Canvas/VML and Comet in Ext?

[glassonion]

Hi

I wonder whether and where the following features can be found in Ext:

- 2D/3D graphics using Canvas/VML
- Comet client (connecting to Orbited server, for example)

Take dojox.gfx and dojox.cometd as inspiration ;-)
http://dojotoolkit.org/projects/dojox
http://redesign.dojotoolkit.org/?q=jsdoc/dojox/HEAD/object/dojox.cometd

Are these features available? How do they work? Does somebody have examples to share or is there a tutorial?

thanks
Andr

[shane.fox]

It's possible to use dojox.gfx within Extjs.
Just extract all of the necessary code from dojo, then create a new Ext.Panel and create the surface onRender.

[glassonion]

ok, this would certainly work (no idea how complex it would be), but should Ext not have its own Canvas/VML/SVG and Comet components? This seems like basic functionality and integrating two complex framework for such fundamental features seems like enormous overhead - or am I missing something here?

thanks
andr

[heidtmare]

I wouldn't call such features fundamental...

[JeffHowden]

Agreed. Canvas, VML, and Comet are not what most would consider fundamental features.

[glassonion]

Ah well, fundamental is maybe the wrong term...

Anyway, what I meant was that these are rather basic features - unlike some ui widget or such - that one would expect from a serious UI application library nowadays. Well, it would be awesome to have 2D/3D graphics and server push in an advanced UI framework like Ext - which is the best of breed (don't get me wrong on this!).

One can dream ;-) Maybe - after working through the Ext internals I maz contribute to this stuff... hopefully.

cheers
andr

[JeffHowden]

I'm really not trying to nitpick, but Canvas, VML, and Comet aren't what anyone would consider "rather basic" features either. If they were "rather basic" features, you'd see them in any of the top 5 libraries. IMO, any one of those things could require as much development time, project management, and bug tracking as the whole of Ext 2.0.

[SeaSharp2]

VML = Yawn.

Canvas = A technology that the Ext Team should watch over the next year.

Comet = Highly interesting layer over Ajax of much interest for intranet apps with a controller user audience.


As for Comet being as big as the whole of Ext, that is silly talk. Jack would have knocked up a framework extension over a long weekend after seeing the light. Comet is baked into DWR.

[JeffHowden]

As for Comet being as big as the whole of Ext, that is silly talk. Jack would have knocked up a framework extension over a long weekend after seeing the light. Comet is baked into DWR.

Unless you're going to develop only server implementation-specific Comet, supporting it client-side requires significant work. If you're going to go the whole way and develop the server components to it as well, which some are doing, then you're talking a bunch more work.

No knock on Jack, but I don't see it being anything more than a proof of concept in a long weekend, even for Jack.

[glassonion]

Well, just a few more remarks.

wrt Canvas:
2D (and eventually 3D) drawing should be a feature of Ext imho and would fit nicely with the rest of the framework. It would be important to support open alternatives to Flash and the like. Canvas (VML for IE) and SVG offer the features necessary for open Web graphics. Maybe I am wrong, but it should not take too much more than prociding a decent interface for the functionality that is already available in the browsers.

wrt. Comet:
I was thinking of the client side only. Ext should not bother about the server side - any server-side Comet implementation would do (e.g. Orbited). The client side is not THAT complex. It requires methods for registering with a provider and receiving the notifications. It is also not so much different than Ajax, except that polling is replaced with subscription. Again, I fell like this might be an important feature for Ext that would fit in nicely with the rest. I may be wrong again... ;-)

Taken together, it would be great to enable pushing of graphically rich content to users...

Unfortunately, I am still not exerienced enough with Ext to add these features myself - otherwise I would at least try.

kind regards and thanks
Andr

[SeaSharp2]

Since my last post I did some further reading on Comet and found a report about one unix web server test-bed that supported 20,000 concurrent Comet connections before memory usage/performance became unacceptable. Previously I assumed a few hundred comet clients would drag down a web server.

I also bumped into another Comet initiative that is trying to define a common comet protocol that could address Jeff's point about the cost of supporting multiple server-side frameworks.

ExtJS would get a lot of cudos for implementing Comet support, just think of the demo... someone in Australia tabs off an updated Ext Grid cell and a second later the changed value appears on the same grid view on a browser screen in New York.

[SyntacticSugar]

Drawing and Data Push support in Ext *drool*

I agree that drawing and data push capabilities would make excellent compliments to Ext. IMHO it would really put the already top notch js library in a league all its own. By no means do I think this would be simple to implement, but, man would it be friggin awesome.