Monday, June 28, 2010

VS2010 patch for Cut and Copy "Insufficient Memory" issue

The Visual Studio 2010 Editor team has released a hotfix to reduce the frequency of the annoying error of VS2010 displaying the error message that there is "insufficient available memory to meet the expected demands of an operation at this time..." that can occur when trying to cut or copy text to the clipboard.

After upgrading to VS2010 a month ago this error plagued our project incessantly. The previous workaround for the team has been to use Steve Harman's documented hack for VS2008, but on the VS2010 executable ( which seemed to work.

The official Microsoft hotfix can be downloaded here

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Friday, May 28, 2010

VS2010 and Resharper 5.0 performance - KB974417

On my current project we have upgraded our solution from VS2008 to VS2010. I'm a big user of Resharper 5.0 in VS2008 and have it also installed in VS2010.

However when the solution was loaded Resharper would completely lock up VS2010 and eventually crash. Disabling Resharper 5.0 didn't help much (phew! can't live without Resharper), but the problem still remained.

The VS2010 IDE became very unstable for our WPF and heavily resourced solution targeted at .Net 3.5. Visual Studio would regularly crash (say every 10 minutes) with an Out of Memory exception of some kind. If it didn't crash then the build would fail with some out of memory or not enough resources message.

Fortunately in the Event Viewer there was this particularly unhelpful message:

Event Type: Error
Event Source: .NET Runtime Optimization Service
Event Category: None
Event ID: 1103
.NET Runtime Optimization Service (clr_optimization_v2.0.50727_32) - Tried to start a service that wasn't the latest version of CLR Optimization service. Will shutdown

This error seems to relate to a failed or corrupted installation of KB974417 - which applies when .Net 4.0 framework is installed.

There are two ways to fix this. One or both may work for you.

The first is to manually install the update via the Geek Lab article.
The second is to remove the conflicting update and then reinstall:
  1. Uninstall update KB976569 manually through Add/Remove programs.
  2. Download KB974417 for your platform and install it.
  3. Re-install KB976569

If you don't have KB976569 installed to start with then it is possible to resolve this issue by installing KB976569 then following the steps above.

Problem solved! Enable Resharper and code away.

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Friday, December 04, 2009

Generic entity auditing in Linq to Sql

In many enterprise, or even non-enterprise, applications, there is generally a requirement for data change auditing.

For many applications this will come in the form of adding auditing columns to each table in the database. For example the fields, CreateDate, CreateUser, ModifiedDate and ModifiedUser would audit the username and timestamp of record creation and modification in each table.

Of course there are many ways to implement such auditing. In this article I will focus on an approach that I like when using Linq to Sql.


In general this approach uses a marker interface to decorate domain entities that require auditing and then uses the extension points of the Linq to Sql generated DataContext to do the auditing of the decorated entities. With the use of generics this can be done very simply with a few lines of code. The main benefit being that other infrastructure code - repositories, business logic etc don't need to worry about entity auditing at all.


Let's first define our marker interface, which exposes the four auditing fields.
public interface IEntityAudit
    DateTime CreateDate { get; set; }
    string CreateUser { get; set; }
    DateTime ModifiedDate { get; set; }
    string ModifiedUser { get; set; }

The marker interface is used by the DataContext to determine which entities need to be audited when they are committed to the database. It also exposes the auditing fields so that the auditing implementation can access the fields generically.

Now let's implement the auditing. Fortunately Linq to Sql provides a very convenient extension point in SubmitChanges. SubmitChanges is called once the DataContext has determined the changeset, but before the entities are persisted.

public partial class MyStoreDataContext
    public override void SubmitChanges(System.Data.Linq.ConflictMode failureMode)
        // Poor separation of concerns here with auditing, we'll revisit this very soon
        var auditDate = DateTime.Now;
        var auditUser = HttpContext.Current.User.Identity.Name;
        var changeSet = GetChangeSet();

        foreach (var insert in changeSet.Inserts.OfType<IEntityAudit>())
            insert.CreateDate = auditDate;
            insert.CreateUser = auditUser;
            insert.ModifiedDate = auditDate;
            insert.ModifiedUser = auditUser;

        foreach (var update in changeSet.Updates.OfType<IEntityAudit>())
            update.ModifiedDate = auditDate;
            update.ModifiedUser = auditUser;


The types and entities of changes to be committed are provided in the changeSet.Inserts and changeSet.Updates IEnumerables.
Using the nice .OfType<>() extension to IEnumerable the entities that have auditing (as indicated by the marker interface, IEntityAudit) are iterated to set the creation or modification audit values.
Lastly we call the base SubmitChanges to do the normal Linq to Sql persistence.

That is it! We have now built a generic auditing mechanism into our DataContext.

So how is it used?

Here is the domain entity in the database and the Linq to Sql designer:

Decorate the Product domain entity using the partial class
public partial class Product : IEntityAudit

Now whenever a Product is committed to the database as an insert or an update the auditing columns will be set.
public class ProductService
    public Product CreateProduct()
        var product = new Product();

        using (var dataContext = new MyStoreDataContext())
            dataContext.SubmitChanges(); // Here is where the Create audit is triggered

        return product;

    public void SetProductName(int productId, string productName)
        using (var dataContext = new MyStoreDataContext())
            var product = dataContext.Products.Single(p => p.ProductId == productId);
            product.ProductName = productName;
            dataContext.SubmitChanges(); // Here is where the Update audit is triggered

In my next blog post I will show how the concern for updating the audit fields (date and username) can be separated from the DataContext and extended to support multiple change processors.

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Monday, November 23, 2009

Using an interface to reuse Linq queries

I just read a post about convention based Linq querying and thought I would followup with an alternative method for implementation.

One downside that I see with the implementation of building the expression tree is that the entity may not have an Id property. In this case I would definitely want to see a compile error rather than runtime.

So a simple solution may be to decorate the entities with a marker interface and the place the constraint on the extension method generic, such as

    public interface IEntity
    public partial class Post : IEntity
        // Id property is declared in the Linq to Sql designer file

    public static T GetById<T>(this IQueryable<T> query, int id) where T : class, IEntity

But why don't we take this a step further and remove a bit of the expression clumsiness? If we were to add an Id property to the interface, then the following would be possible.
    public interface IEntity
        int Id { get; set; }
    public partial class Post : IEntity
        // Id property is declared in the Linq to Sql designer file
    public static T GetById<T>(this IQueryable<T> queryable, int id) where T : class, IEntity
        return queryable.SingleOrDefault(t => t.Id == id);

This implementation won't compile if the query is on an object that doesn't have an Id. Thus making the interface self-documenting and enforced at compile time.

So as an exercise in understanding expressions this implementation is lacking, but the simplicity is certainly appealing to me.

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Saturday, October 31, 2009

iTextSharp PDF rendering in a medium trust ASP.Net environment

Rendering a PDF for download or email is a very common task for an e-commerce website. One thing to consider when deciding on a PDF library for rendering is what environment the site is running in. Most ASP.Net shared hosting solutions will restrict their hosted sites to Medium trust to prevent a rogue site from peeking at other sites on the server.

Medium trust environments can cause funny things to happen between the development environment and the production environment. By default the websites created in Visual Studio have Full trust, this can cause security problems after deployment if you haven't setup your development environment to mimic production. A good first step is to add a trust level to your web.config system.web section.

    <trust level="Medium" />
This will help to find any trust issues while developing.

So to rendering PDF. After trying ReportViewer 2008 in local mode and PDFSharp (both of which are still very good at rendering PDFs), I have found success with iTextSharp. ReportViewer and PDFSharp both require Full trust mode because they use native COM dlls as part of the GDI rendering process. This makes them unsuitable for shared hosting environments unless you can convince your hoster to raise your site's trust level. The PDFSharp Wiki says that release 1.30 solves most medium trust issues and that full support is in the near future, which is promising. My car also has most of it's wheels, but until I put the fourth one on it isn't going to go far on the road.

iTextSharp appears to have less documentation on the web (one of the best being a fairly comprehensive iTextSharp tutorial), but it is just as powerful as PDFSharp or ReportViewer. The best thing about it though is that it can run in Medium trust mode - once a minor change is made to allow partially trusted callers. To make this change download the iTextSharp source distribution (
Modify the AssemblyInfo.cs file to add the partially trusted callers attribute.
[assembly: AllowPartiallyTrustedCallers()]
Rebuild the iTextSharp assembly and it should be good to go in a Medium trust environment.

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Tuesday, May 19, 2009

Unit Testing with Typemock

Unit Testing ASP.NET? ASP.NET unit testing has never been this easy.

Typemock is launching a new product for ASP.NET developers – the ASP.NET Bundle - and for the launch will be giving out FREE licenses to bloggers and their readers.

The ASP.NET Bundle is the ultimate ASP.NET unit testing solution, and offers both Typemock Isolator, a unit test tool and Ivonna, the Isolator add-on for ASP.NET unit testing, for a bargain price.

Typemock Isolator is a leading .NET unit testing tool (C# and VB.NET) for many ‘hard to test’ technologies such as SharePoint, ASP.NET, MVC, WCF, WPF, Silverlight and more. Note that for unit testing Silverlight there is an open source Isolator add-on called SilverUnit.

The first 60 bloggers who will blog this text in their blog and tell us about it, will get a Free Isolator ASP.NET Bundle license (Typemock Isolator + Ivonna). If you post this in an ASP.NET dedicated blog, you'll get a license automatically (even if more than 60 submit) during the first week of this announcement.

Also 8 bloggers will get an additional 2 licenses (each) to give away to their readers / friends.

Go ahead, click the following link for more information on how to get your free license.

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