Successor to Windows Vista

Not sure for how many this will come as a shock. For me, it definitely did!

The next edition of Windows, i.e. the successor to Vista, is not only under development umbrella but started to ship too. The first milestone (M1) has been shipped to MS partners and is available in English only for both x86 and x64 machines. And it's scheduled to do a RTM in H2 2009. It was originally supposed to RTM in 2010 but looks like MS is pulling strings pretty hard.

Not much of information is available as of yet as to what all the new version carries. But since we have some tie-ups with MS, looks-like I can get my hands-on it. 09-10 is going be one heck of a year for us as well as MS, with Rosario also set to be released.

Keep watching this space for more information on what the new OS is all about.

By the way, it's called Windows 7 (previously code-named Blackcomb Vienna)

Source: http://www.tgdaily.com

Workflow with id not found in persistance store

For couple of days now I've been doing extensive debugging of a (Windows) Workflow. And time and again I've been facing this error. So I thought I will elaborate more on this. There are three primary reasons why this might happen:

1. Your workflow has actually terminated. It could have terminated or finished execution, but since you wouldn't try to load a finished workflow, in all probablities, it would have terminated (due to some unhandled exception). You can check this by going to your WorkflowInstance table in your persistence store and check the DbEndDateTime for your workflow instance. If it is null, then you can move to next points :-) else you have found the culprit. All you have gotta do is to debug into your workflow and fix your code.
2. Workflow changes. If you make any changes to your workflow and then try to load previous instances of it, you will see this error. You will have to apply the changes done on the workflow to the old instances also.
   
3. Try to connect to remote persistence store. If you are trying to load a workflow instance from a remote store, this error will come up. Make sure that your remote (store) server DTC is configured to allow this.

Hopefully, this will help people in saving time trying to find why the workflow doesn't load. Pls be aware that this error can come up due to many other reasons and not only the three mentioned above.

State-Machine Workflow Part II

We have the following on the host app:

1. A service class that implements communication-service interface
2. The workflow runtime and its services which are instantiated and added respectively in the host app.

Service Class
The service class basically implements the communication-service interface, promising the interface that it understands which events the workflow would support and that it will raise them. For each of the events that is supported the service class just raises them. That's it!

Workflow Runtime
We come to the centre of the pizza! Workflow runtime is the actual component that hosts the workflow. In effect, it's the translator between the workflow and the rest of the world.

Many services can be registered while instantiating the runtime. Services for External Data Exchange, tracking etc (the list of services can be easily googled) are provided to add extra functionality to the bare-bone runtime. But it's very important to choose the services judiciously as a service without purpose brings down the performance.

Error loading workflow: Runtime capabilities are not available with this type

I just started-off with coding on workflows and the first error that I see:

I did quite a bit of googling but couldn't find any answer. Usually in these kind of errors, the error (written in blue) is given with link which would take the dev to the error line. But here the link doesn't work i.e. you don't go anywhere :)

So the resolution?
Well, just rebuild the whole application. And it works like magic. Now, what's going on here: The scenario was that we were two guys working on same code using TFS. He had checked-in code which was not properly building (he was infact in the middle of making some changes). Once he checked-in properly building code things started working properly.

Going Forward...

Long time that I've updated my blog. I was actually busy with a personal work and couldn't concentrate on this.

Well, as Shakespeare said, All is well that ends well, I'm now going to resume my blog. But going forward the posts would be relating to Windows Workflow Foundation (WF), Windows Communication Foudnation (WCF) and Windows Presentation Foundation (WPF) rather than just C#. Though the theme of the posts would be same, "Not So Obvious..."