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Saturday, February 22, 2014

Common mistakes to avoid in WSO2 ESB - 1 - "org.apache.axis2.AxisFault: The system cannot infer the transport information from the URL"

In the next few weeks, you could expect a series of blog posts from me which explain the remedies to avoid some common mistakes which we do when working with WSO2 ESB. This is the first of many.

During the initial rounds of testing your integration solution or even in production systems, you may have come across the following error.

org.apache.axis2.AxisFault: The system cannot infer the transport information from the URL ....

Some of you may have struggled hours figuring out a solution to address this issue. Let me explain this error in detail and possible causes of this. So, next time when you see this error in your WSO2 ESB setup, you will not have to spend time unnecessarily googling everywhere.

There can be many different causes of this error. I have observed  four main reasons.

Cause 1


This is the simplest cause. Suppose, you have a proxy service similar to the following.

<proxy xmlns="http://ws.apache.org/ns/synapse"
       name="MistakesTest"
       transports="https,http"
       statistics="disable"
       trace="disable"
       startOnLoad="true">
   <target>
      <inSequence>
         <send/>
      </inSequence>
      <outSequence>
         <send/>
      </outSequence>
   </target>
   <description/>
</proxy>
                                

Look at the inSequence of the above proxy. We have defined send mediator without address information. Now, when you send a typical SOAP request over HTTP to this proxy service, ESB does have no way to find where to route the request. The HTTP transport sender which is supposed to route the HTTP request clueless where to forward the request and fails with the following error.

ERROR - ClientUtils The system cannot infer the transport information from the /services/MistakesTest URL.ERROR - Axis2Sender Unexpected error during sending message out
org.apache.axis2.AxisFault: The system cannot infer the transport information from the /services/MistakesTest URL.
    at org.apache.axis2.description.ClientUtils.inferOutTransport(ClientUtils.java:81)


How can we fix this? There are many approaches.

First, you can simply associate address information to the send mediator by defining an endpoint.

        <send>
            <endpoint>
               <address uri="http://localhost:8088/mockaxis2service"/>
            </endpoint>
         </send>

Or else, you can seek help of WS-Addressing framework. You can fix your client application to send your request with WS-Addressing To header as shown below. Then, Axis2 transport sender in WSO2 ESB, extracts the wsa:To header value of the request and forwards the message to back-end service.

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ser="http://service.carbon.wso2.org">
   <soapenv:Header xmlns:wsa="http://www.w3.org/2005/08/addressing"><wsa:Action>urn:echoString</wsa:Action><wsa:MessageID>uuid:86b1f69b-f4a2-4f4c-b5c9-54fea095972e</wsa:MessageID><wsa:To>http://localhost:8088/mockaxis2service</wsa:To></soapenv:Header>
   <soapenv:Body>
      <ser:echoString>
          <ser:s>charitha</ser:s>
      </ser:echoString>
   </soapenv:Body>
</soapenv:Envelope>

We have discussed about the simplest cause for the error which we are trying to solve. Next, let's try to understand another common reason.

Cause 2


Suppose, you have a proxy service similar to the following.

<proxy xmlns="http://ws.apache.org/ns/synapse"
       name="MistakesTest"
       transports="https,http"
       statistics="disable"
       trace="disable"
       startOnLoad="true">
   <target>
      <inSequence>
         <send>
            <endpoint>
               <default/>
            </endpoint>
         </send>
      </inSequence>
      <outSequence>
         <send/>
      </outSequence>
   </target>
   <description/>
</proxy>

Here, we have defined a default endpoint, which does not have an address URI associated with it and the address information is resolved through wsa:To header of the incoming request.
Now, if you send a SOAP request, without wsa:To header, you will get the above error.

How can we fix this?

Obviously, we can include wsa:To addressing header in the request (as explained before).
Or else, you can add an header mediator before send mediator in the above configuration which will set wsa:To header of the request.

<header name="To" value="http://localhost:9090/mockaxis2service"/>

Cause 3


As I explained above, axis2 transport sender, defined at axis2.xml is responsible for forwarding the incoming request.

e.g:-
 <transportSender name="http" class="org.apache.synapse.transport.passthru.PassThroughHttpSender">

HTTP and HTTPS transport senders are enabled by default in axis2.xml. Think about a use case similar to the following.
You need to do a transport protocol switching through WSO2 ESB, which is a quite common use case in any ESB. In that case, suppose you have a proxy service similar to the following.

<?xml version="1.0" encoding="UTF-8"?>
<proxy xmlns="http://ws.apache.org/ns/synapse"
       name="MistakesTest"
       transports="https,http"
       statistics="disable"
       trace="disable"
       startOnLoad="true">
   <target>
      <inSequence>
         <send>
            <endpoint>
               <address uri="jms:/queue1?transport.jms.ConnectionFactoryJNDIName=QueueConnectionFactory&amp;java.naming.factory.initial=org.apache.activemq.jndi.ActiveMQInitialContextFactory&amp;java.naming.provider.url=tcp://localhost:61616&amp;transport.jms.DestinationType=queue"/>
            </endpoint>
         </send>
      </inSequence>
      <outSequence>
         <send/>
      </outSequence>
   </target>
   <description/>
</proxy>
                                

In this proxy configuration, the proxy service acts as a JMS producer and forwards the request coming through HTTP channel to a JMS queue (queue1). If you try this scenario, in vanilla version of WSO2 ESB without any modification, you will get the following error.

ERROR - Axis2Sender Unexpected error during sending message out
org.apache.axis2.AxisFault: The system cannot infer the transport information from the jms:/queue1?transport.jms.ConnectionFactoryJNDIName=QueueConnectionFactory&                 java.naming.factory.initial=org.apache.activemq.jndi.ActiveMQInitialContextFactory&java.naming.provider.url=tcp://localhost:61616&transport.jms.DestinationType=queue URL


How can we fix this?

In the default axis2 configuration, the HTTP transport senders are only enabled. Thus, when you we are trying to forward a message through non-HTTP transport such as JMS (or VFS, SAP, FiX, mail etc), ESB cannot finds the transport sender registered against the transport protocol define in endpoint url (in this example, "jms:/")
Thus, you need to stop ESB and enable the relevant transport sender in ESB_HOME/repository/conf/axis2/axis2.xml as shown below.

<transportSender name="jms" class="org.apache.axis2.transport.jms.JMSSender"/>

Cause 4


Let's conclude our discussion by looking at another common reason for "The system cannot infer transport..." error.

When you are working with scenarios related to blocking transport senders, for example, Callout mediator or message processors, you may have come across the same error. These elements use blocking transports to call the external services hence they cannot make use of the default axis configuration defined in ESB_HOME/repository/conf/axis2/axis2.xml.
Think about a scenario, where you use message processor to query a queue and forward the message to an external file server through VFS transport or route to a SAP endpoint.
In this case, even if you enabled, the relevant transportSenders in the default axis2.xml, message processor or Callout mediator is not aware of that. They read the axis configuration from the following locations by default.

In ESB-4.8.0 or above:
ESB_HOME/repository/conf/axis2/axis2_blocking_client.xml

In ESB-4.7.0 or below:
ESB_HOME/samples/axis2Client/client_repo/conf/axis2.xml

Thus, if you do not enable transport senders in those locations, you get the same error.


1 comment:

Krishantha Dinesh said...

Useful article. there is other comman case which can get this error. if there any space (leading) on URL. (typo)



this leading space before http can give the same error