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CGI Programming in Python

Ankit Kumar
Last Updated: Jan 31, 2023
MEDIUM

Introduction

Have you ever thought about what happens in the backend when you click on a particular link/hyperlink on your favourite website? All we know is that the webpage redirects us to a new page but what is happening behind the scenes is very important to understand. Today’s topic about CGI will let us know the architecture and working of redirections after clicking on a desired link/hyperlink.

Source: https://www.oreilly.com/library/view/cgi-programming-on/9781565921689/images/ch01-f003.jpg

 

Ensure you have a basic understanding of HTML and Python before exploring this article.

In the next section, let us understand what CGI is?

What is CGI

The web application and the browser need to be connected to redirect to a new page whenever we click on any links or hyperlinks. This communication is established by the Common Gateway Interface (CGI). The CGI is Neither a programming language nor it is programming language-specific. It is just a set of rules written in any programming language that helps establish a dynamic connection between the web server and the client. Let us now understand the working of a CGI.

How does CGI Work

Whenever we click on a link or hyperlink on a website, the browser interacts with the HTTP web server and requests the file name. If the file name is found, it is returned, but it displays an error message if the file name is not found. But if we use CGI, then instead of returning the file name, the CGI will be executed, and the output will be displayed to the user by the browser.

The CGI and the programs executed to return and display the output are known as CGI Scripts. If the CGI is written in Python, it is known as Python scripts. Let us now see a python script in the following section.

Example

Let us see a sample URL that passes two values to the First_Cgi.py program using the GET method:

/CGI-bin/First_Cgi.py?Your_name=Ankit&company_name=CodingNinjas

 

Below is the python script to handle the input given by the above sample URL.

#!/usr/bin/python
#Importing CGIT and CGI module
import cgi, cgitb 
# Create an instance of FieldStorage
form = cgi.FieldStorage()
Your_name = form.getvalue('Your_name')
# getting the data from fields
Comapny_name = form.getvalue('Company_name')
print ("Content-type:text/html\n")
print ("<html>")
print ("<head>")
print ("<title>First CGI Script</title>")
print ("</head>")
print ("<body>")
print ("<h2>Hi, %s works in %s</h2>"
% (Your_name, Company_name))


print ("</body>")
print ("</html>")

 

Output

Hi, Ankit works in CodingNinjas

 

You can practice by yourself with the help of online python compiler for better understanding.

Let us now see the advantages and disadvantages of CGI.

Advantages of CGI

The advantages of CGI are as follows:-

  1. They can be written in any language.
  2. They are portable and compatible with every operating system and the webserver.
  3. It enhances the dynamic connection between the web server and the client.
  4. CGI is scalable in nature.
  5. Every coin has two sides, and so does the CGI, so let us now move to the disadvantages of CGI.

Disadvantages of CGI

The disadvantages of CGI are as follows:-

  1. The scripts are sometimes ambiguous and complex to understand.
  2. Every time the program is started, the interpreter must analyze a CGI script. Because there are too many queries from the client-server side, this generates a lot of traffic.
  3. CGI programs may jeopardize server security because they are generally free and widely available, making them extremely vulnerable.

 

With this, we mark the end of this blog. We hope you got a basic idea about CGI programming in Python. Let us now see some of the FAQs related to the topic.

Frequently Asked Questions

What does CGI stand for?

CGI stands for Common Gateway Interface.

What is CGI programming?

CGI or Common Gateway Interface is a set of standards that tells about the information exchange between web and custom scripts.

What are some of the languages in which we can write the CGI scripts?

The CGI scripts are language-independent, so they could be written in any programming language such as Python, PHP, Java, C# etc.

What are some of the advantages of Using CGI?

The CGI scripts are very much portable and are language-independent, which enables anyone to write the CGI scripts with greater ease. These are also compatible with every Operating system and various web servers. These are some of the advantages of Using CGI scripts.

What are some disadvantages of Using CGI?

CGI programs are highly vulnerable, which can lead to lapses in the security of web servers, It also increments the load on an interpreter as it is executed every time the program is initiated, and these programs are very ambiguous and complex to understand.

Conclusion

In this article, we have extensively discussed CGI Programming in Python. We saw CGI working with python, its advantages and disadvantages, and also some faqs related to this topic.

After reading about CGI Programming in Python, are you not feeling excited to read/explore more articles on Python? Don't worry; Coding Ninjas has you covered. To learn, see  Kivy Float layoutNumPy Pandas, Application of Python, and Using Heapq module in Python.

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