Migrating from Silverlight 2 to 4

Question

We have a moderately complex silverlight based application written in Silverlight 2. Eventually we will move to Silverlight 4. In terms of porting effort, would it be better to to port our app from SL2 to SL3, and then to SL4. Or, should be port from SL2 to SL4 in one step.

Answer 1

Bear in mind that Silverlight 4 is currently in beta and does not have an end user runtime; so upgrading your app to Silverlight 4 right now is not really an option.

Answer 2

I'd go with the SL2->SL4 port directly. SL4 simply offers more, so it's a good opportunity to start looking at your app and making optimizations using the latest.

• You'll find that 3 and 4 are more similar and therefore take around the same level of effort in terms of learning curve.
• Assuming porting takes you a while, expect SL4 to be out sometime in Q2 CY10 with or around the same time as VS2010 is released. That should offer you time to iron out the issues in beta and then when RTW happens, you'll be nearly ready with your port.
• After RTW, expect a couple of months for most people to upgrade their run time. It should happen relatively quickly given Windows Update, etc. In a corporate environment, it may happen much quicker if yours is an LOB and certain employee groups rely on your app - you have the upper hand in dealing with IT.