[Seaside] Ajax live updates

[Ramon Leon]

> I investigated the idea and couldn't find an simple 
> workaround for this problem: There is a lot of request 
> related state in WASession, WARender and probably some other 
> classes. Moreover registering and processing callbacks is not 
> thread-save, dictionaries in Smalltalk get screwed up if you 
> modify them concurrently.
> 
> My guess is that making Seaside capable of doing asynchronous 
> request requires a lot of changes in the core framework. 
> After all, you have to pay for all the convenience you get ;-)
> 
> Of course a similar trick as I use in Comet could help to 
> solve the problem, however with the drawback that those 
> special requests are handled outside the context of the 
> Seaside session, what is usually something you don't want.
> 
> Any other thoughts?
> 
> Cheers,
> Lukas
> 

OK, all good points, you're absolutely right, I hadn't considered
concurrency and now the defaults make much more sense.  So maybe something
like an asyncCallback:[] method on SUAjax so you can shoot yourself in the
foot knowingly, when necessary?  In truth I'm not worried about concurrency,
since I don't want to update or change any data, only update the UI
concurrently.  When I think about it, I'd think updating the UI is the most
common case, so I don't think it'd really matter if it was handled outside
the scope of the session.  What do you think, is this reasonable?