Blog for The Well Designed URLs Initiative

This is quiz #2 of our ongoing URLQuiz series.

In this quiz, there are 26 pairs of URLs (A..Z) and for each pair the questions is: “Which of these two URLs are equivlent?” i.e. which return the same resource when dereferenced, and “Which can be cached as the same URL?”

You should answer ‘Yes‘, ‘No‘, or ‘Maybe‘ where ‘Maybe‘ means ‘It might return the same resource but should not be cached according to the specs.’

To answer, leave a comment and ideally explain your reasoning for each. Feel free to group answers based on your reasoning and/or the answer given (Yes, No, and Maybe.) Print it out and take the quiz with pencil and paper if you serious about getting it right, and feel free to use a computer or browser or whatever to test your results before answering. Good luck!

About the TLD .foo[1]

Clarification (2007-March-02): Some people have stated that the server could possibly return the same resource for any two given URLs so they felt the answer could never be ‘No.’ I definitely see their point, for example http://mysite.foo/bar and http://mysite.foo/bazz could possibly return the same thing but nobody would ever reasonably expect them to do so on their on. So let me clarify to say that I meant a quiz taker to select ‘No‘ in the case where where the resource returned would definitely not be the same thing unless the developer or server admin explicity programmed or configured them to do so. On the other hand ‘Maybe‘ would be used in the case where someone might reasonably expect the two URLs to return the same resource even though the RFC 3986 would define the two URLs as being different such as in [footnote 2], or when it depends on the O/S of the server as in [footnote 3]. Regarding fragments, the question is “In a transaction between a client and a server, is the cache allowed to view them as the same?” Regarding which can be cached I was looking for what are appropriate per the spec, not necessarily whether any particular software in the cloud (i.e. routers, proxies, browsers, etc.) actually does cache but instead “Would it be allowed to cache?”

Questions

1. The ‘www’ domain
   1. http://mysite.foo/
   2. http://www.mysite.foo/
2. Letter casing in path
   1. http://mysite.foo/Index.htm
   2. http://mysite.foo/index.htm
3. Letter casing in domain
   1. http://MySite.foo/index.htm
   2. http://mysite.foo/index.htm
4. Index.htm vs. Default.aspx
   1. http://mysite.foo/Index.htm
   2. http://mysite.foo/Default.aspx
5. Trailing slash on domain
   1. http://mysite.foo
   2. http://mysite.foo/
6. Trailing slash on path
   1. http://mysite.foo/path
   2. http://mysite.foo/path/
7. Empty question mark
   1. http://mysite.foo/
   2. http://mysite.foo/?
8. Empty parameter
   1. http://mysite.foo/?
   2. http://mysite.foo/?param=
9. Port 80
   1. http://mysite.foo/
   2. http://mysite.foo:80/
10. Port 443
    1. http://mysite.foo/
    2. http://mysite.foo:443/
11. Https vs. Port 443
    1. https://mysite.foo/
    2. http://mysite.foo:443/
12. Ftp vs. Http
    1. ftp://mysite.foo/
    2. http://mysite.foo/
13. Letter casing in parameter name
    1. http://mysite.foo/?param=bar
    2. http://mysite.foo/?Param=bar
14. Letter casing in parameter value
    1. http://mysite.foo/?param=bar
    2. http://mysite.foo/?param=Bar
15. Hash vs. no hash
    1. http://mysite.foo
    2. http://mysite.foo#
16. Hash vs. Fragment
    1. http://mysite.foo#frag
    2. http://mysite.foo#
17. Fragment vs. no Fragment
    1. http://mysite.foo#frag
    2. http://mysite.foo
18. Plus vs. Space in path
    1. http://mysite.foo/url+design
    2. http://mysite.foo/url design
19. Space vs. Encoded Space in path
    1. http://mysite.foo/url design
    2. http://mysite.foo/url%20design
20. Plus vs. Encoded Plus in path
    1. http://mysite.foo/url+design
    2. http://mysite.foo/url%2Bdesign
21. Slash vs. Encoded Slash in path
    1. http://mysite.foo/top/second
    2. http://mysite.foo/top%2Fsecond
22. Ampersand vs. Encoded Ampersand in path
    1. http://mysite.foo/abc&xyz
    2. http://mysite.foo/abc%26xyz
23. Ampersand vs. Encoded Ampersand in parameter value
    1. http://mysite.foo/?q=abc&xyz
    2. http://mysite.foo/?q=abc%26xyz
24. Equals vs. Encoded Equals in path
    1. http://mysite.foo/abc=xyz/
    2. http://mysite.foo/abc%3Dyxz/
25. Equals vs. Encoded Equals in parameter value
    1. http://mysite.foo/?q=abc=xyz
    2. http://mysite.foo/?q=abc%3Dyxz
26. Parameter order
    1. http://mysite.foo/?abc=123&xyz=987
    2. http://mysite.foo/?xyz=987&abc=123

P.S. Don’t stress if you can’t answer them all. It took me months to uncover all these nuances, and if I were taking this quiz I doubt I could get them right all in one sitting.

FootNotes

1. I’m using the non-existent top-level domain “.foo” to avoid giving any link-love to arbitrary example sites that don’t deserve it! For the purpose of the quiz, just assume that “.foo” is a functioning top level domain.
2. Question A.
3. Question B.

As promised, this is the first of what will be many URLQuizes here are the blog for The Well Designed URLs Initiative. This URLQuiz discusses the convention of using a subdomain with the name ‘www‘ to identify a website.

As most everyone knows, many of the first sites on the web started using this convention. Examples include  www.amazon.com, www.yahoo.com, www.google.com, and www.ebay.com. However, there is nothing about the web that requires a subdomain be named ‘www‘ when selecting the address for a website. To the contrary, many websites use other subdomains for prefixes such as:

• Wikipedia for spoken language:
  1. http://en.wikipedia.org (English)
  2. http://de.wikipedia.org (German)
  3. http://fr.wikipedia.org (French)
• Google for different applications:
  1. http://maps.google.com (Maps of Geography)
  2. http://news.google.com (Local and World News)
  3. http://code.google.com (Open-source Programming Code)
• Craig’s List for cities:
  1. http://atlanta.craigslist.org (Atlanta)
  2. http://boston.craigslist.org (Boston)
  3. http://newyork.craigslist.org (New York) 

There is even a passionate contingent of web developers  that believe the ‘www‘ convention is an anachronism and should be deprecated (or ‘eventually abolished‘, in layman’s terms.)

So how should the base domain and subdomain(s) be handled, and what are the pros and cons of each? Here are the options I’ve identified, but feel free to suggest others that come to mind as well:

1. Establish the ‘www‘ form as the implicit canonical form and issue a 404 - Not Found whenever an inbound request attempts to deference a URL using the root domain (i.e. without ‘www‘ or any other subdomain.)
2. Establish the non-’www‘ form as the implicit canonical form and issue a 404 - Not Found whenever an inbound request attempts to deference a URL using the ‘www‘ subdomain.
3. Establish the ‘www‘ form as the implicit canonical form and use a 301 - Moved Permanently (redirect)  whenever an inbound request attempts to deference a URL using the root domain (i.e. without ‘www‘ or any other subdomain.)
4. Establish the the non-’www‘ form as the implicit canonical form and use a 301 - Moved Permanently (redirect) whenever an inbound request attempts to deference a URL using the ‘www‘ subdomain.
5. Do not establish a canonical form and return 200 - Ok for both the ‘www‘ form and the non-’www‘ form.
6. Abandon both the ‘www‘ form and the non-’www‘ form and always use explicitly subdomains based on your site organization like in the examples shown above.
7. Some combination of 1 through 6 I haven’t already described.
8. Or, something completely different?

So there you go; give your answer(s) in the comments. Though I definitely have my opinions on the subject I will stay out of it unless I don’t see anyone mentioning several of the points I think are relevant. After enough comments come in, I’ll summarize and write a follow up post, just like Dan Cederholm did with SimpleQuiz.

Hint: You might want to consider not only online usage but offline usage as well.

UPDATE: Just days after writing this post Tim Bromhead wrote: Which is better for your site: www or no www?  Is that weird or what? Tim must have had some kind of a Vulcan Mind Meld or similar going on… Anywho, great article Tim and thanks for being a URLian!

UPDATE#2: Looks like I picked the right time to discuss this issue! A few days ago Scott Hanselman talked about the downside of ignoring the distinction between ‘www’ and the root domain, Jeff Atwood discussed how to solve it, to which Phil Haack then responds with a bit of a rant about the www or lack thereof. Since they both have such strong yet opposite opinions on the subject, maybe we can get both Jeff and Phil to weight in on the subject over here…?

Technorati Tags: URL Design | Subdomains | Canconical Form | www | no-www

As a way to gather a broad spectrum of opinion and engage the community on many different URL-related topics, we’ll be offering a URLQuiz from time to time. Inspired by and patterned after Dan Cederholm’s very well received SimpleQuiz series, we’ll take a simple URL Design question, present a few different alternate approaches, and ask readers to weigh in on which they believe to be the best and why.

Dan proved that his SimpleQuiz was very effective at quickly emerging a consensus for a best practice when a consensus was possible. Building on Dan’s pioneering efforts, we hope to leverage his technique to address the constantly debated issues in URL Design and hopefully arrive at some consensuses of opinion on URL-relates issues ourselves.

So look for the first URLQuiz, part of an ongoing series, here at the Well Designed URLs Initiative blog in the near future.