iana - Dave's Blog

HTTP Compression Documentation Reference

Baseball Game Friday, House Things Previously

On Friday Sarah and I went to the Mariners vs Rangers game at Safeco Field with Eric and Jane. The Mariners lost but then before the game the announcement made outside the stadium guaranteed the best service and a good time, not a winning game -- and they were right about the good time.

The night before, we saw The Hangover which was very funny and included Zach Galifianakis who was great. Incidentally, take a look at some of Zach's Between Two Ferns.

Last weekend Sarah and I mounted the TV to the wall which was exciting and we saw a mouse in the house!

Thoughts on registerProtocolHandler in HTML 5

I'm a big fan of the concept of registerProtocolHandler in HTML 5 and in FireFox 3, but not quite the implementation. From a high level, it allows web apps to register themselves as handlers of an URL scheme so for (the canonical) example, GMail can register for the mailto URL scheme. I like the concept:

• Better integration of web apps with your system.
• Its easy for web apps to do.
• Links to URNs can now take the user to the sites the user prefers for the sort of thing identified by the URN. For example, if I have a physical address in HTML, instead of making that an http link to Yahoo Maps, I can make the link a geo scheme URI and those who follow the link will get their preferred mapping site that has registered for that scheme. Actually, looking at the geo scheme's RFC, maybe I'd rather use some other URN scheme to represent the physical location, but you get the point.

• There's no way to know if you are the handler for a particular URL scheme which is an important question for web app URL protocol handler authors.
• There's no way to fallback to an http URL in the case that a particular URL scheme isn't registered. A suggested solution to testing the registration of a scheme is for browsers to provide an additional script method to check if a scheme is registered. I don't like the idea of writing script that walks over all my page's links and rewrites them based on that method. I'd much rather see a declarative and backwards compatible fallback mechanism, although I don't know what that would look like.
• There's no way to register for a namespace within the urn scheme URI, the info scheme URI, or the tag scheme URI. I want to register info:lccn/... (Library of Congress Card Number identifiers) to LibraryThing or Amazon and I want to register urn:duri:... (dated URIs) to the Web Archive, among other things.


• Will this result in a proliferation of unregistered URL schemes with clashing namespaces? The ESW Wiki notes why this would be bad.
• And last, although this is nitpickier than the rest, I don't like the '%s' syntax used in the registration method. I'd much rather pass in an URL template, like the URL template used in OpenSearch. If an URL template is used for matching rather than registering against a particular URL scheme, this could also allow for registering a namespace within a URN. For example something along the lines of: registerProtocolHandler("info:lccn/{lccnID}", "htttp://www.librarything.com/search_works.php?q={lccnID}", "LibraryThing LCCN")

The 'Is It UTF-8?' Quick and Dirty Test

I've found while debugging networking in IE its often useful to quickly tell if a string is encoded in UTF-8. You can check for the Byte Order Mark (EF BB BF in UTF-8) but, I rarely see the BOM on UTF-8 strings. Instead I apply a quick and dirty UTF-8 test that takes advantage of the well-formed UTF-8 restrictions.

Unlike other multibyte character encoding forms (see Windows supported character sets or IANA's list of character sets), for example Big5, where sticking together any two bytes is more likely than not to give a valid byte sequence, UTF-8 is more restrictive. And unlike other multibyte character encodings, UTF-8 bytes may be taken out of context and one can still know that its a single byte character, the starting byte of a three byte sequence, etc.

The full rules for well-formed UTF-8 are a little too complicated for me to commit to memory. Instead I've got my own simpler (this is the quick part) set of rules that will be mostly correct (this is the dirty part). For as many bytes in the string as you care to examine, check the most significant digit of the byte:

F:

This is byte 1 of a 4 byte encoded codepoint and must be followed by 3 trail bytes.

E:

This is byte 1 of a 3 byte encoded codepoint and must be followed by 2 trail bytes.

C..D:

This is byte 1 of a 2 byte encoded codepoint and must be followed by 1 trail byte.

8..B:

This is a trail byte.

0..7:

This is a single byte encoded codepoint.

Investigation of a Few Application Protocols (Updated)

Windows allows for application protocols in which, through the registry, you specify a URL scheme and a command line to have that URL passed to your application. Its an easy way to hook a webbrowser up to your application. Anyone can read the doc above and then walk through the registry and pick out the application protocols but just from that info you can't tell what the application expects these URLs to look like. I did a bit of research on some of the application protocols I've seen which is listed below. Good places to look for information on URI schemes: Wikipedia URI scheme, and ESW Wiki UriSchemes.

Old Miscellaneous Thoughts

• A History Channel program had a reenactment of a 1920's archaeologist discovering a stone tablet, sending the tablet to a warehouse, etc. all behind the voice over giving the dry facts. The reenactor hammed it up a bit and I would have rather had clips from Indiana Jones in the background. If they're already not showing me the archaeologist who discovered the tablet, they may as well show me one who will be entertaining.
• There are many parodies of the Get a Mac ads and so when I saw a UK Get a Mac ad I payed attention to see what the joke was. I was disappointed by the 'parody' because it was a conventional Get a Mac ad with different actors. Apple localized their Get a Mac ad campaign in this fashion in the UK and in Japan. I've got a playlist of the US, UK, and Japan's version of the Piechart ad. Ranking the lovable bumblingness of the PC I give the order UK, Japan, then US and ranking the sumgness of the Mac I give the order UK, US, then Japan. But don't take my word for it, view the ads for yourself.
  
• Yahoo Pipes lets users generate an RSS feed altering service that runs on Yahoo's server using a GUI. This is very different from Microsoft's Popfly which allows users to component-ize and share javascript utilities that run client side on a webbrowser. Both have the awesome power of buzzword associations like 'Web 2.0' and 'Mashup' but in my mind Yahoo Pipes is for server side RSS feed modification and Popfly is about client side javascript webpages. And neither will allow me to run an arbitrary XSLT =).