Question

I am writing a Silverlight 4 (could be 5) app that will run out of browser.

I need to load data from a SQL CE database and also reference GIS data that are both stored on a local drive.

The code to do both of these things will be stored in a separate data access layer assembly as it will be shared with other solutions.

How do I use the DAL assembly from the Silverlight project? Do I have to go down the P/Invoke route or is there an easier way?

Answer 1

RickNZ is correct. A Silverlight app can’t access a non-Silverlight library (unless its a portable library) nor can they access local files without the user uploading them. I n my opinion, the following is your list practical options:

• Rewrite the DAL in Silverlight
• Create a simple Soap or Rest service for the DAL and have the Silverlight app access it that way
• Stick with WPF and convert your other applications to WPF as well (if they are also OOB)

Converting from Silverlight to WPF is typically very is since Silverlight is more or less a subset WPF. Of course this might not be an option if the other two apps are not OOB apps.

If you want to stick with Silverlight, then I would suggest writing a quick Rest service to sit on top of your DAL so your applications can access it.

Note: As per SteveChadbourne’s correction, you can use platform invocation, but only in Silverlight 5. As soon as your application makes use of this new feature, it must be run as a full-trust application on a Windows machine.