Henry and Arslan,
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The Publish-Subscribe Developer’s Guide can be found in the \Developer\Doc\Guides folder as well as on Advantage. You may also want to review the description for the pub.publish:publishReply service.
The service processing the document type published by publishAndWait should use publishReply to publish a response document type to the broker. There is no option to retrieve a document type directly from a service. Request/reply routing is handled by the broker not be the publishing or replying services themselves.