• Choose a category
• All
• Classic-Fiction

" & full_request & "

")

addLine("connection_ID", connection_id)

addLine("action", action)

set s to s & "

set s to s & ""

return s

end handle CGI request

We start by defining the header that will precede our HTML. Then comes a pair of utility handlers that will make the code for generating each line of our HTML a bit less tedious. Our plan for generating the HTML is to append line after line of this format:

param_name:param_value

and these utilities make the job a bit more elegant. Finally we have the actual handler for the Apple event that will come from acgi dispatcher. As long as this returns a correct HTTP header followed by some reasonably legal HTML, it should work.

Save the script as a Stay Open applet. (Chapter 27 will explain the implications of this designation.) Let's name it echo.acgi. (After saving the applet, you may have to use the Finder's Get Info dialog to remove the .app suffix appended by your script editor application. It is crucial that the file extension should be .acgi, not .app.)

Now let's set up Apache to use acgi dispatcher as a CGI process. This is easy because acgi dispatcher automates the configuration for you. Start up acgi dispatcher and provide your admin password when requested, and the configuration will be performed. Go into the Sharing pane of System Preferences and confirm that Personal Web Sharing is turned on (turn it on if not). Confirm that Apache is serving by opening a browser and asking for the default web page. For example, from the same machine you would ask for http://localhost; from another machine on the same network you would use the machine's Bonjour name (so, for example, my test machine is called tangerineScream.local, so I would ask for http://tangerineScream.local).

Now move echo.acgi into /Library/WebServer/CGI-Executables, and double-click it to start it up. Take a deep breath and, in your browser, ask for it by appending /cgi-bin/echo.acgi to the working URL of your Apache server. For example, I would ask for http://localhost/cgi-bin/echo.acgi in a browser on the same machine, or http://tangerineScream.local/cgi-bin/echo.acgi in a browser on a different machine. Presto! You should get a web page in response, containing such information such as your IP number and what browser you're using, and showing the current date and time at the bottom. That's the script in echo.acgi doing its thing! You've successfully written an AppleScript CGI script.

A question that arises with CGI applets (or any applet, really) is what happens if a request arrives when the applet is already in the middle of handling a pending request. Your web server and your CGI dispatcher may be multithreaded, but AppleScript is not, so Apple events that arrive during execution must be queued and then handled in some definite order. Starting with Panther (AppleScript 1.9.2), that order is FIFO—first in, first out. This means that CGI requests are processed in the order in which they arrive; if a request arrives while another request is already being processed, the new request must wait its turn and will be taken as soon as all currently pending requests are handled.

(This is a big improvement over past systems, where the order was LIFO—last in, first out. Under LIFO ordering, if an Apple event arrives, all pending execution is put on hold until the execution triggered by this latest Apple event has finished. This used to mean that if many requests arrived close to one another, it was quite possible for the earliest ones to be edged out of the queue by newcomers; if this went on for long enough, then from the client's point of view, the web page request would time out, which was thoroughly unfair.)

Timers, Hooks, Attachability, Observability

A number of applications will trigger your script in response to the arrival of a certain day or time. Your choice of such an application will depend upon your particular needs (and possibly what you're willing to spend). Possibilities to examine include Script Timer