Archive for July, 2007

Very often, in most of the windows application, there is a functionality in which the mouse cursor changes to hour-glass whenever the application is doing some background processing or is busy. This is done to give user an intimation to wait for application to finish processing.

We had a similar requirement in one of our web-applications. In the application, the mouser cursor has to be changed to hour-glass when user clicks on a particular button or whenever post-back happens. The cursor has to return back to normal as soon as the processing of the page finishes.

We achieved this functionality using JavaScript and HTML.

For this first we write a JavaScript function which changes the mouse cursor to hour-glass.

function ChangeToHourGlass()
  document.body.style.cursor = ‘wait’;

Now we need to call this function appropriately so that the required effect is achieved. So we call this function in two page events – onbeforeunload and onunload. This is done by adding these events handlers in the “body” tag of your ASPX/HTML page.

<body onbeforeunload=”ChangeToHourGlass();” onunload=”ChangeToHourGlass ();”>

Now let’s explain in short about both these event handlers:-

Onbeforeunload – This event is fired before a page is getting unloaded.
OnUnload – This event is fired just before the page is getting unloaded.

How the actual functionality works:-

When we click on a submit button in a page, the current page is unloaded. So one of these events is fired and the mouse cursor changes to hour-glass. While the request goes to back-end and returns back with the result, the current page continues to display. So mouse cursor appears as hour-glass. As soon as the back-end processing is finished, the page is re-created in which the mouse cursor returns back to normal. Hence the desired functionality is achieved.

The reason for using both these event handlers is that Internet Explorer browser prefers “Onbeforeunload” event while other browsers prefer “OnUnload” event. So to make this functionality work in all types of browsers, the JavaScript function is called in both these events.


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Many times it is our requirement to perform various types of processing in XSL file using functions. There are many in-built functions in XSL for doing various types of tasks like string manipulation, number calculations etc but sometimes we need to do some custom processing which can only be achieved by writing our own custom functions. These custom functions can be written in either JavaScript or in some other language. This BOK focuses on how to write these custom functions in a .NET compliant language (like VB.NET, C#) and then use it in our XSL file.

Here are the steps to achieve the same:-

1. Create the custom function in a class. If you need to write many custom functions, it is better to place these functions in a separate class; otherwise the function can be written in same class file as your calling code.

Here a separate class “XSLCustomFunctions” is created which has a function for date formatting.

Public Class XSLCustomFunctions
Public Function Format_Date(ByVal sDateTime As String) As DateTime
         Return CDate(sDateTime)
     End Function
End Class

Point to Note – Here class name is “XSLCustomFunctions” and custom function name is “Format_Date”

2. Create an object of the custom function class. This has to be done in the function where the XSL transform is being applied.

Dim oCustFunc As New XSLCustomFunctions

3. Now we need to create XML namespace declaration in the XSL file for this custom class

<xsl:stylesheet version=”1.0″ xmlns:xsl=”http://www.w3.org/1999/XSL/Transform” xmlns:myCustFunc=”urn:custFunc”>

Point to Note – Here “myCustFunc” is the XML namespace which refers to “urn:custFunc”. This will be passed as XSL extension while adding XSL extension object in step 5

4. Use the custom function in the XSL at the required place. Please note that function is used in the format – “XML_NameSpace:CustomFunction”.

<xsl:value-of select=”myCustFunc:Format_Date(Value)” />

5. Create an object of XSLT argument list in the VB.NET code and add extension object to it and then only apply the XSL transform.

Private Function ApplyXSLTransform(ByVal sXml As String) As String

Dim oArgsList As New XsltArgumentList
      Dim oXmlDocument As New XmlDocument
      Dim oXslTransform As New XslTransform
Dim oStringWriter As New System.IO.StringWriter
Dim oCustFunc As New XSLCustomFunctions


oArgsList.AddExtensionObject(“urn:custFunc”, oCustFunc)

oXslTransform.Transform(oXmlDocument, oArgsList, oStringWriter, Nothing)

Return oStringWriter.ToString
End Function

In this way, we can use our own custom functions created in VB.NET/C# in the XSL file. 


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From quite some time, I have been thinking of starting a technical blog. I already have my personal blog at http://diaryofmayank.blogspot.com/. While my personal blog is restricted to topics and happenings revolving around myself, the technical blog will be purely focused on my daily technical learning, new topics I learn and implement in my professional work. Sometimes, I learn quite a few things by searching on various website etc. Some links are quite interesting sometimes but I am never able to keep track of them. They always get lost in the myriad web. This blog is an attempt to keep track of all those learning and also share it with the whole world.

With that, I announce the launch of my Tech-Turf.

Hoping this blog will become a center of learning not only for me but for others too.


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