Comments on: Decoupling data and UI layers with PubSub architecture

By: sfoster

sfoster — Fri, 05 Dec 2008 09:52:44 +0000

This really is a powerful technique - both for where you control the whole UI and for when you need arbitrarily imported components to communicate. Its been in Dojo for a while of course, and is a part of the base librar, and even documented! Its also a feature of the OpenAjax hub - something I'd really like to hear more about here. This is a specification for a standard api for use in mashups, ajax libraries- providing a baseline for ajax functionality and reliable communication between components on the same page, where its critical they dont step on each other's toes. One of the things pubsub buys you is a degree of freedom from the tyrannies of execution order. Components can subscribe to an event before the publisher of that event even exists, and publishers can push out events without having to know or care if any thing is setup and ready to respond to them

By: aniketn

aniketn — Thu, 04 Dec 2008 12:02:37 +0000

Hi, I had worked on a similar but a little more evolved (supports wildcard subscriptions) version of pubsub Details are here Your comments will be appreciated. Unfortunately there is no demo on that page.

By: beckie

beckie — Thu, 04 Dec 2008 11:55:41 +0000

It’s simple, it’s lite, it’s JS lib independent, it works. I like it!

By: narcvs

narcvs — Thu, 04 Dec 2008 04:06:48 +0000

Hey guys,

The presentation/post was intended to demostrate 2 points:

1) the pubsub model is great for decoupling your data and UI
2) javascript is a freakin’ awesome language. Some 25 lines is enough to create a pubsub tool with non-trivial functionality such as currying

Also we don’t see enough pure javascript out there – while js libraries made production quality js apps possible, the language itself is interesting enough to warrant discussion.

Cheers,
Marcus Westin

By: Jordan1

Jordan1 — Thu, 04 Dec 2008 02:54:51 +0000

I’ve been using Prototype’s implementation for some time now and it is syntactically beautiful.

And I believe a little wittiness would benefit this article:

Marcus Westin (who we fingered on finger print) gave a talk at the SF JavaScript meetup on a top that is very interesting:

By: ashendw

ashendw — Thu, 04 Dec 2008 01:06:00 +0000

It's a useful idea and good to understand the concepts, not just how to implement a library. Having said that I've been using dojo's implementation for several years now and would highly recommend people dig around their code for good ideas and practices. dojo.publish dojo.subscribe

By: hblink

hblink — Wed, 03 Dec 2008 20:26:56 +0000

Was not XForms designed exactly for this see http://www.w3.org/TR/2007/REC-xforms-20071029/

By: aheckmann

aheckmann — Wed, 03 Dec 2008 19:06:01 +0000

I think YUI has this in it’s customEvent as well.

By: Schill

Schill — Wed, 03 Dec 2008 18:01:16 +0000

This was a nice, thoughtfully-presented topic at the JS meetup. I think it would have been meaningful and interesting particularly to people not familiar with the pubsub approach. Rather than starting with some huge framework, Marcus nicely showed how to build one from the ground up. I liked his approach.

By: AndrewHerron

AndrewHerron — Wed, 03 Dec 2008 17:09:48 +0000

@Bjorg: Why not?! You know how many home brewed variants of all sorts of things there are? It’s simple, it works, and that’s about it. Why mess with it? Take screwdriver handles for instance! They all let you hold the driver but there’s lots of implementations. I don’t see anyone complaining that there’s too many ways to make a screwdriver handle, eh?

@aw2xcd: I use custom mootools events too, I suppose it’s just a different kind of screwdriver.

We should really stop trying to standardize everything and really think about what works best and for who. Why can’t there be many frameworks and plugins? Why must we feel that everything has to be the same or it isn’t any good. I think I’ll make my own pub/sub-custom-event framework just to spite you guys. Standardization is nothing more than forced subjectivity and I won’t stand for it! I call for the end of standardized implementations and leave things alone! Javascript is the driver, my frameworks the handle, and both are used to screw you!

/end_rant

By: heswell

heswell — Wed, 03 Dec 2008 14:45:13 +0000

re converging on existing implementations…have a look at the OpenAjax hub, it is designed precisely to standardise this kind of pubsub mechanism (whilst allowing pluggable implementations, of which PageBus is one)

By: Johan

Johan — Wed, 03 Dec 2008 13:37:16 +0000

Appcelerator (http://appcelerator.org) is a beautiful framework that offers this and much more.
If you like the idea of a loosely coupled UI and backend via a publish/subscribe model – you’ll love Appcelerator (and no – I don’t work for them).

By: aw2xcd

aw2xcd — Wed, 03 Dec 2008 13:24:22 +0000

hi guys, noob question, how is this different from creating a custom event like this. its a mootools script to lazy load images. This seems cleaner other than the fact I used globals to do it. can I still use this style and pass data without globals?

By: Bjorg

Bjorg — Wed, 03 Dec 2008 11:55:37 +0000

Tibco’s PageBus (http://www.tibco.com/devnet/pagebus) is a bit more sophisticated and has been used for mashups by various applications such as MindTouch Deki (http://www.mindtouch.com) for a while. OpenSocial also has a PubSub mechanism for gadgets (http://code.google.com/apis/opensocial/docs/0.8/reference/gadgets/#gadgets.pubsub).

In other words, please let’s try to converge on some existing implementations and not add more homebrewed ones! :)