WSO2 ESB: How to download a file over HTTP?

问题

I want to download an XML file from a Web site using WSO2 ESB. Assume that the URL is static for the sake of simplicity.

I have tried VFS both as a proxy service and an individual sequence without success, and couldn't find any relevant material on the Internet.

Here is the sequence XML:

<sequence xmlns="http://ws.apache.org/ns/synapse" name="download">
   <in>
      <log level="headers">
         <property name="?" value="[download] in: started"/>
      </log>
      <property name="OUT_ONLY" value="true" scope="default" type="STRING"/>
      <property name="transport.vfs.ContentType" value="text/xml" scope="transport" type="STRING"/>
      <property name="transport.vfs.FileURI" value="http://static.nvd.nist.gov/feeds/xml/cve/nvdcve-2.0-2013.xml" scope="transport" type="STRING"/>
      <log level="headers">
         <property name="?" value="[download] in: sending over vfs"/>
      </log>
      <send>
         <endpoint>
            <address uri="http://static.nvd.nist.gov/feeds/xml/cve/nvdcve-2.0-2013.xml"/>
         </endpoint>
      </send>
      <log level="headers">
         <property name="?" value="[download] in: ended"/>
      </log>
   </in>
   <out>
      <log level="headers">
         <property name="?" value="[download] out: started"/>
      </log>
      <send/>
      <log level="headers">
         <property name="?" value="[download] out: ended"/>
      </log>
   </out>
</sequence>

So, how to download a large file over HTTP with WSO2 ESB?

回答1:

I have a similar problem, and by the moment I've solved it with an API and this code:

<api xmlns="http://ws.apache.org/ns/synapse" name="EcoRest" context="/services/ecorest">
   <resource methods="GET" uri-template="/{idFile}">
      <inSequence>
         <send>
            <endpoint>
               <http method="get" uri-template="http://slx00012001:8888/repositoryfiles/{uri.var.idFile}">
                  <suspendOnFailure>
                     <errorCodes>101500,101510,101001,101000</errorCodes>
                     <initialDuration>10</initialDuration>
                     <progressionFactor>1.0</progressionFactor>
                     <maximumDuration>10</maximumDuration>
                  </suspendOnFailure>
               </http>
            </endpoint>
         </send>
         <property name="enableSwA" value="true" scope="axis2"></property>
      </inSequence>
      <faultSequence>
         <log level="custom">
            <property name="FAULT GETTING FILE" expression="get-property('uri.var.idFile')"></property>
         </log>
         <payloadFactory media-type="json">
            <format>           {"descError":"$1", "error": "true"}           </format>
            <args>
               <arg evaluator="json" expression="$.descError"></arg>
            </args>
         </payloadFactory>
         <property name="HTTP_SC" value="500" scope="axis2" type="STRING"></property>
         <respond></respond>
      </faultSequence>
   </resource>
</api>

This API works perfectly and make a throught-pass with the files. But if I send an id_file doesn't exist, the backend service return an http 400 with a json-message, the process go into the faultsequence, but the payloadFactory in the faultsequence doesn't work, and I don't know why :(

回答2:

Have a go with this configuration:

<proxy xmlns="http://ws.apache.org/ns/synapse" name="download" transports="https,http,vfs" statistics="disable" trace="disable" startOnLoad="true">
   <target>
      <inSequence>
         <property name="OUT_ONLY" value="true" scope="default" type="STRING"/>
         <property name="ClientApiNonBlocking" value="true" scope="axis2" action="remove"/>
         <send>
            <endpoint>
               <address uri="vfs:file://home/secondary/file.xml"/>
            </endpoint>
         </send>
      </inSequence>
   </target>
   <parameter name="transport.vfs.Streaming">true</parameter>
   <parameter name="transport.vfs.FileURI">http://static.nvd.nist.gov/feeds/xml/cve/nvdcve-2.0-2013.xml</parameter>
   <parameter name="transport.vfs.Locking">disable</parameter>
   <description></description>
</proxy>

You can initiate the download using:

curl -v http://localhost:8280/services/download

You can find out more about the VFS Transport specific parameters here: http://docs.wso2.org/wiki/display/ESB460/VFS+Transport. You can also find another VFS example here: http://docs.wso2.org/wiki/pages/viewpage.action?pageId=16846489. Hope this helps.

来源：https://stackoverflow.com/questions/15874928/wso2-esb-how-to-download-a-file-over-http