More than one export was found that matches the constraint

Don’t deploy the same assemblies twice …MEF DeploymentCatalog and Reference¬†assemblies

Making WCF RIA Services work in a DMZ/Multitier architecture using Application Request Routing

If your web services are running on a server that is not in the DMZ and you are not able to open port 80 to these services either then you will encounter a common scenario. Your Silverlight application will not be able to connect to these services because it can’t get to the clientaccesspolicy.xml file that is required to access services on a different server to the one that served your Silverlight application.

If you hosting your Silverlight application on a machine running IIS 7.5 (Windows Server 2008) then help is at hand – click here for more details.

Telerik Silverlight RadGridView Styles etc.

To save me repeating myself ūüôā …

Styles, StyleSelectors and BasedOn – a working solution

Silverlight/WPF Design Time data

Like all good things, its simple and straight forward. For more details take a look at this post

INotifyDataErrorInfo & Silverlight 4

Mike’s post provided me with a very useful solution.

Silverlight events and the CallMethodAction

I have been using the CallMethodAction behavior to call specific methods when an event is raised. The CallMethodAction can call either:

  1. A public method that takes no arguments and returns no value
  2. A public method whose signature matches that of the event handler

I had used the first option a couple of times quite successfully but had difficulty getting the second option to work using the DisplayDateChanged event for a DatePicker control. That was until I came across this post which provided me with the necessary pointers to get my DisplayDateChanged event to work. I just needed to ensure:

  • The signature of my method matched that for the DisplayDateChanged event handler (of course)
  • The method needed to be listed in the ViewModel I was using for the DataContext of the DatePicker control

So my markup code for the DatePicker looks like this:

<telerik:RadDatePicker .... >
    <i:EventTrigger EventName="DisplayDateChanged">
      <ei:CallMethodAction MethodName="SetRadioButtons" 
        TargetObject="{Binding}" />                                           

And the ViewModel code for my SetRadioButtons method is declared as:

public void SetRadioButtons(object sender, CalendarDateChangedEventArgs e)

Solution – XamlParseException [Line : 0, Position 0] in Expression Blend Design Mode

Sometimes it just really helps to read the manual. This is a link to my post in the Expression Blend forum.