HP e3000 web server CGI programming

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Introduction

Over the past two years the World Wide Web has experienced a phenomenal surge in popularity.

The contributing factors to the popularity of the Web are its inherent client/server architecture; its

ability to make physical location and underlying platform incompatibilities transparent to users; and

the simplicity with which information can be accessed through a browser such as Netscape Navigator

or Microsoft's Internet Explorer. The browser offers a ready-made graphical user interface which is

capable of interpreting HyperText Markup Language (HTML) documents. HTML is a tagging

language used to create Web documents. For more information on HTML, visit

<http://www.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html >

The availability of HyperText Markup Language (HTML) authoring tools combined with the Web's

tremendous reach has made it easy for almost anyone to publish for a global audience. Companies

are recognizing the need to capitalize on the wide ranging business opportunities offered by the

World Wide Web. Although the information published on the Web is multimedia format, the majority of

Web pages today simply provide access to manually-maintained "static" documents. This limits

business activity

Figure 1. Static Web Page

For example, there are many possible business applications (such as retail and distribution) which

could be deployed to the external (Internet) Web, as well as to a company's internal network

(Intranet). Static documents would still to be periodically updated. Instead, businesses require the

ability to implement "dynamic" on-line applications, integrated with legacy systems and databases

where the

business data is currently located.

The purpose of this paper is to explain the technology and tools available to access data via an HP

3000 web server and integrate existing or create new HP 3000 applications with a web server.

Initially your Web server (either internal or external) may be serving web pages containing information

which does not

change often. These are static documents (text files). Now, let's say you want to

connect a database to the Web, to allow people in your organization (or the world) to query it. What is

the mechanism to do this? The native mechanism is the Common Gateway Interface (CGI). CGI is a

standard protocol for interfacing external applications with Web servers. A CGI program is executed,

in real-time, so that it can output dynamic information. So, to connect to the database, you need to

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HP e3000 Web Server CGI Programming

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Summary of content (10 pages)

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HP e3000 Web Server CGI Programming Page 1 of 10 Jazz home > Papers & Training HP e3000 web server CGI programming » Return to original page Introduction Over the past two years the World Wide Web has experienced a phenomenal surge in popularity.
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HP e3000 Web Server CGI Programming Page 2 of 10 create a CGI program or script that the Web daemon will execute to transmit information to the database engine, and receive the results back and display them to the client. This is an example of a gateway and is the origin of CGI. Figure 2. Common Gateway Interface Any program, in any language can serve as a CGI program as long as it follows these rules: l l The program reads standard input (STDIN) and writes to standard output (STDOUT).
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HP e3000 Web Server CGI Programming Page 3 of 10 Therefore, the CGI Web program must contain code to keep track of the user, all requests associated with that user and what information was sent to the user to create the illusion of a "state" environment. Note: It is beyond the scope of this paper to "teach" CGI programming. For more information or tutorials on CGI, visit the following sites: < http://hoohoo.ncsa.uiuc.edu/cgi > < http://www.jmarshall.
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HP e3000 Web Server CGI Programming Page 4 of 10 Figure 4. Webbified VPLUS application CGI programming on the HP e3000 The rest of this paper will demonstrate CGI programming in some popular languages on the HP 3000. CGI was first developed on UNIX derivatives, and since MPE/iX supports POSIX, it is quite easy to write CGI programs on the HP 3000. The same example has been provided in C, PASCAL and PERL to demonstrate the differences in using these languages.
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HP e3000 Web Server CGI Programming Page 5 of 10 Phone Book
Phone Book
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HP e3000 Web Server CGI Programming Page 6 of 10 Figure 6. Phonebook HTML When the user clicks on the "ADD" button, the following encoded string is sent to the CGI application: name=Praveen&number=4081234567&ACTION=ADD Since the format of CGI input is a standard, some good samaritans have put out "CGI parsing libraries" on the WWW which can be downloaded and used. These libraries are available in many popular languages.
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HP e3000 Web Server CGI Programming Page 7 of 10 Now change the permissions so that it is executable by your WWW user ("chmod 755 cgitest" from the POSIX shell). Using your favorite web browser, load the URL http:///cgi-bin/cgitest , where is the name of your webserver. If you don't see the one liner "WELCOME TO THE WORLD OF CGI" and get an error message instead, that means that your cgi-bin/ directory hasn't been set up correctly for your web server.
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HP e3000 Web Server CGI Programming Page 8 of 10 CCXL CGILIBC, YCGILIB, LCGILIB; INFO = '-Aa -D_POSIX_SOURCE -DMPE' LINK FROM=YPHONE, YCGILIB; TO=./phonebook.c;RL=/lib/libc.a;cap=ph;posix; Now install the application in the cgi-bin directory of your webserver using the following steps: 1. 2. 3. 4. Invoke the shell by running "SH.HPBIN.SYS -L". Change to the directory containing the above source code ("cd ..
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HP e3000 Web Server CGI Programming Page 9 of 10 Copy phonebook.pas to the cgi-bin directory and set the appropriate permissions and ownership (refer to the C example subsection).Also make sure that the cgi-bin directory is writable by the web user since the phonebook application needs to create a flat file in that directory. Now create the HTML form that has been provided at the beginning of this section.
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HP e3000 Web Server CGI Programming Page 10 of 10 separate server program and make the CGI program a small and lightweight client that communicates with this server program via IPC mechanisms (like message files) to get the task done. This will be simple to do with the FastCGI architecture which will become available on the HP 3000 soon. With FastCGI, your CGI program will become a true server, always running (as opposed to being created, executed and destroyed with every request).