TweetFollow Us on Twitter

Apple Event CGIs

Volume Number: 15 (1999)
Issue Number: 8
Column Tag: Web Development

Apple Event Terminology for CGIs

by Chuck Shotton, BIAP Systems
Edited by Cal Simone, Technical Edit by Grant Neufeld

What changed in Mac OS 8.5?

A Little History

In 1993, MacHTTP was one of only 3 Web server products in existence. The other 2 were Unix-based servers from CERN in Switzerland and NCSA at the University of Illinois Urbana-Champaign. When they first appeared on the scene, all these servers could do is send back files of data. It quickly became apparent that to do really useful stuff, Web servers had to be able to interact with applications on the local machine.

Initially, the only external interface provided by URLs, HTTP, and HTML was an ability to specify search terms to some external program by putting those terms after a "?" in a URL. While it is rarely used today, many features besides free text searches were implemented with this mechanism. In order to implement search functions on the Mac, MacHTTP implemented a simple mechanism for invoking an AppleScript and passing some arguments to it.

In its first incarnation, the AppleScript source was loaded from disk, compiled by MacHTTP, and then executed each time a request for the "search engine" was received by the server. In order to pass arguments to the script, variable assignment statements were actually prepended to the AppleScript source read from disk, and compiled into the program. The output from this script was then returned to the HTTP client. Since this was in the days of HTTP 0.9, no HTTP header was required and most scripts just returned plain text or simple HTML documents that were generated on the fly.

As it turns out, this was one of the first applications that actually used AppleScript on the Mac in any significant way, but MacHTTP's performance when compiling and running AppleScripts for each request was painfully slow. It quickly became apparent that there had to be a better way to quickly load and execute external AppleScripts as well as stand-alone programs written in other languages. So a new AppleEvent was defined so that MacHTTP could launch external programs and pass the necessary parameters to the external application.

This was the genesis of the WWWOmegaSRCH, or "search" AppleEvent. It passed a single argument string (the data appearing after a "?" in a URL) to an external application and received a text response. While it increased performance by removing the overhead of recompiling an AppleScript each time a request was made, there was still the overhead of launching the application or script each time a request came in. In addition, it was about this time that the NCSA server implemented the first version of the CGI (Common Gateway Interface) standard.

In typical Unix fashion, CGIs were passed all of their arguments in Unix shell environment variables. Since the Mac OS had no similar function, implementing the CGI standard on a Mac required a different approach. Since MacHTTP already had a way to pass arguments to external applications, it made sense to simply extend the existing AppleEvent to pass all the parameters necessary to implement the CGI standard. Since older scripts and applications depended on the "search" event, a new event was created called "search document", or WWWOmegaSDOC.

Because AppleScript doesn't provide a convenient user-level mechanism for specifying your own English-like terminology for events that you create in AppleScripts, the familiar but totally unfriendly syntax of:

on «event WWWOmegaSDOC» ...

sprang into being. In order to list all the parameters passed to a script, an AppleScript CGI author had to carefully craft the event handler syntax, using the chevron syntax for the event and all of its parameters. While functional, it was not very readable and greatly complicated the learning curve for new users.

As the Mac CGI standard matured, the parameters passed to CGI applications from MacHTTP were extended to include approximately 15 different arguments. In order to make some sense out of the parameter list, Wayne Walrath of Acme Technologies created an Apple event terminology file that AppleScript CGI authors could install on their Macs that made the cryptic chevron syntax into something more human readable. While not widely distributed, this terminology file greatly improved the readability of AppleScripts.

With the advent of Mac OS 8, Apple began including a basic HTTP server for performing personal Web sharing. This server had the ability to send the same sorts of AppleEvents to external CGI applications provided by MacHTTP providedand other Mac servers like WebSTAR, Quid Pro Quo, and NetPresenz. However, it wasn't until the release of Mac OS 8.5 that the very widely used "SDOC" AppleEvent finally got officially-supported Apple event terminology as part of the core operating system.

What this means is that now AppleScript CGI authors can write CGI event handlers using simple English-like syntax without having to revert to the cryptic chevron syntax. In Mac OS 8.5, Apple included its version of the AppleEvent terminology as part of the "Standard Additions" file in the "Scripting Additions" folder in the OS 8.5 System Folder. In order to see the new syntax, users should use the Script Editor application to open the AppleEvent dictionary of the "Standard Additions" file.

The Handle CGI Event Syntax

  • handle CGI request: Sent to a script to process a Common Gateway Interface request
  • handle CGI request string - the path of the URL
  • [searching for string] - the data for the GET method or data after the '?' in a POST method
  • [with posted data string] - the POST arguments
  • [of content type string] - the MIME content type of POST arguments
  • [using access method string] - either 'GET' or 'POST'
  • [from address string] - the IP address of the entity making the request
  • [from user string] - the user name associated with the request
  • [using password string] - the password sent with the request
  • [with user info string] - additional information about the user, usually the email address
  • [from server string] - the name of the server application sending this request
  • [via port string] - the IP port number of the server
  • [executing by string] - the path to the script executing this CGI, in URL form
  • [referred by string] - the URL of the page the client used to link to the CGI
  • [from browser string] - the name of the client software
  • [using action string] - the path to the file or CGI
  • [of action type string] - either PREPROCESSOR, POSTPROCESSOR, CGI, or ACGI
  • [from client IP address string] - the Internet address of the client
  • [with full request string] - the full request as sent to the server
  • [with connection ID integer] - the ID of the connection from the server to the client
  • Result: web page - An HTML page resulting from the CGI execution

Format upgrade drawbacks

There are some drawbacks to Apple's addition of this AppleEvent terminology in Mac OS 8.5 that users need to be aware of. First, it can prevent existing, correctly written CGIs from being compiled. I found that every single one of my CGIs (based on the old MacHTTP CGI template scripts) failed to compile under the Mac OS 8.5 terminology, even though they compiled and ran fine under OS 8.1. This is because Apple chose to use relatively verbose and somewhat nonstandard terminology for their version of this event, causing several commonly used variable names to conflict with the Apple event keywords in the new terminology.

In order to correct this problem, you need to find all of the parameters in your old version of the SDOC event handler that have name conflicts with Apple's new terminology and rename those parameters. In my case, Apple had chosen to use the term "action" as a part of one of their keywords and I had used it as the name of one of my event's parameters. In order to clearly see which event parameters are causing problems, you may need to disable Apple's new terminology so you can easily examine your old script in the Script Editor. To do this:

  1. Quit the Script Editor
  2. Move the "Standard Additions" file out of the Scripting Additions folder temporarily, and reopen your old CGI in the Script Editor.

You'll then see the old chevron syntax for the SDOC event, and can easily compare your parameter names to the keywords found in Apple's dictionary entry for the CGI event.

Once you've changed your parameter names:

  1. Quit the editor, saving your script
  2. Reinstall the "Standard Additions" file,
  3. Reopen your CGI.

You should now have a script that compiles correctly and uses the new terminology.

One other problem that you should note stems from the fact that Apple implemented terminology for the SDOC event that is slightly out of date from the event commonly supported by the recent versions of Mac Web servers. Specifically, the "DIRE" parameter, which typically contains a string representing the Web server's current working directory, is not present in Apple's version of the SDOC event terminology. If your existing CGI script uses the DIRE parameter, it will still be available but it will revert to the old chevron syntax for that one parameter. If you need to write a new CGI that uses the DIRE parameter, you'll have to append a parameter to the end of Apple's parameter list that looks like:

given «class DIRE»: dir_path

An example script that uses the URL path, search arguments and server directory might look like:

Sample AppleScript using URL path, search args, and server directory

on handle CGI request inURLPath ¬ 
searching for inSearchArgs given «class DIRE»:dir_path
- build your HTTP header and response data, and return them...
end handle CGI request


For the most part, the addition of a standard terminology for the SDOC AppleEvent for AppleScript authors is a great benefit. If you have existing AppleScript CGIs, you'll have to be careful about the potential impact this new terminology can have on your CGIs. But with a small amount of modifications as described above, you can quickly take advantage of this new feature of Mac OS 8.5 and start writing much more readable, maintainable AppleScript CGIs.

Debugging an AppleScript CGI

Writing a CGI can be rewarding - and for a simple task, you can write the CGI in the Script Editor and, after a couple of tries, you should be able to get it to work.

The simple (limited) method:

  1. Write your CGI and save it as a stay-open script application ("CGI applet").
  2. Go to your browser and submit requests. Your web server software will send Apple event messages to your CGI applet.
  3. If the CGI doesn't work properly, you can examine the script in the Script Editor (or your favorite editor), searching for the problem command or commands, correcting the script, and saving again.

If you get stuck, you can insert dialog boxes, beeps, and writing stuff out to a text file. Any of these involves modifying your CGI, which means you aren't debugging the same CGI that you'll use for real - and you must take care to remove anything you placed in your script purely for debugging purposes.

While this method is straightforward, because of the indirect method of invoking the CGI handler in your script, it will be effective only if your CGI is short and simple.

But suppose something goes wrong? Or suppose your CGI is complex, involving several applications? How can you perfect it?

The deeper (cooler) method

If you have Main Event Software's Scripter, you have several tools available to debug your CGI "live". Getting a scripting environment beyond Apple's free Script Editor may cost a little bit, but how much is your time worth?

  • Drag the CGI applet onto the Live Edit application, which can be found in the Scripter Extras folder. The applet will quit if it's running. After several seconds, a dialog box will appear indicating that the CGI is ready for editing in Scripter.
  • Choose Observe in the Windows menu to open the Observe window. If you triple-click the first line of your CGI handler declaration (the line that starts with "on handle CGI request") and command-drag the line from your CGI's editing window to the Observe window, all your parameter values will appear in the Observe window whenever your CGI is called. You can also drag variable names from your script into the Observe window, useful to see their values change as you single step through your CGI.
  • If you want to see every line that executes in your script and every result, choose Log in the Windows menu to open the Log window.
  • Now you can go to your browser and submit requests. Your web server software will send Apple event messages to your CGI, but they will be diverted to Scripter. Each CGI request will appear in the Call Box window, where you can examine and modify it before calling the script and single-stepping through the handler. The handler's result will be displayed in the Call Box's result area, and will also be sent back to the web server.
  • The Live Edit application leaves behind another application called Reinstate xxxx, where xxxx is part or all of the name of your CGI applet (note that you can have several CGIs open for editing and debugging at the same time). When you're finished debugging, double-click the Reinstate application, and your revised CGI applet will be started and again made available directly to your web server.

Chuck Shotton ( is the creator of MacHTTP, the first Mac webserver, which later evolved into WebSTAR.


Community Search:
MacTech Search:

Software Updates via MacUpdate

Path Finder 7.2 - Powerful, award-winnin...
Become a master of file management with Path Finder. Take full control over your file system. Save your time: compare and synchronize folders, view hidden files, use Dual Pane and full keyboard... Read more
Sid Meier's Civilization: Beyond Ea...
Sid Meier's Civilization: Beyond Earth is a new science-fiction-themed entry into the award-winning Civilization series. Set in the future, global events have destabilized the world leading to a... Read more
ForkLift 2.6.6 - Powerful file manager:...
ForkLift is a powerful file manager and ferociously fast FTP client clothed in a clean and versatile UI that offers the combination of absolute simplicity and raw power expected from a well-executed... Read more
Microsoft Remote Desktop 8.0.21 - Connec...
With Microsoft Remote Desktop, you can connect to a remote PC and your work resources from almost anywhere. Experience the power of Windows with RemoteFX in a Remote Desktop client designed to help... Read more
OnyX 3.1.0 - Maintenance and optimizatio...
OnyX is a multifunctional utility for OS X. It allows you to verify the startup disk and the structure of its System files, to run miscellaneous tasks of system maintenance, to configure the hidden... Read more
Spotify - Stream music, crea...
Spotify is a streaming music service that gives you on-demand access to millions of songs. Whether you like driving rock, silky R&B, or grandiose classical music, Spotify's massive catalogue puts... Read more
ExpanDrive - Access cloud storag...
ExpanDrive builds cloud storage in every application, acts just like a USB drive plugged into your Mac. With ExpanDrive, you can securely access any remote file server directly from the Finder or... Read more
Markly 1.5.3 - Create measurement and de...
Markly is a measurement and design-spec plugin/extension for Photoshop and Sketch. It is made for modern Web designers and app front-end developers. You can add specification marks simply by clicking... Read more
Suitcase Fusion 6 17.3.0 - Font manageme...
Suitcase Fusion 6 is the creative professional's font manager. Every professional font manager should deliver the basics: spectacular previews, powerful search tools, and efficient font organization... Read more
Nisus Writer Pro 2.1.2 - Multilingual wo...
Nisus Writer Pro is a powerful multilingual word processor, similar to its entry level products, but brings new features such as table of contents, indexing, bookmarks, widow and orphan control,... Read more

Balls & Holes - Tips and tricks to h...
Balls & Holes is a gorgeous new endless runner that challenges you to make it as far up a mountain as possible before inevitably being sliced into a load of gooey bits. Making this task more difficult are both the wide variety of balls that... | Read more »
Balloony Land offers a fresh twist on th...
Balloony Land by Palringo offers a fresh twist on the match three genre and is out now on iOS and Android. First-off, you'll be popping balloons instead of crushing candy and the balloons will float up and fill the empty spaces instead of dropping... | Read more »
Graphic - vector illustration and design...
Graphic - vector illustration and design 1.0 Device: iOS iPhone Category: Productivity Price: $2.99, Version: 1.0 (iTunes) Description: Autodesk Graphic is a powerful full-featured vector drawing and illustration application right in... | Read more »
Sago Mini Babies (Education)
Sago Mini Babies 1.0 Device: iOS Universal Category: Education Price: $2.99, Version: 1.0 (iTunes) Description: Introducing the Sago Mini babies. Boys and girls love caring for these adorable characters. Feed Robin her favorite mush... | Read more »
PAUSE - Relaxation at your fingertip (H...
PAUSE - Relaxation at your fingertip 1.1 Device: iOS iPhone Category: Healthcare & Fitness Price: $1.99, Version: 1.1 (iTunes) Description: | Read more »
Super Sharp (Games)
Super Sharp 1.1 Device: iOS Universal Category: Games Price: $1.99, Version: 1.1 (iTunes) Description: Your finger has never been so sharp! Cut with skill to complete the 120 ingenious physics levels of Super Sharp and become a cut... | Read more »
Assembly - Graphic design for everyone...
Assembly - Graphic design for everyone 1.0 Device: iOS Universal Category: Photography Price: $2.99, Version: 1.0 (iTunes) Description: Assembly is the easiest most powerful design tool on the App Store. Create anything you can... | Read more »
Dub Dash (Games)
Dub Dash 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: ARE YOU READY FOR THE ULTIMATE CHALLENGE? UNIQUE SYMBIOSIS OF MUSIC AND GRAPHICS | Read more »
Leave Me Alone (Games)
Leave Me Alone 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: 33% off launch sale!!! Somewhere between the 1980s and 1990s there exists a world that never was. A world of skatepunks,... | Read more »
YAMGUN (Games)
YAMGUN 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: The invasion has begun! Protect the walls of the citadel against waves of enemies! But watch out, you will soon run out of ammo...... | Read more »

Price Scanner via

Apple Products Four Of 2015′s Top Ten Most Wa..., Future’s global technology brand and the UK’s biggest technology website, has unveiled results from extensive research that show • The Smart Home is what excites the public most about... Read more
13-inch 2.7GHz/128GB Retina MacBook Pro on sa...
Best Buy has the 13″ 2.7GHz/128GB Retina MacBook Pro on sale for $1174.99 for a limited time. Choose free shipping or free local store pickup (if available). Sale price for online orders only, in-... Read more
App Tamer 2.1 Makes El Capitan Cooler, Quiete...
St. Clair Software has announced the availability of a free update to its App Tamer utility for Mac OS X. App Tamer 2.1 delivers compatibility with Yosemite and improves its support for a number of... Read more
15-inch Retina MacBook Pros on sale for up to...
B&H Photo has 2015 15″ Retina MacBook Pros on sale for up to $160 off MSRP including free shipping plus NY sales tax only: - 15″ 2.2GHz Retina MacBook Pro: $1849.99 $150 off - 15″ 2.5GHz Retina... Read more
12-inch Retina MacBooks on sale for $100 off...
Best Buy has 12″ Retina MacBooks available for $100 off MSRP on their online store. Choose free shipping or free local store pickup (if available). Discounted prices available for online orders only... Read more
MacBook Airs on sale for up to $100 off MSRP
Save up to $100 on the purchase of a new 2015 13″ or 11″ 1.6GHz MacBook Air at the following resellers. Shipping is free with each model: 11" 128GB MSRP $899 11" 256GB... Read more
Save 15% with Apple refurbished Mac Pros
The Apple Store has Apple Certified Refurbished Mac Pros available for up to $600 off the cost of new models. An Apple one-year warranty is included with each Mac Pro, and shipping is free. The... Read more
Apple restocks refurbished Mac minis for up t...
Apple has restocked Certified Refurbished 2014 Mac minis, with models available starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: - 1.4GHz Mac mini: $419 $... Read more
TP-LINK Next-Gen Routers Support a Large Numb...
TP-LINK, specialists in consumer and business networking products, have announced the availability of Archer C2600, the company’s next-generation router featuring wireless AC, multi-user MIMO, and 4-... Read more
Apple refurbished 2014 MacBook Airs available...
Apple has Certified Refurbished 2014 MacBook Airs available starting at $679. An Apple one-year warranty is included with each MacBook, and shipping is free: - 11″ 1.4GHz/128GB MacBook Air: $679... Read more

Jobs Board

Project Manager: *Apple* Pay - Apple (Unite...
…The iOS Systems team is looking for a project manager who will manage Apple Pay server side integration project resources in a matrix organization, track tasks, prepare Read more
*Apple* Retail - Multiple Positions (US) - A...
Job Description:SalesSpecialist - Retail Customer Service and SalesTransform Apple Store visitors into loyal Apple customers. When customers enter the store, you're Read more
Validation Engineering Manager - *Apple* Wa...
…hardware and software development to lead the validation of the next generation Apple Watch and related products. The Validation Team works closely with many Read more
Senior Payments Architect - *Apple* Pay - A...
**Job Summary** Apple , Inc. is looking for a highly motivated, innovative and hands-on senior payments architect to join the Apple Pay Engineering team. You will Read more
*Apple* Retail for Business Support Supervis...
…is looking for a motivated, outgoing, and creative individual who wants to offer Apple Business Customers an unparalleled customer experience. The Apple Retail for Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.