[whatwg] Custom protocol handlers

[Ben Schwarz]

After recently discovering custom protocol handlers[1], it struck me that it would be difficult to provide a decent user experience for those who used browsers which did not support the feature.

There have been previous calls to add further methods to the custom protocol ecosystem, such as a mozilla bug from 2008[2], and a separate discussion from January 2009[3]. However there’s been no solution, so I'd like to raise the issue of the registerProtocolHandler feature again.

Here are some user stories that I feel represent these issues:

1) 

As a web developer
I want to be able to tell when registration of protocols/schemes has either failed or been successful
So that I can provide a fluid user experience

2)
As a web developer
I want to be able to ascertain whether the user-agent supports the registerProtocolHandler feature
So that I can have an alternate experience for the user

Note: I have submitted a pull request to Modernizr to cover story #2[4], I left my story above for posterity. 

3) 
As a web designer / developer
I want to be able to ascertain if another website has registered a custom protocol handler in the user’s browser
So that I can knowingly design and implement an integration experience

4) 
As a web designer / developer
I want to be able to ascertain whether the user has "installed" a custom protocol handler within their operating system
So that I can knowingly design and implement an integration experience



Footnotes:

[1] http://updates.html5rocks.com/2011/06/Registering-a-custom-protocol-handler
[2] https://bugzilla.mozilla.org/show_bug.cgi?id=440620
[3] http://lists.whatwg.org/pipermail/whatwg-whatwg.org/2009-January/018101.html
[4] https://github.com/Modernizr/Modernizr/pull/324/files

Further feature reference:
» https://developer.mozilla.org/En/DOM/Window.navigator.registerProtocolHandler
» https://developer.mozilla.org/en/Web-based_protocol_handlers
» http://developers.whatwg.org/timers.html#custom-handlers


NB:

Thanks for the review from Mr Doug Schepers & Mr Oli Studholme

Cheers, 

Ben