Jeroen Derde's Blog

My Software Engineering Universe

xVal - a validation framework for ASP.NET MVC

clock June 24, 2009 03:03 by author Jeroen Derde

Via Codeplex, and a bit later on Steve Sanderson’s blog I found some information on xVal.
xVal is, as the title of this post states) a validation framework for ASP.Net MVC.


A qoute from Steve's post that got me very exited to start using xVal.

"xVal lets you link up your choice of server-side validation mechanism with your choice of client-side validation library.
It guides you to fit them both into ASP.NET MVC conventions, so everything plays nicely with model binding and errors registered in ModelState."

What this means to me is that I can implement clientside validation via JQuery Validation( but if the client does not support JavaScript all validations will also be done serverside.
The validation is also only defined once (on the modal) which makes for much easier maintenance. This is quite a big deal because many of our customers require that the webapplications we build adhere to the accessability rules set by the Dutch government.(

Order a pile of pizza's because I'll be experimenting with xVal and ASP.Net MVC the next couple of days.

PS: if you don't know about DataAnnotaions yet, read this first:

Web Platform Installer 2.0 Beta

clock June 24, 2009 01:20 by author Jeroen Derde

Today I was creating a new Virtual PC to do some ASP.Net MVC programming. After duplicating my standard image I went to and was preparing myself to download a couple of installers. Then I saw a button in the top left corner that said: Install Now with the Microsoft Web platform installer.

Web Platform Installer is like a stack. It enables you to install everything you need to start web developing at once and then some more.

This made getting my development machine up and running much easier. It also introduced me to some tools I had never heard of before, which is a big plus aswell.








Yahoo Pipes

clock June 18, 2009 23:19 by author Jeroen Derde




At QNH we are always looking for ways to put the company name and knowledge out there on the internet. For quite a while we had been pondering the idea of starting a company weblog to share that knowledge with the on-line community. The thing that held us back was the difficulty of getting our engineers to post on this company weblog. Lost of our engineers have their own personal weblogs and we did not want them having to copy-paste each and every relevant blog entry into the company weblog. While trying to come up with a solution to this problem, one of our senior software engineers and architect stumbled upon Yahoo Pipes.

Yahoo Pipes according to Yahoo

"Pipes is a powerful composition tool to aggregate, manipulate, and mashup content from around the web".
Like Unix pipes, simple commands can be combined together to create output that meets your needs:

  • combine many feeds into one, then sort, filter and translate it.
  • geocode your favorite feeds and browse the items on an interactive map.
  • power widgets/badges on your web site.
  • grab the output of any Pipes as RSS, JSON, KML, and other formats.

Getting Started on combining RSS feeds

Go to and sign-up, or use a yahoo account you already own.
We decided not to use a personal account, but opted to creating a new company account. The company account is

Creating a Pipe

Create a new Pipe and open it, and click the "Edit Source" Tab.
The Pipes Editor is shown.

  1. Add a "Fetch Feed" source from the left menu and add some RSS 2.0 feeds as URL's
  2. Add a "Filter" operator from the left
  3. Connect the "Fetch Feed" To The "Filter" by dragging and dropping a connection starting from the fetch feed
  4. Because we only want posts containing the category QNH to be aggregated we configure the filter as follows:
    - Permit items that match All of the following
    - Add a Rule: Item.Category contains QNH
    - Add a Rule: Item.Category contains qnh

    The editor should look something like this











If we connect the filter to the Pipe Output we would get all entries of the blogs defined in the Fetch Feed that have a category named QNH.
But now we want to cap the description of every entry to 500 characters and add "..." at the end of the description. We also want to get rid of some illegal characters some blogs create.
These are the steps required.

  1.  Add a Loop Operator.
    - For each item.description in input feed
    - Add a Sub String String (from 0 to 500)
    Assign results to item.description
  2. Add a RegEx Operator and add the following rules
    - item.description replace (.*)(\[...\]) with $1
    - item.description replace <pre.*?> with empty (empty field)
    - item.description replace <img.*?> with empty (empty field)
  3. Add a Loop Operator.
    - For each (empty field) in imput feed
    - Add a String Builder String (item.description + ...) and assign the results to the item.description

The part we just created should look like the next picture.















Now we are almost done. But because some weblog engines put the author in the item.dc.publisher or in the item.dc.creator in stead if the we need to correct this.

  1. Add a Loop Operator.
    - For each (empty field) in imput feed
    - Add a String Builder String (item.dc.publisher + + and assign the results to the
  2. Add a Sort Operator
    sort by item.pubDate in descending order
  3. Connect the sort operator to the pipe output

The last part created should now look like














 Save the pipe! 

End result

Now we end up with an agregated RSS feed that we can integrate into any part of the organisation.
For example: The feed is featured on the QNH AD&S website, but also shown on the homepage of our company intranet,

Good times!


clock June 4, 2009 01:27 by author Jeroen Derde


Tweeting from outlook using OutTwit works like a charm, but I was missing something to soothe my Mobile twitter attacks.
This is when I discovered Twikini and PocketTwit for Windows Mobile. I tried PocketTwit first, but could not get it to connect to twitter on my HTC P4350.
So after uninstalling it I tried
Twikini. Twikini looks like a million dollars in all of it's simplicity.














It is compatible with all Windows Mobile® 5 and 6 devices, including touch and non-touch.
I'm already hooked on this app. Hope you will enjoy it too.

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