WPF applications often needs to call time consuming methods or processes, the time consuming methods or processes can be, huge time consuming calculation or perhaps a web service call. In case of WPF specially XBAP (wpf browser application) which run on remote client machines browser, this sort of calls can make your user interface unresponsive.  I am working with WPF for more than four month. Lot of things come in to way and dealt with nicely. Well in this post I am going to share a simple trick for avoiding unresponsiveness of user interface. We have already used this technique in many cases in our application, but this is for WPF.

The "Thread & Invoke"

BackgroundWorker is a very smooth and useful tool for our purpose of making more responsive UI(user interface). Before discussing more about BackgroundWorker lets take a flash back of legacy technique (which is pretty smart)  implementation of making  more responsive UI. Previously I used threading for implementing such kind of UI smoothness. What I did is to create a background thread and call expansive operation on that thread. When the job is finished use the "MethodInvoker" method to let know the UI thread that the job is finished. And this model is called asynchronous model. And this is quite smart model and rest of the models are based on this approach. Here is a quick code snippet for demonstration the technique.

//first start the method with tread
System.Threading.ThreadStart ts = new System.Threading.ThreadStart(ExpansiveMethod);
System.Threading.Thread t = new System.Threading.Thread(ts);
t.Start();
protected void ExpansiveMethod()
{
//Very expansive call will go here...
//after the job is finished call method to update ui
MethodInvoker updaterMI = new MethodInvoker(UpdateChange);
this.BeginInvoke(UpdateChange);
}
protected void UpdateChange()
{
//again back to main ui thread
}

The "Background Worker"

Okay, its time to use the BackgroundWorker. An amazing thing about background worker is, its simple to use.  First, lets see what a background worker is. "BackgroundWorker" is a class under "System.ComponentModel" which executes an operation on a separate thread. Which is introduced from dot net framework 2.0. Things are again pretty simple just like tread, All you have to do is instantiate a BackgroundWorker and subscribe its events, and call the "RunWorkerAsync()" method. Lets put a code snippet. Since we are programmers we understand code better.

void MyMethodToCallExpansiveOperation()
{
//Call method to show wait screen
BackgroundWorker workertranaction = new BackgroundWorker();
workertranaction.DoWork += new DoWorkEventHandler(workertranaction_DoWork);
workertranaction.RunWorkerCompleted += new RunWorkerCompletedEventHandler(workertranaction_RunWorkerCompleted);
workertranaction.RunWorkerAsync();
}
void workertranaction_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
//Call method to hide wait screen
}
void workertranaction_DoWork(object sender, DoWorkEventArgs e)
{
//My Expansive call will go here...
}

As you can see in above code I have subscribed two event "DoWork" (which is the main function) and "RunWorkerCompleted", In dowork event handler we will put our expansive time consuming operations, as the name imply's RunWorkerCompleted event is fired when the work is finished . BackgroundWorker also has "ProgressChanged" event which is used to let the main UI thread know how much work is completed.

The "Dispatcher"

In few cases the BackgroundWorker needs to access the main UI thread. In WPF we can use "Dispatcher" which is a class of "System.Windows.Threading" and a delegate to access the main thread. First of all we have to declare a delegate for our candidate methods, and then use the delegate to call the method using Dispatcher. Dispatcher has few thread priority and you can use various priority from DispatcherPriority enum. "Send" has the highest priority in DispatcherPriority.

//delegate for our method of type void
public delegate void Process();
//and then use the dispatcher to call the method. 
Process del = new Process(UpdateMyUI);
this.Dispatcher.Invoke(System.Windows.Threading.DispatcherPriority.Background, del);
void UpdateMyUI()
{
//get back to main UI thread
}

For more reading about this Asynchronous Programming please visit the references.

Reference

http://msdn.microsoft.com/en-us/library/system.componentmodel.backgroundworker.aspx

http://weblogs.asp.net/justin_rogers/articles/126345.aspx

http://www.eggheadcafe.com/articles/20050926.asp

Recently I had to work with window SharePoint Service 3.0 and its development. I download the visual studio 2005 project templates for SharePoint development. I downloaded the project msi from Microsoft download site.

http://download.microsoft.com/download/e/8/a/e8aa8476-5af6-4f38-aed2-0247a99d2bc6/VSeWSS.msi

Installed in my local computer… but when I opened the IDE2005 project templates are not there…..

I got confused… and try reinstall the msi… but noting happed… I went to google and found few people is also suffering from this problem… the problem is my vs2005 is installed in different drive other that “c:\” and the installed temples are in default “c:\”… and then I moved my template in the drive where the IDE2005 is installed….

Location of the project templates is [your dive letter]:\Program Files\Microsoft Visual Studio 8\Common7\IDE…

There were two directories one if project template and other is item template… last thing that I did is to make ide identity the project templates….

For this I had to just a command in vs2005 comma prompt..

devenv /installvstemplates

I found help from the following forum… please go there for more detailed discussion…

http://geekswithblogs.net/ehammersley/archive/2005/11/08/59451.aspx

Hope this will help someone someday….

Option One

Step One add the sn.exe to External Section of VS2005

1. Click on Menu->Tools->External Tools
2. A window with all external tool listed will popup.. click on add button
3. In title type “String Name tool”
4. In command brows for sn.exe tool [Generally in the bin directory of your sdk folder]
5. Check the use output window and prompt for argument check box…
6. Click on apply to dismiss the widow…

Now you can see that in tools menu you will have a menu item named “Strong Name Tool”. Click on the menu will launch a window asking the argument …. In the argument text box type

–k “c:\\mykeypair.snk”Click on okey to dismiss the window… in output window you will see that successful keypart creation message will be shown…

Your key is reated but not yet associated with any

Adding the key to the project to associate with assembly1. Open your project…
2. Open the property of the project…
3. You will see a tab called signning is bottom of the window… click on the signning button
4. In siginning tab check the sign the assembly check box.
5. In choose a strong name key file … click on brows …. And brows for your mykeypair.snk file…
6. save the project and build it…

That’s it your assembly is strong name signed on….

Option Two [Too Easy]

1. Open your project…
2. Open the property of the project…
3. You will see a tab called signning is bottom of the window… click on the signning button
4. In siginning tab check the sign the assembly check box.
5. In choose a strong name key file … click on new…
6. A window asking for snk file will popup… type the desiered name and click on okey to dismiss the window… save the project and build it…

That’s it your assembly is strong name signed on….

Deploy the assembly in GAC…

1. Add the gacutil.exe tool just like the sn.exe tool
2. Now open the gacutil tool from tools….
3. In the argument window type….
4. -i "$(ProjectDir)\bin\debug\DataBaseHelper.dll" or [-I “yourprojectdir\buildmode[debug or release]\bin\filename.dll”]
5. Click on okay to dismis the window..
6. In output window you will see a successful message….
7. “Assembly successfully added to the cache”

Happy programming!

AjaxControlTookKit is a very nice addition of Asp.net 2.0 Ajax Extension. Recently I had very nice experience using asp.net 2.0 Ajax in few of my projects. "update panel" is very use full control as far as easy Ajax is concern. I haven't explored the whole area of client side scripting, but so far the experience with the server side controls are pretty much good and satisfactory.

Problem with Calender

In one of my project, I had to use the Calendar Extender of Ajax. Well in the page level the Calender Extender worked fine. but when i put the extender in one of my usercontrol. after the page render in browser the calender popup's position is pretty strange. No deterministic behavior was found in popup. when I click on the button of the calender the popup window appeared way up where it should actually show.

I went on trying few things to fix the thing and succeed on the setting position to relative. I just put the position behavior of the parent div of the Extender to relative.

style="position:relative"

worked like cramp

Another problem

If you set the css property of the calender extender suddenly the calender loose all its default behaviour and color skim. And no detail guide line is found in the ajax.asp.net site for customizing the style of the calender control.

Since ajaxControlToolKit is under development we hope this issues will be fixed in the actual release product.

Asp.net 2.0 ships with a whole new set of controls. Navigation controls are one of them. In navigation control we have three options

1. Sitemap path
2. Menu
3. Tree View

Recently I have worked in a project which is a demo project where I had the pleasure of using the asp.net 2.0 tree view control. Below I will be demonstrating a simple way to use the treeview and some things that we should know while we use tree view control of asp.net 2.0 in our projects.

Obviously tree view control has node property and nodes can be create dynamically and modify the node collection on runtime. But it’s for only level one node. For level two nodes node is created just the way it is, but need to add in the child node property. So in a sense tree view has node property and nodes have no recursive node property and to deal with child node, node has child node collection.

Constructor of Node class has several overloads. Actually 5 of them are there.

TreeNode tn = new TreeNode("Text");

TreeNode tn = new TreeNode("Text", _value);

Here we should always be careful about the value property. This value property must be distinct for each collection.

For example if we have a Tree Node consists of three Nodes and each and every done has value property as a same value. SelectedNodeChanged even returns always the first node of the collection.

TreeNode tn1 = new TreeNode("Node One",-1);

TreeNode tn2 = new TreeNode("Node Two",-1);

TreeNode tn3 = new TreeNode("Node Three",-1);

TreeView1.Nodes.Add(tn1);

TreeView1.Nodes.Add(tn2);

TreeView1.Nodes.Add(tn3);

In the web application if we select node three that is tn3 … in SelectedNodeChanged event we will have th1 as SelectedNode. I don’t know how this happened but surely it happened. But if we provide different value in the value field of the node constructor this was okay. Even if we don’t provide any value things work just fine.

Tree view has a wide range of configuration and style settings. Among these StaticItemStyle and StaticItemHoverStyle is most useful.

Well sometime we need to disable a node in our view. But TreeNode class do not have any enable or disable property, rather it has selection Action Property. We need to set the selection property value to none to make a node disabled.