Ajax technology accesses server-side power using callbacks without reloading the browser page. Easily create Rich Internet Applications without writing JavaScript!
Q: How does LiveControls handle ViewState?
A: With the release of v1.4 of LiveControls, ViewState management has been optimized to increase performance while reducing bandwidth and providing maximum flexibility in your application design.

By default, control and page level ViewState is available and can be altered within the context of a callback. At the same time, the encoded and often cumbersome ViewState is not transferred between the client and server, thereby saving on bandwidth and increasing application performance. These improvements are even more pronounced in pages using many controls, or when using complex controls such as the LiveDataGrid with many rows and columns.

Optionally, LiveControls may also be configured to send encoded ViewState between the client and server in each callback.
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Q: Does PowerWEB LiveControls for ASP.NET work under .NET 2.0?
A: Yes, since version 1.1.3, LiveControls has provided compatibility with Visual Studio 2005 and .NET 2.0.
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Q: How do I use Response.Redirect or Server.Transfer within a callback?
A: With the release of v1.3.1 of LiveControls, Response.Redirect and Server.Transfer methods are used with no modifications. Alternatively, you may use the BufferedScript property of any LiveControl to issue a client-side location change. For example: LiveButton1.BufferedScript.Write(“window.location=’’”)
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Q: Why is my application not rendering the same way in all browsers?
A: While LiveControls were designed to function with all modern browsers, each browser vendor may interpret HTML, DHTML, CSS and other rendering specifications differently. If there is a specific browser type or application implementation that is not functioning to your satifaction, please contact as we may have already identified the problem and can provide more information on when this may be addressed.
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Q: Are there any limitations I should be aware of?
  • If you use LiveTimer to regularly update page data, be aware of the server loading involved with many simultaneous connections and short (sub-second) update intervals.
  • 3rd party controls can only be updated from within LiveControl callbacks if they use basic rendering techniques, so you should test them for interop with LiveControls.
  • The LiveWrapper is used to isolate the HTML and JavaScript generated by 3rd party controls, but fails to provide interoperabilty for some products such as Intersoft Grid, PetersDatePackage and FarPoint Spread.

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Q: How is LiveControls different from .NET 2.0 Client Callback Manager?
  • .NET 2.0 Client Callback Manager provides a basic Remote Procedure Call (RPC) machanism from the browser to the server. PowerWEB LiveControls for ASP.NET adds:
    • development UI support with full-featured Web Controls (standard properties, methods and events) that generate necessary JavaScript and event hooks
    • interpretation of all changes made in code-behind and the updating of "dirty" client elements (Live controls, Microsoft controls, and compatible 3rd party controls) without refreshing the page
    • complex operations such as updating databound grids and lists as source data changes
    • automatic ViewState management
    • broader browser compatibility not limited to XmlHttp-equiped browsers, with automatic degradation of callback techniques to match browser capabilities
  • LiveControls can enable complex application development where similar projects using Client Callback Manager may exceed budgets because of the large amount of javascript programming required.

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Q: My IIS Server uses the .NET Framework 1.0 and the samples keep giving me an error about "ValidateRequest." What does this mean and how do I fix it?
A: The samples were created to use .NET Framework 1.1 when running on an IIS Server. The 1.1 ASPX pages require that the Page Directive "ValidateRequest=false" be set in the code. The 1.0 Framework does not understand this setting. To remedy this, remove the words "ValidateRequest=false" wherever they appear in the code.
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Q: When I run the samples, VS.NET asks me for a default start page. Which one should I use?
A: Default.aspx is the index for the samples and should be the start page. While the Web project in IIS already has that marked, the IDE needs to be notified that Default.aspx is the start page when you are debugging.
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Q: Under Visual Studio 2005, I do not see any help pages when I hit F1. How do I correct this?
A: To see the help topics within Visual Studio 2005 and Visual Web Developer 2005, go to Tools > Options. Under Environment > Help > Online (make sure "Show all settings" is checked), ensure that "Try local first" is selected. This will find the installed help files before attempting to look online.
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Q: Why do I see an 'Attempting to deserialize an empty stream' exception when I build my VS.NET 2008 Website?
A: Websites create an App_Licenses.dll for component licensing which must be distributed with the application.  Due to an apparent VS.NET 2008 bug, this dll is faulty when created during compilation on a 64 bit Operating System.  To work-around the problem, the App_Licenses dll in the 2008 Website can be replaced. 

Options include:
a) Compile a 2005 WebSite on the same (licensed) machine using the same controls/components
b) Compile a 2005 or 2008 WebSite on a 32 bit OS machine, provided this machine is also licensed (Dart Developer licenses allow installation on up to two machines)

Replace the faulty App_Licenses.dll with the resulting dll from one of the options above, and the Website should build and deploy without issue.  Do not delete the new dll, or VS.NET will again create a new faulty one in its place.

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