Ever wondered how to display the correct cursor in an application that is databinded to async methods?

Pretty easy solution, just databind the cursor on the window itself.

Here's how:

• Add an IsBusy property on the DataContext (and implement INotifyPropertyChanged on it)
• Addt the following to your window xaml

• Create the following ValueConverter

Note: Use of MarkupExtension

I'm really loving this declarative approach with silverlight and wpf... (ask me why and I can't tell you ! :-)

Anyway I've just stumbled across a way of managing RiaDataContexts Declaratively
I found it on the Telerik samples.... If you've not looked at these guys controls then check them out!!

A few people have asked me what's the easiest way of doing transitions on Silverlight.

One of the easiest ways has to be to use the VisualStateManager with Expression Blend, see screen show for sample logged in state.
If you don't know how to use this tool then start watching a few vids!

To change between states you can use this code..

If you wish to prevent clients accessing your data

Over the w/end I was helping a mate with his Data-driven Silverlight app.

I was gobsmacked that his developer spent days and weeks writing plumbing code, hand coding infrastructure code and even worse my friend had to pay for it.
Being able to focus on the business needs is important so having a development platform that better enables that focus and increased productivity is an absolute must.

The solution to this problem is codenamed Alexandria i.e. .NET RIA Services, this technology provides a set of server components and ASP.NET extensions that ease the n-tier development process, making your applications almost as easy to develop as if they were running on a single tier, In addition, services such as authentication, roles and profile management are provided. The combination of client and server enhancements to Silverlight 3 and ASP.NET along with the addition of .NET RIA Services, streamline the end-to-end experience of developing data-driven Web applications also known as Rich Internet Applications, or RIAs.

I’m not going to show you how to do it as there are many-many training resources available but a good place to start is here: http://silverlight.net/getstarted/riaservices/

So if you find yourself writing needless plumbing code for a DAL in Silverlight, then spend some time figuring RIA services out!
(Spend some get some diesel for that digger and opposed to grabbing a shovel and diving in!!)

Ever want to filter data in Silverlight? here's a simple example that uses a lambda expression to search on name (case sensitive)

If you've got a data driven application, databinding is the infrastructure of choice that makes the link between data and your UX

Silverlight 4 has a few improvments that brings it closer to WPF

• TargetNullValue  - lets you specify the what to display in the target when the source value is null
  e.g.  {Binding Path=Name, TargetNullValue=NoName}
• StringFormat - specify how a strnig should be formatted
  e.g.  {Binding Path=Salary, StringFormat=C}
• FallbackValue - I love this one, comes in pretty handy when dealing with polymorphic classes where a you know in advance what properties specialized classes have and want to display them... or display a fallback value if they don't exist.
  e.g.  {Binding Path=LastLoggedOn, FallbackValue=Never}

Tonight I tried to use the FlowDocument that you'll know well if you are familiar with WPF....

Important part above "tried to use"  .... but  ... silverlight version 3 doesn't support it :-(

Thats a second thing I've found lacking as I move some code to Silverlight, i've also found that DataTriggers don't work like the do in WPF

In my early WPF days I noticed the magic that having two different controls bound to the Same ObservableCollection meant that when I selected an item in one control, the same item got selected in the other.... which i I didn't want.

CollectionViewSource To the rescue

<Window.Resources>
<local:MyData x:Key="MyData"/>  
    <CollectionViewSource x:Key="AllData" Source="{StaticResource MyData}"/>  
    <CollectionViewSource x:Key="SearchData" Source="{StaticResource MyData}" Filter="MySearch"/>  
</Window.Resources> 
 
<ListBox ItemsSource="{Binding Source={StaticResource AllData}}"/>  
<ListBox ItemsSource="{Binding Source={StaticResource SearchData}}"/>

·      Authentication

·      Access control

·      Auditing

Authentication.

One of the critical requirements of any LOB application ia authentication; before the user can use any function he will authenticate by giving a user id and password.

In ASP.NET web application, thi can easily be done by taking advantage of the membership provider and the server-side ASP.NET login controls. In Silverlight, there are two ways to enforce authentication: authentication outside and authentication inside.

Authentication outside is very straightforward and is similar to ASP.NET applications, with this approach, authentication happens in anASP.NET based web page before the Silverlight application is displayed. The authentication context can be transferred into the Silverlight application through the InitParams parameter before a Silverlight application is loaded. The other approach is to use a webservice.