Your First WSGI Application

WSGI is a specification that describes how a web server communicates with web applications. Most if not all Python web frameworks are WSGI compliant, including Flask and Django; but to quickly test if you have your Apache configuration correct you’ll write a very basic WSGI application.

You just defined the name of the file you need to write within your Apache configuration by using the WSGIScriptAlias directive. Despite having the extension .wsgi, these are just Python applications. Create the /var/www/html/myapp.wsgi file using the command sudo nano /var/www/html/myapp.wsgi. Within this file, write the following application:

def application(environ, start_response):
    status = '200 OK'
    output = 'Hello Udacity!'

    response_headers = [('Content-type', 'text/plain'), ('Content-Length', str(len(output)))]
    start_response(status, response_headers)

    return [output]

This application will simply print return Hello Udacity! along with the required HTTP response headers. After saving this file you can reload http://localhost:8080 to see your application run in all its glory!