TweetFollow Us on Twitter

REALbasic CGIs

Volume Number: 16 (2000)
Issue Number: 4
Column Tag: Programming

REALbasic CGI’s

by Diana Cassady
Contributiong Editor, Erick Tejkowski

About REALbasic

REALbasic is an object-oriented implementation of the BASIC programming language for Mac OS, and is available from REAL Software at <http://www.realsoftware.com>. It's a language that can be mastered, even by a novice, in days. Its drag and drop builder allows programmers to create stand alone applications with windows, menu bars, text areas, radio buttons, checkboxes, and all the usual user interface features found in commercial programs that have taken months to write. REALbasic programs can send and receive Apple events to communicate with other scriptable programs, including webservers. REALbasic can be used to create a customized, stand alone CGI with an interface for webmasters to store program preferences. Real time logging results can also be displayed in a REALbasic interface.

In this article, I present a framework for writing CGI's for Mac OS Web servers using the REALbasic environment. It is assumed the reader is already familiar with the basics of authoring CGI's.

CGI Basics

A CGI for Mac OS needs to accomplish three main tasks:

  1. Accept the Apple event from the web server.
  2. Process the data contained in the Apple event.
  3. Return an Apple event to the web server containing the requested data.

Accepting the Apple Event

REALbasic contains a built-in event handler to accept Apple events within a class. The application contains an event called HandleAppleEvent. This handler will contain the code to interpret incoming Apple events.

Start a new REALbasic program by opening your REALbasic application. Create a new class by choosing New Class from the File menu. Access the properties of this new class by highlighting it in the project window and choosing Show Properties under the Window menu. Choose Application beside Super in the new class properties. This application class will be the location of the Apple event handler. The new class' default name is Class1.

Double-click Class1 in the project window. The first item on the left of the Class1 window is Events. Double-click on Events. A list of events will appear. The last event in the list is HandleAppleEvent. Double-click on HandleAppleEvent to open the code window.

Three variables are provided within this handler: event as AppleEvent, eventClass as String, and eventID as String. The eventClass and eventID are used to identify the Apple event. The Apple event coming from the web server will have an eventClass of WWWOmega. The Omega sign is made with command z on the keyboard. The eventID will be sdoc. The variable event contains the data. The data coming from the web server is broken up into parameters. A list of these parameters can be found at <http://www.biap.com/DataPig/mrwheat/cgiParams.html> courtesy of Biap Systems, Inc. These parameters are for the WebStar webserver, but are common to most Macintosh webservers. A four character keyword identifies each parameter within the Apple event. Form data passed using the post method in a form action is identified by the keyword post. The event variable contains all the parameters, including the post parameter. To isolate the post parameter within the event variable, use event.Stringparam("post"). This function provides the form data as one long strong.

The code in the Apple event handler should verify that the incoming Apple event is the proper type. A string variable also needs to be initialized to contain the isolated form data.

Dim post_args as string

if eventClass="WWWOmega" and eventID="sdoc" then
	post_args=event.Stringparam("post")
end if

Sending a Reply

The program can now accept the Apple event and isolate the data it contains. If the program wanted to collect raw form data and return a simple thank you to the user, no further code is necessary except for a reply. The reply statement sends a string back to the server which is then returned to the browser. The return string should contain a header and HTML to be returned to the user. You may want to build the return_string in pieces to make your code easier to read. The carriage Return Line Feed variable stands for control return line feed.

crlf=chr(13)+chr(10)
return_string="HTTP/1.0 200 OK" + crlf + "Server: WebSTAR/2.0 ID/ACGI" 
 	+ crlf + "MIME-Version: 1.0" + crlf + "Content-type: text/html" + crlf + crlf
return_string=return_string+"<html><body><h2>Thanks for submitting your info.
	</h2></body></html>"
event.ReplyString=return_string

This much code will function as a CGI. It won't do anything with the form data, but it will accept and respond to the Apple event and the web server will return the response to the browser.

The CGI will be much more useful if it can work with the information sent from the web server. Some of this information can be dealt with as is. For example, you could get the username of a user who has logged into a password protected realm by using the keyword user instead of post. You could also get the name of the web browser they're using with the keyword Agnt.

Dim the_user as string
Dim the_agnt as string

if eventClass="WWWOmega" and eventID="sdoc" then
	the_user=event.Stringparam("user")
	the_agnt=event.Stringparam("Agnt")
	event.ReplyString="Hi " + the_user + ". I see you're using " + the_agnt + "."
end if

If-then statements can be incorporated to send back different replies depending on the data contained in the various Apple event parameters, or other data from the system brought in by REALbasic functions such as date and time of day.

Data Processing

Form parameters require more processing before the contents of the form can be interpreted. Form parameters are sent as a string with field names and values delimited with equal signs and ampersands. Spaces are represented by either "+" or encoded as "%20" (the hexidecimal value for a space character) depending on the browser. A typical form containing field names first name, last name, address and phone might look like this:

first+name=Joe&last+name=Cool&address=123+Summer+Brook+
Lane&phone=555-1212

Field and value pairs are divided by ampersands and the field names are separated from the value pairs by equal signs. Separating the field and value pairs and isolating the values is the first step in decoding form data.

Several variables need to be defined for this process:

Dim post_args, one_field, field_value, field_label as string
Dim num_fields, x_field as integer
Count the number of fields on the form.
num_fields=CountFields(post_args, "&")
Use a For Next loop to process every field.
For x_field=1 to num_fields
	one_field=NthField(post_args, "&", x_field)
	field_label=NthField(one_field, "=", 1)
	field_value=NthField(one_field, "=", 2)
Next

The first line in the loop isolates a field name and value pair. The second line isolates the field name of that pair. The third line isolates the value.

If the form data consisted of one word field names and one word options with no special characters then no further processing would be needed, but most likely, the data contains spaces and other encoded special characters.

Plus signs need to be replaced with spaces within each isolated field and field label:

the_field=ReplaceAll(the_field, "+", " ")

A percent sign within the field means that it still contains encoded characters. Use the REALbasic inStr() function to get the position of the first percent sign in the string. If zero is returned, the string does not contain a percent sign. There is nothing more to decode within the isolated field.

loc_hex=inStr(a_deplus, "%")

If a value greater than zero is returned, a percent sign exists. Use the REALbasic Mid() function to isolate the character pair after the percent sign.

a_hex=Mid(a_deplus, loc_hex+1, 2)

The two characters following the percent sign are the hexadecimal version of the original character. They need to be converted to their ascii equivalent before the chr() function can be used to restore them to their original identity.

To convert the characters to their ascii equivalent, convert each to a number, multiple the first number by sixteen, and add the result to the second number.

Each character will be zero through nine or A through F as a string. Zero through nine can be taken at Its face value. A through F corresponds to the values ten through fifteen. Use the left() and right() functions to isolate each character of the pair.

char1=left(a_hex, 1)
char2=right(a_hex, 1)

Use a case statement to map the appropriate numbers to the characters.

Select Case char1
Case "0"
	num1=0
Case "1"
	num1=1
End Select

Include case statements for numbers zero through nine mapping to zero through nine and letters A through F mapping to ten through fifteen. The resulting num1 will be the ascii equivalent of the first character. Repeat the process for the second character.

Select Case char2
Case "0"
	num2=0
Case "1"
	num2=1
End Select

Multiply num2 by sixteen and add that to num1 to get the ascii equivalent of the encoded character.

ascii_equiv=(num1*16)+num2

Convert the ascii equivalent back to the original character using the REALbasic chr() function.

de_hex=chr(ascii_equiv)

Plug the decoded character back in to the field in place of the percent sign and character pair.

the_field=ReplaceAll(the_field, "%"+a_hex, de_hex)

So far, only the first instance of an encoded character in the field has been addressed. The ReplaceAll() function has eliminated all occurances of that encoding within the field, but there may still be other encoded characters that need to be sent through this process. Every encoded character will start with a percent sign. A while loop should be used to send the field through the process until inStr(a_deplus, "%") is no longer greater than zero.

Making the Code Efficient

Repetitive code may be eliminated with subroutines. Subroutines are stored as methods in REALbasic programs. The case select code that converts a character to zero through fifteen would be a good piece of code to include as a subroutine. One set of case statements could accept a character and return a numeric value.

Define a new method in the class by choosing New Method under the Edit menu. A window appears with fields for name, parameters, and return type. Name the new method with a simple one word description like Dehex. This method accepts one character to convert to a numeric value. The character being accepted is the parameter for the method. Define that parameter in the blank provided. Include the data type.

char as string

The method returns a numeric value. Integer can be chosen to describe this value as the return type by using the pop down menu to the right of the return type field.

Enter the select case statement in the method. Send char1 and char2 through the subroutine to get num1 and num2 without wasteful code repetition.

num1=Dehex(char1)
num2=Dehex(char2)

Expanding REALbasic CGI's

This method of decoding can be applied to field names and values in post args and search args. Once field names are decoded, they may be referred to in if-then statements to format and arrange their corresponding decoded field values. Decoded data may be set to variables and sent to a text file or a scriptable application for further processing and storage. Results containing decoded data may be returned to the user to assure them that their information has been received.

Code Shortcut

The complex code for decoding search and post arguments need not be written from scratch. A code shell is available for download on the site index page of the VivaLaData web site at <http://www.vivaladata.com>.

Conclusion

If you happen to run across a web automation task for which you have no cgi, or if you're already running an applescript application as a cgi, you should consider using REALbasic to accomplish your goal. Several users have reported that REALbasic cgi's performed faster than their existing applescript cgi's.

REALbasic cgi's can be used to interface with scriptable programs for which no commercial cgi's have been developed. REALbasic is also a quick way for shareware authors to provide a cgi for their scriptable applications. In addition to working with other applications, REALbasic provides lots of built in functions for sending and receiving mail as well as other network protocols and data processing functions.

If you want to add a new function to your Macintosh web site, but feel a $500+ commercial solution is overkill, REALbasic's flexible, rapid development environment and reasonable price tag may be just the solution for you.


Diana Cassady is a freelance consultant in Danbury, Connecticut. Her web site is http://www.vivaladata.com. She can be reach at diana@vivaladata.com.

 
AAPL
$117.73
Apple Inc.
-0.90
MSFT
$47.49
Microsoft Corpora
-0.10
GOOG
$541.24
Google Inc.
+1.97

MacTech Search:
Community Search:

Software Updates via MacUpdate

MacUpdate Desktop 6.0.3 - Discover and i...
MacUpdate Desktop 6 brings seamless 1-click installs and version updates to your Mac. With a free MacUpdate account and MacUpdate Desktop 6, Mac users can now install almost any Mac app on macupdate.... Read more
SteerMouse 4.2.2 - Powerful third-party...
SteerMouse is an advanced driver for USB and Bluetooth mice. It also supports Apple Mighty Mouse very well. SteerMouse can assign various functions to buttons that Apple's software does not allow,... Read more
iMazing 1.1 - Complete iOS device manage...
iMazing (was DiskAid) is the ultimate iOS device manager with capabilities far beyond what iTunes offers. With iMazing and your iOS device (iPhone, iPad, or iPod), you can: Copy music to and from... Read more
PopChar X 7.0 - Floating window shows av...
PopChar X helps you get the most out of your font collection. With its crystal-clear interface, PopChar X provides a frustration-free way to access any font's special characters. Expanded... Read more
Carbon Copy Cloner 4.0.3 - Easy-to-use b...
Carbon Copy Cloner backups are better than ordinary backups. Suppose the unthinkable happens while you're under deadline to finish a project: your Mac is unresponsive and all you hear is an ominous,... Read more
ForeverSave 2.1.3 - Universal auto-save...
ForeverSave auto-saves all documents you're working on while simultaneously doing backup versioning in the background. Lost data can be quickly restored at any time. Losing data, caused by... Read more
Voila 3.8.1 - Capture, annotate, organiz...
Voila is a screen-capture, recording, and annotation tool that is a full-featured replacement for Mac's screen-capture and screen-recording capabilities. It has a large and robust set of editing,... Read more
SyncTwoFolders 2.0.6 - Syncs two user-sp...
SyncTwoFolders simply synchronizes two folders. It supports synchronization across mounted network drives and it is a possibility to run a simulation showing in a log what will be done. Please visit... Read more
Duplicate Annihilator 5.1.1 - Find and d...
Duplicate Annihilator takes on the time-consuming task of comparing the images in your iPhoto library using effective algorithms to make sure that no duplicate escapes. Duplicate Annihilator detects... Read more
HandBrake 0.10.0 - Versatile video encod...
HandBrake is a tool for converting video from nearly any format to a selection of modern, widely supported codecs. Supported Sources: VIDEO_TS folder, DVD image or real DVD (unencrypted -- CSS is... Read more

Latest Forum Discussions

See All

Tilt to Live Bundle Set to Arrive This T...
Tilt to Live Bundle Set to Arrive This Thanksgiving Posted by Ellis Spice on November 25th, 2014 [ permalink ] One Man Left has unveiled an upcoming Tilt to Live bundle, allowing players to get the series for a di | Read more »
BattleLore: Command (Entertainment)
BattleLore: Command 1.0 Device: iOS Universal Category: Entertainment Price: $9.99, Version: 1.0 (iTunes) Description: ***NOTE: Compatible with iPad 2/iPad mini, iPod touch 5 and up and iPhone 4S and up – WILL NOT RUN ON EARLIER... | Read more »
Weather Or Not Review
Weather Or Not Review By Jennifer Allen on November 25th, 2014 Our Rating: :: STYLISH WEATHER REPORTINGiPhone App - Designed for the iPhone, compatible with the iPad Check the weather quickly and conveniently with Weather or Not... | Read more »
The All-New Football Manager Handheld 20...
The All-New Football Manager Handheld 2015 is Available Now Posted by Jessica Fisher on November 25th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Six iOS Games to Get You Ready for Thank...
Image Source: Friends Wiki At this point in the month, you or at least a few people you know are probably getting ready to scramble around (or are already scrambling around) for Thanksgiving Dinner. It’s a hectic day of precise oven utilization, but... | Read more »
Call of Duty: Heroes: Tips, Tricks, and...
Hello Heroes: What’d we think of Call of Duty‘s take on Clash of Clans? Check out our Call of Duty: Heroes review to find out! Just downloaded Call of Duty: Heroes and need some handy tips and tricks on how to get ahead of the rest? As we often do,... | Read more »
Call of Duty: Heroes Review
Call of Duty: Heroes Review By Jennifer Allen on November 25th, 2014 Our Rating: :: CLASH OF FRANCHISESUniversal App - Designed for iPhone and iPad Mix Clash of Clans with Call of Duty, and this is what you get.   | Read more »
Slider Review
Slider Review By Jordan Minor on November 25th, 2014 Our Rating: :: SLIDE TO PLAYUniversal App - Designed for iPhone and iPad Slider has all the excitement of unlocking your phone screen.   | Read more »
oh my giraffe (Games)
oh my giraffe 1.0.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0.0 (iTunes) Description: Eat fruits while being chased by lions. Cut the vines to send fruit plummeting onto the lions. Don't worry, your flexible... | Read more »
One of 2000’s Most Loves Adventure Games...
One of 2000’s Most Loves Adventure Games, The Longest Journey, has Come to iOS Posted by Jessica Fisher on November 25th, 2014 [ permalink ] | Read more »

Price Scanner via MacPrices.net

Early Black Friday MacBook Pro sale: 15-inch...
 Best Buy has posted early Black Friday prices on 15″ Retina MacBook Pros, with models on sale for $300 off MSRP on their online store for a limited time. Choose free local store pickup (if available... Read more
A9 Chips Already?
It’s barely more than a couple of months since Apple got the first A8 systems-on-chip into consumer hands, but rumor and news focus is already turning to the next-generation A9 SoC. Apple Daily... Read more
NewerTech Announces NuGuard KXs Impact X-Orbi...
NewerTech has announced updates to its family of Impact X-Orbing Screen Armor bringing military grade, triple layer protection to Apple’s new iPhone 6 and 6 Plus. Like all models in the NuGuard KXs... Read more
13-inch 1.4GHz MacBook Air on sale for $889,...
 B&H Photo has the 13″ 1.4GHz/128GB MacBook Air on sale for $889 including free shipping plus NY tax only. Their price is $110 off MSRP. B&H will also include free copies of Parallels Desktop... Read more
Save up to $300 on Macs and iPads with your A...
Purchase a new Mac or iPad at The Apple Store for Education and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free,... Read more
Apple refurbished Mac Pros available for up t...
The Apple Store is offering Apple Certified Refurbished Mac Pros 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
Jumptuit Launches One-Tap Windows 8.1 iTunes...
Jumptuit has launched Windows 8.1 support for One-Tap iTunes Sync. with which Windows 8.1 users can now easily sync their iTunes libraries with Microsoft OneDrive. Jumptuit provides easy access from... Read more
Apple restocks refurbished 13-inch 2014 Retin...
The Apple Store has restocked Apple Certified Refurbished 2014 13″ 2.6GHz Retina MacBook Pros for up to $230 off the cost of new models. An Apple one-year warranty is included with each model, and... Read more
CEA Study Finds More People Recycling Electro...
A new study by the Consumer Electronics Association (CEA) finds that electronics recycling receives the continued and growing support of consumers. According to the CEA,s Recycling and Reuse Study,... Read more
15″ 2.2GHz Retina MacBook Pro on sale for $17...
 B&H Photo has the 2014 15″ 2.2GHz Retina MacBook Pro on sale today for $1749. Shipping is free, and B&H charges NY sales tax only. B&H will also include free copies of Parallels Desktop... Read more

Jobs Board

*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
*Apple* Solutions Consultant (ASC)- Retail S...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
Project Manager, *Apple* Financial Services...
**Job Summary** Apple Financial Services (AFS) offers consumers, businesses and educational institutions ways to finance Apple purchases. We work with national and Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.