BlazeDS and Flex 2 compatibility

There was a question over on the BlazeDS forums about weather Flex 2 would work with BlazeDS. The answer is most definitely YES. You can use Flex 2.0.1 hotfix 2 or Flex 3 with BlazeDS 3. Jon Rose also blogged about this question back in January.

Jon was getting a message:

“Destination ’simple-topic’ requires FlexClient support which was introduced in version 2.5. Please recompile the client application with an updated client framework.”

The “2.5″ in the message that refers to LiveCycle Data Services 2.5, which was shipped requiring a hotfix (#2) for the Flex compiler/SDK.

The AMF3 protocol did not change. The remoting and proxy services interoperate without issue between Flex 2 and BlazeDS.

However, the messaging and data management service implementations on the server required several core changes in channel/endpoint handshaking and in how messages are queued and routed to subscribers that are not backwards compatible with clients compiled against the ORIGINAL Flex 2 client library. This is a low level incompatibility, so previous messaging and data management code doesn’t need to be altered or edited in any way. You just need to recompile your app against the hotfixed Flex 2 or Flex 3 SDK.

Thanks for Seth Hodgson for the details about what changed (it predates me moving over to Data Services).