This directory contains a basic sample server and client program. The server demonstrates the use of either non-blocking accept using the select function or asynchronous accept using the WSAAsyncSelect function.
Skip to main content. This browser is no longer supported. Download Microsoft Edge More info. Contents Exit focus mode. Is this page helpful? Please rate your experience Yes No. Any additional feedback? The server creates it using the system call socket , and it can't be shared with other processes. There are several different types of socket that determine the structure of the transport layer. The most common types are stream sockets and datagram sockets.
The client-server model distinguishes between applications as well as devices. Network clients make requests to a server by sending messages , and servers respond to their clients by acting on each request and returning results. For example, let's talk about telnet. When we connect to a remote host on port 23 with telnet the client , a program on that host called telnetd , the server springs to life. It handles the incoming telnet connection, sets us up with a login prompt, etc.
One server generally supports numerous clients, and multiple servers can be networked together in a pool to handle the increased processing load as the number of clients grows. Some of the most popular applications on the Internet follow the client-server model including email, FTP and Web services. Each of these clients features a user interface and a client application that allows the user to connect to servers.
In the case of email and FTP, users enter a computer name or an IP address into the interface to set up connections to the server. The steps to establish a socket on the server side are: Create a socket with the socket system call. The server process gives the socket a name. For network sockets, the filename will be a service identifier, port number, to which the clients can make connection. This identifier allows to route incoming connections which has that the port number to connect server process.
A socket is named using bind system call. The server process then waits for a client to connect to the named socket, which is basically listening for connections with the listen system call.
If there are more than one client are trying to make connections, the listen system call make a queue. The machine receiving the connection the server must bind its socket object to a known port number. A port is a bit number in the range that's managed by the operating system and used by clients to uniquely identify servers.
Ports are reserved by the system and used by common network protocols. Accept a connection with the accept system call. At accept , a new socket is created that is distinct from the named socket. This new socket is used solely for communication with this particular client.
For TCP servers, the socket object used to receive connections is not the same socket used to perform subsequent communication with the client.
In particular, the accept system call returns a new socket object that's actually used for the connection. This allows a server to manage connections from a large number of clients simultaneously. Send and receive data. The named socket remains for further connections from other clients. A typical web server can take advantage of multiple connections. In other words, it can serve pages to many clients at once.
But for a simple server, further clients wait on the listen queue until the server is ready again. The steps to establish a socket on the client side are: Create a socket with the socket system call.
Connect the socket to the address of the server using the connect system call. There are a number of ways to do this, but the simplest is to use the read and write system calls. Next we have to bind the created socket to structure ipOfServer.
For this we are calling bind functional. Which includes port, ip addresses as details. So maximum 20 queue process can be handled by server. But it may eat up all CPU processing, to avoid that we have written sleep 1 , which server went to sleep for 1 sec. When server hit by client, it prints date and time on clients socket through descriptor returned by accept. Port number of the process and IP address both bundled in a structure. We connect these with socket.
0コメント