1. Project 2 Data Communication Spring 2010, ICE 3025-44 Stephen Kim, Ph.D.

2. Due Date April 9th, 2010

3. Mission You will modify the previous project to make the server to handle multiple connections simultaneously. Echo Server ◦ The server uses a thread library. On a successful connection, the accept() function returns a new socket. You create a new thread with a communication function, and the new socket and the client address are passed to the communication function that communicate with a client until it receive an empty message. ◦ The child thread, or the communication function, receives a message from the client and print the client’s IP address and optionally the client’s port number followed by the message, repeatedly. For example, 115.145.203.30:4874 > Hello. World! ◦ The parent thread waits for another connection with the accept() function.

4. Echo Client ◦ The previous client reads only one line from the keyboard. This short- lived execution is improper to demonstrate multiple connections at the server side. ◦ You modifies the client to repeat the process of reading keyboard, sending, receiving, printing until a user enters an empty line. Be aware that the client sends the empty line to the server so that the server recognize the end of connection to close it properly. ◦ The client shows the source of a message by using a keyboard prompt, and the server’s IP address and optionally the server’s port number followed by the message, repeatedly. For example, KEYBORD > Hello. World! 142.35.203.30:3000 > Hello. World! Empty message ◦ Each message is terminated by a new line character, LF, CR, or CR/LF depending OS. ◦ An empty message is a message containing no user message but the new line character.

5. Team You will form a group of 5 persons. Each group submits ONE copy of the project report, but each member completes a “Peer Rating” form and submits it to the instructor CONFIDENTIALLY.

6. Requirement The project description must be properly demonstrated in the project report. Use either C or C++ programming language. Period. The submission must include soft and hard copy of ◦ source files (C files and H files) ◦ text trace of compilation ◦ text trace of execution (the client side, and the server side) All codes must be properly formatted and tabbed, and include proper in-line documents (comments). All submission must be archived (compressed) into a single file for submission of soft copy.

7. Tips for POSIX Thread Pthread tutorials and resources ◦ http://en.wikipedia.org/wiki/POSIX_Threads http://en.wikipedia.org/wiki/POSIX_Threads ◦ http://ko.wikipedia.org/wiki/POSIX_ 쓰레드 http://ko.wikipedia.org/wiki/POSIX_ 쓰레드 #include #define NUM 5 void *PrintHello(void *threadid) { long tid; tid = (long)threadid; printf(“Thread #%ld!\n", tid); pthread_exit(NULL); } #include #define NUM 5 void *PrintHello(void *threadid) { long tid; tid = (long)threadid; printf(“Thread #%ld!\n", tid); pthread_exit(NULL); } int main (int argc, char *argv[]) { pthread_t threads[NUM]; int rc; long t; for(t=0; t<NUM; t++){ rc = pthread_create(&threads[t], NULL, PrintHello,(void *)t); if (rc) { fprintf(stderr, "ERROR;%d\n“,rc); exit(-1); } pthread_exit(NULL); } int main (int argc, char *argv[]) { pthread_t threads[NUM]; int rc; long t; for(t=0; t<NUM; t++){ rc = pthread_create(&threads[t], NULL, PrintHello,(void *)t); if (rc) { fprintf(stderr, "ERROR;%d\n“,rc); exit(-1); } pthread_exit(NULL); }