

The configuration is working as expected when Oracle SP throws error. But when the email send fails ( gave a wrong host), client is receiving error in the below format. The Oracle SP error message is not sent back.

---- Json message received by client when email send fails:------
{
 "timestamp": 1501639940143,
 "status": 500,
 "error": "Internal Server Error",
 "exception": "org.springframework.messaging.MessagingException",
 "message": "failure occurred in error-handling flow; nested exception is org.springframework.messaging.MessageHandlingException: error occurred in message handler [org.springframework.integration.handler.MessageHandlerChain#0$child#2.handler]; nested exception is org.springframework.mail.MailSendException: Mail server connection failed; nested exception is javax.mail.MessagingException: Unknown SMTP host: xxx.com;..",
 "path": "/init/5c82d1f4-e550-4bb1-be9c-8d0ddbc7f4401/NEW"
}

How do I send response in the expected json format - {"status": false,"message": Oracle SP error payload}?

Also how to handle the email send error.i.e may be how to store the email error in a DB table?

XML Configuration:

<int:channel id="spOutClobChannel"/>
<int:publish-subscribe-channel id="gatewayErrorChannel"/>


<int-http:inbound-gateway
    request-channel="gatewayInitChannel"
    error-channel="gatewayErrorChannel"
    supported-methods="GET"
    path="/init/{refId}/{refStatus}"        
    payload-expression="#pathVariables.refStatus">

  <int-http:header name="UNIQUE_PROCESS_ID" expression="#pathVariables.refId"/>

</int-http:inbound-gateway>

<int-jdbc:stored-proc-outbound-gateway
            id="sp-get-data"
            data-source="dataSource"
            request-channel="gatewayInitChannel"
            reply-channel="spOutClobChannel".... >
    ...
    ...             
</int-jdbc:stored-proc-outbound-gateway>


<int:transformer input-channel="spOutClobChannel"    expression='{"status": true, "message": "RECEIVED"}'/>
<int:transformer input-channel="gatewayErrorChannel" expression='{"status": false,"message": payload.message}'/>

<int:transformer expression="payload.failedMessage.headers['UNIQUE_PROCESS_ID']"   
               input-channel="gatewayErrorChannel" output-channel="appEmailChannel"/>

<int:chain input-channel="appEmailChannel" >
    <int-mail:header-enricher>
        <int-mail:from     value="${email.from}"/>
        <int-mail:to       value="${email.to}"/>
        <int-mail:subject  value="${email.subject}"/>
        <int-mail:content-type value="text/html"/>
   </int-mail:header-enricher> 
   <int-mail:outbound-channel-adapter   host="${email.host}" />
</int:chain>

Upvotes: 2

Views: 1177

Answers (1)

Artem Bilan
Artem Bilan

Reputation: 121552

To avoid errors thrown from the appEmailChannel flow, plus get a gain do not wait for the successful email shipment, it would be better to add to your gatewayErrorChannel an executor configuration. This way all the subscribers to this publish-subscriber channel will be performed in parallel and in their own threads. Therefore any exception in those threads won't impact the reply to the <int-http:inbound-gateway> which you've done with the 

<int:transformer input-channel="gatewayErrorChannel" expression='{"status": false,"message": payload.message}'/>

Also how to handle the email send error.i.e may be how to store the email error in a DB table?

With this goal you can use ExpressionEvaluatingRequestHandlerAdvice with its trapException = true and failureChannel properties.

This advice can be configured with the request-handler-advice-chain sub-element.

See Reference Manual and Sample on the matter.

Upvotes: 1

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