SOAP intermediaries

[Pradeep bhatt]

When a SOAP message is sent, I was under the impresssion that there is a client and web service. Now, I read of intermediaries which process the
SOAP header? In an typical application where do these intermediaries exist ?
Thanks
Pradeep

[Lasse Koskela]

A typical example would be a message gateway on the edge of a company's network where all integrated business partners send their SOAP requests to. This message gateway then processes incoming SOAP requests by proxying them forward according to what the SOAP headers say. The benefit is a more loose coupling between the service and clients, and that certain operations such as authentication & authorization, translation, etc. can be implemented once in the message gateway instead of repeating the work for each individual service.

[Pradeep bhatt]

How is SOAP message passed through these intermediaries ? Who makes sure that the SOAP message passes through these intermediate nodes?
The client only knows about the web service(the ultimate receiver), right?
Is the concept similar to Filters in J2EE?
Thanks
Pradeep

[Lasse Koskela]

How is SOAP message passed through these intermediaries ? Who makes sure that the SOAP message passes through these intermediate nodes?
The client only knows about the web service(the ultimate receiver), right?

Wrong. The client only knows of the address of the gateway. The gateway is responsible for passing the request forward to the ultimate receiver (or any other intermediaries in between). If you have Monson-Haefel's "J2EE Web Services" at hand, the subject is discussed (to some degree) from page 95 onward.

Is the concept similar to Filters in J2EE?

I'd say it's closer to a HTTP Proxy than Filters.

[Lasse Koskela]

Some references to check out: (better read the spec than to blindly trust my memory )
http://www.w3.org/TR/2003/REC-soap12-part0-20030624/#L635
http://www.w3.org/TR/2003/REC-soap12-part1-20030624/#relaysoapmsg
http://www.w3.org/TR/2003/REC-soap12-part1-20030624/#forwardinter

[Pradeep bhatt]

HTTP GET does not have a payload area and so is not suitable for carrying SOAP messgaes. Can some one explain what pay load means?

[Lasse Koskela]

Originally posted by Pradeep Bhat:
HTTP GET does not have a payload area and so is not suitable for carrying SOAP messgaes. Can some one explain what pay load means?

Payload is something one carries. A paperboy's payload is a pile of newspapers and a HTTP POST request's payload is whatever comes in the "body". HTTP GET doesn't have payload because it doesn't have a "body" (although custom HTTP headers and request parameters could be considered as payload).