Despite recent news regarding Silverlight, I expect some of my projects to continue using it for the near term. Others may be taking the same tack, so I thought I’d go ahead and offer this up.
Several of the projects I support have the requirement to periodically refresh specific layers in order to track change or movement. These layers can range from weather to vehicle locations and such. I have typically accomplished this with a timer that refreshes the layer(s) on a specified interval. This can get rather cumbersome if you have different layers that require different refresh intervals.
Working within Silverlight, I have the option of using an existing layer class as a base class and extending it to include an automatic refresh capability. However, some classes, such as the ArcGISDynamicMapServiceLayer, are sealed and cannot be extended. Luckily, the Expression Blend SDK enables me to get around this by attaching a custom behavior.