Lesson 1: Socket Communications. Lesson 1: Socket Communications. The RMI example allows multiple client programs to communicate with the same server program without any explicit code to do this because the RMI API is built on sockets and threads. This lesson presents a simple sockets- based program to introduce the concepts of sockets and multi- threaded programming. A multi- threaded program performs multiple tasks at one time such as fielding simultaneous requests from many client programs. Note: See Creating a Threaded Slide Show Applet for another example of how multiple threads can be used in a program. The socket associates the server program with a specific hardware port on the machine where it runs so any client program anywhere in the network with a socket associated with that same port can communicate with the server program. A server program typically provides resources to a network of client programs. Client programs send requests to the server program, and the server program responds to the request. One way to handle requests from more than one client is to make the server program multi- threaded. A multi- threaded server creates a thread for each communication it accepts from a client. A thread is a sequence of instructions that run independently of the program and of any other threads. Using threads, a multi- threaded server program can accept a connection from a client, start a thread for that communication, and continue listening for requests from other clients. The server program is not multi- threaded and cannot handle requests from more than one client. ![]() Java socket programming tutorial. Java By Silver Moon On Jul 22, 2012 13 Comments. By now you must have learned the basics of socket programming in Java. Java Networking - Learn Java in simple and easy steps starting from basic to advanced concepts with examples including Java Syntax Object Oriented Language, Methods. Example 2 converts the server program to a multi- threaded version so it can handle requests from more than one client. Example 1: Client- Side Behavior. The client program presents a simple user interface and prompts for text input. When you click the Click Me button, the text is sent to the server program. The client program expects an echo from the server and prints the echo it receives on its standard output. Example 1: Server- Side Behavior. The server program presents a simple user interface, and when you click the Click Me button, the text received from the client is displayed. The server echoes the text it receives whether or not you click the Click Me button. Example 1: Compile and Run. To run the example programs, start the server program first. If you do not, the client program cannot establish the socket connection. Here are the compiler and interpreter commands to compile and run the example. It reads data sent to it and sends that same data back to the server in its action. Performed method. Socket Method. The listen. Socket method creates a Server. Socket object with the port number on which the server program is going to listen for client communications. The port number must be an available port, which means the number cannot be reserved or already in use. For example, Unix systems reserve ports 1 through 1. This action. Performed method uses the text stored in the line object to initialize the text. Area object so the retrieved text can be displayed to the end user.
The action. Performed method also receives the data back from the server and prints it to the command line. Socket Method. The listen. Socket method first creates a Socket object with the computer name ( kq. Next, it creates a Print. Writer object to send data over the socket connection to the server program. This example introduces you to Java socket programming. The server listens for a connection. When a connection is established by a client. The client can send data. Hello World for Socket Programming using Java . To use Java Programming language. Simple Servlet and JSP Examples using Eclipse and JBoss AS. It also creates a Buffered. Reader object to read the text sent by the server back to the client. This action. Performed method code gets the text in the Textfield object and passes it to the Print. Writer object, which then sends it over the socket connection to the server program. The action. Performed method then makes the Textfield object blank so it is ready for more end user input. Lastly, it receives the text sent back to it by the server and prints the text out. To allow multiple client connections, the server program has to be converted to a multithreaded server program. In this example the listen. Socket method loops on the server. Client. Worker class for each client connection it accepts. The text. Area component that displays the text received from the client connection is passed to the Client. Worker instance with the accepted client connection. The run method executes independently in each thread. If three clients request connections, three Client. Worker instances are created, a thread is started for each Client. Worker instance, and the run method executes for each thread. In this example, the run method creates the input buffer and output writer, loops on the input stream waiting for input from the client, sends the data it receives back to the client, and sets the text in the text area. Multi- threaded programs should close all Files and Sockets they use before exiting so they do not face resource starvation. The call to server. Socket connection used by each thread in this program. Java : Socket programming example. The quotation- marks should be . That is, you should have. Socket s = new Socket(. If you import the classes properly, it will print something like. UTC(NIST) *. This is roughly how I would have written itimport java.
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