Ajax and Web Services

Advanced Proxies

If you need total control of URL transformations, mod_rewrite lets you assign an external script to handle it.

RewriteMap  lb prg:/var/www/rewrite.pl
RewriteRule ^/ysearch/(.*) ${lb:$1,%{QUERY_STRING}} [P]

The RewriteMap directive assigns a server script that handles the URL rewriting. The RewriteRule directive tells the web server to use that server script any time a URL matches the pattern ^/ysearch/(.*).

The second part of the directive takes a little explaining. lb is a reference to the server script we assigned. $1 and %{QUERY_STRING} are values that will be sent to the server script. $1 will contain the part of the URL that matches the regular expression in parentheses in the search pattern (the (.*) part of /ysearch/(.*)). In regular expression parlance the dot character (“.”) matches any character. In regular expressions the asterisk character is a modifier that affects the character that precedes it. It means “0 or more occurrences”. So “.*” is a regular expression that says “match 0 or more of any character.”

Using our earlier example:

/ysearch/webSearch?query=ajax%20javascript

The (.*) part of our pattern matches “webSearch.” This will be the first piece of information sent to our server script. You might be wondering why the pattern doesn’t match “webSearch?query=ajax%20javascript.” That’s because the web server handles the parameters separately.

The %{QUERY_STRING} part of the directive contains those parameters, and it’s the second piece of information ...