http://blogs.msdn.com/ralph.squillace/archive/2006/10/10/Sessionless-duplex-services_3F00_-No-problem.-Small-issues_2C00_-yes_3B00_-problems_2C00_-no_2E00_.aspxDuplex is neato, definitely, because among other things it allows a service to push information at clients as it sees fit. You could just have two services, and one service throws an endpoint at the other and then listens for stuff coming back, too, buten-USCommunityServer 2.1 SP1 (Build: 61025.2)http://blogs.msdn.com/ralph.squillace/archive/2006/10/10/Sessionless-duplex-services_3F00_-No-problem.-Small-issues_2C00_-yes_3B00_-problems_2C00_-no_2E00_.aspx#845233Thu, 19 Oct 2006 21:21:47 GMT91d46819-8472-40ad-a661-2c78acb4018c:845233Ralph Squillace -- Docs, Samples, Docs, Samples....<p>Two posts ago I wrote the following post about how to build a duplex service and client that does NOT</p> http://blogs.msdn.com/ralph.squillace/archive/2006/10/10/Sessionless-duplex-services_3F00_-No-problem.-Small-issues_2C00_-yes_3B00_-problems_2C00_-no_2E00_.aspx#2656401Tue, 15 May 2007 23:32:37 GMT91d46819-8472-40ad-a661-2c78acb4018c:2656401La masa, el ladrillo, la bota, el bocadillo...<p>Desde el punto de vista de la escalabilidad, en teoria, es mejor crear y destruir el proxy, si es que</p> http://blogs.msdn.com/ralph.squillace/archive/2006/10/10/Sessionless-duplex-services_3F00_-No-problem.-Small-issues_2C00_-yes_3B00_-problems_2C00_-no_2E00_.aspx#9941869Tue, 29 Dec 2009 09:32:57 GMT91d46819-8472-40ad-a661-2c78acb4018c:9941869MushroomHunter<p>I don't think it is possible for this to work with any binding using a client that is behind NAT or a firewall unless they are reconfigured. If this is not true I am missing something and would love some clarification.</p> http://blogs.msdn.com/ralph.squillace/archive/2006/10/10/Sessionless-duplex-services_3F00_-No-problem.-Small-issues_2C00_-yes_3B00_-problems_2C00_-no_2E00_.aspx#9942032Tue, 29 Dec 2009 20:09:20 GMT91d46819-8472-40ad-a661-2c78acb4018c:9942032ralph.squillace<p>Hi Mushroom Hunter! No, you're right -- as is, a client that is expecting inbound messages -- that is, messages that will arrive on a different network connection but which are correlated with a specific client proxy instance by WCF so as to appear like an event or notification -- will not receive them if they are behind a firewall and/or a NAT router.</p> <p>Tough problem, yes? NO! At least, not now that you have the AppFabric ServiceBus, which solves EXACTLY this problem, among others. I'll post an example of how to use Service Bus with WCF soon, but the SDK has several examples. Go here: <a rel="nofollow" target="_new" href="http://msdn.microsoft.com/en-us/library/ee732537.aspx">http://msdn.microsoft.com/en-us/library/ee732537.aspx</a>. </p> <p>The short version is this: The Service Bus (and the Access Control Service, which it trusts as a claims provider by default) enable you to build a WCF service AND WCF client (in fact, you can use any client that supports a REST stack) that can communicate without requiring anyone to open any inbound ports or alter NAT router tables. It's an amazingly useful technology. Go have a look.</p>