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20041225 Saturday December 25, 2004

Hasta La Vista, mod_perl - Hola mod_parrot! While I've become more fond of running my application outside of the webserver (i.e. using mod_jk2 to wire Tomcat to Apache is my preferred modus operandi these days), mod_perl will always have a place in my heart; I'm actually writing a mod_perl handler for a simple web application right now.

Well, I'm painfully aware of how mod_perl is getting long in the tooth. So I was pleased to read of mod_parrot. While it's probably going to be a while before I get a chance to mess with Perl 6 and Parrot (or even Python and Parrot), I'm hopeful that mod_parrot will provide high productivity with application with modernized programming facilities in the future.

Oh, by the way, Happy Festivas!

( Dec 25 2004, 05:39:09 PM PST ) Permalink


20041218 Saturday December 18, 2004

PHP's mbstring is a 2 bit thief Normally, PHP's strlen function reports back the number of bytes in a string. When dealing with western characters, that will equal to the number characters as well. However, strange things can happen when PHP's mbstring extension for multi-byte character support is enabled to alias that function.

If you have mbstring.func_overload configured to alias mb_strlen for strlen (i.e. when the 2 bit is flipped), then strlen starts counting characters, not bytes. If you need to count the number of bytes, it's not obvious how you're supposed to do it.

This is how I did it:
In places where I really needed to know the number of bytes, I used a homebrewed function byte_count instead strlen. Here's the function definition for byte_count. 

     function byte_count($val) {  
         $len = (function_exists('mb_strlen')) ? 
             mb_strlen($val, 'latin1') :
             strlen($val);
         return $len;
     }

Perl is hokey about it too. The length is supposed to count the number of characters but if you want to force it to count bytes, you need to use the bytes pragma. From the manpage: 

           $x = chr(400);
           print "Length is ", length $x, "\n";     # "Length is 1"
           printf "Contents are %vd\n", $x;         # "Contents are 400"
           {
               use bytes;
               print "Length is ", length $x, "\n"; # "Length is 2"
               printf "Contents are %vd\n", $x;     # "Contents are 198.144"
           }

Java is not without it's pickiness but it as least it has byte and char as distinct primitives.

( Dec 18 2004, 12:50:23 AM PST ) Permalink


20041215 Wednesday December 15, 2004

Tool to defeat a DOS against an Apache server farm Throttling the number of requests that come in to a single web server instance isn't rocket science but it requires keeping track of a state shared amongst processes/threads. But how would you efficiently throttle requests that come to a set of servers?

Apparently, there's some Apache goodness available for this now. At least I think it sounds good! Ian Holsman has written mod_ip_count for Apache 2.0. It uses the APR portability layer and memcached for shared state (actually apr_memcache from Paul Querna). This would enable a whole server farm to keep track of request rates from and throttle specific IP addresses.

( Dec 15 2004, 04:24:13 PM PST ) Permalink