Web Programming Models and Technologies
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Slides from talk about Tornado Web framework for Dnipro Ruby community
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Web Programming Models and Technologies
- 1. – different Web programming Dima Malenko for Ruby Meetup
- 2. C++ Win32 MFC CORBA 2002
- 3. ASP.NET Web Forms public class FirstPage: System.Web.UI.Page { public System.Web.UI.WebControls.Label lblMessage; private int i = 0; protected void Page_Load(object sender, EventArgs e) { i = i + 1; lblMessage.Text = i.ToString(); } }
- 4. Web Programming Model Request with parameters Client Server HTML response
- 6. How Web Server Works? • Create socket • Bind socket • Listen on socket • Accept new connection from a client • Receive data from the client • Process the request somehow • Send response to the client • Wait for a new connection
- 7. How Web Server Works? • Create socket • Bind socket • Listen on socket • Accept new connection from a client Separate thread • Receive data from the client • Process the request somehow • Send response to the client • Wait for a new connection
- 8. Why the “separate thread”?
- 9. How Web Server Works? • Create socket • Bind socket • Listen on socket • Accept new connection from a client Separate thread • Receive data from the client • Process the request somehow • Send response to the client • Wait for a new connection
- 11. Threads cost • Memory overhead – Default thread stack size in Linux – 8M • Context switches cost – It takes ~2-3µs to switch context in Linux – http://blog.tsunanet.net/2010/11/how-long-does- it-take-to-make-context.html
- 15. What would you put in front of loaded Web site?
- 17. Why Nginx?
- 18. Ability to handle more than 10,000 simultaneous connections with a low memory footprint (~2.5 MB per 10k inactive HTTP keep-alive connections) Wikipedia
- 19. How is that possible? • Non-blocking networking using fastest interface on any given platform – kqueue (FreeBSD 4.1+) – epoll (Linux 2.6+) – rt signals (Linux 2.2.19+) – /dev/poll (Solaris 7 11/99+) – event ports (Solaris 10) – select – poll
- 20. • Python web framework and async networking library • Originally developed for FriendFeed • Ideal for long polling, WebSockets and long- lived connections www.tornadoweb.com
- 23. import tornado.ioloop import tornado.web class MainHandler(tornado.web.RequestHandler): def get(self): self.write("Hello, world") application = tornado.web.Application([ (r"/", MainHandler), ]) if __name__ == "__main__": application.listen(8888) tornado.ioloop.IOLoop.instance().start()
- 24. Handling Requests class ProductHandler(tornado.web.RequestHandler): def get(self, product_id): self.write("Information about " + product_id) @tornado.web.authenticated def post(self, product_id): # store updated product info application = tornado.web.Application([ (r"/product/([0-9]+)", ProductHandler) ])
- 25. Templates <html> <head> <title>{{ title }}</title> </head> <body> <ul> {% for item in items %} <li>{{ escape(item) }}</li> {% end %} </ul> </body> </html> class MainHandler(tornado.web.RequestHandler): def get(self): items = ["Item 1", "Item 2", "Item 3"] self.render("template.html", title="My title", items=items)
- 26. And That’s It?
- 27. Web Site Node Show list of currently Runs many real-time running apps with their applications titles App Changes titles whenever it wants
- 28. Web Site Node Show list of currently Runs many real-time running apps with their applications titles How would you make App sure user can see updated Changes titles titles on the web? whenever it wants
- 29. Web Site Node 300-400ms Show list of currently Runs many real-time running apps with their applications titles What if… App App App App App App Changes titles Changes titles whenever it wants Changes titles whenever it wants Changes titles whenever it wants Changes titles whenever it wants Changes titles whenever it wants whenever it wants
- 30. Non-blocking Requests class AppUpdatesHandler(tornado.web.RequestHandler): @tornado.web.asynchronous def get(self): http = tornado.httpclient.AsyncHTTPClient() request = tornado.httpclient.HTTPRequest( "http://www.frontend.com", method="POST", ...) http.fetch(request, callback=self.on_response) self.finish() def on_response(self, response): if not response.error: log.debug("Title updated”)
- 31. WebSockets class WebSocket(websocket.WebSocketHandler): def open(self): print "WebSocket opened" def on_message(self, message): print "Message: " + message def on_close(self): print "WebSocket closed"
- 32. How is it possible? Cooperative Multitasking
- 33. How does it work? • Event loop – Tornado.ioloop.IOLoop – Level-triggered, uses epoll on Linux and kqueue on BSD • Futures – Result of an async operation
- 34. Coroutines class AppUpdatesHandler(tornado.web.RequestHandler): @tornado.web.asynchronous @tornado.gen.coroutine def get(self): http = tornado.httpclient.AsyncHTTPClient() request = tornado.httpclient.HTTPRequest( "http://www.frontend.com", method="POST", ...) self.finish() response = yield http.fetch(request) if not response.error: log.debug("Title updated”)
- 35. Conclusions • Web has changed, so programmers should too • You want to face C10k problem • There means to solve it • Learn to think asynchronously • Check out www.tornadoweb.org
- 36. Questions? www.dmalenko.org dmalenko@rollapp.com @dmalenko