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

Apple Remote Desktop 3.8 - Remotely cont...
Apple Remote Desktop is the best way to manage the Mac computers on your network. Distribute software, provide real-time online help to end users, create detailed software and hardware reports, and... Read more
NeoOffice 2014.7 - Mac-tailored, OpenOff...
NeoOffice is a complete office suite for OS X. With NeoOffice, users can view, edit, and save OpenOffice documents, PDF files, and most Microsoft Word, Excel, and PowerPoint documents. NeoOffice 3.x... Read more
DesktopLyrics 2.6.6 - Displays current i...
DesktopLyrics is an application that displays the lyrics of the song currently playing in "iTunes" right on your desktop. The lyrics for the song have to be set in iTunes; DesktopLyrics does nothing... Read more
Ember 1.8.3 - Versatile digital scrapboo...
Ember (formerly LittleSnapper) is your digital scrapbook of things that inspire you: websites, photos, apps or other things. Just drag in images that you want to keep, organize them into relevant... Read more
Apple iTunes 12.1 - Manage your music, m...
Apple iTunes lets you organize and play digital music and video on your computer. It can automatically download new music, app, and book purchases across all your devices and computers. And it's a... Read more
LibreOffice 4.4.3 - Free, open-source of...
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
FoldersSynchronizer 4.2.1 - Synchronize...
FoldersSynchronizer is a popular and useful utility that synchronizes and backs-up files, folders, disks and boot disks. On each session you can apply special options like Timers, Multiple Folders,... Read more
Simon 4.0.2 - Monitor changes and crashe...
Simon monitors websites and alerts you of crashes and changes. Select pages to monitor, choose your alert options, and customize your settings. Simon does the rest. Keep a watchful eye on your... Read more
Cocktail 8.1.2 - General maintenance and...
Cocktail is a general purpose utility for OS X that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more
Cyberduck 4.6.4 - FTP and SFTP browser....
Cyberduck is a robust FTP/FTP-TLS/SFTP browser for the Mac whose lack of visual clutter and cleverly intuitive features make it easy to use. Support for external editors and system technologies such... Read more

Playworld Superheroes Review
Playworld Superheroes Review By Tre Lawrence on January 30th, 2015 Our Rating: :: HERO CRAFTINGUniversal App - Designed for iPhone and iPad It’s all about the imagination, fighting bad creatures — and looking good while doing so.   | Read more »
Join the SpongeBob Bubble Party in this...
Join the SpongeBob Bubble Party in this New Match 3 Bubble Poppin’ Frenzy Posted by Jessica Fisher on January 30th, 2015 [ permalink ] | Read more »
Handpick Review
Handpick Review By Jennifer Allen on January 30th, 2015 Our Rating: :: TANTALIZING SUGGESTIONSiPhone App - Designed for the iPhone, compatible with the iPad Handpick will make you hungry, as well as inspire you to cook something... | Read more »
Storm the Halls of Echo Base in First St...
Storm the Halls of Echo Base in First Star Wars: Galactic Defense Event Posted by Jessica Fisher on January 30th, 2015 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Contradiction Review
Contradiction Review By Tre Lawrence on January 30th, 2015 Our Rating: :: SPOT THE LIEiPad Only App - Designed for the iPad Contradiction is a live action point and click adventure that’s pretty engaging.   Developer: Tim Follin... | Read more »
Unlock Sunshine Girl in Ironkill with th...
Unlock Sunshine Girl in Ironkill with this special 148Apps code Posted by Rob Rich on January 29th, 2015 [ permalink ] Robo-fighter Ironkill has been out on iOS a | Read more »
Crossroad Zombies Review
Crossroad Zombies Review By Jordan Minor on January 29th, 2015 Our Rating: :: CROSSWALKING DEADiPad Only App - Designed for the iPad Crossroad Zombies is a rough draft of a cool genre mash-up.   | Read more »
Blood Brothers 2 – Tips, Cheats, and Str...
War is hell: Is it the kind of hell you want to check out? Read our Blood Brothers 2 review to find out! Blood Brothers 2, DeNA’s follow-up to the original Blood Brothers, is an intriguing card collecting / role-playing / strategy hybrid. There’s... | Read more »
Blood Brothers 2 Review
Blood Brothers 2 Review By Nadia Oxford on January 29th, 2015 Our Rating: :: AN AGGRAVATING RELATIVEUniversal App - Designed for iPhone and iPad Blood Brothers 2 is built on a simple, solid foundation, but its free-to-play system... | Read more »
I AM BREAD, the Toast of the Town, is Ro...
Have you ever dreamt of being deliciously gluten-y? Do you feel passionate about Rye and Wheat? The guys at Bossa Studios do and that is why they are bringing I AM BREAD to iOS soon. The loafy app will feature all the new content that is being... | Read more »

Price Scanner via MacPrices.net

Amazon offers 15-inch 2.2GHz Retina MacBook P...
 Amazon.com has the 15″ 2.2GHz Retina MacBook Pro on sale for $1879 including free shipping. Their price is $120 off MSRP, and it’s the lowest price available for this model from any reseller (except... Read more
Intel Aims to Transform Workplace With 5th-Ge...
Intel Corporation today announced the availability of its 5th generation Intel Core vPro processor family that provides cutting-edge features to enable a new and rapidly shifting workplace. To meet... Read more
iOS App Sharalike Introduces New Instant Smar...
Sharalike slideshow and photo management software for iOS, is making it easier than ever to create shareable meaningful moments with its new instant SmartShow technology. Staying organized is a goal... Read more
Apple Becomes World’s Largest Smartphone Vend...
According to the latest research data from Strategy Analytics, as global smartphone shipments grew 31 percent annually to reach a record 380 million units in the fourth quarter of 2014. Apple became... Read more
Cut the Cord: OtterBox Resurgence Power Case...
Dead batteries and broken phones are two of the biggest issues for smartphone users today. Otterbox addresses both with the new Resurgence Power Case for Apple iPhone 6, promising to make those panic... Read more
13-inch Retina MacBook Pros on sale for up to...
B&H Photo has 13″ Retina MacBook Pros on sale for $200 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.6GHz/128GB Retina MacBook Pro: $1199.99 save $100 - 13″ 2.6GHz/... Read more
15-inch 2.5GHz Retina MacBook Pro on sale for...
 B&H Photo has the 15″ 2.5GHz Retina MacBook Pro on sale for $2319.99 including free shipping plus NY sales tax only. Their price is $180 off MSRP, and it’s the lowest price available for this... Read more
Back in stock: Refurbished iPod nanos for $99...
The Apple Store has Apple Certified Refurbished 16GB iPod nanos available for $99 including free shipping and Apple’s standard one-year warranty. That’s $50 off the cost of new nanos. Most colors are... Read more
Apple lowers price on refurbished 256GB MacBo...
The Apple Store has lowered prices on Apple Certified Refurbished 2014 MacBook Airs with 256GB SSDs, now available for up to $200 off the cost of new models. An Apple one-year warranty is included... Read more
New Good Management Suite Simplifies Enterpri...
Good Technology has announced the availability of the Good Management Suite, a comprehensive cross-platform solution for organizations getting started with mobile business initiatives. Built on the... Read more

Jobs Board

At-Home Chat Specialist- *Apple* Online Stor...
**Job Summary** At Apple , we believe in hard work, a fun environment, and the kind of creativity and innovation that only comes about when talented people from diverse Read more
Sr. Mac Expert- *Apple* Online Store - Apple...
**Job Summary** The World Wide Apple Online Store (AOS) Sales and Service team is looking for motivated, outgoing, and tech savvy individuals who want to offer Apple Read more
*Apple* Solutions Consultant- Retail Sales (...
**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
Event Director, *Apple* Retail Marketing -...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global engagement strategy and team. Delivering an overarching brand Read more
At-Home Chat Specialist- *Apple* Online Stor...
**Job Summary** At Apple , we believe in hard work, a fun environment, and the kind of creativity and innovation that only comes about when talented people from diverse Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.