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.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

NetShade 6.3.1 - Browse privately using...
NetShade is an anonymous proxy and VPN app+service for Mac. Unblock your Internet through NetShade's high-speed proxy and VPN servers spanning seven countries. NetShade masks your IP address as you... Read more
Dragon Dictate 4.0.7 - Premium voice-rec...
With Dragon Dictate speech recognition software, you can use your voice to create and edit text or interact with your favorite Mac applications. Far more than just speech-to-text, Dragon Dictate lets... Read more
Persecond 1.0.2 - Timelapse video made e...
Persecond is the easy, fun way to create a beautiful timelapse video. Import an image sequence from any camera, trim the length of your video, adjust the speed and playback direction, and you’re done... Read more
GIMP 2.8.14p2 - Powerful, free image edi...
GIMP is a multi-platform photo manipulation tool. GIMP is an acronym for GNU Image Manipulation Program. The GIMP is suitable for a variety of image manipulation tasks, including photo retouching,... Read more
Sandvox 2.10.2 - Easily build eye-catchi...
Sandvox is for Mac users who want to create a professional looking website quickly and easily. With Sandvox, you don't need to be a Web genius to build a stylish, feature-rich, standards-compliant... Read more
LibreOffice 5.0.1.2 - Free, open-source...
LibreOffice is an office suite (word processor, spreadsheet, presentations, drawing tool) compatible with other major office suites. The Document Foundation is coordinating development and... Read more
f.lux 36.1 - Adjusts the color of your d...
f.lux makes the color of your computer's display adapt to the time of day, warm at night and like sunlight during the day. Ever notice how people texting at night have that eerie blue glow? Or wake... Read more
VirtualBox 5.0.2 - x86 virtualization so...
VirtualBox is a family of powerful x86 virtualization products for enterprise as well as home use. Not only is VirtualBox an extremely feature rich, high performance product for enterprise customers... Read more
File Juicer 4.43 - Extract images, video...
File Juicer is a drag-and-drop can opener and data archaeologist. Its specialty is to find and extract images, video, audio, or text from files which are hard to open in other ways. In computer... Read more
Apple MainStage 3.2 - Live performance t...
MainStage 3 makes it easy to bring to the stage all the same instruments and effects that you love in your recording. Everything from the Sound Library and Smart Controls you're familiar with from... Read more

ReBoard: Revolutionary Keyboard (Utilit...
ReBoard: Revolutionary Keyboard 1.0 Device: iOS Universal Category: Utilities Price: $1.99, Version: 1.0 (iTunes) Description: Do everything within the keyboard without switching apps! If you are in WhatsApp, how do you schedule a... | Read more »
Tiny Empire (Games)
Tiny Empire 1.1.3 Device: iOS Universal Category: Games Price: $2.99, Version: 1.1.3 (iTunes) Description: Launch cannonballs and blow tiny orcs into thousands of pieces in this intuitive fantasy-themed puzzle shooter! Embark on an... | Read more »
Astropad Mini (Productivity)
Astropad Mini 1.0 Device: iOS iPhone Category: Productivity Price: $4.99, Version: 1.0 (iTunes) Description: *** 50% off introductory price! ​*** Get the high-end experience of a Wacom tablet at a fraction of the price with Astropad... | Read more »
Emo Chorus (Music)
Emo Chorus 1.0.0 Device: iOS Universal Category: Music Price: $1.99, Version: 1.0.0 (iTunes) Description: Realistic Choir simulator ranging from simple Chorus emulation to full ensemble Choir with 128 members. ### introductory offer... | Read more »
Forest Spirit (Games)
Forest Spirit 1.0.5 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.5 (iTunes) Description: | Read more »
Ski Safari 2 (Games)
Ski Safari 2 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: The world's most fantastical, fun, family-friendly skiing game is back and better than ever! Play as Sven's sister Evana, share... | Read more »
Lara Croft GO (Games)
Lara Croft GO 1.0.47768 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.47768 (iTunes) Description: Lara Croft GO is a turn based puzzle-adventure set in a long-forgotten world. Explore the ruins of an ancient... | Read more »
Whispering Willows (Games)
Whispering Willows 1.23 Device: iOS Universal Category: Games Price: $4.99, Version: 1.23 (iTunes) Description: **LAUNCH SALE 50% OFF** - Whispering Willows is on sale for 50% off ($4.99) until September 9th. | Read more »
Calvino Noir (Games)
Calvino Noir 1.1 Device: iOS iPhone Category: Games Price: $3.99, Version: 1.1 (iTunes) Description: The film noir stealth game. Calvino Noir is the exploratory, sneaking adventure through the 1930s European criminal underworld.... | Read more »
Angel Sword (Games)
Angel Sword 1.0 Device: iOS Universal Category: Games Price: $6.99, Version: 1.0 (iTunes) Description: Prepare to adventure in the most epic full scale multiplayer 3D RPG for mobile! Experience amazing detailed graphics in full HD.... | Read more »

Price Scanner via MacPrices.net

Big Grips Lift Handle For iPad Air and iPad A...
KEM Ventures, Inc. which pioneered the extra-large, super-protective iPad case market with the introduction of Big Grips Frame and Stand in 2011, is launching Big Grips Lift featuring a new super-... Read more
Samsung Launches Galaxy Tab S2, Its Most Powe...
Samsung Electronics America, Inc. has announced the U.S. release of the Galaxy Tab S2, its thinnest, lightest, ultra-fast tablet. Blending form and function, elegant design and multitasking power,... Read more
Tablet Screen Sizes Expanding as iPad Pro App...
Larger screen sizes are gaining favor as the tablet transforms into a productivity device, with shipments growing 185 percent year-over-year in 2015. According to a new Strategy Analytics’ Tablet... Read more
Today Only: Save US$50 on Adobe Elements 13;...
Keep the memories. lose the distractions. Summer’s winding down and it’s time to turn almost perfect shots into picture perfect memories with Elements 13. And get the power to edit both photos and... Read more
1.4GHz Mac mini on sale for $449, save $50
Best Buy has the 1.4GHz Mac mini on sale for $50 off MSRP on their online store. Choose free shipping or free local store pickup (if available). Price for online orders only, in-store price may vary... Read more
12-inch 1.1GHz Gold MacBook on sale for $1149...
B&H Photo has the 12″ 1.1GHz Gold Retina MacBook on sale for $1149.99 including free shipping plus NY sales tax only. Their price is $150 off MSRP, and it’s the lowest price available for this... Read more
27-inch 3.3GHz 5K iMac on sale for $1849, sav...
Best Buy has the 27″ 3.3GHz 5K iMac on sale for $1849.99. Their price is $150 off MSRP, and it’s the lowest price available for this model. Choose free shipping or free local store pickup (if... Read more
Worldwide Tablet Shipments Expected to Declin...
Does Apple badly need a touchscreen convertible/hybrid laptop MacBook? Yes, judging from a new market forecast from the International Data Corporation (IDC) Worldwide Quarterly Tablet Tracker, which... Read more
Continued PC Shipment Shrinkage Expected Thro...
Worldwide PC shipments are expected to fall by -8.7 percent in 2015 and not stabilize until 2017, according to the latest International Data Corporation (IDC) Worldwide Quarterly PC Tracker data. The... Read more
Imminent iPhone 6s Announcement Leads To 103%...
NextWorth Solutions, with its online and in-store electronics trade-in programs including http://NextWorth.com, reports that it has experienced a 103 percent surge in quoted trade-in values over the... Read more

Jobs Board

*Apple* Retail Online Store: Customer Insigh...
**Job Summary** Apple Retail (Online Store) is seeking an experienced e-commerce analytics professional to join the Customer Insights Team. The Web e-Commerce Analyst Read more
*Apple* Music, Business Operations - Apple I...
Changing the world is all in a day039s work at Apple . If you love innovation, here039s your chance to make a career of it. You039ll work hard. But the job comes with Read more
WW *Apple* Retail Online Store: Customer In...
**Job Summary** The Apple Retail - Online Store is seeking an experienced web merchandising analytics professional to join the Customer Insights Team. The Web Read more
Senior Payments Security Manager - *Apple*...
**Job Summary** Apple , Inc. is looking for a highly motivated, innovative and hands-on senior payments security manager to join the Apple Pay security team. You will Read more
Software QA Engineer, *Apple* Pay Security...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.