Clever Geek Handbook

How to Respond to Application / PDF Content from WSO2 ESB

I am trying to respond with PDF

content from wso2 esb rest api

and want view

in a browser. I included messageFormatter

and messageBuilder

for application/pdf

. But when i call my api from browser i get below exception in wso2 esb.

axis2.xml:

<messageBuilder contentType="application/pdf" class="org.wso2.carbon.relay.BinaryRelayBuilder"/>

<messageFormatter contentType="application/pdf" class="org.wso2.carbon.relay.ExpandingMessageFormatter"/>

An exception:

ERROR {org.apache.synapse.transport.passthru.PassThroughHttpSender} -  Failed to submit the response {org.apache.synapse.transport.passthru.PassThroughHttpSender}
java.lang.RuntimeException: ContentID is null
    at org.apache.axiom.om.impl.llom.OMTextImpl.getDataHandler(OMTextImpl.java:381)
    at org.wso2.carbon.relay.ExpandingMessageFormatter.findAndWrite2OutputStream(ExpandingMessageFormatter.java:179)
    at org.wso2.carbon.relay.ExpandingMessageFormatter.writeTo(ExpandingMessageFormatter.java:97)
    at org.apache.synapse.transport.passthru.PassThroughHttpSender.submitResponse(PassThroughHttpSender.java:573)
    at org.apache.synapse.transport.passthru.PassThroughHttpSender.invoke(PassThroughHttpSender.java:264)
    at org.apache.axis2.engine.AxisEngine.send(AxisEngine.java:442)
    at org.apache.synapse.core.axis2.Axis2Sender.sendBack(Axis2Sender.java:230)
    at org.apache.synapse.core.axis2.Axis2SynapseEnvironment.send(Axis2SynapseEnvironment.java:531)
    at org.apache.synapse.mediators.builtin.SendMediator.mediate(SendMediator.java:118)
    at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:97)
    at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:59)
    at org.apache.synapse.mediators.base.SequenceMediator.mediate(SequenceMediator.java:158)
    at org.apache.synapse.rest.Resource.process(Resource.java:343)
    at org.apache.synapse.rest.API.process(API.java:338)
    at org.apache.synapse.rest.RESTRequestHandler.apiProcess(RESTRequestHandler.java:123)
    at org.apache.synapse.rest.RESTRequestHandler.dispatchToAPI(RESTRequestHandler.java:101)
    at org.apache.synapse.rest.RESTRequestHandler.process(RESTRequestHandler.java:56)
    at org.apache.synapse.core.axis2.Axis2SynapseEnvironment.injectMessage(Axis2SynapseEnvironment.java:304)
    at org.apache.synapse.mediators.builtin.LoopBackMediator.mediate(LoopBackMediator.java:63)
    at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:97)
    at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:59)
    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:148)
    at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:97)
    at org.apache.synapse.mediators.base.SequenceMediator.mediate(SequenceMediator.java:260)
    at org.apache.synapse.core.axis2.Axis2SynapseEnvironment.mediateFromContinuationStateStack(Axis2SynapseEnvironment.java:775)
    at org.apache.synapse.core.axis2.Axis2SynapseEnvironment.injectMessage(Axis2SynapseEnvironment.java:282)
    at org.apache.synapse.core.axis2.SynapseCallbackReceiver.handleMessage(SynapseCallbackReceiver.java:554)
    at org.apache.synapse.core.axis2.SynapseCallbackReceiver.receive(SynapseCallbackReceiver.java:188)
    at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:180)
    at org.apache.synapse.transport.passthru.ClientWorker.run(ClientWorker.java:262)
    at org.apache.axis2.transport.base.threads.NativeWorkerPool$1.run(NativeWorkerPool.java:172)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Unexpected error sending message back {org.apache.synapse.core.axis2.Axis2Sender}
org.apache.axis2.AxisFault: Failed to submit the response
    at org.apache.synapse.transport.passthru.PassThroughHttpSender.handleException(PassThroughHttpSender.java:632)
    at org.apache.synapse.transport.passthru.PassThroughHttpSender.invoke(PassThroughHttpSender.java:266)
    at org.apache.axis2.engine.AxisEngine.send(AxisEngine.java:442)
    at org.apache.synapse.core.axis2.Axis2Sender.sendBack(Axis2Sender.java:230)
    at org.apache.synapse.core.axis2.Axis2SynapseEnvironment.send(Axis2SynapseEnvironment.java:531)
    at org.apache.synapse.mediators.builtin.SendMediator.mediate(SendMediator.java:118)
    at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:97)
    at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:59)
    at org.apache.synapse.mediators.base.SequenceMediator.mediate(SequenceMediator.java:158)
    at org.apache.synapse.rest.Resource.process(Resource.java:343)
    at org.apache.synapse.rest.API.process(API.java:338)
    at org.apache.synapse.rest.RESTRequestHandler.apiProcess(RESTRequestHandler.java:123)
    at org.apache.synapse.rest.RESTRequestHandler.dispatchToAPI(RESTRequestHandler.java:101)
    at org.apache.synapse.rest.RESTRequestHandler.process(RESTRequestHandler.java:56)
    at org.apache.synapse.core.axis2.Axis2SynapseEnvironment.injectMessage(Axis2SynapseEnvironment.java:304)
    at org.apache.synapse.mediators.builtin.LoopBackMediator.mediate(LoopBackMediator.java:63)
    at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:97)
    at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:59)
    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:148)
    at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:97)
    at org.apache.synapse.mediators.base.SequenceMediator.mediate(SequenceMediator.java:260)
    at org.apache.synapse.core.axis2.Axis2SynapseEnvironment.mediateFromContinuationStateStack(Axis2SynapseEnvironment.java:775)
    at org.apache.synapse.core.axis2.Axis2SynapseEnvironment.injectMessage(Axis2SynapseEnvironment.java:282)
    at org.apache.synapse.core.axis2.SynapseCallbackReceiver.handleMessage(SynapseCallbackReceiver.java:554)
    at org.apache.synapse.core.axis2.SynapseCallbackReceiver.receive(SynapseCallbackReceiver.java:188)
    at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:180)
    at org.apache.synapse.transport.passthru.ClientWorker.run(ClientWorker.java:262)
    at org.apache.axis2.transport.base.threads.NativeWorkerPool$1.run(NativeWorkerPool.java:172)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

API content:

<payloadFactory media-type="xml">
                  <format>
                     <soapenv:Envelope xmlns:soapenv="http://www.w3.org/2003/05/soap-envelope">
                        <soapenv:Body>
                           <ns:binary xmlns:ns="http://ws.apache.org/commons/ns/payload">$1</ns:binary>
                        </soapenv:Body>
                     </soapenv:Envelope>
                  </format>
                  <args>
                     <arg evaluator="xml" expression="//*[local-name()='Binary']/text()"/>
                  </args>
               </payloadFactory>
               <property name="NO_ENTITY_BODY" scope="axis2" action="remove"/>
               <property name="ContentType" value="application/pdf" scope="axis2" type="STRING"/>
               <property name="messageType" value="application/pdf" scope="axis2" type="STRING"/>
               <respond/>

I tried to convert the binary to pdf using an online tool and it works great.

+3


source to share


1 answer


Find out in the end how to do it.

I am using postgres in my experiments. Let's create a table that will hold the contents of the files. It's pretty simple. Anyway, there are 2 cases. The file can be saved as base64 or blob (bytea in postgres). I have implemented a case where the file is stored as a base64 string in the database.

drop table if exists pdf_files ;
create table pdf_files(
     id serial primary key, 
     file_name text, 
     pdf_base64 text, 
     pdf_binary bytea
 );

Paste the contents of the data file into a base64 table. The base64 file can be converted online here or any other online tool http://www.motobit.com/util/base64-decoder-encoder.asp

insert into pdf_files(file_name, pdf_base64)
values('title.pdf',   'JVBERi0x.....................NjMKJSVFT0YK');

Now you can get the filled binary field

update pdf_files set pdf_binary = decode(pdf_base64, 'base64');

I got this in the database:

Table content

I first tried to implement a soap service that will respond with pdf. There is a service I made:

<proxy xmlns="http://ws.apache.org/ns/synapse" name="Sample" startOnLoad="true" statistics="disable" trace="disable" transports="http,https">
    <target>
        <inSequence>
            <dblookup>
                <connection>
                    <pool>
                        <dsName>pgConn</dsName>
                    </pool>
                </connection>
                <statement>
                    <sql>select pdf_base64 from pdf_files where id = ?</sql>
                    <parameter xmlns:nb="http://mru" expression="//nb:id" type="INTEGER"/>
                    <result column="pdf_base64" name="pdf_base64"/>
                </statement>
            </dblookup>
            <payloadFactory media-type="xml">
                <format>
                    <ns:binary xmlns:ns="http://ws.apache.org/commons/ns/payload">$1</ns:binary>
                </format>
                <args>
                    <arg evaluator="xml" expression="get-property('pdf_base64')"/>
                </args>
            </payloadFactory>
            <loopback/>
        </inSequence>
        <outSequence>
            <script language="js">
            var binaryNode = mc.getEnvelope().getBody().getFirstElement().getFirstOMChild();  
            binaryNode.setBinary(true);
            </script>
            <property name="messageType" scope="axis2" type="STRING" value="application/pdf"/>
            <respond/>
        </outSequence>
    </target>
    <description/>
</proxy>

It accepts a request with a tag id that refers to the table id (primary key)



<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope" xmlns:nb="http://mru">
    <soap:Body>
        <nb:id>1</nb:id>
    </soap:Body>
</soap:Envelope>

Make the request using curl (I am assuming the request is saved in the request.xml file)

curl -v -X POST -H "Content-Type:text/xml" -d @./request.xml http://localhost:8280/services/Sample.SampleHttpSoap12Endpoint > title1.pdf

This is what I got

Curl request for soap service

As you can see after I can open the pdf returned by the service.

Now it's the same for the API. It's actually easy and pretty much the same. You just need to customize the url template to catch the parameter ID for the SQL query.

 <api xmlns="http://ws.apache.org/ns/synapse" name="GetPdf" context="/pdf">
    <resource methods="GET" uri-template="/id/{fileId}">
      <inSequence>
         <property name="ID" expression="get-property('uri.var.fileId')"/>
         <dblookup>
            <connection><pool><dsName>pgConn</dsName></pool></connection>
            <statement>
               <sql>select pdf_base64 from pdf_files where id = ?</sql>
               <parameter expression="get-property('ID')" type="INTEGER"/>
               <result name="pdf_base64" column="pdf_base64"/>
            </statement>
         </dblookup>
         <payloadFactory media-type="xml">
            <format>
               <ns:binary xmlns:ns="http://ws.apache.org/commons/ns/payload">$1</ns:binary>
            </format>
            <args>
               <arg evaluator="xml" expression="get-property('pdf_base64')"/>
            </args>
         </payloadFactory>
         <loopback/>
      </inSequence>
      <outSequence>
         <script language="js">
             var binaryNode = mc.getEnvelope().getBody().getFirstElement().getFirstOMChild();     
             binaryNode.setBinary(true);
         </script>
         <property name="messageType" value="application/pdf" scope="axis2" type="STRING"/>
         <respond/>
      </outSequence>
   </resource>
</api>

This api will return the PDF file using the correct Content-Type header for the browser to understand.

Image below. The browser correctly identifies the content using the content type header and uses the built-in PDF rendering to render the pdf file served by the wsoesb server.

PDF file open in browser

+2


source






More articles:


All Articles