Did you try accessing the external Web Service through any other client?
Can you check if the webservice in question returning the right SOAP content?
I didn't try any other client.
To access the external webservice in JDeveloper I enabled the proxy in Jdeveloper.
The external webservice is returning the right content but when I test it in EM console getting invocation error as mentioned above.
Okay can you try setting the HttpProxyHost, HttpProxyPort, HttpProxyUsername and HttpProxyPassword through the following steps
Login to the em console,Navigate to SOA Infrastructure->SOA Administration->Common Properties -> More SOA Infra Advanced Configuration Properties.
Enter the HttpProxyHost, HttpProxyPort, HttpProxyUsername and HttpProxyPassword
Click on Apply and then restart Server
I am assuming that you are behind a proxy and the SOA Suite needs communication to happen through the proxy to the outside world.
For 11G maybe you can refer to the link Proxy Configuration in Oracle SOA Suite 11g,
can you paste a soap request you are sending
I set the proxy at composite level but its not working.
Could you explain what do you mean by " The external webservice is returning the right content " ? If you have not tested with any other client, how did you infer that the web service is returning with the right content ?
Please find the below link and it will help you to set up the proxy server settings @ server level and @ composite service level. Also suggest you test the service using SOAP UI client.
hope it helps.