Re: [hybi] Addressing Minimal Events

[Greg Wilkins <[e-mail]>]

Mark Lentczner wrote:

> What I'm wondering is: How does one, given a Minimal, Event style 
> protocol, handle when there are two or more widgets on the page that 
> need updates? The home page view on Facebook, for example, has at least 
> four separate areas being live-updated.

I see the "many widgets on one page" as just the simplest case of
a need for multiplexing events over a single transport.

Very few sites like facebook actually put multiple widgets on
the same page, since those widgets potentially come from different
untrusted sources (and in the igoogle example, you don't want your
hot-babe-of-the-day widget sneaking a peek at your stock-ticker
widget).

So normal practise is to put widgets into iframes that are
used as sandboxes to isolate widgets.

So the first challenge is to get events in and out of these
sandboxes before they can be multiplexed onto a common channel.

This has to be coordinated by the parent page, because by
definition the sandboxed widgets can't know if there are
other widgets around with whom they should be multiplexing.

View like this, multi-widgets on a page really becomes
multiple frames with communication needs to the same
domain.     Which in turn is just a specific case of
the problem of multiple frames, tabs and/or windows
on the same domain.

It may be that as well as multiplexing events for
different widgets on the same page, we need to multiplex
and/or distribute events for different instances of the
same widget on different pages.

These are some of the issues the open ajax alliance
is trying to deal with - but I'm out of touch with their
latest thinking.

Anyway, my point is, that when considering multiplexing
events onto the same transport, we could consider the
multi frame/tab/window issues as well.


cheers