Don't think there will be any solution for this will succeed 100%
Both processes run in a different world.
your soa process - server site
your client browser - client side (of which you're not even sure if it's up and running)
easiest way i would say is , just email the pdf
You could FTP JCA adapter to read from a machine and write the pdf file in your client machine.
You can read the file as an attachment using File adapter and copy the file FTP adapter provided the client machine has the FTP server.
Hope this helps.
You could try exposing an xml web service that can be initiated by simply invoking the service URL from a web browser. Once invoked via simple URL request it picks up the file via JCA adapter and responds with the base64 binary version of the pdf content wrapped in a <img> html tag e.g.
<img src="data:image/gif;base64,R0lGODlhEA.... Alternatively you can pick up the file via JCA and perhaps email the base64 binary pdf content to the user?