Definition
Common Gateway Interface (CGI)
A standard protocol that allows web servers to interact with external programs, often written in languages like **Perl **or Python.
CGI enables dynamic content generation by executing scripts in response to user requests.
Note
CGI scripts are typically stored in a special directory, such as cgi-bin, on the web server.
How CGI Works
- User Request: A user submits a form or requests a resource that requires dynamic processing.
- Server Execution: The web server identifies the request as a CGI call and executes the corresponding script.
- Script Processing: The CGI script processes input data, such as form fields, and generates output (e.g., HTML).
- Response: The server sends the script's output back to the user's browser.
Analogy
Think of CGI as a translator that converts user input into actions performed by the server, then translates the results back into a web page.
Advantages and Disadvantages of CGI
Advantages
- Simplicity: Easy to implement with basic scripting knowledge.
- Language Flexibility: Supports multiple programming languages.
Disadvantages
- Performance: Each request spawns a new process, leading to high overhead.
- Scalability: Not suitable for high-traffic websites due to resource constraints.
Example
A CGI script can process form data by reading environment variables like QUERY_STRING for GET requests or stdin for POST requests.
