Need help about read() and write() on TCP/IP


 
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# 1  
Old 11-07-2010
Need help about read() and write() on TCP/IP

HI

I need to implement a client/server TCP application. the customer is the client and the bartender is the server.

When the customer enter the Bar, client connects to the server
Server should reply the client immediately. Other wise if the server is busy, it should send an update message every 10 seconds.

Depending on which message replied by the server:

10 seconds expired, no reply: client leave, that is disconnect
server is busy update: client reply --waiting or "leave and disconnect"
select beer: client reply -- light or black
select quantity: client reply liter or bottle, then disconnect

I have done the part before 'connection', but i don't know how to complement the function about read() and write(), so, please help me have a look at it, many thanks!!
Code:
#include <sys/wait.h>
#include <malloc.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <errno.h>
#include <stdlib.h>
#include <arpa/inet.h>
int main(int argc, char *argv[])
{
    int   socket1,n;   
        int blond=0 , brun=0;//string buf;
    char buffer[256];
    if(argc<2) {
        printf ("usage socket_clt \n");
        exit(0);
    }
 
    printf("client1 is coming\n");
        struct sockaddr_in local;
        struct sockaddr_in from;
        int fromlen =sizeof(from);
    bzero(&from, sizeof(from));
        from.sin_family=AF_INET;
        from.sin_port=htons(5000); //lisening 5000
        from.sin_addr.s_addr=INADDR_ANY; //address of local computer
    /*creat a socket*/   
    if (( socket1=socket(AF_INET, SOCK_STREAM,0))<0)
         {
        printf("socket error ourverture\n");exit(0);
    }
 
    if (connect(socket1, (struct sockaddr*)&from, sizeof(from))<0)
         {
        printf("socket error connection\n");
        exit(0);
    }
 
    bzero(buffer,256);
      fgets(buffer,255,stdin);
      n = write(socket1,buffer,strlen(buffer));
      if (n < 0)
           error("ERROR writing to socket");
 
  bzero(buffer,256);
      n = read(socket1,buffer,255);
      if (n < 0)
           error("ERROR reading from socket");
      printf("%s\n",buffer);
      return 0;
 
}

I need to add a function of 'timeout' on read(),but i don't know how to do that.
thus how can i add a circle to implement many customers entering?

Last edited by lixiao1212; 11-07-2010 at 04:20 PM.. Reason: Please use code tags
# 2  
Old 11-07-2010
Is it a homework? In this case, post in the Homework forum...

You first need to define a protocol between your server and your client (on top of TCP), so that both understand the command "server is busy update", "select beer", "light/black", "select quantity", "liter/bottle"

On the client side:
- The client connects to the server.
- The client reads the answer from the server. Note that you will have to implement a timeout on the read().
- The client sends back answer to the server as appropriate.

On the server side:
- the server accepts the connection
- the server sends reply to the client
- the server reads reply from the client
The implementation of the "server busy update" is tricky: you'll have to fork (or create a new thread) upon each connection. Only one client can be served at a time; the other children/threads should take care of the "busy update".

HTH,
Loc
# 3  
Old 11-07-2010
Quote:
Originally Posted by Loic Domaigne
Is it a homework? In this case, post in the Homework forum...

You first need to define a protocol between your server and your client (on top of TCP), so that both understand the command "server is busy update", "select beer", "light/black", "select quantity", "liter/bottle"

On the client side:
- The client connects to the server.
- The client reads the answer from the server. Note that you will have to implement a timeout on the read().
- The client sends back answer to the server as appropriate.

On the server side:
- the server accepts the connection
- the server sends reply to the client
- the server reads reply from the client
The implementation of the "server busy update" is tricky: you'll have to fork (or create a new thread) upon each connection. Only one client can be served at a time; the other children/threads should take care of the "busy update".

HTH,
Loc
thanks Loic but i just need to finish the part of client, so could you tell me how can i implement it? thanks again!!
# 4  
Old 11-07-2010
How does the protocol between server and client look like?
# 5  
Old 11-07-2010
Quote:
Originally Posted by Loic Domaigne
How does the protocol between server and client look like?

TCP
# 6  
Old 11-07-2010
"what format is the data in?" "file"

You can send anything you want over TCP. It's up to you to decide what the protocol is.
# 7  
Old 11-07-2010
i don't understand, i have decided to use the protocol on TCP.
data format? what's your mean?
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