Servers, WSGI & Flask

• WSGI: Webserver gateway interface
  • a protocol that makes it easy to swap python web application frameworks
• Client downloads html document
  • container page
  • typically in ascii
  • contains instructions for site rendering
  • links to other pages
• can contain embedded objects
  • automatically retrieved
• carriage return and line feed indicate end of headers
• headers may contain private information
  • os used
  • browser used
  • cookie information

HTTP Request types

• get: retrieve a file (95% of requests)
• head: just get meta-data
• post: submitting a form to a server
• put: store enclosed document as uri
• delete: removed named resource
• trace: http echo for debugging
• connect: used for proxies for tunneling
• options: request for server or proxy options

HTTP Response types

• 1XX: Informational
  • 100 Continue, 101 Switching protocols
• 2XX: Success
  • 200 OK, 206 Partial Content
• 3XX: Redirection
  • 301 Moved Permanently, 304 Not Modified
• 4XX: Client Error
  • 400 Bad Request, 403 Forbidden, 404 Not Found
• 5XX: Server Error
  • 500 Internal Server Error, 503 Service Unavailable, 505 HTTP Version Not supported