HTML5 Web Workers and Geolocation

After having missed the first session about upcoming HTML5 features, I decided to go to Peter Lubbers talk "HTML5 Web Sockets, Web Workers and Geolocation Unleashed". Peter is the author of the recently published Apress book "Pro Html 5 Programming". He works for a company called Kaazing which I think is based in the Netherlands. Some time ago, my boss forwarded me a mail which was from Kaazing. It was about a Web Sockets presentation which they wanted to held at our office, since game clients are one of the primary use cases where Web Sockets can come in handy. I have to admit that back then I did not want to meet them. Primarily because I do not work with client products. In addition to that, I thought it was immature, but it was rather that I did not know so much about it back then and did not care.

Anyway, Peters talk covered three of the most interesting API's around HTML5 - Web Workers, Geolocation and Web Sockets. These API's have initially been part of the HTML5 spec but have now been removed and put into their own specification. The idea behind all three is to make life simpler for the developers. With the current generation of browsers and HTML4, developers have to come up with complicated hacks or they have to use plugins in order to mimic bi-directional communication. What HTML5 is aiming for, is to support this natively powered through the browser instead of building something similar based on a bad foundation.

Web Workers are a new feature which brings back UI responsiveness while long running, heavy Javascript is executed. It enables background processing of such script while the user can still use the browser. Peter had an excellent example of this and hopefully I can put this up here on my blog later on. In his example he had a webform with two buttons. Each of the buttons would fire a busy-keeping Javascript for 10 seconds. One button would do this without, the other one with using a Web Worker. Clicking the first button, it was impossible to use the dropdown element or even open a new tab in Firefox. All this worked with Web Workers. Currently this feature is available in Firefox, Chrome, Safari and Opera but not in Internet Explorer. Actually it would be fun to write a web application using Web Workers, where you print a message to the IE users like "if you cannot navigate right now, consider switching to another browser". Web Workers are an incentive that comes for free if you use anything else than Internet Explorer.

The second API Peter talked about was Geolocation. Again, Geolocation is only supported in some browsers right now. You want to check out to see if your browser supports it. Also is a great site to check HTML5 compatibility. Geolocation is a name that stands for native support of user location inside a browser. There are really only two methods that the API supports, getCurrentPosition() and watchPosition(). The first one doing a one time call, the latter constantly receiving the location of the user. This of course makes much more sense on mobile devices than from withing a fixed network. What the two calls return is simply longitude, latitude and accuracy. It is up to the developer how he uses this information within the web application, ie. by displaying it using the Google Maps API. Along with the API calls, you can also request additional metadata but if your browser can not give it to you (like altitude, heading, speed) you might end up getting NULL instead. Looking under the hood, Geolocation is implemented by the browser vendors by using an external location service. The browser asks this service for the location and returns this to the user. I was thinking, the watchPosition() method from the API is probably a candidate where you want to use a Web Worker, unless it is already implemented on top of a Web Worker. Have to find this out.

Would like to blog more about Web Sockets but the next session about CSS3 has already started...

1 Kommentare:

Peter Lubbers hat gesagt…

Thanks for the nice summary of the session. Kaazing is actually based in Mountain View, California--I am originally from Holland and the Orange overload probably made it look Dutch ;-)
Look me up tomorrow for a copy of the book!
Peter Lubbers