call perl program from php script

[libra]

I am receiving an xml request and sending back a response. The sender of the request is opening a socket.

The situation is this:
After receiving the request,
I am parsing the request and then I need to call a perl search engine from within my php script. I must pass 3 values to the search engine. The search engine uses the values I pass as search criteria, performs the search and writes results to a mysql table. Once this is complete the php script should resume on the line after I called the perl search engine and the php script should read the mysql table and send the data back as an xml response.

The problem is:
How do I call the perl script from the php script, and pass the 3 values to the perl script and continue with the php script when the perl script is done.... but keep the socket open?

I tried the perl extension for php but I keep getting exceptions. The perl search engine is working and can not be modified by me because it is used elsewhere.

I read an interesting post by dnxzero from 2002.Which seems to say it is possible but I cant get it to work.

Help please, anyone?

[quadmyre]

One way would be to call the perl interpreter using the exec() or sys() functions - you could pass variables over the command line if your perl script works that way - alternatively you could use a temp file to store the variables or something similar. You can use output buffer functions to read any output from the script into a variable to extract it if that's applicable.
Overall this seems a bit of a odd thing to be doing - is it not possible to port the search engine to PHP and cut out a whole load of overhead?