Web server gateway interface for communication between web server and web applications of python.

1. Python WSGI
Protocol
-Presented By
Rinkal Modi
Divya Ahuja
Krisha Jain

2. Outlines
 Why WSGI?
 Introduction
 What is WSGI?
 Middleware
 Requests and Responses
 Example
 Advantages

3. Why WSGI?
• WSGI servers are designed to handle many requests
concurrently.
• WSGI speeds up Python web application development because
you only need to know basic things about WSGI.
• WSGI gives you the flexibility of changing web stack components
for alternatives without changing the application that runs with
WSGI.

4. Introduction
• The Web Server Gateway Interface (WSGI) is a specification for
simple and universal interface between web servers and web
applications for the python.
• The WSGI has two sides:
1. server/gateway
2. Application/framework.
• To process a WSGI request, the server side executes the
application and provides environment information and a callback
function to the application side.

5. Continue…
• The application processes the request, returning the response to
the server side using the callback function.
• Between the server and application, there may be a WSGI
middleware, which implements both sides of API.
• The server receives a request from a client and forwards it to the
middleware.
• After processing, it sends a request to the application.
• The applications response is forwarded by the middleware to the
server and ultimately to the client.

6. What is WSGI?
• HTTP = Hyper Text Transfer Protocol
• WSGI = Web Server Gateway Interface

7. Middleware
• Middleware : A component that play both sides.
• A single object may play the role of server with respect to some
applications, while also acting as an application with respect to
some servers.
• Thus it is transparent to both the server/gateway and the
application/framework sides of interface.

8. Continue…
• FUNCTIONS :
i. Routing request to different applications based on target
URL.
ii. Allowing multiple applications/framework to run side by
side in same process.
iii. Load balancing and remote processing, by forwarding
requests and responses over a network.
iv. Perform content post processing, such as applying XSL style
sheets.

9. Requests and Responses

10. Example
#web_application.py
from wsgiref.simple_server import make_server
def application(environ, start_response):
path = environ.get('PATH_INFO')
if path == '/':
response_body = "Index"
else:
response_body = "Hello"
status = "200 OK"
response_headers = [("Content-Length", str(len(response_body)))]
start_response(status, response_headers)
return [response_body]
httpd = make_server(
'127.0.0.1', 8051, application)
httpd.serve_forever()

11. Advantages
• Applications can be run by different users.
• No need to restart the web server to upgrade code.
• Applications with different versions of python.
• No shared libraries conflicts.

12. Thank You..