Transcript ppt
Programming Project #4 Web Server CS-502 Operating Systems Spring 2006 CS502 Spring 2006 Programming project #4 1 Programming Assignment 1. Build a simple but real web server using sockets; also build a simple web client for testing your server 2. Make your server fork a process for each new request 3. Make your server spawn a new thread for each request CS502 Spring 2006 Programming project #4 2 Purpose • To gain some insight into sockets and communication over networks. CS502 Spring 2006 Programming project #4 3 Part 1 – Web Server • Create a socket() and bind() it to a port. • listen() on that port for requests • Wait for requests; upon receipt of a request – – – – – accept() the request Interpret the HTTP request Find and deliver the page; or return an error Close the accepted request Loop back and wait for another request • Figure out a way of exiting from the server cleanly. CS502 Spring 2006 Programming project #4 4 Part 1 – Web Server (continued) • Command line:% server <directory> [optional port #] • Directory is prefixed to every request. – WPI directory for web pages is /www/docs • Port is port number for your server – You may specify a default port in your code, but don’t choose one to conflict with another student! – Warning: Unix does not let you reuse ports until after a reasonable waiting period (30 seconds?) • A request to your server of http://ccc4.wpi.edu:4242/admissions.html means return the file at /www/docs/admissions.html on port #4242 CS502 Spring 2006 Programming project #4 5 Class discussion next week • Review experience with using sockets to actually do something. • Discuss how to exit server program cleanly. CS502 Spring 2006 Programming project #4 6 Part 1 – Web Client • Simple test program that requests web pages and prints out their contents. • Use to see what your server is doing. • Use to see what another server is actually serving when you request the same pages. CS502 Spring 2006 Programming project #4 7 HTTP commands • Your server must interpret HTTP GET command • See written project description for examples • All command lines must end with CR/LF – i.e., in Unix \r\n • Series of HTTP commands ends with blank line – i.e., a stand alone \r\n CS502 Spring 2006 Programming project #4 8 HTTP Response • Once you accept a command and have found the page, respond with HTTP success response 200 – See written project description – Be sure to follow with a blank line • If you cannot find or read the page, respond with HTTP error response 404 • You only need to serve real file pages. – Ignore scripts, etc. • WPI’s home page is a script. – Remember: some pages are not all text! CS502 Spring 2006 Programming project #4 9 Sample code • See http://www.cs.wpi.edu/~cs502/s06/CodeFragments/ • Includes • sockserver.c • sockclient.c • sockreadline.c CS502 Spring 2006 Programming project #4 10 Part 2 – Multi-process Web Server • Modify your web server to fork() a process each time it receives a request. • This allows it to serve multiple requests in parallel. • Test with multiple web clients or browsers in parallel. • Be sure to clean up “zombie” processes on the fly – Use wait3() • Be sure that your server leaves time for each process to finish before exiting cleanly. CS502 Spring 2006 Programming project #4 11 Part 3 – Threaded Web Server • Modify your web server to spawn a thread each time it receives a request. • This also allows it to serve multiple requests in parallel. • Test with multiple web clients or browsers in parallel. • Be sure to threads exit cleanly after finishing with each connection. • Be sure that your server leaves time for each thread to finish before exiting cleanly. CS502 Spring 2006 Programming project #4 12 Project Submission • Project due at start of class on April 17 • (i.e., one week before the last class of the term) • Submit via turnin • command = ‘/cs/bin/turnin’ on CCC machines • classname = ‘cs502’ • assignment = ‘project4’ • Include • Code, makefiles, test files or input, test output CS502 Spring 2006 Programming project #4 13