Just a quick note to make readers aware of a new blogging site called #Fellows. This community site aggregates the blogs of a number of smart .Netters from the UK. Enjoy.

I have been seeing quite a lot of talk on the tweet feeds and blog posts recently about the new Reactive Extensions that are being released. Now I was struggling to get my head around it at first but read this simple blog post which really helped clarify what Rx actually offers. It seems very powerful, and could be a game changer for event processing in the same way Linq was for list data. Really like the drag and drop example in this  post as it becomes very clear the intention of the code shown below. 

Define the events you wish to monitor

Then define your query which will tie these events together into a logical form for your requirement (In this case drag and drop)

The other day I came across a comment in the code base of the application I'm currently working on that said the following.

// Having to loop through the GetMethods() array is pretty rubbish, even if we are using LINQ. If someone knows how to use GetMethod to get the generic method definition, then correct the code, email me and I'll buy you a pint.

Now looking into this issue it turns out that the author is correct, you cannot actually use Type.GetMethod() to invoke a Generic Method. As a result the approach the dev used was to call Type.GetMethods() which returns all methods on the type and then apply some linq filtering to identify the generic method they wish to invoke. Once filtered a quick call to MakeGenericMethod then you can invoke it. This is shown below.

So having a think about this for a bit and then recalling some great blog posts I had read from Bart De Smet's blog about expression tree's I wondered if we could use the Expression.Call method to achieve the same results. After some tinkering with the overloads for this method I eventually figured it out and result is shown below.

In the code above we create an instance of a Parameter expression which requires the Type of the parameter we are going to pass to the method. Then in order to invoke the method we need to build the call expression on line 2. Here we use the Expression.Call static method which has a number of overloads.

The first param is the type which holds the static method we wish to invoke, the next paramter is the method name which is passed as string. The third paramter is the types that the method signature defines. This is passed as an array of objects. Finally is the ParamExpression we constructed on the previous line. The final part once we have the methodInfo is to invoke it by pa ...

I had a request to make the defensive coding source code available.  So here you go.

Download

I had a problem recently where I had an inheritance hierarchy of which I needed to find a common ancestor type between two objects. Below shows a quick mock up of the situation I faced.

As you can see the Person type is the common ancestor for both Student and Teacher. In order to solve this issue I decided to write the following extension method for the Type type to be able to locate it easily in the future. Code below for anyone interested. Hope it helps.

I currently working on retro fitting some SQL server reports into the application we are building. I needed a quick way to view all the parameters each report uses. The code below is a quick snippet to do just that. Just point it at a directory with the RDL files in an away you go.  Note: This code does the bare minimum and is used for SQL Server 2005 RDL. I haven't checked to see if it works on SQL 2008 RDL. Thought it might help someone.

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Want to start developing for Silverlight 3.0? Well you can now download the tools you need for Visual Studio from Microsoft.

Download here

Today see's the start of MIX09. As a result I decided to look on the agenda for the sessions that are taking place over the next few days and I came across this little nugget if information on Silverlight 3. The session is titled "What's new in Silverlight 3" The brief synopsis gives us a sneak peak as to what to expect from Scotts Keynote.

"Take a tour of the new features in Silverlight 3 including a dive into some of the new experience oriented features like pixel shaders, perspective 3D, animation enhancements, bitmap APIs and improvements to the media stack. Also hear about new Silverlight base framework additions including updates to the style model, data binding improvements, improved resource handling and improvements to the web services stack."

Looking forward to those 3D demo's already!

So it s been a while since I have blogged. I wont bore you with the details but what with moving home, project commitments and lots going on in my personal life I've just not had time to focus. This post is to get me started again .

The next SLUG meeting has been announced. You can find details of it here . Its going to follow a GROK TALK format, this means that anyone can have 15 mins talking to the group about experiences they have had with Silverlight. Mark is also looking for MIX attendees to come along and share their thoughts on this years announcements etc.

Back at the beginning of the year I wrote a blog post about the awkward conflict that BizTalk faced now that WF was on the scene.  Although at the time of writing there was an obvious cross over between the products, BizTalk still offered a number of key advantages over bog standard workflow. Due to some emails I received I decided to look around Microsoft's code projects and see what I could find. It was way back in Feb that I came across OSLO.

9 Months later and with PDC out of the way, OSLO and Microsofts strategy for WF is far more clear. OSLO seemed to evolve over the last few months into the codename primarily used for the modelling language and toolset announced. Microsoft also showed off a whole new version of WF for .NET 4.0. This new version of WF comes with some major improvements.

• WF has been rewritten from the ground up.
• Performance has been dramatically increased
• Services and Workflow can be written purely with XAML
• A new customisable designer surface
• Large number of new activities for developing workflows
• Seamless integration with WCF

So with WF being upgraded to a spanky new version which offers a wealth of new features please bare in mind that BizTalk'ers are still waiting for their orchestration engine to be updated to use the new WF engine. Given the new version of WF being announced I would be wondering how long its going to take before I see that in BizTalk?

Back to the original OSLO article I found way back in Februrary, the article talked of a new WF hosting engine. This part of the puzzle we now know has been codenamed "Dublin". If you haven't heard of Dublin yet and your into BizTalk then hold your breath as the diagram below (taken from MSDN) may look familiar.

 Dublin is the application server that has long been missing from the Microsoft product set. Announced to be a part of Windows Server , Dublin provides a runtime which hosts WF workflows and provides services for persistence, tracking, management, message forwarding and much more. The Dublin runtime is implemented on SQL Server server which allows WF developers to create long running workflows. Prior to Dublin this was only possible by either rolling your own or implementing BizTalk.

Is this sounding familiar to you? Well it doesn't stop there I'm afraid. Dublin can also run as part of farm of servers whereby each instance  can use a single shared persistence store. Dublin also provides automatic workflow activation as part of its message routing architecture.

As you can see Dublin is the future. Even Microsoft recognise the awkward overlap of features as evidenced by this MSDN article.

For anybody familiar with BizTalk Server, looking at “Dublin” might cause a slight sense of déjà vu. Supporting workflow-based logic, providing a monitoring and management infrastructure: These are things that BizTalk Server does today. What’s the future of BizTalk Server in a “Dublin” world?

The key thing to understand is that “Dublin” doesn’t directly target traditional BizTalk scenarios. For example, enterprise application integration and business-to-business connections via EDI will still use BizTalk Server. Similarly, bringing existing applications into the service-oriented world by exposing their functions and/or data through BizTalk Server will continue to make sense. While the reach of “Dublin” may grow over time, BizTalk Server r ...

Scott Gu has a post today highlighting a couple of features that we can expect to see in Silverlight 3. Good to hear on the list are the following

• Increased databinding support (Lets hope we get element binding)
• 3D graphics support (With GPU Acceleration)
• H.264 Codecs for high quality video streams.

His full post can be found here.