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May 15

Bespin gives you some Pie and will do more Web Work for you

Bespin, Tech, UI / UX with tags: , , Add comments

There have been a couple of things that have been really fun to see and work on in Bespin recently.

First up, is our new Pie Menu that Ben just posted on. The short reasons why I like the new look are:

  • Giving as much area to your code as possible. Why show a command line all the time when you only need it when you run commands? Why have headers and subheaders?
  • Pushing the boundaries on subtle animated effects that full screen change the bits “on the glass”

The implementation is interesting too. We took the nice animation and easing functions that Dojo already provides, but instead of it powering the DOM, we hook in and have it power our Canvas animations instead.

For example, to show an incoming animation we use a fadeIn effect with the backOut easing. In onAnimate we use the opacity setting that the animation provides to render our own animation:

var anim = dojo.fadeIn({
    node: { // fake it out for Dojo to think it is changing the style :)
        style: {}
    duration: 500,
    easing: dojo.fx.easing.backOut,
    onAnimate: function(values) {
        var progress = values.opacity;

Here you can see it in action in video form:

Or, go to the live sample.

We are excited to pump up the “fun” in the UI (with options to tone it down of course). Once nice side effect is that the editor component will have this all baked in, so where ever you see a Bespin, you will be able to access the features you want.

Web Workers; Not having them do too much

Malte Ubl continues to do much appreciated interesting work for the Bespin project. His facade around Web Workers is good stuff.

Since we are trying to push the boundaries of the Web hard, and giving some sexy to the UI, we need to make sure that we keep responsiveness as the highest priority, else users will go nuts.

Web Workers give us the ability to do a lot more in Bespin, but outside of the main browser “thread”. For example, doing real-time analysis on the code itself (e.g. setsyntaxcheck all). The problem that we ran into as we started to use Workers for this type of thing, was making sure that we weren’t killing the poor CPU. It is all well and good to fire off work to a Worker, but how many are running crunching? Malte has done work to make sure that the CPU fan doesn’t go nuts if you are doing a lot of work, and this is something that people will have to generally work around as they start to do more and more in their Web applications. It may be nice in the future to have a richer API that you could use to time slice your background tasks in a better way, as there is a lot of work that fits into the “kick this out and run at your convenience” mould.

Malte recently posted on how added support for the Bespin event loop into the Workers themselves. This is really nice as a Bespin developer as you can use the same publish/subscribe event metaphor, and the Worker facade handles it all for you, so you can talk across the boundaries. This hugely changes the amount of code that you have to write.

He also added support to help the asynchronous issues around “Can you fire this, but make sure that it only fires after foo, bar, and baz are all fired”. We will probably need to cache certain published events so we don’t get into a situation where you run this code after a main initialization event has fired, and thus you will never see it again.

Building a Web application using the latest and greatest HTML5 features is a lot of fun, and we hope that developers will like it too.

2 Responses to “Bespin gives you some Pie and will do more Web Work for you”

  1. Chris J Says:

    Hi Dion, excellent writeup, however as of yesterday the real-time analysis is done using “set syntaxcheck all” (or set it to “error” or “warning” or back to “off”), and you don’t need to set jslint.

  2. Malte Says:

    Did I mention that console.log also works inside bespin workers. Helps a lot because debugging support for workers is non-existing.

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