1. SEED Infotech Pvt. Ltd. 1 Networking in Java

2. SEED Infotech Pvt. Ltd. 2 Objectives of This Session Describe issues related to any type of network using OSI model State what is a protocol Describe the TCP/IP protocol Describe the client-server concept with respect to Internet State the features of http. State the need for client side scripts Identify the reasons for popularity of java as a client side script

3. SEED Infotech Pvt. Ltd. 3 Host based Processing Data Application Logic Application Logic Server Clients Mainframe Keystrokes Terminal Characters Terminal 1Terminal 2Terminal 3Terminal 4

4. SEED Infotech Pvt. Ltd. 4 Client - Server DBMS Network Server Requests Results Client Workstation 1 Application Logic Application Logic Application Logic Application Logic Application Logic Application Logic Application Logic Application Logic Client Workstation 2Client Workstation 3Client Workstation 4 Application Logic Application Logic

5. SEED Infotech Pvt. Ltd. 5 Web Based Architecture INTERNET UNIX WINDOWS MACINTOSH WEB SERVER HTTP TCP/IP

6. SEED Infotech Pvt. Ltd. 6 Protocol Protocols are rules and procedures for communication. Lays out the details of how a computer can send & receive data on a network. Protocols here govern: Packaging of data into packets. Speed of transmission. Recreation of data to its original form. Eg: of network protocols: TCP/IP, AppleTalk, NetBEUI etc

7. SEED Infotech Pvt. Ltd. 7 OSI (Open System Interconnection)Model APPLICATION PRESENTATION SESSION TRANSPORT NETWORK DATA LINK PHYSICAL

8. SEED Infotech Pvt. Ltd. 8 The OSI Layers 7) Application: Provides different services to the applications 6) Presentation: Converts the information 5) Session: Handle problems which are not communication issues 4) Transport: Provides end to end communication control 3) Network: Routes the information in the network 2) Data Link: Provides error control between adjacent nodes 1) Physical: Connects the entity to the transmission media

9. SEED Infotech Pvt. Ltd. 9 The OSI Layers Application Layer Provides different services to the applications Serves as a window for applications to access network services. Handles general network access, flow control and error recovery.

10. SEED Infotech Pvt. Ltd. 10 The OSI Layers Presentation Layer Determines the format used to exchange data among the networked computers. Translates data from a format from the Application layer into an intermediate format. Responsible for protocol conversion, data translation, data encryption, data compression, character conversion, and graphics expansion. Redirector operates at this level.

11. SEED Infotech Pvt. Ltd. 11 The OSI Layers Session Layer Allows two applications running on different computers to establish use and end a connection called a Session. Performs name recognition and security. Provides synchronization by placing checkpoints in the data stream. Implements dialog control between communicating processes.

12. SEED Infotech Pvt. Ltd. 12 The OSI Layers Transport Layer Responsible for packet creation. Provides an additional connection level between the Session layer. Ensures that packets are delivered error free, in sequence with no losses or duplications. Unpacks, reassembles and sends receipt of messages at the receiving end. Provides flow control, error handling, and solves transmission problems.

13. SEED Infotech Pvt. Ltd. 13 The OSI Layers Network Layer Responsible for addressing messages and translating logical addresses and names into physical addresses. Determines the route from the source to the destination computer. Manages traffic such as packet switching, routing and controlling the congestion of data.

14. SEED Infotech Pvt. Ltd. 14 The OSI Layers Data Link Layer Sends data frames from the Network layer to the Physical layer. Packages raw bits into frames for the Network layer at the receiving end. Responsible for providing error free transmission of frames through the Physical layer.

15. SEED Infotech Pvt. Ltd. 15 The OSI Layers Physical Layer Transmits the unstructured raw bit stream over a physical medium. Relates the electrical, optical mechanical and functional interfaces to the cable. Defines how the cable is attached to the network adapter card.

16. SEED Infotech Pvt. Ltd. 16 TCP/IP Architecture APPLICATION LAYER TRANSPORT LAYER NETWORK LAYER LINK LAYER

17. SEED Infotech Pvt. Ltd. 17 IP Addressing Scheme (IPV4) ClassIP Address Range A0.0.0.0to127.255.255.255 B128.0.0.0to191.255.255.255 C192.0.0.0to223.255.255.255 D224.0.0.0to239.255.255.255 CLASSSES OF IP ADDRESSES CLASS A CLASS B CLASS C CLASS D 0Net idHost id 10Net idHost id 110Net idHost id 1110Multicast group id

18. SEED Infotech Pvt. Ltd. 18 TCP/IP Architecture HTTP TFTP Ping FTP TelnetDNS SMTP SNMP NNTP TCPUDP Internet Protocol (IP) ICMP ARPRARP Ethernet, to ken Ring, RS232 ………

19. SEED Infotech Pvt. Ltd. 19 TCP protocol Provides communications in a heterogeneous environment. Routable, defacto standard for internetworking. Connection oriented protocol. Relies on IP for addressing & routing Guarantees reliable delivery in the order in which packets were sent. E.g.’s of app’s that run on top of TCP: FTP, TelNet, HTTP

20. SEED Infotech Pvt. Ltd. 20 UDP protocol Connectionless protocol. Relies on IP for addressing & routing If you send datagram over a UDP protocol, it may not arrive, if it does, it may arrive out of order etc. E.g.’s of app’s that run on top of UDP: SNMP, TFTP

21. SEED Infotech Pvt. Ltd. 21 Server Applies to any program that offers a service that can be reached over a network. Accepts a request over the network, performs its service & returns the result to the requester. Usually servers are implemented as application prgs.

22. SEED Infotech Pvt. Ltd. 22 Client An executing program that sends a request to a server & waits for an response. client Server Request Response

23. SEED Infotech Pvt. Ltd. 23 Client Side Scripts HTML Javascript VB script Jscript Applets