When we start doing this two way style of messaging, we now open up to start modeling some interesting business problems.  In the previous post, you'll note that I did not include the code, because I mentioned we needed to be more clever in scenarios where we listen in parallel.  First, a brief diversion into how the Receive activity works.  Everybody remembers the workflow queues, the technology that underlies all communication between a host and a workflow instance.  The Receive

So, we've seen in part 1 how to manage context, we saw in part 2 how we can take that basic knowledge to do duplex messaging.  Once we start doing duplex work, there are some interesting patterns, and the first one is one that we like to call "long running work".  Why are we interested in this?  Well, as you probably know, the execution of a workflow is single threaded (this is a feature, not a bug).  We also don't have a mechanism to force the workflow to be "pinned"

Martin posted an interesting question here on my last post: <quote> The first thing that we need to do in order to enable this duplex messaging to occur is that the "client" workflow has to explicitly provide its context token to the service so that the service can address the appropriate instance of the client workflow. Note, in the real world, you'll probably need to supply more than just the context token, you will need some address and binding information. </quote> Shouldn't

A continuation of my series of demos from my advanced workflow services talk.  Here we focus on duplex message exchange patterns. Duplex messaging is something that we model at the application level (as opposed to the infrastructure level) because we want to model that message exchange at the level of the application.  Here's some scenarios where I could use duplex messaging: [concrete] I submit an order, and you tell me when it ships [abstract] I ask you do to do some long running work,

So, last week I wrapped up a conversation at TechReady, our internal conference, where I was talking about the integration between WF and WCF in .NET 3.5.  This talk was somewhat bittersweet, it's the last conference where I'm scheduled to talk about WF 3.0/3.5, I'll start talking about WF 4.0 at PDC this fall.  There are a series of 4 demos that we'll talk about in this series: Basic Context Management Simple Duplex Long Running Work Pattern Conversations Pattern I've gotten a lot of requests

A question recently came up on an internal list about how to start a workflow to do some work and then have it accept a message via a Receive activity.  This led to an interesting discussion that provides some insight into how the WorkflowServiceHost instantiates workflows in conjunction with the ContextChannel. Creating a Message Activated Workflow By default, the WorkflowServiceHost will create a workflow when the following two conditions are true: The message received is headed for an operation

As widely reported on blogs far and wide , Visual Studio 2008 has been released to manufacturing (or shipped, available, ready to get, etc).  MSDN subscribers can do their part to degrade the global bandwidth supply and get in the download queue via the subscription center, trial editions are available here .  One can also simply get the updated version of the .NET Framework, .NET 3.5 here , and I'd strongly recommend the web setup to only get the bits you need on the machine, and not ones

Yesterday, following my "What's the context for this conversation" presentation, I was approached with the following question: I am sharing a singleton client that I want to use to interact with multiple workflow instances, how do I change the context for each of them. Completely unbeknownst to me, Wenlong, one of the product team's more prolific bloggers, addressed this very topic in his post here , conveniently posted yesterday :-)

This past Friday we released Beta 2 of Visual Studio that contains the .NET Framework 3.5. Get it here . This releases stabilizes a lot of the stuff which had been in the previous releases, and includes some of the new tools, like the WCF test client. The main feature relating to WF is the introduction of the Workflow Services project templates which contain a complete, working implmentation of a WCF service as a WF workflow using the new send and receive activities.

So, per Soma's blog , this great Channel9 video , and a bunch of other places, VS 2008 Beta 2 is available for download ( go here ). Others are covering their favorite feature in depth, I want to cover one of mine: the WCF test client, which I will show by way of creating a Workflow Service application. Real quick, for those of you who didn't read the readme file, I know sometimes you just forget, there is an important note regarding how to get this to work (out of the box you will probably get an