Ordina Stage 07

Internship over!

2007-07-17T01:04:00.001-07:00

Since our internship is all over (16/20 :-)), it's time to set sail for new things. Please visit my new blog here!

http://www.dominiek.eu/blog

njoy!

ASP.Net Membership ReturnUrl Problem

2007-05-02T06:12:00.000-07:00

If you click the Login link on the main page, ASP.Net will auto create a ReturnUrl Querystring. After you logged in succesfully you will be redirected to the page you came from. The problem is that the DestinationPageUrl property won't work anymore if you have a ReturnUrl Querystring. This causes a problem for us because the user will be redirected to the login page instead of the DestinationPageUrl.

We've searched for solutions but there isn't a clean solution. Here's a way to solve the problem (redirect to the Default page if a ReturnUrl querystring is present).

protected void Page_Load(object sender, EventArgs e)
{
string strRedirect;
strRedirect = Request["ReturnUrl"];
if (strRedirect != null)
Response.Redirect("~/Default.aspx", true);
}

Trick for adding a default image to a Windows Media Player video

2007-04-19T05:32:00.000-07:00

When you're surfing the net you see a lot of videos with a default image before it's playing. An embedded HTML video that uses Windows Media Player doesn't have that option. We found a little trick to make it look like there is a default image before it's playing and after it's finished. You can easily implement these function in a javascript in the head of your page.

Steps:
1. When loading the video, you hide the video and you show a default image. Hiding the video is possible by setting the default property document.video.uiMode = 'invisible'
2. Set the uiMode property to 'none' when the video starts playing (check on playing with the property: currentPosition (!= 0)).
3. The image will pop up again after playing because the currentPosition will be zero again.

that's it, add a cool background image like ours :p

Sorting once, sorting twice...

2007-04-02T06:56:00.000-07:00

We came across a situation in which we had to sort a table (limited by a WHERE clause) and order this again by another column. We thought this was easy to do using a subselect but SQL Server refuses to sort views. After some experimenting we came up with the following query:

SELECT * FROM
(
SELECT TOP 5 topicKnowledgeID, topicID, rating, tblTopicKnowledge.date, username
FROM dbo.tblTopicKnowledge
WHERE (topicID = @topicID AND username = @username)
ORDER BY topicKnowledgeID DESC
) AS sortedTopicKnowledgeTable
ORDER BY topicKnowledgeID ASC

Great succes!!

Using System.Reflection

2007-04-01T01:27:00.000-07:00

Ever since I read a great article about using the builtin reflection API in C#, I wanted to use it in a real life situation. The idea is that at runtime, you can list classes, get info about their methods, attributes, super class, ... and even make instances of them using the Activator class.

For our import application, which will load data from an Excel spreasheet to an SQL Server 2005 database, we wanted to give the user a scala of ways in which the console application could notify the user. We came up with the following diagram...

The Open methods will be fired first, in the console output class they won't do much but they could be responsible for initializing a stream, connecting to the mailserver...
The Format method is passed an OutputItem object, which contains message data and a category (error/success/default)...
The Close method would close streams, send a mail with all the notifications, contact a webservice...

Now at runtime, we will use reflection to detect all classes which implement the IOutputFormatter abstract class and they will be instantiated by our FormatterReflectionManager class. By default this class will enable all formatters and stack them up in a generic list, but the user can choose which Formatters should be used. The idea is similar to the Enterprise Library, we didn't use the EntLib because it's a really big library and we didn't want to bring in extra dependencies. Another reason why we didn't use EntLib is because we already use it in another project and because we wanted to experiment with System.Reflection...

public void ReflectOutputFormatters()
{
foreach (Type type in Assembly.GetCallingAssembly().GetTypes())
{
if (type.IsSubclassOf(typeof(IOutputFormatter)))
_formatters.Add((IOutputFormatter)Activator.CreateInstance(type));
}
}

This chunck of code will look for all classes the extend the superclass and add them to a Generic List.

ASP.Net Membership: IsLockedOut property

2007-03-29T08:04:00.000-07:00

Hello bloggers!

Today we looked up some info about the ' IsLockedOut ' property of the ASP.Net Membership Control. If a user enters a wrong password more than three times in a row, IsLockedOut will be true. The problem is that a user can't login anymore until an administrator unlock his account.

Password crackers can brute force user accounts. So it can happen you can't login because someone else tried to crack your account with several invalid passwords. To solve this problem, we can just raise the number of maximum invalid attempts.

Well, for those who agree with our statement here are 2 ways to disable it.

Simple Way (and still effective):
Just add the maxInvalidPasswordAttempts property to your web.config file:
example:

Remember, the counter resets when a successful attempt is logged.

Advanced Way (it auto-unlocks your account if you reached the maximum invalid attempts):
Click Here to go to the CodeGuru Tutorial

Changing CSS Styles at runtime
Oh yeah, another quick tip, if you change the css style of a webpage in Visual Studio, you need to Clear your cache before reloading the page. You can do this using CTRL-F5 instead of the normal refresh (F5)

MSSQL Handling NULL Values

2007-03-23T12:33:00.000-07:00

One of the most horrific problems in database-access are fields which allow Null-values, I remember all the IF statements it took in COBOL to handle this problem (with a CSV file) and I was afraid I had to go through the same hell as back then. By making use of the ISNULL method we were able to remove the evil at it's root, the database...

An example :

SELECT username, ISNULL(email,"") FROM tblUser

This query will set the emailadres to an empty string instead of a null value if no value is entered.
Since the abilities to handle Null values with Typed Datasets are rather limited, this was a fine solution..

Visual Studio makes your properties!

2007-03-22T07:00:00.000-07:00

This is something I already know for a while but it's a very handy features which the Visual Studio developers have made quite hard to find. When your declaring your business logic / domain classes, this feature will surely be handy. When you want to encapsulate a private/protected field (the good OO way...), you'll probably make accessors for it. Writing all of these getters & setters is a lot of work if you've got around 10 attributes you want to cover.

Here's the trick, just right click the field you want to encapsulate

And Visual Studio will create the property methods:

Everybody who has coded with Visual Studio before is probably aware of this tip but for new coders, this is a real timesaver!

The other refactoring options are also extremely handy for code optimization. The Extract Method options is also one of the features I use quite frequent...

Using XML Serialization

2007-03-21T07:53:00.000-07:00

While finishing our Interactive Course project, we decided we had to do something about the rather oldschool way we parsed our XML files. The code to parse an XML file was divided into two classes, a parser and a schema validator, totalling for some 150 lines of code. Luckily Kurt (who is guiding our internship) let us in on the whole XmlSerialization thingie...

Click for a larger view...

Using the xsd.exe program, which can be easily found in the Visual Studio directory, we made an XSD scheme for our xml file. After the XSD was created by the program, we fed the program the XSD and a serializable class is created for our XML file. After we had imported this class file into our solution, the code to load the course from an XML file looked like this:

XmlSerializer xs = new XmlSerializer(typeof(Course)); FileStream fstrm = new FileInfo(fileName).OpenRead(); return (Course)xs.Deserialize(fstrm);

These 3 lines replace the 150+ lines we coded to parse and validate the XML file, if only we would have known ;-) Luckily, now you do! So don't go using the good old (even deprecated) XmlReader class, serialization is the next best thing!

ASP.NET Roles & Membership

2007-03-19T05:29:00.000-07:00

We spent the morning trying to figure out how we could migrate the ASP.NET membership database (which is a SQLExpress DB) to SQL Server 2005. This great article gave us more than enough info to do this, although we ran into some problems along the way. Nevertheless we got things up and running again...

Interactive Course player!

2007-03-16T04:58:00.000-07:00

Good news today, we've finished developing a small additional project. It's an ASP.NET Ajax powered website that will enable the competence leaders to post online video courses on the net for the consultants, here's a list of features:

- Completely XML customizable
- Customizable themes
- Animated Text while the video is playing (like subtitles...)
- Nice & simple Ajax GUI!

I have to say I'm pretty exicted about the result, I like it alot :D

I have to say we've had a bit of trouble updating the playtime of the video with the text, the final solution is a mixture of iframe,ajax,javascript and a good old Session variable. The text also fades out and in when it changes, cool :) For anyone who's interested, we based our mediaplayer code on this article, we had to recompile the DLL and make some code modifications first to optimize things. There was also an error in the code so that the height of the videoplayer wasn't set, luckily we managed to fix this to!

ASP.NET Panel Control problem

2007-03-16T03:50:00.000-07:00

Took us just a few Google lookups, but we've had some problems with the Panel control in the standard ASP.NET toolbox. The panels were drawn over the other content of our site. The solution: simply remove the height attribute of the panel... Guess solutions don't have to be that hard al of the time...

Some technical info on our project

2007-03-16T01:06:00.000-07:00

The project will be built using a service-oriented architecture. The methods we'll be using are:

- ASP.NET
- C#
- The new MS Ajax 1.0 framework (+the control toolkit)
- SQL Server 2005
- The EntLib library (for logging purposes)

Througout this blog we'll be posting some of the things we've learned...

Some info on our project...

2007-03-16T00:57:00.000-07:00

Our internship project is all about knowledge management. We were assigned to build a knowledge management application which will track individual knowledge for all of Ordina's consultants. Another purpose of this application is to supply resources (webcast, trainings, books) to the employees. No question about it, an application like this could be a great asset for a consulting company like Ordina, so we'll give it all we've got ;-)

Introduction

2007-03-16T00:41:00.000-07:00

We are 2 Belgian students in informatics at Hogeschool Gent, currently we are working on our internship with Ordina, an IT-consulting company. Purpose of this blog is to summarize some of the things we've learned during the internship and to keep people posted about the stuff we are doing. Hope you like it...

Jonas Van de Biest
Dierickx Dominique