Field Guide to Programmers

This isn’t an article about how to setup a redirect. There are plenty of those out there already.

If you switch servers or just move some pages around your site, you’ll need to set up redirects on your server so folks find their way to the new home for the old content. Search engine spiders use those redirects too, and if you set up your redirects as permanent (HTTP 301), the spider should update the index with the new URL and your page will keep it’s nice archive of backlinks.

Here are the official HTTP redirect status code definitions:

301 Moved Permanently

The requested resource has been assigned a new permanent URI and any future references to this resource SHOULD use one of the returned URIs. Clients with link editing capabilities ought to automatically re-link references to the Request-URI to one or more of the new references returned by the server, where possible. This response is cacheable unless indicated otherwise.

302 Found

The requested resource resides temporarily under a different URI. Since the redirection might be altered on occasion, the client SHOULD continue to use the Request-URI for future requests. This response is only cacheable if indicated by a Cache-Control or Expires header field.

In other words: 301 means new URL replaces old URL; 302 means keep using old URL.

If you’re the one setting up the redirect, chances are that you’re setting it up right, so this is all old school… But what happens if someone else does it? How do you check?

There are a million ways of course. Maybe you’ll get fancy and write a script. Maybe your marketing person has a contract with an SEO firm and they’ll happily send along spreadsheets of links that are in dire straights. Or maybe, you can just take a quick peek with a nifty Firefox plug-in called LiveHTTPHeaders.

LiveHTTPHeaders does what you’d expect. It shows you all the HTTP requests and responses that flow between your browser and the web. It captures the requests you make when you click a link or type in a URL. It shows all the requests the browser makes when building a page. It reminds you that you are sending Google lots of data if you have the Google Toolbar plugged in. It’s pretty sweet actually.

I like LiveHTTPHeaders because it allows you to filter what it records using regex. You can also use it to build test cases for Apache-Flood (see the docs on the Generator) though I haven’t done that and would probably use Selenium for that.

To check a redirect, just pop open LiveHTTPHeaders (under the Tools menu) and it will start recording. Surf on to the URL in question and see what LiveHTTPHeaders records:

GET /somepage.html HTTP/1.1
Host: www.somesite.com
User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en-US; rv:1.8.1.6) Gecko/20070725 Firefox/2.0.0.6
Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive
Referer: http://www.google.com/search?q=this+was+the+query+that+returned+the+old+URL
Cookie: (not today)

HTTP/1.x 302 Moved Temporarily
Location: http://www.somesite.com/newpage.html
Content-Length: 1
----------------------------------------------------------
http://www.somesite.com/newpage.html

GET /newpage.html HTTP/1.1
Host: www.somesite.com
User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en-US; rv:1.8.1.6) Gecko/20070725 Firefox/2.0.0.6
Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive
Referer: http://www.google.com/search?q=this+was+the+query+that+returned+the+old+URL
Cookie: (not today)

HTTP/1.x 200 OK
Content-Type: text/html
Content-Length: 17279
----------------------------------------------------------

LiveHTTPHeaders allows you to save this log as a text file that you can happily mail along to friends and family.