Writing a server program java

The client program is implemented by a single class, KnockKnockClientand is very similar to the EchoClient example from the previous section. The server program is implemented by two classes: KnockKnockServer, which is similar to EchoServercontains the main method for the server program and performs the work of listening to the port, establishing connections, and reading from and writing to the socket. The class KnockKnockProtocol serves up the jokes.

Writing a server program java

The client program is implemented by a single class, KnockKnockClient, and is based on the EchoTest example from the previous page. The server program is implemented by two classes: KnockKnockServer contains the main method for the server program and performs all the grunge work of listening to the port, establishing connections and reading from and writing to the socket.

KKProtocol serves up the jokes: This page will look in detail at each class in these two programs and finally show you how to run them.

Developing Java programs with the JDK

Here's the complete source for the KnockKnockServer class. The server program begins by creating a new ServerSocket object to listen on a specific port.

writing a server program java

When writing a server, you should choose a port that is not already dedicated to some other service. KnockKnockServer listens on port because 4 happens to be my favorite number and port is not being used for anything else in my environment.

Typically, the ServerSocket class sits on top of a platform-dependent implementation hiding the details of any particular system from your Java program. Thus, when working with ServerSockets, you should always use the java.

ServerSocket class and bypass the underlying system-dependent functions. In this way, your Java programs will remain system neutral. The constructor for ServerSocket will throw and exception if for some reason the port is already in use it could not listen on the specified port.

In this case, the KnockKnockServer has no choice but to exit. If the server successfully connected to its port, then the ServerSocket object was successfully created and the server continues to the next step which is to accept a connection from a client.

When the client requests a connection, the accept method accepts the connection, if nothing goes wrong, and returns a socket. This Socket object is a reference to the socket that the client used to establish the connection with the port. Now, both the server and the client are communicating to each other via the Socket and the ServerSocket is out of the picture for now.

There's little bit more about the ServerSocket later. The code within the next try block implements the server-side of the communication with the client.

This section of the server is remarkably similar to the client-side which you saw and example of on the previous page and will see later when we walk through the KnockKnockClient class: The next two lines similarly open an output stream on the same socket.

The line simply declare and create a couple local strings used to read from and write to the socket.

Writing the Server Side of a Socket

And finally, the last line creates a KKProtocol object. This is the object that keeps track of the current joke, the current state within the joke and so on.

This object implements the protocol, that is, the language that the client and server have agreed to use to communicate. The server is the first to speak with these lines of code:This Java program will send a message from client to server and receive a response back Server (leslutinsduphoenix.com) sends back the result (message) to the client (leslutinsduphoenix.com) 6.

In case the number sent by the client was not a proper number, server (leslutinsduphoenix.com) sends back the message “Please send a proper number” to the client (leslutinsduphoenix.com).

This classic JavaWorld tutorial presents an introduction to sockets programming over TCP/IP networks and demonstrates how to write client/server applications in Java.

A bit of history of Unix I/O The Unix input/output (I/O) system follows a paradigm usually referred to as Open-Read-Write-Close. I'm writing my first java client/server program which just establishes a connection with the server sends it a sentence and the server sends the sentence back all capitalized.

The client and the server can now communicate by writing to and reading from the socket. and the leslutinsduphoenix.comSocket class provides a mechanism for the server program to listen for clients and establish connections with them.

Compile the client and the server and then start the server as follows − $ java GreetingServer Waiting. Jun 23,  · Java has a very good networking support, allows you to write client server application by using TCP Sockets.

In this tutorial, we will learn how to create a simple HTTP Server in Java, which can listen HTTP request on a port let's say 80 and can send response to client.

Introduction. This example shows you how to create a WebSocket API server using Oracle Java. Although other server-side languages can be used to create a WebSocket server, this example uses Oracle Java to simplify the example code.

writing a server program java
Essentials, Part 1, Lesson 1: Compiling & Running a Simple Program