Possible for webservice to send message from server to client?

I'm pretty sure this isn't possible开发者_JS百科 with HTTP 1.1 or webservices, but just want to double check with you guys (and thus will probably be switching this application to WCF).

I want to send a message from the server an asp.net webservice is running on, to the client consuming it. Is this possible without polling (IE an interrupt based model)?

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In WCF, you do have a thing called duplex bindings, which allows the server to call back into the client at a specific address.

See the MSDN documentation on duplex channels for a first impression of what those are.

I don't think you can do this with ASMX.

Marc