Anders Lybeckers Weblog!

Transferring SQL Server logins

2010-03-01T17:31:53Z

I had to migrate a SQL Server 2008 instance on to new hardware.

I choose to detach the databases and attach the databases on the new SQL Server 2008 instance on the new hardware. This was easy, but the origin SQL Server instance used mixed SQL Server and Windows Authentication Mode. This also meant that I had to migrate SQL Server logins, as the logins where a mix of SQL Server logins and Active Directory domain accounts/groups.

Both the SQL Server logins and domain accounts/groups has an unique SID (Security Identifier), which ties the logins in the SQL Server with the users in the database.

While the domain accounts/groups resides in the Active Directory domain controllers, the SQL Server logins only resides in the SQL Server. This means, moving domain accounts/groups is easy, by just creating the same users in the new SQL Server instance, but SQL Server logins is not. I could either choose to:

Recreate the SQL Server logins with new users in each of the databases, as new SQL Server logins will get new SIDs and therefore not be tied to the old database users. This also requires that you know all the passwords – alternative reconfigure all the client applications using SQL Server logins
Transfer the SQL Server logins with SID and password

How to transfer SQL Server logins? See the KB article: How to transfer the logins and the passwords between instances of SQL Server 2005 and SQL Server 2008. Easy

Cisco VPN (IPSec) support on 64 bit platforms

2010-01-16T18:12:04Z

I like Windows 7 x64, but I hate Cisco’s lack of support for the IPSec protocol on 64-bit platforms. Many of our customers use IPSec and the Cisco VPN Client – therefore I cannot connect to the customer’s network via IPSec VPN tunnels on my primary laptop

Until today

A colleague of mine recommended Shrew Soft VPN Client. It’s free and works like a charm. It’s a lot faster connecting and negotiating to the remote network than Cisco VPN Client, so fast in fact, that I initially thought that the connection failed. I’ve been using it for a couple of days, connecting to multiple customers, without any issues.

Why does Cisco implement a VPN client for x64 platforms?

I guess it is a money making scheme. They want to push their new Cisco VPN boxes and their new Cisco AnyConnect VPN client (expensive!), which makes use of SSL VPN.

Greg Ferro has another critical article Early Death of Cisco VPN Client Forces VPN License Fees with more details about Cisco’s SSL VPN.

I know of a commercial IPSec VPN client from NCP that works fine with Cisco IPSec VPN tunnels, but the steep price tag of $144 USD + taxes is too much.

Configuring the DTC for WCF with OleTx

Lucene.Net and Transactions

2009-12-03T20:00:46Z

Lucene.Net is an open source full text search engine library (a port from Java). It is stable and works like a charm – I’ve been using Lucene.Net for a couple of years now and implement a handful of solutions. Lucene is awesome.

If you want to try working with Lucene.Net, then the DimeCast.Net crew has recently made two short webcasts introducing Lucene.Net.

.Net 2.0 made it simple to use transactions with the System.Transactions namespace. Two of the great features are automatic elevation to distributed transactions (and utilize the Distributed Transaction Coordinator) and the other is the simplicity of creating your own transactional resource managers.

The .Net Framework defines a resource manager as a resource that can automatically enlist in a transaction managed by System.Transactions – which means that any object that implements any of the following interfaces can enlist in a transaction:

IEnlistmentNotification for the two-phase-commit protocol
IPromotableSinglePhaseNotification for the single-phase-commit protocol (non-distributed transactions)

To implement a resource manager for the Lucene.Net IndexWriter, and therefore make it transactional, all you have to do is the following:

public class TransactionalIndexWriter : IndexWriter, IEnlistmentNotification
{
    #region ctor
    public TransactionalIndexWriter(Directory d, Analyzer a, bool create, MaxFieldLength mfl)
        : base(d, a, create, mfl)
    {
        EnlistTransaction();
    }
    /* More constructors */
    #endregion

    public void EnlistTransaction()
    {
        // Enlist in transaction if ambient transaction exists
        Transaction tx = Transaction.Current;
        if (tx != null)
            tx.EnlistVolatile(this, EnlistmentOptions.None);
    }

    #region IEnlistmentNotification Members
    public void Commit(Enlistment enlistment)
    {
        base.Commit();
        enlistment.Done();
    }

    public void InDoubt(Enlistment enlistment)
    {
        // Do nothing.
        enlistment.Done();
    }

    public void Prepare(PreparingEnlistment preparingEnlistment)
    {
        base.PrepareCommit();
        preparingEnlistment.Prepared();
    }

    public void Rollback(Enlistment enlistment)
    {
        base.Rollback();
        enlistment.Done();
    }
    #endregion
}

You can use it like so:

IndexWriter indexWriter = null;
TransactionScope tx = null;

try
{
    tx = new TransactionScope();
    indexWriter = new TransactionalIndexWriter(...);

    // Perform transactional work
    indexWriter.AddDocument(new Document());
    indexWriter.AddDocument(new Document());
    indexWriter.AddDocument(new Document());

    // Connect to Database, MSMQ etc. to elevate to a distributed transaction

    // Commit transaction
    tx.Complete();
}
finally
{
    if (tx != null)
        tx.Dispose();

    if (indexWriter != null)
        indexWriter.Close();
}

Fairly simply uh? Just remember to instantiate the TransactionalIndexWriter or call the public method EnlistTransaction within the scope of an ambient transaction.
You might consider implementing IDisposable for TransactionalIndexWriter so you can take advantage of the using statement.

I will leave it to the reader to implement a TransactionalIndexReader.

If you want to try working with Lucene.Net, then the DimeCast.Net crew has recently made two 10 short webcast introducing Lucene.Net (http://dimecasts.net/Casts/ByTag/Lucene).

TechEd Berlin 2009

2009-11-06T20:21:47Z

I’m going to TechEd conference in Berlin next week. Are you going?

I haven’t taken the time to browse through the session catalogs yet, but I will be seeking information about:

Microsoft’s acquisition of FAST Search and how Microsoft incorporates into their products
Microsoft SQL Server 2008 R2 and especially the spatial support for Reporting Services
The new features of Windows Communication Foundation 4.0, the redesigned Windows Workflow Foundation 4.0 and .Net 4.0 in general.
The Windows Azure Platform
ASP.Net MVC 2

If you are going, drop me a mail and I’ll buy you a beer. That’s the least I can do for my readers

World’s first electronic annual general meeting

ASP.NET MVC Best Practices

2009-10-29T19:06:22Z

I love ASP.Net MVC – It has made web development fun. It also introduced new pitfalls…

Microsoft MVP Simone Chiaretta has fathered 12 ASP.NET MVC Best Practices worth reading.

In particular I find the these items interesting:

“DomainModel != ViewModel” with the ASP.NET MVC View Model Patterns
“Pay attention to the Verbs” with the PRG Pattern (Post-Redirect-Get)

Initial slow WCF request

2009-10-23T21:01:06Z

If working with any of the HTTP Bindings you might experience that the first WCF request takes a long time to complete.

This is because the initial HTTP connection tries to get the proxy settings automatically. This is done by requesting the configuration via a HTTP GET http://wpad/wpad.dat. If proxy server automatic configuration is not configured, the request times out and the initial WCF can send the request directly to the destination address. This may add 30 seconds to the initial WCF request!

You can disable this behavior by specifying UseDefaultWebProxy = false on the binding.

You can read more about Web Proxy Auto-Discovery Protocol ( WPAD ) at Wikipedia.

This applies to basicHttpBinding, wsHttpBinding, wsDualHttpBinding, webHttpBinding, ws2007FederationHttpBinding, wsFederationHttpBinding, basicHttpContextBinding, wsHttpContextBinding and the new Azure ServiceBus bindings basicHttpRelayBinding, wsHttpRelayBinding, webHttpRelayBinding

Reuse in SQL Server 2008 Integration Services

2009-10-22T19:27:34Z

Or lack of

My current project requires SSIS (SQL Server 2008 Integration Services) packages for ETL processing.

SSIS seems very capable, but lacks fundamental things that a developer like me takes for granted. I did not expect SSIS to have the ability of inheritance as it isn’t object-oriented, but I did expect functions or methods like a procedural language or set-based languages like T-SQL. Sadly the answer is no.

You can make script tasks or script component with custom T-SQL or .Net code, but logic in expressions you have to duplicate.

I goggled reuse and SSIS and found this statement in an article about reuse in SSIS at SqlServerCentral.com:

Let’s not forget, copy&paste is the first level of code reuse

In essence it’s true, but I would hope the entire Information Technology industry has move way beyond this point years ago.

This post at the Microsoft SQL Server forum confirms this horrific truth about lack of reuse in SSIS

Monitors and thread context

2009-10-15T19:27:54Z

Running the below code will fail – why?


var syncRoot = new object();

Monitor.Enter(syncRoot);

ThreadPool.QueueUserWorkItem(x => Monitor.Exit(syncRoot));

It will throw a SynchronizationLockException with the message “Object synchronization method was called from an unsynchronized block of code.”

It is because System.Threading.Monitor requires the Enter and Exit methods must be executed on the same thread for the same synchronization object.

I did not know that :-/

New blog – NoTech

2009-10-14T06:24:34Z

A talented colleague of mine Thomas Schou-Moldt has started blogging about software development processes and methods. He is passionate about the subject and writes well.

The blog is in Danish and called NoTech.

Blog description:

Here I’ll share my opinions, joys and frustrations about software development and IT projects – both the good stories and horrendous experiences.

Microsoft product launch 2008

Amazon Virtual Private Cloud

2009-08-26T20:16:12Z

If you are interested in cloud computing, but you never known how to adopt this new paradigm in your shop due to ignorance I encourage you to look at the Amazon EC2 and related services.

One of the things that have kept me and properly many others from migrating our applications and services to the cloud has been due to the nature of most software requiring integration to legacy systems behind a company firewall.

Amazon’s new service – Amazon Virtual Private Cloud enables you to extend the company’s network to Amazon’s cloud via a secure VPN connection.

Read more about this new service from Amazon on Werner Vogels’ article Seamlessly Extending the Data Center – Introducing Amazon Virtual Private Cloud.

Configuring the DTC for WCF with OleTx

Change Data Capture (CDC) in SQL Server 2008

2009-08-11T13:38:53Z

I where planning to write a blog post about Change Data Capture (CDC) in SQL Server 2008, but then I stumbled upon Pinal Dave’s article Introduction to Change Data Capture (CDC) in SQL Server 2008.

It is a thorough overview of Change Data Capture (CDC).

MSDN reference for Change Data Capture (CDC).

40+ Essential Front End Web Developer Cheat Sheets

2009-06-23T06:32:21Z

tripwiremagazine.com has gathered a neat collection of cheat sheets for web developers.

I’m not a front end web developer, so I’m in desperate need of tools and cheat sheets that can help me look good, when venturing into the world of web design

No related posts.

Visual Studio 2010 Beta 1 available

2009-07-13T18:57:25Z

I can’t wait to see what Microsoft can get out of WPF with the new WPF-based IDE.

The Microsoft developer and platform evangelist Dan Fernandez has written an installation cheat sheet guide.

Update 13th July 2009: On the BCL Team Blog Justin Van Patten has written the blog post What’s New in the BCL in .NET 4 Beta 1.

How to view default values for a WCF binding

2009-04-23T20:31:27Z

… or create a custom binding from a build-in binding.
… or create an administrative XML-based configuration from an administrative programmatic configuration.

Below codes does all that:

// Specify the source binding
// - Programmatic binding
// - Administrative XML-based binding
// - Convert to custom binding

/* Programmatic binding */
var binding = new BasicHttpBinding();
binding.TransferMode = TransferMode.Streamed;
binding.MaxReceivedMessageSize = 10000;

/* Administrative XML-based binding */
// var binding = new BasicHttpBinding("basicHttp");

/* Convert to custom binding */
// var wsBinding = new WSHttpBinding("wsHttp");
// var binding = new CustomBinding(wsBinding);

string outputConfigFile = "out.config";

Configuration machineConfig = ConfigurationManager.OpenMachineConfiguration();

var fileMap = new ExeConfigurationFileMap();
fileMap.ExeConfigFilename = outputConfigFile;
fileMap.MachineConfigFilename = machineConfig.FilePath;

Configuration config = ConfigurationManager.OpenMappedExeConfiguration(fileMap, ConfigurationUserLevel.None);
config.NamespaceDeclared = true;

var scg = new ServiceContractGenerator(config);

string sectionName, configName;
scg.GenerateBinding(binding, out sectionName, out configName);
config.Save();

The programmatic source binding will create a configuration file with all default values for the BasicHttpBinding except for TransferMode and MaxReceivedMessageSize attributes like so:

<basichttpbinding>
    <binding name="BasicHttpBinding"
             closeTimeout="00:01:00"
             openTimeout="00:01:00"
             receiveTimeout="00:10:00"
             sendTimeout="00:01:00"
             allowCookies="false"
             bypassProxyOnLocal="false"
             hostNameComparisonMode="StrongWildcard"
             maxBufferSize="65536"
             maxBufferPoolSize="524288"
             maxReceivedMessageSize="10000"
             messageEncoding="Text"
             textEncoding="utf-8"
             transferMode="Streamed"
             useDefaultWebProxy="true">
        <readerquotas maxDepth="32"
                      maxStringContentLength="8192"
                      maxArrayLength="16384"
                      maxBytesPerRead="4096"
                      maxNameTableCharCount="16384" />
        <security mode="None">
            <transport clientCredentialType="None"
                       proxyCredentialType="None"
                       realm="" />
            <message clientCredentialType="UserName"
                     algorithmSuite="Default" />
        </security>
    </binding>
</basichttpbinding>

I found this tip by Brian McNamara on the MSDN WCF forum.

World’s first electronic annual general meeting

2009-04-16T12:02:16Z

Today I just witness the electronic annual general meeting for the investment company SparIndex. This is the first 100% electronic annual general meeting ever.

The stakes was high, especially for the system owner VP Securities as journalists and photographs wandered around the offices ready to report success or failure in the media.

My job as a technical consultant, together with a handful of other techies, was to monitor the solution during the live annual general meeting. Our job was to prevent any technical glitches or in the event of a crash recover as fast as possible.

The tension was high right up to the last minute before the premiere, but everything went smooth.

Screenshot of the World’s first electronic annual general meeting

No related posts.

Loooong running sql statement

2009-04-06T10:39:29Z

I was using SQL Server Profiler on a SQL Server 2005 Enterprise Edition looking for performance culprits, when I stumbled upon this very long running process.

I think this must be a world record.

This statement has only used 16 milliseconds of CPU but it has been running for more than 500.000 years!

Easy win – index candidates on SQL Server 2005

In-flight entertainment running on Windows

2009-03-24T10:33:13Z

Recently when I was flying back to Europe from South Africa with Lufthansa on Airbus A340-600 the In-flight entertainment crashed just before takeoff. They had to restart the entire system. I could see the entire reload of the system including the initial download with 115K baud XModem protocol download.

Yikes! I hope that only non-vital systems are running Windows for an airliner.

Scary SQL Server 2005 & 2008 bug

2009-03-28T14:27:28Z

Watch out when using @@IDENTITY and SCOPE_IDENTITY() in your applications. Below is a quote from a Microsoft SQL Server engineer.

… whenever a parallel query plan is generated @@IDENTITY and SCOPE_IDENTITY() are not being updated consistently and can’t be relied upon.

You can find more about the bug and workarounds at the SQL Server bug report.

UPDATE 28MAR2009: Pinal Dave has a more detailed blog post about the bug with workaround.

ASP.Net MVC 1.0 released

2009-03-18T21:02:12Z

I have been playing around with the ASP.NET MVC for a couple of month and cannot wait to start the first commercial project – hopefully next week

Frameworks like the ASP.NET MVC, MVCContrib and jQuery has sparked a renewed interest in web development, which has been dormant for years.

No related posts.

How to check for and enable read committed snapshot isolation

2009-03-18T11:51:14Z

Run the below query to see which databases that uses read committed snapshot isolation:

SELECT name, is_read_committed_snapshot_on FROM sys.databases

To enable it on a specific database run the below query:

ALTER DATABASE [<databasename>]
SET READ_COMMITTED_SNAPSHOT ON

As a developer I am in love with read committed snapshot isolation feature for SQL Server 2005+. Transactions can read and write simultaneously the same piece of data – no read/write contention due to row versioning.

Normal conflicting scenarios:

Simultaneously write and read of the same data.

Read committed isolation: The reader will wait for the writer to release the exclusive lock.
Read committed snapshot isolation: The reader will not block, but receive the latest committed data (latest row version).

Simultaneously writes of the same data.

Read committed isolation: The second writer will wait until the first transaction completes because of an exclusive lock.
Read committed snapshot isolation: The first transaction committing will “win” and if the second tries to commit, it will abort and error will be raised.

In effect this is optimistic concurrency control without coding anything. Read more about read committed snapshot isolation and isolation levels in the Isolation Levels in SQL Server 2005 article.

Handcrafting the WCF client

2009-03-08T15:58:47Z

Two years ago I wrote an article Building a Windows Communication Foundation client, describing three ways of creating WCF clients. I did not mention the fourth one, as I did not know at the time. Now I am older and wiser

The four ways of creating a WCF client are:

Visual Studio’s “Add Service” reference
Service Model Metadata Utility Tool (SvcUtil.exe) command line tool
Dynamic proxy with ChannelFactory
Handcrafting the WCF client

The last two options are only viable for WCF to WCF implementations where you either have control of both service and client or the service provider supplies a .Net assembly. Because both of them require the service contract aka the .Net interface marked with ServiceContractAttribute and OperationContractAttribute.

Anybody that has tried the “Add Service” reference in Visual Studio knows it is broken. First of all it generates an enormous amount of files, even for the simplest service contract.

Secondly it sometimes corrupts the state of the generated files, so you have to remove the reference and then add it again.. Just try to google it and you will find many frustrated developers. Do not use it!

The SvcUtil.exe is better and has a vast number of options. This is the preferred option for non .Net services or where the service contract interface is not available.

The dynamic proxy with ChannelFactory is useful, but be aware that the interface returned does not implement IDisposable, but the implementation does. See below:

var factory = new ChannelFactory<ihelloworldservice>("myEndPoint");

IHelloWorldService proxy = factory.CreateChannel();

using (proxy as IDisposable)
{
   MessageBox.Show(proxy.HelloWorld());
}

Finally the handcrafted version – the one I want to talk about. Writing the WCF client by hand is fairly easy – it requires the implementation to inherit from ClienBase and implementing the service contract interface. Below is first a simple service contract IHelloWorldService:

[ServiceContract(Namespace = "www.lybecker.com/blog/HelloWorldService")]
public interface IHelloWorldService
{
   [OperationContract]
   string HelloWorld();
}

Next the handcrafted WCF client with constructors and service contract interface implementation:

public class HelloWorldClient : ClientBase<ihelloworldservice>, IHelloWorldService
{
   public HelloWorldClient()
   { }

   public HelloWorldClient(string configurationName) : base(configurationName)
   { }

   public HelloWorldClient(Binding binding, EndpointAddress address) : base(binding, address)
   { }

   public string HelloWorld()
   {
      return Channel.HelloWorld();
   }
}

That’s it.

Now you have full control of the WCF client implementation.

Download the sample application Hello World WCF clients including a handcrafted version

Visiting Microsoft in Johannesburg, South Africa

2009-02-11T20:54:48Z

I live and work in the suburbs of Copenhagen in Denmark, but I’m currently in South Africa on business. While I’m here I might as well visit Microsoft South Africa – I did that today. I attended a presentation of the .Net services by Juval Löwy.

Microsoft South Africa is situated in a nice and fairly new building, as you can see on the picture above.

I was amazed about the level of security – first I had to cleared by the security guards before entering the parking lot. This is not uncommon in South Africa, but very uncommon in Denmark.

Inside in the reception the security check barriers prevent unauthorized people to enter.

When I finally was granted access to the presentation, Microsoft served sodas, pizza and beer!

Visual Studio 2008 shortcuts features

2009-02-02T16:18:08Z

Two years ago I wrote an article about the shortcut features in Visual Studio 2005. So I thought, why not write one for Visual Studio 2008.

I am a big fan of shortcuts – it increases productivity and ergonomically better than using the mouse all the time.

There is a large arsenal of shortcuts not only for Visual Studio, but also for the add-ins like ReSharper. Most developer forgets the basic ones in Windows besides the cut and paste shortcuts. But they do provide a huge productivity boost. Take a look at this list – how many of these shortcuts do you know and use?

SQL Server 2008 System Views poster

2009-02-02T16:17:40Z

Microsoft has released a poster for download, where you can see all the system views for SQL Server 2008 and the relationships between them.

Microsoft also released the system views poster for SQL Server 2005 a couple of years ago.

You need a huge printer/plotter to print these…

Easy win – index candidates on SQL Server 2005

2008-12-01T07:44:43Z

Below is my real life story telling how easy it can be to find index candidates if you use your tools.

This weekend we deployed a new version of a medium/large solution to the production environment for one of our customers. Normally this is not a big issue, as we are always prepared to roll back to the previous version – the one currently in production. The deployment and configuration processes are well-prepared and highly automated to minimize faults and late-night-bug-hunting-frenzy.

After the deployment is complete we smoke test the setup to make sure that it is configured correctly and all is sound.

This weekend after the successful deployment the smoke test failed miserably. We received TimeOutExceptions all over. It was coming from the user repository service.

We decided to investigate a little before the decision of aborting the deployment of the new version and therefore rolling back to the previous version.

The steps to resolve the issue is what I want to share with you.

A quick look in the source repository showed that almost no changes to the user repository service – none that could cause TimeOutExceptions.

With the SQL Server Profiler it was easy to spot the cause of the exception.

This simple select statement was isolated and copied into the Management Studio to view the Actual Execution Plan. The execution plan did show much, but by execution the below statement which instructs the SQL Server not to execute the Transact-SQL statements. Instead, SQL Server returns detailed information about how the statements are going to be executed in the form of a well-defined XML document.

SET SHOWPLAN_XML ON

The SQL Server will include loads in information and one of these are suggested indexes which you will not see with the graphical execution plan in Management Studio. Look for the MissingIndex elements:

<missingindexes>
  <missingindexgroup Impact="96.6222">
    <missingindex Database="[DOIPEI]" Schema="[dbo]" Table="[OrganisationalUnit_Stack]">
      <columngroup Usage="EQUALITY">
        <column Name="[org_pkid]" ColumnId="2" />
      </columngroup>
    </missingindex>
  </missingindexgroup>
</missingindexes>

By creating this single index on [DOIPEI].[dbo]. [OrganisationalUnit_Stack]. [org_pkid] the TimeOutExceptions disappeared, as the query no longer took minutes but milliseconds.

We were able to continue and successfully deploy the new version of the solution with only minimal disruption and a delay of only half an hour. Why the index where missing is still a mystery.

It makes all the difference in the world if you know the capabilities of your tools at hand.

.Net 3.5 installation WTF

2008-11-27T19:24:11Z

Installing .Net 3.5 SP1 can be difficult, especially when below screen appears

A colleague of mine stumbled upon this today. You cannot install SP1 because the SP1 install setup process is running

I just had to share it with you.

Serialization in .Net 3.5 SP1

2008-11-23T07:17:55Z

In .Net 3.5 SP1 it is now possible to serialize any object that has a default constructor without decorating it with [DataContract] or [Serializable].

Developers have these choices now when serializing objects:

Implicit serialization – requires public default constructor and only serialize public read/write fields
Use the [Serializable] attribute
Use [DataContract] and [DataMember] attributes
Implement the ISerializable interface

I must say, that I’m not keen on this new feature. I prefer explicit serialization to implicit serialization. I predict that implicit serialization of entire object graphs will cause performance problems for many .Net developers in the years to come. This could also be a good thing as I am a consultant

Aaron Skonnard has a more detailed blog post about the new serialization features in .Net 3.5 SP1.

SQL Server 2008 Microsoft ISV Partner events presentations

2008-11-15T07:23:32Z

This week I hosted two sessions at two different events for Microsoft Denmark. One at Radisson SAS Scandinavia Hotel in Århus and one in Microsoft Denmark’s headquarter in Hellerup.

It was fun at the feedback was very positive. The best part was during the breaks with great edifying technical discussions. All the slides are available at Miracle’s homepage.

.Net debugger visualizers

2008-10-12T15:35:28Z

The .Net framework 2.0 gave some great tools for debugging – they are a great help when writing code.

Some of these features are the DebuggerDisplay and DebuggerStepThrough attributes. I seldom use any of them, as I prefer to just overriding the ToString method instead of using the DebuggerDisplay attribute. This makes it easy to instrument the code too, as I can reuse the ToString method implementation for tracing.

Another feature is the ability to develop custom debugger visualizers. They enable smart developers to build their own. I find some really useful, especially the WCF visualizer. But there a many – check out this list of custom .Net debugger visualizers.

These small enhancements make it so easy to get an overview of the current state, instead of inspecting properties.

Disable and enable all database constraints

2009-01-03T17:41:01Z

We (my colleagues at Miracle and I) are currently in the process of upgrading a customer’s solutions. One of task is migrating 100 gigs of data into an existing database schema. This can easily become a tedious task and can take considerable calendar time. Therefore we decided to disable all constraints on the database, move the data and then enable them again, as we know the data integrity is sound.
We could have written a script that gets all the constraints in the database and generates a SQL script, but there is an easier way…
-- Disable all Constraints exec sp_MSforeachtable 'ALTER TABLE ? NOCHECK CONSTRAINT ALL'

--Enable all Constraints exec sp_MSforeachtable 'ALTER TABLE ? CHECK CONSTRAINT ALL'

That’s easy…

I found this on the Internet somewhere – the sp_MSforeachtable procedure is nowhere to be found in books online.
You can check if foreign keys and check constrains are disabled via the sys.foreign_keys and sys.check_constraints views.

Another obvious triviality in our situation is disabling and enabling triggers – that is easy too:

-- Disable all Triggers exec sp_MSforeachtable 'ALTER TABLE ? DISABLE TRIGGER ALL'

-- Enable all Triggers exec sp_MSforeachtable 'ALTER TABLE ? ENABLE TRIGGER ALL'

How to check for and enable read committed snapshot isolation

WCF certified

2008-10-17T19:17:46Z

I just got word from Microsoft, that I passed the Microsoft Certified Technology Specialist: .NET Framework 3.5, Windows Communication Foundation Applications certification (70-503).

It was not easy, as the preparation guide was incomplete and I didn’t have time to properly prepare for the test. I took the beta exam in January, but had totally forgotten about it.

I am proud to be one of the first to pass this exam

32-bit WCF memory allocation trouble

2008-10-05T10:30:21Z

With a 32 bit platform a process can only address 2 GB of memory by default on windows. For most applications this is not an issue. But today I really messed up – OOM (OutOfMemoryException) exceptions all over

I added loads of test data to our 32 bit development servers and tried to run a development utility. It failed and failed and failed with OOM exceptions. The cause was actually quite simple as the application tried to allocate more than 500 MB of consecutive memory.

The utility is a console app and the search index is a WCF server and they communicate via TCP buffered binary format (netTCPBinding).

The console utility retrieved all the unique identifiers in the search index (based on Lucene.Net) to compare these with the records in the SQL Server, to see if everything is in sync. The number of unique identifiers where now in the millions, but that was not the root cause. The process consumed twice the memory, because I use buffered transfer mode instead of streamed.

Buffered transfer mode serializes everything before sending the message from the server to the client. So in effect our WCF server not only had the huge array of unique identifiers but also a serialized version. It never got the stage where it could send the message.

Moral of the story – use streamed transfer mode with large messages.

As this is a development utility, I sidestepped

I enabled the 3GB switch allowing processes to allocate up to 3 GB of memory, and tried again. Same result: OOM.

I figured that the .Net might have a limitation and perhaps a switch to enable larger memory allocation. Apparently there is a small program called Microsoft COFF Binary File Editor (EDITBIN.EXE) that modifies Common Object File Format (COFF) binary files. This binary file editor can enable applications to address more than 2 GB of memory with the LARGEADDRESSAWARE option.

The steps to enable LARGEADDRESSAWARE for an application:

Start Visual Studio Command Prompt or run VSVARS32.BAT (in the visual studio subdirectory: Common7\Tools) which in effect does the same things.
Run editbin /LARGEADDRESSAWARE <yourApp>.exe

Tomorrow I will change the implementation to use streamed transfer mode. Promise

Transferring SQL Server logins

Do you know how many types there are in the .Net Framework?

2008-10-05T10:29:42Z

The answer is not 42 , but 11.417. I will never be able to grasp the vast capabilities of the .Net Framework.

With more than 100.000 member it’s no wonder that I am addicted IntelliSense.

You can get more details on Brad Abrams blog entry.

My presentation at the Microsoft product launch 2008

2008-10-05T10:29:23Z

All the presentations from the product launch are recorded as webcasts. They are available here (it’s in Danish). Later this year the webcast will be moved to TechNet.

I spoke about long overdue features in SQL Server for developers.

See the webcast
Download the presentation and demo

Some of the webcasts has poor sound quality (not mine ), which is a shame.

The webcasts where recorded at Microsoft. They used Camtasia Studio which I highly recommend as it is easy, intuitive and have some great features.

I guess the poor sound quality is due to lack of proper microphones and the recording was done in a regular meeting room. They used the build-in microphone on my laptop. Microsoft Denmark should have better sound equipment and a recording studio if they are serious about webcasts.

Microsoft product launch 2008

2008-10-05T10:28:55Z

I am speaking at the launch of Windows Server 2008, Visual Studio 2008 and SQL Server 2008 in Denmark February 28th. It will be an online launch – meaning that you can watch in comfort of your personal development sphere

As it is a Danish event and we Danes speak Danish – the event will be in Danish

You can sign-up here.

.NET Framework Library Source Code now available

2008-10-05T10:28:27Z

As I blogged about a couple of months ago, Microsoft will release the .Net Framework source code – but only for sneak peaking.

This is now a reality. Only a limited subset of the libraries, but more is to come in the future.

This is the list of what is currently available:

.NET Base Class Libraries (including System, System.CodeDom, System.Collections, System.ComponentModel, System.Diagnostics, System.Drawing, System.Globalization, System.IO, System.Net, System.Reflection, System.Runtime, System.Security, System.Text, System.Threading, etc).
ASP.NET (System.Web, System.Web.Extensions)
Windows Forms (System.Windows.Forms)
Windows Presentation Foundation (System.Windows)
ADO.NET and XML (System.Data and System.Xml)

To enable this feature, you need to setup Visual Studio 2008 – here is a guide.

You can read more on Scott Guthrie’s blog.

Victoria is One Year Old

2008-10-17T19:16:29Z

At her birthday celebration family and friends came by with greetings and gifts.

Incidentally Victoria took her first steps alone with a baby carrier at the morning of her birthday. She was proud – as was her father who quickly grabbed the camera and took this shot

Free SQL Server tools

2008-10-05T10:27:26Z

I just found this list of free SQL Server tools that I want to share with you.

I use some of these already, but will check out the others too.

Microsoft releasing the .Net framework source code

2009-01-03T17:41:46Z

But only for sneak peaking.

JAOO 2007 – Wednesday

2009-01-03T17:43:04Z

The third and last day at the JAOO conference was the best in regards of the sessions I attended. My day session schedule looked like this:

“MonoRail: Building Maintainable and Testable Web Applications” by Oren Eini and Hamilton Verissimo
“Fault Tolerance” by Robert S. Hanmer
“Performance Art” by Kevlin Henney
“Applying Craftsmanship” by Pete McBreen
Panel discussion: “Enterprise Application Frameworks” with Graeme Rocher, Eberhard Wolff, Erik Dörnenburg, Oren Eini, Justin Gehtland, and Alef Arendsen

I have written an abstract of the session “Applying Craftsmanship” by Pete McBreen in a separate blog post, because it deserved it. It made me think (which is a good thing ). Read it here.

JAOO 2007 conference summary
I enjoyed the JAOO conference, but was a bit disappointed with the technical level. Again, maybe my expectations were too high? But then again, I will consider coming back next year. That has absolutely nothing to do with the fact that I won an Apple iPod at an IBM contest.

Below is a picture of the price I won in the IBM contest.

JAOO session “Applying Craftsmanship” abstract

JAOO session “Applying Craftsmanship” abstract

2009-01-03T17:43:12Z

The session “Applying Craftsmanship” at the JAOO conference by Pete McBreen was by no means technical but made me think. The stuff he talked about is, in my opinion, common sense. Below is an abstract of what I got out of the session. I wanted to share it with you and wrote it down so that I don’t forget about it in 6 months time.

Currently the norm for gaining the title as senior developer is only 5 years of experience. Does that make sense? Can you really gain enough knowledge in such a short time? What is the next step in the career path for technical for a developer? Architect or project manager? Not all developers make good architects, as the skill required differs. Almost no developers make good project managers. What is often seen is the organization ends up with a lousy project manager and loosing their prime developer.

Why have two teams – one to develop the solution and another to maintain it. It does not make any sense, as the initial developers are the best source of knowledge of implementation details. Give the initial developer’s incentives to build the best possible solution by having them maintain the code base afterwards.

Developers fresh out of college or university should learn from the more experienced developers (senior developers?). The best way to learn is by looking at others code or paring up with a more experienced developer. Pete McBreen favored having the newbies help maintain existing code. That makes sense in my ears, as they then get exposed to others (hopefully) high quality code, while paring up with the experienced developers.

Another issue he addressed was the current trend of discarding existing code and redeveloping the same functionality over and over again. He made a point out of continuously improving the software quality, so the need to discard the existing code would be pointless. The goal is not solely to continuously refactor, but to improve the user experience – functionality wise.

This ties very well to the last point of shifting the developers’ focus to the system functionality that improves the users’ experience. The users are paying for our salaries so of cause we should focus on their needs. This requires that developers talk to users and understand their needs, because developers are not domain experts and do not have any clue of the users needs.

Pete McBreen has written a book about the subject called “Software Craftsmanship: The New Imperative“. I haven’t read it, so I can’t tell you if it is any good. Maybe I should read it…

JAOO 2007 – Tuesday

2009-01-03T17:43:18Z

The day at JAOO was better than yesterday, but still not great. Maybe my expectations are too high?
Today’s JAOO conference of the honorable mentionable:

“Painless Persistence with Castle ActiveRecord” by Oren Eini and Hamilton Verissimo – which was a tutorial of Castle ActiveRecord. The session was fairly good – I learned some new stuff but knew most of it in advance. I like the idear of minimizing the complexity of data access logic, but I do not fancy the solution where the domain model objects are bound by attributes. I prefer the XML based solution found in for example nHibernate. It is a lot more tedious work, but the solution benefits of separation of concerns.
“C# 3.0 under the hood” by Mads Torgersen – this session was a good recap of something I read a while ago. I can’t recall the source, sorry. The session wasn’t as much under the hood as the title states, but still Mads delivered a compelling walkthrough of the construct of LINQ (Language Integrated Queries).
“Using LINQ to SQL to Access Relational Data” by Luca Bolognese – I was delighted to see that Microsoft has taken concepts from nHibernate and adopted them as their own. There are many similarities between nHibernate and LINQ to SQL, but I need to dig further into the subject to see if I should make the switch from nHibernate to full blown LINQ, with all it entitles. Alternatively I could just use the LINQ for nHibernate when it is released in version 1 in 3-6 months.

My last day at JAOO is tomorrow. Let us see what tomorrow brings.

JAOO 2007 – Monday

2009-01-03T17:43:25Z

The keynote by Robert C. Martin “Craftsmanship and Ethics” was all about agile processes and development. You couldn’t really ague the test are not good and the developers should have the best tools available. It was one of those talks where everybody nods and goes their separate ways and continues doing what they have always done. Good talk though.

Afterwards I went to a session by Pramod Sadalage where he talked about evolutionary database design with database refactoring. Pramod Sadalage is a co-author of the Martin Fowler series Database Refactoring book which I have on my to-read-list-but-have-not-have-found-the-time.
He tragically failed to deliver a point about database refactoring until then end of the session where most had lost interest. He kept on talking about continues integration and ANT script – this is all fine, but I expected some thoughts and ideas of how to do database refactoring without loosing business value and precious development time. Give me some pointers, tools or patterns!
I certainly need to reevaluate if the database refactoring book should stay on my list.

After lunch I went to a session about the functional programming language Erlang by the inventor Joe Armstrong. He is a great speaker and was able to keep most attendee’s at the tip of their toes, due to implicit knowledge of current hardware architectures in the talk. He confidently delivered his views of how concurrent development should be done – not the Java, C++ or C# way, but as a simple construct of the programming language. Concurrency in Erlang is based on message parsing instead of share memory.

The rest of the day failed miserably for me. None of the talk I went to was enlightening, made me think or inspired new ideas. I went to “Testing Database Access Code Programmatically” by Roy Osherove, “Information cards and .Net – Cardspace” by René Løhde and “An Introduction to Spring.Net” by Mark Pollack.
Most (in truth all) of my colleagues was better at choosing sessions and they especially talk positively about the session “Beautiful Debugging” by Andreas Zeller.

The rest of the day I served Miracle beer from our very own Miracle Brewery at the JAOO conference party. Apparently developers like Miracle beer, because all 400 liters were consumed.

I am looking forward to tomorrow and hope that I am better at choosing the right/high-class sessions.

Geek Train to JAOO

2009-01-03T17:43:32Z

I am on my way to the JAOO conference in Aarhus, Denmark with a colleague. We booked a late train and ended up on a geek train!
Addicted as we are, we logged on the Internet via our mobil phones and noticed that we were not the only ones with Bluetooth enabled laptops/mobil phones!
This was what we say.

That is pretty amazing as Bluetooth is a personal network and the range is about 10 meters.

Constrained-based assert model

2009-03-08T14:06:12Z

The latest version of NUnit Framework (version 2.4 and forward) comes with a new constrained-based assert model, which allows you to write complex assertions relatively easy with a new syntax. The old classical syntax for assertions with static methods still works and according to the NUnit blog there are no plans to deprecate the classical assertion syntax.

Assert.AreEqual(5, 5.0);

Assert.AreSame(person, person);

Assert.Greater(7, 5);

Assert.IsInstanceOfType(typeof(ArrayList), new ArrayList());

Assert.IsAssignableFrom(typeof(ICollection), new List());

StringAssert.StartsWith("Anders", "And");

CollectionAssert.AreEquivalent(col1, col2);

FileAssert.AreEqual(stream1, stream2);

The new constrained-based assert model uses a single method on the Assert class for all assertions:

Assert.That("Anders", new EqualConstraint("Anders"));

The second parameter is the type of assertions – here an equal constraint that works on all types of data – primitives, collections, streams etc.

NUnit comes with a number of constraints covering most scenarios, but also allows you to extend the model by developing custom constraint by realizing the IConstraint interface.

public interface IConstraint
{
    bool Matches(object actual);
    void WriteMessageTo(MessageWriter writer);
    void WriteDescriptionTo(MessageWriter writer);
    void WriteActualValueTo(MessageWriter writer);
}

If the syntax of constrained-based assert model seams a bit to complex and not very reader friendly, the NUnit team has implemented a range of syntax helper classes like so:

Assert.That("Anders", Is.EqualTo("Anders"));
Assert.That("Anders", Is.Not.EqualTo("Anja"));
Assert.That("Hello World!", Text.StartsWith("HELLO").IgnoreCase);
Assert.That("make me happy", Text.Contains("make"));

Assert.That(person, Is.SameAs(person));
Assert.That(null, Is.Null);
Assert.That(new object(), Is.Not.Null);
Assert.That("", Is.Empty);

Assert.That(new ArrayList(), Is.Empty);
Assert.That(myCol, Is.Unique);

Assert.That(7, Is.GreaterThan(5));
Assert.That(2.0d + 2.0d, Is.EqualTo(4.0d).Within(.000005d));

Assert.That(myPerson, Is.InstanceOfType(typeof(Person)));
Assert.That(new EqualConstraint(), Is.AssignableFrom(typeof(IConstraint)));

Assert.That(new int[] { 4, 5, 6 }, Is.All.GreaterThan(0));
Assert.That(new string[] { "abc", "bac", "cab" }, Has.All.Length(3));
Assert.That(new int[] { 4, 5 }, Is.SubsetOf(new int[] { 4, 5, 6 }));

The change of syntax separates NUnit from other unit test frameworks and therefore separates from the common approach of creating unit tests.

I like the new syntax – It is intuitive and easy to comprehend. All change is not, but it is simple rules of evolution. The notion of constraints is also found in NMock.

No related posts.

SCRUM Certified Master

2009-01-03T17:43:53Z

Yesterday I returned from Milan, Italy, after completing a great Scrum Master Certification course taught by the experienced Scrum trainer Joseph Pelrine.

Scrum is an agile project management method for managing projects with continuously changing requirements
and/or complex social and technical domains.

Joseph brought his friend Tim Mackinnon, whom is also a Scrum master and the originator of mock objects. I really enjoyed the course and learned a lot. We had some enlightening discussions during the course and social engagements in the evenings.

I highly recommend this course and the teachings of Joseph Pelrine to all whom looking to improve their ability to delivery quality solutions.

WCF certified

WCF Sessions and Reliable Messaging

2008-10-05T16:29:06Z

There are a couple of ways to establish a session between client and service. The session is established by identifying clients via a unique identifier. The unique identifier is either conveyed by

the client credentials when WS-Security is utilized to established secure session
the TCP/IP socket connection when using an underlying connection-oriented protocol such as TCP
the WS-ReliableMessaging protocol token when requiring message ordering and message delivery assurance for transport protocols.

Read more about how WS-Reliable Messaging protocol in my article “How does Reliable Messaging work?”

Enabling sessions are all done in the configuration file. Some bindings are sessionful by default like the tcpBinding and wsHttpBinding.

I continue with Hello World WCF code sample from my earlier articles: “Building a Windows Communication Foundation client” and “A simple Windows Communication Foundation Web Service”. You can download the source code from here: Hello World WCF with clients.

Just by changing the binding in the code sample configuration to wsHttpBinding in the service and the clients, you get secure sessions; wsHttpBinding is by default secured with message security. The secure session context is established with the WS-SecureConversation protocol.

In the service type implementation it is possible to retrieve the session identifier via the OperationContext.Current.SessionId.

If you want un-secure reliable ordered messages with sessions, then change the behavior of the wsHttpBinding by configuring the binding like below. The configuration shown is for the service, but the changes (in bold) are exactly the same as required in the clients’ configuration files.

< ?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <system .serviceModel>
    <behaviors>
      <servicebehaviors>
        <behavior name="myBehavior">
          <servicemetadata httpGetEnabled="true"
                           httpGetUrl="http://localhost:8080/HelloWorldService" />
        </behavior>
      </servicebehaviors>
    </behaviors>
    <bindings>
      <wshttpbinding>
        <binding name="reliableBinding">
          <reliablesession enabled="true" ordered="true"/>
          <security mode="None" />
        </binding>
      </wshttpbinding>
    </bindings>
    <services>
      <service name="HelloWorldService"
               behaviorConfiguration="myBehavior">
        <endpoint address="http://localhost:8080/HelloWorldService"
                  binding="wsHttpBinding"
                  bindingConfiguration="reliableBinding"
                  contract="IHelloWorldService" />
      </service>
    </services>
  </system>
</configuration>

Now the session identifiers are conveyed by the WS-Reliable Messaging protocol (linie 13-18). It is possible to use secure and reliable messages, but security is disabled to prove the point of WS-Reliable Messaging can be used to establish sessions.

If the implementation of your service requires sessions, decorate the service contract with the SessionMode.Required – this will demand that every endpoint bindings exposing the service support sessions. The possible values of the SessionMode enum are Required, Allowed and NotAllowed where Allowed is default.

[ServiceContract(SessionMode=SessionMode.Required)]
public interface IHelloWorldService
{
    [OperationContract]
    string HelloWorld();
}

If guaranteed ordering of messages is assumed by the implementation and therefore required for dependable behavior of the service, then decorate the service contract with the DeliveryRequirements attribute with the parameter RequireOrderedDelivery set to true.

[ServiceContract(SessionMode=SessionMode.Required)]
[DeliveryRequirements(RequireOrderedDelivery=true)]
public interface IHelloWorldService
{
    [OperationContract]
    string HelloWorld();
}

If the configuration of an endpoint does not fulfill the requirements, the host throws an exception detailing the missing requirements.

When to use the sessions
Sessions in WCF does not deliver the same functionality as in ASP.Net or ASMX based Web Services. For instance the HttpSessionState store is not available, not even if the WCF service is hosted in the IIS. WCF sessions are similar to Remoting sessions and are only for service instancing.

[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession)]
public class HelloWorldService : IHelloWorldService
{
    public string HelloWorld()
    {
        Console.WriteLine("Invoked by client with session ID {0}",
            OperationContext.Current.SessionId);

        return "Hello World";
    }
}

To control the instancing of the service type objects, decorate the service type with the ServiceBehavior attribute and specify the InstanceContextMode enum as in the above code.

The InstanceContextMode values are:

PerCall – A new InstanceContext object is created prior to and recycled subsequent to each call. If the channel does not create a session this value behaves as if it were PerCall.
PerSession – A new InstanceContext object is created for each session.
Single – Only one instance of the service type object is used for all incoming calls and is not recycled subsequent to the calls. If a service type object does not exist, one is created.

Download the sample code with reliable messaging here (Hello World WCF Reliable Messaging) and read more about WCF sessions here.

Reading performance counters

2009-01-03T17:44:02Z

It is apparently possible to read performance counters without administrator privileges.

This is useful information – read more here

No related posts.

Strings in .Net

2009-03-08T14:18:54Z

Strings in .Net are immutable reference types, but can be confusing because they sometimes have similar characteristics as value types.

Below is a code sample that shows the value type characteristics of string.

string s1 = "Anders";
string s2 = "Anders";

Console.WriteLine("s1 and s2 are equal : {0}", s1 == s2);

Output:
s1 and s2 are equal : True

For regular reference types this would have been an object reference compare, but the == operator is overloaded to execute the same logic as the String.Equals method.

Continuing the example by implicit cast each string to an object:

object o1 = s1;
object o2 = s2;

Console.WriteLine("o1 and o2 are equal : {0}", o1 == o2);

Output:
o1 and o2 are equal : True

These two strings are equal due to the CLR optimization called interning. Interning works by having an internal pool of unique literal strings. If the same literal string is assigned to multiple variables the runtime retrieves the reference to the literal string in the internal pool and assigns it to each variable.

Console.WriteLine("s1 and s2 are same : {0}", object.ReferenceEquals(s1, s2));
Console.WriteLine("o1 and o2 are same : {0}", object.ReferenceEquals(o1, o2));

Output:
s1 and s2 are same : True
o1 and o2 are same : True

The Object.ReferenceEquals determines whether the specified object instances are the same instance.

When comparing the strings or objects all of them are the same instance! This is again due to interning. All of the variables reference to the same object.

Let us rewrite the code and try something a little bit different:

string s1 = "Anders";
string s2 = new StringBuilder("Anders").ToString();

object o1 = s1;
object o2 = s2;

Console.WriteLine("s1 and s2 are equal : {0}", s1 == s2);
Console.WriteLine("o1 and o2 are equal : {0}", o1 == o2);
Console.WriteLine("s1 and s2 are same : {0}", object.ReferenceEquals(s1, s2));
Console.WriteLine("o1 and o2 are same : {0}", object.ReferenceEquals(o1, o2));

Output:
s1 and s2 are equal : True
o1 and o2 are equal : False
s1 and s2 are same : False
o1 and o2 are same : False

The above code is almost identical to the previous code except that s2 is initialized with a StringBuilder. Will this return the same result? No, because interning only occur when an assembly gets loaded or the String.Intern method is called.

The first string compare is true because of the operator overloading discussed earlier, but all the other compares are false. Even the o1 and o2 compare, because the runtime is unaware of the object types at the time of the comparison and can therefore not use the overload operator.

If you want to know more about strings, interning or internationalization issues with strings – read on.

Garbage Collection Flavors

2009-04-12T07:21:05Z

Why should you care about Garbage Collection? Well, it may very well improve performance for your applications.

The .Net framework garbage collector can operate in different modes depending on platform and requirements. There are three modes available for .Net framework version 2.0 and 3.0. Each of these modes is tailored for specific situations.

Concurrent Workstation Garbage Collection

This mode is optimized for interactivity by frequent short garbage collects. Each collect is split up into smaller pieces and are interleaved with the managed applications threads. This improves responsiveness at the cost of CPU cycles. This is ideal for interactive desktop applications where freezing application is an annoyance for the users and ideal CPU time is abundant when waiting for user input. Concurrent workstation mode improves the usability with perceived performance.

Note that interactive GC only applies for Gen2 (full heap) collects because Gen0 and Gen1 collects are in nature very fast.

Non-concurrent Workstation Garbage Collection

Non-concurrent workstation mode works by suspending managed application threads when a GC is initiated. It provides better throughput but might appear as application hiccups where everything freezes for the users.

Server Garbage Collection

In server mode a managed heap and a dedicated garbage collector thread is created for each CPU. This means the each CPU allocates memory in its own heap therefore results in lock-free allocation. When a collect is initiated all the managed application threads are suspended and all the GC threads collect in parallel.
Another thing to note is that the size of the managed heap segments is larger in server mode than workstation mode. A segment is the unit of which the memory is allocated on the managed heap.

It is possible to choose the type of GC for a managed application in the configuration file. Under the <Runtime> element add one of the below three settings and depending on the number of CPU, the garbage collector will run in the configured mode.

Running a standalone managed application the GC mode is by default concurrent workstation. Managed application hosts like ASP.Net and SQLCLR run with Server GC by default.

If you want to know more about how the GC works, read the blog entries “Using GC Efficiently”
by Maoni.