An interface called the Common Gateway Interface (CGI) is used by web servers to send users’ requests for information and other resources outside of the web server and to get the processed data back so that the user can see it. To understand what Common Gateway Interface (CGI) is, read this post. It will explain how it works, when and how it is used and what its features are, as well as its advantages and disadvantages.
What is Common Gateway Interface (CGI)
It is called the Common Gateway Interface (CGI) because it is a set of rules for how web servers and scripts can exchange information. When web servers send data to users, they use CGI. C, C++, Java, Perl, Python, or VB are some of the programming languages that can be used. They can also be used (Visual Basic).
Forms are used on a lot of HTML pages. CGI programs are used to process the data in forms. Scripts or programs are another way to give feedback to web users. These run on the user’s computer instead of the Web server and use programs like Java Scripts, Java applets, and ActiveX controls. CGI, on the other hand, is known as a server-side solution because the web server does the work.
How Common Gateway Interface Works
Users can see how CGI works when they click on a link to search and look at any web page in the diagram on the next page. HyperText Transfer Protocol (HTTP) is used by a web browser on a client machine to send and receive information from a web server. There is a CGI program on the same computer as the web server. They both work from the same computer.
Based on the type of request that the browser makes, the web server tries to either give the document to the browser from its own document file system or run a CGI program. Using CGI scripts, you can make an HTML document by following these steps:
- A person asks for the URL from the HTTP web server. When the user types in a web address in a browser’s location bar, it can be a link or an example of HTML form> tags.
- The web server will look at the URL and see if there is a file name in it. There is nothing else to do. If it doesn’t work this way, it starts a gateway program and sends parameters to that program by using the URL.
- The Common Gateway Interface gateway processes the information and sends the file/HTML text to the webserver, so the webserver can show it. Also, the server adds the MIME header to the HTML text and sends it to the browser.
- Web browsers show either the document that was sent to them or an error message when they get a result from a web server.
Features of Common Gateway Interface (CGI)
The features of CGI are:
- These apps run on the server.
- They can be used again and again.
- It is a very well defined standard that most modern browsers can use. They can be written in many different languages like C, C++, Java, and PERL because the interface is pretty much the same across all of them.
- This means that the person who is writing the Common Gateway Interface program doesn’t have to know what kind of operating system the server has.
- You can send information about a user’s request from the web server to the application program and get the response back. It’s very simple and easy to do.
- It is by default that the CGI scripts run in the web server’s security context, but you can change this.
Advantages of Common Gateway Interface (CGI)
CGI scripts have a lot of benefits, like the ones below:
- People who write programs can choose which language they want to work in because they aren’t limited by language.
- They are very easy to use and can do more complicated things than other server-side programming languages. This is because they are very simple.
- There is already a lot of CGI code that can be used.
- There is no risk to them because they run on the web server.
- They are very light because they don’t need a specific library to run the code.
Disadvantages of Common Gateway Interface (CGI)
CGI programs come with their own set of disadvantages such as:
- This is because the CGI program creates a new process for each HTTP request. This takes up a lot of the server’s memory.
- Each time a request is made, it also has to open another connection to the database. This is a very slow and costly process, too.
- Data can’t be stored in memory between page loads, so it’s less efficient, so it takes longer to load pages.
Applications of Common Gateway Interface
CGI changes the Web from a place where static data is collected to a place where users can interact with the number of questions to run applications. Some of the applications that are made with CGI are:
Forms
People use CGI a lot with forms. Forms let people share information and are part of HTML. A CGI program makes these forms very interactive for both the user and the provider by processing and selecting the right forms that meet the user’s needs.
Gateway
A web gateway is a computer program or script that lets you get to the web. It is used to get the information that the client can’t see right away from the database. The CGI program is used to act as a gateway and use the right programming language to read the information, format it, and share it with the client. This is how it works:
Virtual Documents
When it comes to CGI, the most important thing is making virtual documents. It can be hard to tell what a virtual document will look like because it’s made for the user. They can be made out of virtual HTML, images, plain text, and even audio.
