Friday, November 06, 2009

.Net Application on a network share

I'd developed a .net framework 2.0 winform application for a customer which had to be started on a client pc from a network share. I'd already had framework 3.5 sp1 on my machine, but with setting the .net target right I thought I made solid solution.

The customer could not start it. They got a System.Security.Security exception when starting the application on a client with .net framework 2.0 from the network. When copying the application on the client machine first, it started with no problems.

On clients which already had framework 3.5 sp1 there was no problem starting the application from the network share.

The answer lies in some sort of trust policies, which are changed (or gone) on framework 3.5

By giving the share full trust of the client:

C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\caspol.exe -m -ag 1 -url "file:////\\computername\sharename\*" FullTrust -exclusive on

The application can be started on a client with .net framework 2.0 from a network share.

NOTE: do not run this command twice on the same computer, the full trust does not work anymore!

Thursday, September 24, 2009

Rabobank Overview

Om een duidelijk overzicht te krijgen van de in- en uitgaven in de maand heb ik een programmaatje gemaakt die aan de hand van Rabobank internet bankieren een overzicht maakt van de in- en uitgaven.

Ook is het mogelijk om binnen de transacties te zoeken en mutaties "af te vinken".
Meer informatie vind je in de snel start gids.

Start de applicatie

Tuesday, June 23, 2009

Guid.comb and synchronization

Synchronize an entity between two databases.

I had set up this records with a GUID and used the guid.comb from NHibernate to generate these for me.
Then I needed to synchronize this object with an other database.

Using NHibernate, just create a new session, evict the object from the first one, and save it the next one. No problem, except a new GUID was generated....

My assumption was that an entity with a generated GUID kept its value. I was wrong.

The answer lies in the ISession.Replicate. This allowes me to copy an entity from one session to another witout losing the generated key.
  foreach (var person in persons)
targetSession.Replicate(person, ReplicationMode.Overwrite);

The ReplicationMode lets you choose the behaviour (Overwrite, LatestVersion, Ignore etc.)

Thursday, June 18, 2009

Linq To NHibernate

Compile your queries

One of the hardest things to do with a database application (e.g. a c# WinForm) is to create all the queries in your app. Where to put them in the model? Use queries, or make stored procedures on the database etc etc.
Then creating all these queries in your code as strings;
"SELECT name, age, .. FROM ..."

This is a lot of work and causes runtime errors because these queries aren't checked at compile-time. Then there are issues of caching, relational data, locking etc etc. All these issues can be solved by NHibernate. This framework maps your OO-Model to your relational model and creates the queries, relations, locking etc for you.
But still there are these runtime errors which may occur, because even a Criteria/Expression in NHibernate uses strings as properties.

.Add(Expression.Like("Title", "Linq To%"))

This can be solved using Linq To NHibernate. This extension to the ISession creates an IQueriable which uses the intellisense of Visual Studio

var q = from tasks in session.Linq<task>()
where tasks.Title.StartsWith("Linq To")
select tasks;

Linq To NHibernate also eases creating queries with multiple joins:

var q = from tasks in session.Linq<task>()
where tasks.Owner.Address.City == "Dalem"
select tasks;

I find Linq To NHibernate a great help with developing my database applications.

Friday, March 13, 2009

Optimize SQL Server 2005 Procedures

I had a stored procedure which took about 3 minutes to run, but starting this query in the management studio of sql server took 2 seconds! The problem lies in the "parameter sniffing". Google it for the exact cause, but copying the parameter variables to local variables within the procedure like the example below does the trick.

Slow procedure:

@param1 NVARCHAR(20)
SELECT id, name, otherstuff
FROM dbo.table1
WHERE param1 = @param1

Fast procedure:

@param1 NVARCHAR(20)
DECLARE @localParam1 NVARCHAR(20)
SET @localParam1 = @param1
SELECT id, name, otherstuff
FROM dbo.table1
WHERE param1 = @localParam1

At first I tought it had something to do with an outdated version of SQL Server, but it even occurs on SQL Server 2005 SP3.

Thursday, February 26, 2009

Fast Clone

Ever had to make a in memory copy of a simple object? You then have to copy each property or create an IClonable implentation. Just like the simple reflection form you can use reflection to create a fast clone.
Just call the static method FastClone.Clone:

Customer c = new Customer
Id = Guid.NewGuid(),
Name = "Frank",
Age = 31,
Married = true

Customer c2 = (Customer)FastClone.Clone(c, "Id");

Optionally properties can be given to exclude from the clone.
You can download the source of FastClone here.