Silverlight Slim and Fat Flex

A couple of days ago, I talked about Silverlight 2.0. One of the interesting things to me was that it was how Silverlight RIA-style apps could be a lot smaller than Flex apps. I posted a comment to Scott Guthrie and he was kind enough to post a reply to my question. His reply indicates that for Beta 1, a relatively complex application will be slightly smaller than the same thing in Flex. However, much more of the framework is going to be included with the initial Silverlight download starting in Beta 2, thus giving Siliverlight a huge advantage in terms of app size.

When Adobe announced that the Flex framework could be cached on the Flash player across domains, I wondered why the didn't just included it with the Flash player. I have even bugged Flex evangelist Ted Patrick with this question. His response to me was that they would open themselves up to "DLL hell." In other words, there could be problems with people building their app against Flex framework version X, but a user has an older version installed.

As if this doesn't already happen! Let's not forget that Adobe jumped ActionScript from version 2.0 to 3.0 and thus required Flash player 9 or higher for anything authored using 3.0. This was not just some update in framework, it was the entire programming language being overhauled. It is common to use JavaScript to detect Flash player version and require people to upgrade. It is so common and so part of Flash development, that Adobe distributes the ExpressInstall SWF for doing this as easily as possible. Heck, I usually require users to be on 9.0.28 or higher, since that is the version that fixed some bugs with ExternalInterface.

So back to the Flex framework/DLL hell issue. It would simply require people to check for a certain minimum version of the Flash player (since that would correspond to a version of the Flex framework) and prompt for an upgrade if needed. In other words, it would require something that most folks already do today.

To me the real reason is that it is more economical for Adobe to not include the Flex framework. Ted has a widget he wrote showing over 3.9 billion downloads of Flash player 9. Add an extra 200K to that and you get over 726 TB. That's a lot of bandwidth to pay for. That's a price Microsoft wants to pay, because it would indicate lots of folks with Silverlight installed. Perhaps once that happens, Adobe will reconsider.