Transcript Networks - Dr. Ramesh R. Manza

Networking in Java
SEED Infotech Pvt. Ltd.
1
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
SEED Infotech Pvt. Ltd.
2
Host based Processing
Application
Logic
Server
Data
Mainframe
Clients
Terminal 1
SEED Infotech Pvt. Ltd.
Terminal 2
Terminal 3
3
Terminal 4
Client - Server
DBMS
Application
Logic
Network Server
Client Workstation 1
Application
Logic
SEED Infotech Pvt. Ltd.
Client Workstation 2
Client Workstation 3
Application
Logic
Application
Logic
4
Client Workstation 4
Application
Logic
Web Based Architecture
HTTP
TCP/IP
WEB SERVER
UNIX
INTERNET
WINDOWS
WEB SERVER
SEED Infotech Pvt. Ltd.
MACINTOSH
5
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
SEED Infotech Pvt. Ltd.
6
OSI (Open System Interconnection)Model
APPLICATION
PRESENTATION
SESSION
TRANSPORT
NETWORK
DATA LINK
PHYSICAL
SEED Infotech Pvt. Ltd.
7
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
SEED Infotech Pvt. Ltd.
8
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.
SEED Infotech Pvt. Ltd.
9
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.
SEED Infotech Pvt. Ltd.
10
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.
SEED Infotech Pvt. Ltd.
11
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.
SEED Infotech Pvt. Ltd.
12
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.
SEED Infotech Pvt. Ltd.
13
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.
SEED Infotech Pvt. Ltd.
14
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.
SEED Infotech Pvt. Ltd.
15
TCP/IP Architecture
APPLICATION LAYER
TRANSPORT LAYER
NETWORK LAYER
LINK LAYER
SEED Infotech Pvt. Ltd.
16
CLASSSES
OF IP(IPV4)
ADDRESSES
IP Addressing
Scheme
CLASS A
0
Net id
CLASS B
10
CLASS C
110
CLASS D
1110
Host id
Net id
Host id
Net id
Multicast group id
Class
IP Address Range
A
0.0.0.0 to
127.255.255.255
B
128.0.0.0 to
191.255.255.255
C
192.0.0.0 to
223.255.255.255
D
224.0.0.0 to
239.255.255.255
SEED Infotech Pvt. Ltd.
Host id
17
TCP/IP Architecture
HTTP
FTP
SMTP
TFTP
Telnet
SNMP
Ping
DNS
NNTP
TCP
UDP
Internet Protocol (IP)
ICMP
ARP
RARP
Ethernet, to ken Ring, RS232 ………
SEED Infotech Pvt. Ltd.
18
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
SEED Infotech Pvt. Ltd.
19
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
SEED Infotech Pvt. Ltd.
20
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.
SEED Infotech Pvt. Ltd.
21
Client
An executing program that sends a request to a
server & waits for an response.
Request
Server
client
Response
SEED Infotech Pvt. Ltd.
22
Client Side Scripts
HTML
Javascript
VB script
Jscript
Applets
SEED Infotech Pvt. Ltd.
23