The term network programming refers to writing programs that execute across multiple devices (computers), in which the devices are all connected to each other using a network.
The java.net package of the J2SE APIs contains a collection of classes and interfaces that provide the low-level communication details, allowing you to write programs that focus on solving the problem at hand.
The java.net package provides support for the two common network protocols −
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TCP − TCP stands for Transmission Control Protocol, which allows for reliable communication between two applications. TCP is typically used over the Internet Protocol, which is referred to as TCP/IP.
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UDP − UDP stands for User Datagram Protocol, a connection-less protocol that allows for packets of data to be transmitted between applications.
This chapter gives a good understanding on the following two subjects −
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Socket Programming − This is the most widely used concept in Networking and it has been explained in very detail.
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URL Processing − This would be covered separately. Click here to learn about URL Processing in Java language.
TCP − TCP stands for Transmission Control Protocol, which allows for reliable communication between two applications. TCP is typically used over the Internet Protocol, which is referred to as TCP/IP.
UDP − UDP stands for User Datagram Protocol, a connection-less protocol that allows for packets of data to be transmitted between applications.
Socket Programming − This is the most widely used concept in Networking and it has been explained in very detail.
URL Processing − This would be covered separately. Click here to learn about URL Processing in Java language.
Java Networking Basics
Typically a client opens a TCP/IP connection to a server. The client then starts to communicate with the server. When the client is finished it closes the connection again. Here is an illustration of that:
A client may send more than one request through an open connection. In fact, a client can send as much data as the server is ready to receive. The server can also close the connection if it wants to.
Java Networking Terminology
The widely used java networking terminologies are given below:
- IP Address
- Protocol
- Port Number
- MAC Address
- Connection-oriented and connection-less protocol
- Socket
1) IP Address
IP address is a unique number assigned to a node of a network e.g. 192.168.0.1 . It is composed of octets that range from 0 to 255.
It is a logical address that can be changed.
2) Protocol
A protocol is a set of rules basically that is followed for communication. For example:
- TCP
- FTP
- Telnet
- SMTP
- POP etc.
3) Port Number
The port number is used to uniquely identify different applications. It acts as a communication endpoint between applications.
The port number is associated with the IP address for communication between two applications.
4) MAC Address
MAC (Media Access Control) Address is a unique identifier of NIC (Network Interface Controller). A network node can have multiple NIC but each with unique MAC.
5) Connection-oriented and connection-less protocol
In connection-oriented protocol, acknowledgement is sent by the receiver. So it is reliable but slow. The example of connection-oriented protocol is TCP.
But, in connection-less protocol, acknowledgement is not sent by the receiver. So it is not reliable but fast. The example of connection-less protocol is UDP.
6) Socket
A socket is an endpoint between two way communication.
Visit next page for java socket programming.