Emil’s Blog

Templates for SQL Server Management Studio 2008 are stored in this folder on WIndows XP:

C:\Documents and Settings\[user]\Application Data\Microsoft\Microsoft SQL Server\100\Tools\Shell\Templates\Sql

On my new WIndows 7 machine, the location is:

C:\Users\[user]\AppData\Roaming\Microsoft\Microsoft SQL Server\100\Tools\Shell\Templates\Sql

Create sub-folders and SQL files there and they show up in the Template Explorer. Really useful…

/Emil

This is an example of how to do script parameter parsing in PowerShell:

Pretty neat, huh?

/Emil

SQLite and unit testing is a great combination for testing database operations without having to manage database files. You can simply create an in-memory database in your setup code and work with that. Perfect in combination with NHibernate for example.

If you want to do this in the current .Net 4.0 beta your out of luck though, you'll get an exception:

The solution is pointed out by Jomo Fisher. What you do is to include this snippet in the application config file:

When unit testing assemblies that references System.Data.SQLite.DLL then you have to put that snippet in NUnit's config file (C:\Program Files\NUnit 2.5.2\bin\net-2.0\nunit.exe.config).

If you combine this with the tip in my post NUnit with Visual Studio 2010 Beta 2, you should insert the following

plus

under the runtime tag.

This works for me, hopefully it will for you as well.

/Emil

I just found a very useful XSD for editing log4net configurations:

http://csharptest.net/?p=38

Just copy the schema file to C:\Program Files\Microsoft Visual Studio *\Xml\Schemas and add the correct namespace to the log4net element in your config file:

/Emil

Here's a tip of how to run NUnit tests in .Net 4 code:

Running NUnit 2.5 against Visual Studio 2010 .Net 4 code

Note that it's the NUnit.exe.config file in C:\Program Files\NUnit 2.5.2\bin\net-2.0 that should be updated.

I'm now on Twitter...

http://twitter.com/emilast

Wonder if it's gonna be useful or a time-stealer...

/Emil

I recently started working on a new project in which we wanted to use WCF services that utilized NHibernate for database work. We also wanted those services to support distributed transactions so that several calls to one or more service would be done within the same client transaction. This is possible thanks to functionality in the System.Transactions namespace and in WCF which supports transaction flowing and of course the Distributed Transaction Coordinator in the operating system (see MSDN for more info on the DTC).

Note: The code below has been tested on NHibernate 2.1.1, Windows XP and .Net 4 Beta 2. Older versions of the .Net Framework should also work, but not necessarily older versions of NHibernate. I believe distributed transaction support was introduced in 2.1.0, but it may or may not work in similar ways to what is described here in older versions since the ADO.Net supports the System.Transactions namespace.

The goal is to write code like this on the WCF client side:

If all goes well, the results of both service calls are comitted to the database. If the call to service2 fails and we get an exception so that tx.Complete() is never executed, then all database updates are rolled back are rolled back and nothing is persisted, even if service1 is hosted in another process or on another machine.

Note also that we're not limited to database updates, any resource that supports transactions and knows about System.Transactions will be able to roll back updates.

For the above to work, we have to do several things:

• Configure the service binding to support transaction flow (on both the client and service side). Example:
  <system.serviceModel>
    <services>
      <service ...>
        <endpoint ... bindingConfiguration="TransactionalWsHttp">
           ...
        </endpoint>
        ...
      </service>
    </services>

    <bindings>
      <wshttpbinding>
        <binding name="TransactionalWsHttp" transactionFlow="true" />
      </wshttpbinding>
    </bindings>
  </system.serviceModel>

• Mark the methods that should be enlisted in the distributed transaction with the TransactionFlow attribute. Do this on the service contract interface:
  [TransactionFlow(TransactionFlowOption.Allowed)]
  void SaveMyObject(Foobar object);

  That setting dictates that the client's transaction will be used, if there is one. If there isn't, a new one will be created automatically for the method call and it will be auto-committed when the method returns.

  You can also use TransactionFlowOption.Mandatory to require the client to supply the transaction. If it doesn't then WCF will throw an exception.

• Mark the method implementation with the OperationBehavior attribute like this:
  [OperationBehavior(TransactionScopeRequired=true)]
  public void SaveMyObject(Foobar object)
  {
     ...
  }

  This will supply the method with the transaction (the other settings are not enough, they simply indicate that WCF should be configured to be prepared supply the transaction and this setting says that the method really wants it).

This is actually all that is required! NHibernate will now detect if there is a so called ambient transaction (to do this yourself, look at the System.Transactions.Transaction.Current static property, if it's non-null there there is a transaction) and will enlist its session in it. When the transaction completes, then the saved data will be comitted to the database. If there is an exception so that transaction is never completed then all data will be rolled back.

Important notes:

• Don't close the NHibernate ISession explicitly when using the above pattern as NHibernate will do that itself when the distributed transaction completes or is rolled back. If you do, then you will get an exception later when the transaction tries to do it.
• Don't create transactions explicitly, let System.Transactions do that for you.
• If you get this error:
  Network access for Distributed Transaction Manager (MSDTC) has been disabled. Please enable DTC for
  network access in the security configuration for MSDTC using the Component Services Administrative tool.

  then you have to do as it says and enable network access in the DTC on the server where the WCF service is hosted (and also on the database server I woul assume, but I haven't actually checked). Here's an instruction on how to do that:
  Network access for Distributed Transaction Manager (MSDTC) has been disabled

I think this is really cool stuff. Not only does it simplify transaction management in NHibernate, it also allows us to write much more robust distributed service-oriented application with very little effort. You also get support in the operating system, for example för statistics:

I haven't tried with other databases than SQL Server but as NHibernate seems to support System.Transactions it is possible that it works with other DB systems as well. If you have any experience with that, please leave a comment

I will continue to update this post if I do more findings on this subject. When I google about this there wasn't much information on this subject so hopefully this post will help others with the same needs.

/Emil

Here's som simple code to transform an array or list from one type to another:

Both alternatives will give the same result but the first one contains slightly less code. Which is better from a performance point of view? If you know, feel free to leave a comment...

/Emil

I was recently contacted by Patrick Smacchia, one of the developers behind NDepend and he asked me if I'd like to try it out, which I did. This is a report of my first impressions.

If you're not familiar with NDepend, it can be described as a tool to analyze a set of .Net assemblies for code quality. I suppose its name indicates that it originally was focused on analyzing dependencies but these days that name is rather misleading, in my opinion, as it can do much more that that. I'll go through some of its capabilities below.

When you first analyze a set of assemblies, NDepend displays a screen similar to this:

If you're like me, then you didn't check out any tutorials or web casts before running the tool and your first reaction is likely "Holy cow! What's all this?" or something similar.

It turns out that there is a ton of useful information in these displays but you have to know how to interpret them which takes a little learning.

Briefly, here's what I gathered so far:

• The Metrics display (with the gray blobs) lets you select a metric (such as the number of lines of code) and display it on the selected code level (method, field, type, namespace or assembly). The the blobs represent code entities of the given level and their sizes correspond to the metric's value. All children blobs of the parent level are grouped together to indicate which parents have high accumulated values of the metric. This display was really bewildering to me at first but once you decode its structure then it's really powerful.
• The Dependency graph is more intuitive and let's you see call dependencies between code components of different levels. Works well on small numbers of components but once you start to display larger dependency chanins, e.g. between methods, then it quickly becomes very difficult to use.
• The Dependency matrix is also fairly unintuitive at first, but very powerful.
  
  It contains the so called Dependency Structure Matrix with displays dependencies between code elements. Each non-empty cell in the matrix represents a dependency but the number can have different meaning depending on user selections in the GUI. Green and blue cells indicate one-way dependencies (hover mouse over a cell to display a small arrow indicating the direction) while black cells represent bidirectional dependencies, which might be a cause for concern. This display can really show many interesting aspects of usage dependencies and it can also be used to generate dependency graphs for subsets of these dependencies (try the popup menu to see what I mean).
• Finally, there the CQL query display where you can use the NDepend Code Query Language to further analyze your code. By default a set of standard queries are executed, listing potentional problems with naming, performance, and many others.

In addition to the displays described above, an HTML report is also generated after analyzing assemblies. It displays much of the same information as the graphical and interactive displays above, but also contains the "Abstract vs instability diagram":

Obviously you want to be in the green area with all your assemblies, but the dimensions used might not be completely clear at first sight. This seems to be a good article describing it it detail.

So, what are my first impressions? Well, I must say that NDepend really is a very powerful tool for analyzing code but it does require investing some time to use its many features properly. To me, that seems like an investment well worth doing.

/Emil

Let's take a break and post a tip about my favorite hobby, photography and image editing...

Look here for some fantastics images and tips of how to create them: http://www.smashingmagazine.com/2009/04/22/the-ultimate-photography-round-up

This is really stunning stuff!

/Emil