scheme page 2 - Dave's Blog

A Brief History of Microsoft's Live Search's New Domain Bing

• 2003 July: The first archived version of bing.com features "bing! is a small device (e.g., possibly even a small Band-Aid(R)-like sticker!) that vibrates when a person's cell phone rings." I can't recall 2003 cell phones, were they big enough to require this device?
• 2004 August: Site for the same device is rewritten and looks much better, IMHO.
• 2006 June: The domain is now parked by easyDNS. I guess the "bing!" device didn't work out?
• 2006 November: Its now "BING*" and they won't say what they're working on ("we're still in stealth mode") but they are hiring C#/.NET developers.
• 2007 January: And they're gone. Without even exiting stealth mode. Too bad, I liked their logo. Their domain is now for sale...
• 2007 February: Looks like EasyMail buys the domain and offers a physical mailing service in Australia: "By simply clicking a button on your computer, mail is beamed electronically to a bing post office. Your mail is automatically printed, folded, enveloped and dispatched into the Australia Post network the very same day."
• Present: Now its the new home for Live Search of course.

The new name reminds me of the show Friends. Also, I hope they get a new favicon - I don't enjoy the stretched 'b' nor its color scheme.

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")

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.

Tag Metadata in Feeds

As noted previously, my page consists of the aggregation of my various feeds and in working on that code recently it was again brought to my attention that everyone has different ways of representing tag metadata in feeds. I made up a list of how my various feed sources represent tags and list that data here so that it might help others in the future.

Update 2009-9-14: Added WordPress to the Tag Markup table and namespaces to the Tag Markup Scheme table.

URI Fragment Info Roundup

Information about URI Fragments, the portion of URIs that follow the '#' at the end and that are used to navigate within a document, is scattered throughout various documents which I usually have to hunt down. Instead I'll link to them all here.

Definitions. Fragments are defined in the URI RFC which states that they're used to identify a secondary resource that is related to the primary resource identified by the URI as a subset of the primary, a view of the primary, or some other resource described by the primary. The interpretation of a fragment is based on the mime type of the primary resource. Tim Berners-Lee notes that determining fragment meaning from mime type is a problem because a single URI may contain a single fragment, however over HTTP a single URI can result in the same logical resource represented in different mime types. So there's one fragment but multiple mime types and so multiple interpretations of the one fragment. The URI RFC says that if an author has a single resource available in multiple mime types then the author must ensure that the various representations of a single resource must all resolve fragments to the same logical secondary resource. Depending on which mime types you're dealing with this is either not easy or not possible.

HTTP. In HTTP when URIs are used, the fragment is not included. The General Syntax section of the HTTP standard says it uses the definitions of 'URI-reference' (which includes the fragment), 'absoluteURI', and 'relativeURI' (which don't include the fragment) from the URI RFC. However, the 'URI-reference' term doesn't actually appear in the BNF for the protocol. Accordingly the headers like 'Request-URI', 'Content-Location', 'Location', and 'Referer' which include URIs are defined with 'absoluteURI' or 'relativeURI' and don't include the fragment. This is in keeping with the original fragment definition which says that the fragment is used as a view of the original resource and consequently only needed for resolution on the client. Additionally, the URI RFC explicitly notes that not including the fragment is a privacy feature such that page authors won't be able to stop clients from viewing whatever fragments the client chooses. This seems like an odd claim given that if the author wanted to selectively restrict access to portions of documents there are other options for them like breaking out the parts of a single resource to which the author wishes to restrict access into separate resources.

HTML. In HTML, the HTML mime type RFC defines HTML's fragment use which consists of fragments referring to elements with a corresponding 'id' attribute or one of a particular set of elements with a corresponding 'name' attribute. The HTML spec discusses fragment use additionally noting that the names and ids must be unique in the document and that they must consist of only US-ASCII characters. The ID and NAME attributes are further restricted in section 6 to only consist of alphanumerics, the hyphen, period, colon, and underscore. This is a subset of the characters allowed in the URI fragment so no encoding is discussed since technically its not needed. However, practically speaking, browsers like FireFox and Internet Explorer allow for names and ids containing characters outside of the defined set including characters that must be percent-encoded to appear in a URI fragment. The interpretation of percent-encoded characters in fragments for HTML documents is not consistent across browsers (or in some cases within the same browser) especially for the percent-encoded percent.

Text. Text/plain recently got a fragment definition that allows fragments to refer to particular lines or characters within a text document. The scheme no longer includes regular expressions, which disappointed me at first, but in retrospect is probably good idea for increasing the adoption of this fragment scheme and for avoiding the potential for ubiquitous DoS via regex. One of the authors also notes this on his blog. I look forward to the day when this scheme is widely implemented.

XML. XML has the XPointer framework to define its fragment structure as noted by the XML mime type definition. XPointer consists of a general scheme that contains subschemes that identify a subset of an XML document. Its too bad such a thing wasn't adopted for URI fragments in general to solve the problem of a single resource with multiple mime type representations. I wrote more about XPointer when I worked on hacking XPointer into IE.

SVG and MPEG. Through the Media Fragments Working Group I found a couple more fragment scheme definitions. SVG's fragment scheme is defined in the SVG documentation and looks similar to XML's. MPEG has one defined but I could only find it as an ISO document "Text of ISO/IEC FCD 21000-17 MPEG-12 FID" and not as an RFC which is a little disturbing.

AJAX. AJAX websites have used fragments as an escape hatch for two issues that I've seen. The first is getting a unique URL for versions of a page that are produced on the client by script. The fragment may be changed by script without forcing the page to reload. This goes outside the rules of the standards by using HTML fragments in a fashion not called out by the HTML spec. but it does seem to be inline with the spirit of the fragment in that it is a subview of the original resource and interpretted client side. The other hack-ier use of the fragment in AJAX is for cross domain communication. The basic idea is that different frames or windows may not communicate in normal fashions if they have different domains but they can view each other's URLs and accordingly can change their own fragments in order to send a message out to those who know where to look. IMO this is not inline with the spirit of the fragment but is rather a cool hack.

Reusing Internet Explorer's Builtin CSS

When throwing together an HTML page at work that other people will view, I stick the following line in for style. Its IE's error page CSS and contaits a subtle gradient background that I like.