Interesting. My guess is that the pub.client:soapRPC service is treating the long string as something that needs to be interpreted as base64Binary. There could even be a part of the soap spec that was behind that behavior or maybe its just a plain ole bug.
At any rate, interoperability issues like this one are one of the big reasons that the rpc/encoded style of soap messaging is not recommended by many. I read a post on the SOAP::Lite (perl Soap toolkit) website seeking volunteers for an open source project to re-write the toolkit to better support the document/literal style and the WS-* standards that have caught on.
I would submit an SR to webMethods with adequate examples to reproduce this behavior.
Let us know what you learn.
A possible workaround is to build the soap rpc/encoded message manually (using document types or just plain ole string maniuplation) and then post that to your perl service using pub.client:http. You would then be able to convert the resulting XML string into a node and parse out the troublesome description string.
Mark
#webMethods#soa#API-Management