Java Networking

Java Networking is a concept of connecting two or more computing devices together so that we can share resources.

Java socket programming provides facility to share data between different computing devices.

Advantage of Java Networking

1. Sharing resources
2. Centralize software management

The java.net package supports two protocols,

1. TCP: Transmission Control Protocol provides reliable communication between the sender and receiver. TCP is used along with the Internet Protocol referred as TCP/IP.
2. UDP: User Datagram Protocol provides a connection-less protocol service by allowing packet of data to be transferred along two or more nodes

Java Networking Terminology

The widely used Java networking terminologies are given below:

1. IP Address
2. Protocol
3. Port Number
4. MAC Address
5. Connection-oriented and connection-less protocol
6. 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 address.

For example, an ethernet card may have a MAC address of 00:0d:83::b1:c0:8e.

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 communications.

Visit next page for Java socket programming.

java.net package

The java.net package can be divided into two sections:

1. A Low-Level API: It deals with the abstractions of addresses i.e. networking identifiers, Sockets i.e. bidirectional data communication mechanism and Interfaces i.e. network interfaces.
2. A High Level API: It deals with the abstraction of URIs i.e. Universal Resource Identifier, URLs i.e. Universal Resource Locator, and Connections i.e. connections to the resource pointed by URLs.

The java.net package provides many classes to deal with networking applications in Java. A list of these classes is given below:

• Authenticator
• CacheRequest
• CacheResponse
• ContentHandler
• CookieHandler
• CookieManager
• DatagramPacket
• DatagramSocket
• DatagramSocketImpl
• InterfaceAddress
• JarURLConnection
• MulticastSocket
• InetSocketAddress
• InetAddress
• Inet4Address
• Inet6Address
• IDN
• HttpURLConnection
• HttpCookie
• NetPermission
• NetworkInterface
• PasswordAuthentication
• Proxy
• ProxySelector
• ResponseCache
• SecureCacheResponse
• ServerSocket
• Socket
• SocketAddress
• SocketImpl
• SocketPermission
• StandardSocketOptions
• URI
• URL
• URLClassLoader
• URLConnection
• URLDecoder
• URLEncoder
• URLStreamHandler

List of interfaces available in java.net package:

• ContentHandlerFactory
• CookiePolicy
• CookieStore
• DatagramSocketImplFactory
• FileNameMap
• SocketOption<T>
• SocketOptions
• SocketImplFactory
• URLStreamHandlerFactory
• ProtocolFamily