	ACADEMIC COMPUTING and COMMUNICATIONS CENTER

Short URLs

Why Make a Short URL?

You want a popular Web site? There are only three really important criteria:

Content - Give them what they want.
Navigation - Help them find what they want.
Download Time - Give it to them fast.

Note that a short URL is not on the list. Yahoo would have been popular with a long, ugly name, just because it gave users what they wanted.

Most people follow links, or find pages in search engines. And, once found, they bookmark the URL. For these people, it doesn't matter at all what the URL is. However, if you plan on advertising your URL in conventional media, such as print or TV, it's easier to advertise a short URL. If this is the case for you, read on.

Files and URLs

Each URL ultimately corresponds to a certain file on a certain server. The logical relationship between URLs is given by links on one or more pages. This is really independent from the physical relationship between files on a server, usually given by a hierarchical directory structure.

Use the directory structure to help the page maintainer deal with files; use the link structure to help your users navigate your Web files. Understand the difference.

In particular, we use directories to manage files from everybody's Web pages on tigger and icarus. We don't create arbitrary URLs because they really aren't needed, and because it would interfere with our directory structure.

Anatomy of a URL

A simple URL (missing a few optional parts) has the form:

protocol://machine/path/file

	protocol	machine	path	file
examples	http https ftp	www.uic.edu www2.uic.edu	htbin depts/accc	acdepts.html index.html

Basically, this says to go to machine, present the string path/file, and expect the server to figure out which physical file to return.

Two ways to shorten the URL are:

Use a default filename (simple)
Use a new machine name to refer to the old machine+path (complicated)

Filename Defaults

The file part of the URL is actually optional. If it is missing, tigger or icarus will check for any files named index.html, index.htm or index.asis. So all you have to do is give your file one of the default filenames, and you don't need the file part of the URL.

For example, http://www.uic.edu/ really gets you http://www.uic.edu/index.html

Domain Name Service (DNS)

If filename defaults aren't good enough, your other choice is a CNAME. This means you want something like http://my.pages.uic.edu/ to send people to your real Web page at http://www.uic.edu/very/long/path/to/file.html

This can be done, but is a little complicated and there are a number of restrictions.

Ask Networks to create a CNAME, using the email address below. There are significant restrictions on what names are allowed. Some details are given below.
Once the CNAME is created and entered in the Domain Name Servers, contact www@uic.edu and ask that that CNAME be redirected to your existing Web page.

Note that your existing Web page and the existing URLs will continue to work. All we are doing is adding an extra name to your pages, at the expense of some internal configurations and a little performance penalty to the user.

Creating a CNAME

Domain names are things like tigger.cc.uic.edu that ultimately get translated into IP addresses for network access. A CNAME is just a secondary name that resolves to an existing machine. However, it lives in the same name space as all machine names. To manage this name space, we need to impose some restrictions on what new names are allowed.

No new 3-level names. You can't be important.uic.edu. We reserve 3-level names for campus-wide resources like www.uic.edu
4-level (or more) names. If you already have a 3-level departmental zone, e.g. accc.uic.edu, your REACH person can request anything inside of that. You can have, e.g. www.my.org.within.accc.uic.edu Whatever makes sense to the owning department.
If your organization doesn't really fit in your (or a) department, we already made a zone for you: pages.uic.edu So you are welcome to use myorganization.pages.uic.edu if you don't fit anywhere else.

Making a CNAME Request

The DNS name of your current machine is:

(none)
If you are in your office, this very likely uses the existing zone for your department. If you aren't sure about what zone is appropriate, send a note anyway, and Networks will tell you what they can do for you.

When you are ready to request a CNAME, send email to: wwwtech@uic.edu. Be sure to include the following information:

Your UIC netid
The requested CNAME. This cannot be arbitrary. See the above section for proper CNAMES.
The existing URL that you want the new CNAME to be directed to.
Any other questions.

URL Redirection

Getting a CNAME assigned is almost enough. The last step is to get the CNAME URL redirected to the real URL. Normally, we'll take care of this internally. But, if your CNAME gets assigned and the new URL doesn't go to your old page, send a note to wwwtech@uic.edu.

Limitations

Be aware that redirection using the CNAME will not work with ssl, i.e., with https:// URLs. If you need encryption or Bluestem for security, you won't be able to construct URLs of the form http://CNAME/....

This is not a major deal, becuase the URLs of the form https://www.uic.edu/... will still work for your site. You just have to be careful to use www.uic.edu for URLs that point back to your site, even if you advertise your main page at http://CNAME/.

2006-8-10 wwwtech