Homework1
System programming 2011Ď
Introduction
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In this assignment
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You have to modify a simple chat server to a multiplexing chat server
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You don’t have to handle the network communication. We will handle that partĎ
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Chat server
Chat serverĎ
<RD>Ď <RD>Ď
<RD>Ď
<WR>Ď
<WR>Ď <WR>Ď
Client AĎ Client BĎ
Client CĎ
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We will provide
!
A simple Chat Server
! Handle only one request
! Handle only one msg Ď
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File desĎ 0Ď 1Ď 2Ď 3Ď 4Ď …Ď …Ď 1022Ď 1023Ď
flagĎ 1Ď 1Ď 1Ď 0Ď 0Ď 0Ď 0Ď 0Ď 0Ď
requestP：Ď
The server.listen_fdĎ
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File desĎ 0Ď 1Ď 2Ď 3Ď 4Ď …Ď …Ď 1022Ď 1023Ď
flagĎ 1Ď 1Ď 1Ď 1Ď 0Ď 0Ď 0Ď 0Ď 0Ď
requestP：Ď
The server.listen_fdĎ accept return fd =conn_fdĎ
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DEMO TIMEĎ
Your Job is
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A Multiplexing Chat Server
! Handle!mutiple requests simultaneously
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What you should do?
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Use select
! Select() allows a program to monitor multiple file
descriptors,waiting until one or more of the file descriptors become “ready” for some class of I/O operation
! If we have a nonblocking descriptor that we Want to read from and we call select with timeout value of 5 seconds,select will block for up to 5 seconds.Ď
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Detail Spec
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You can download the files from:
! http://www.csie.ntu.edu.tw/~pjcheng/course/sp2011/
assignments.html
! You can start up server using:
! $> gcc –wall sp_hw1_chatsvr.c
!
You can start up server using:
! $> ./a.out 6000
! 3000<port<30000
How Can I get full Score
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Prevent from waiting for reading(2%)
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Prevent from waiting for writing(2%)
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message passing (2%)
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Detect disconnection (1%) Ď
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Example
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Client A : <RD> !
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Client B:
<WR>hello ! everyone ! !
hello everyone
Ď Client A’s screenĎ
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Example
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Client A : <RD> !
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Client C : <RD> ! !
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Client B:
<WR>hello ! everyone!
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Ď
hello everyone
Ď Client A’s screenĎ
Client C’s screenĎ
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Example
! Client A : <RD> ! !
! Client C :
<WR> it’s my life!
! Client B:
<WR>hello ! everyone!
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! Client C:
I know !
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Client A’s screenĎ hello
Everyone it’s my life I know
Ď
Example
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Client A : <WR>hello ! (break connection)
Server Detect disconnection and out put msg
”someone logout” on server side
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Pseudo code
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Set_fd();
ret = select(nfds,& rfds, &wfds, &efds, &timeout);
If(ret>0) then check new condiction;
For i=4 to maxfd {
if(FD_ISSET(i,&rfds))handle_read();// may create a pool here.
if(FD_ISSET(i,&wfds))handle_write();//may use the data in pool.
}
Submission
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! Course website: http://newslabx.csie.ntu.edu.tw/courses
! 1. Makefile
! 2. README.txt
! 3. sp_hw1_chatsvr.
! You should tar this three files
! And submission the tared file named
! SPHW1_STUDENT_ID.tar.gz ex: SPHW1_b98902000.tar.gz
! And the first lines of her sp_hw1_chatsvr.c would be /* b97902000林玲綾*/
! **please do not use .rar or other file type.**
Questions
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Ptt2 :SysProgram
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Email:[email protected]
! Title:[sp][hw1]question title
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Come to lab302
Finally
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Submit your program before 4/10 23:59
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Demo your program after 4/10
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Check your ptt2 frequently Ď
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