Data Communication and Networking
STANDARD ORGANIZATIONS
Standards are developed through the cooperation of standards creation committees, forums, and government regulatory agencies.
STANDARD CREATION COMMITTEES:
While many organizations are dedicated to the establishment of standards, data telecommunication in North America rely primarily on those published by the following:
Ø International Organization for standardization(ISO):The ISO is a multinational body whose membership is drawn mainly from the standards creation committees of various governments throughout the world. The ISO is active in developing cooperation in the realms of scientific, technological, and economic activity.
Ø International telecommunication Union-Telecommunication Standards Sector(ITU-T):By the early 1970’s, a number of countries were defining national standards for telecommunication, but there was still little international compatibility. The UN responded by forming ITU, a committee, CONSULTATIVE COMMITTEE FOR INTERNATIONAL TELEGRAPHY AND TELEPHONY(CCITT).
Ø American National Standards Institute(ANSI):Despite its name, the American National Standards Institute is a completely private, nonprofit corporation not affiliated with the U.S federal government.
Ø Institute of Electrical and electronics engineers(IEEE):The IEEE is the largest professional engineering society in the world. As one of its goals, the IEEE oversees the development and adoption of international standards for computing and communication.
Ø Electronic Industries Association(EIA):Aligned with ANSI, the EIA is a non profit organization devoted to the promotion of electronics manufacturing concerns.
FORUMS:
Telecommunications technology development is moving faster than the ability of standards committees to ratify standards. Standards committees are procedural bodies and by nature slow-moving. The forums work with universities and users to test, evaluate, and standardize new technologies.
Regulatory Agencies:
All communication technology is subject to regulation by Government agencies such as Federal Communications Commission (FCC) in the United States. The FCC has authority over interstate and international commerce as it relates to communications.
BY
V.DHIVYA
III BCA
DATABASE MANAGEMENT SYSTEM
TYPES OF DATABASE
Ø Hierarchical database
Ø Network database
Ø Relational database
Ø Object oriented database
HIERARCHICAL DATABASE:-
The earliest database management systems were based on hierarchical method of storing data.
The early systems were an extension of the COBOL file structure.
To provide flexible access, this system was extended with network database.
The hierarchical database approach begins by claiming that business data often exhibits a hierarchical relationship.
The hierarchical database approach relatively fast-as long as only want to access the data from the top.
The most serious problem related to data storage is difficulty of searching for item in the bottom or middle of the hierarchy.
Example:
To find all of the customers who ordered a specific item, the database would have to inspect each customer, every order, and each item.
NETWORK DATABASE:-
The network database has nothing to do with physical networks. Instead, the network model is named from the network of connection between the data elements.
The primary goal of the network model was to solve the hierarchical problem of searching for data from different perspectives.
The problems with the network approach is that the indexes must be built before the user can ask a questions. Consequently, the developer must anticipate every possible question that user must ask about the data. Worse, building and maintaining the indexes can require huge amounts of processor item and storage space.
Example:
LAN (Local Area Networks)
RELATIONAL DATABASE:-
The relational database approach in the 1970’s and within several years three elements came together to make the relational database the predominant method for storing data.
FIRST: theoreticians define the basic concepts and illustrated advantages.
SECOND: programmers who built database management system software created efficient components.
THIRD: hardware performance improved to handle the increased demands of the system.
Example:
Each table stores attributes in columns that describes specific entities:
Customer (customer ID, Name, …..) order (order ID, customer ID, Order Date ,…….) Items Ordered (order ID, item ID, Quantity,…….) Items (items ID, description, price,……….)
OBJECT ORIENTED DATATYPES:
An object-oriented (OO) database is a new and evolving method of organizing data. The object oriented approach began as a new method to create programs.
The goal is to define objects that can be reused in many programs –thus saving time and reducing errors.
The properties describe the object, just as attributes describe an entity in the relational database.
The “methods” are the true innovation of the (OO) approach. Methods are short programs that defines the action that each object can take.
The (OO) approach is fundamentally alternating the way programmers create applications. As an application developer, you will be using DBMS software that was created with an (OO) approach. Hence, you will use the objects, properties, and methods that have already been defined.
There are two basic approaches to handling true Object -Oriented Data:
1. Extend the relational model so that it can handle typical Object Oriented features
2. Create a new Object-oriented DBMS, now a days most commercially successful database systems follow the first approach by adding object features to the relational method.
FEATURES:-
There are three features suggested to add (OO) capability:
· Abstract the data type.
· Sub tables
· Persistent stored modules.
Example:
The code to add a new customer would be stored with the customer object. The innovation is that this method is stored with the object definition.
DONE BY
NAME: Farana Begum.M.S
MULTIMEDIA
WHAT IS MULTIMEDIA?
Multimedia is any combination of text, art, sound, animation, and video delivered to you by computer or other electronic or digitally manipulated means. It is richly presented sensation.
WHERE TO USE MULTIMEDIA
Multimedia is appropriate whenever a human interface connects a human interface connects a human user to electronic information of any kind. Multimedia enhances minimalist, text-only computer interfaces and yields measurable benefits by gaining and holding attention and interest.
· Multimedia in Business.
· Multimedia in Schools.
· Multimedia at Home.
· Multimedia in public places.
MULTIMEDIA IN BUSINESS:
ü Business application for multimedia includes presentations, trainings, marketing, product demos, advertising, simulations, databases, catalogs, instant messaging and networked communication.
ü Flight attendants learn to manage international terrorism and security through simulation.
ü Drug enforcement agencies of the UN are trained using interactive videos and photographs to recognize likely hiding places on airplanes and ships.
ü Medical doctors and veterinarians can practice surgery methods via simulation prior to actual surgery.
ü Mechanics learn to repair engines.
ü Salespeople learn about product lines and leave behind software to learn their customers.
MULTIMEDIA IN SCHOOLS:
ü Multimedia will provoke radical changes in the teaching process during the coming decades, particularly as smart students discover they can go beyond the limits of traditional teaching methods.
ü An interesting use of multimedia in schools involves the students themselves. Students can put together interactive magazines and Newsletters, make original art using image manipulation software tools, interview students, townspeople, coaches and teachers and they can even make quick time movies. They can also design and run websites.
ü ITV (Interactive TV) is widely used among campuses to join students from different locations into one class with one teacher.
MULTIMEDIA AT HOME:
ü From gardening, cooking, home design, remodeling multimedia has entered the home.
ü Today, home consumers of multimedia either own a computer with an attached CD-ROM or DVD drives or a set-top player that hooks up to the television.
ü Live Internet pay-for-play gaming with multiple players has also become popular, bringing multimedia to homes on the data highway, often in combination with CD-ROMs inserted into the users machine.
MULTIMEDIA IN PUBLIC PLACES:
ü In hotels, train stations, shopping malls, museums, libraries and grocery stores, Multimedia is already available at stand-alone terminals providing information and help for customers.
ü Multimedia is piped to wireless devices such as cell phones and PDAs.
BY
S.JOTHI LAKSHMI
III BCA
NETWORKS
NETWORKS:
A network is a set of devices (often refer to as nodes) connected by media links. A node can be a computer, printer, or any other device capable of sending and/or receiving data generated by other nodes on the network. The link connecting the devices are often called communication channels
Distributed Processing
Networks use Distributed processing, in which a task is divided among computers, Instead of a single large machine being responsible for all aspects of a process, each separate computer (usually a personal computer or workstation) handles a subset.
Advantages of distributed processing include the following:
§ Security/encapsulation: A system designer can limit the kinds of interactions that a given user can have with entire system for example. A bank can follow users access to their own accounts through an automated teller machine(ATM) without allowing them access to the bank`s entire database
§ Distributed databases: No one system needs to provide storage capacity for entire database. For example, the world wide web give users access to information that may me actually stored and manipulated anywhere on the internet.
§ Faster problem solving: Multiple computers working on parts of a problem concurrently often can solve the problem faster than a single machine working alone .for example, networks of pCs have broken encryption codes that were presumed to be unbreakable because of the amount of time it would take a single computer to crack them.
§ Security through redundancy: Multiple computers running the same program at the same time can provide security through redundancy. For example, in the space of shuttle, three components run the same program so that if one has a hardware error, the other two can override it.
§ Collaborative processing: Both multiple computers and multiple users may interact on a task. For example, in multiuser network games the action of each player are visible to and affect all the others
Network Criteria
To be considered effective and efficient, a network must meet a number of criteria. The most important of these are performance, reliability, and security.
Performance:
Performance can be measured in many ways, including transit time and response time. Transit time is the amount of time required for a message to travel from one device to another. Response time is elapsed time between an inquiry and a response
The performance of a network depends on a number of factors, including the number of users, the type of transmission medium the capabilities of the connected hardware, and the efficiency of the software.
§ Number of users: Having a large number of concurrent users can show response time in a network not designed to coordinate heavy traffic loads. The design of a given network is based on an assessment of the average number of users that will be communicating at any one time. In peak load periods, however, the actual number of users can exceed the average and thereby decrease performance. How a network responds to loading is a measure of its performance.
§ Type of transmission medium: The medium defines the speed at which data can travel through a connection. Today`s networks are moving to faster and faster transmission media, such as fiber-optic cabling A medium that can carry data at 100 megabits per second is 10 times more powerful than a medium that can carry data at only 10 megabits per second. However, the speed of light imposes an upper bond on the data rate.
§ Hardware: The types of hardware included in a network affect both the speed and capacity of transmission .A higher-speed computer with greater storage capacity provides better performance.
§ Software: The software is used to process data at the sender,receiver, and intermediate nodes also affects network performance .Moving a message from node to node through a network requires processing to transform the raw data into transmittable signals to route these signals to the proper destination , to ensure the error-free delivery. Well-designed software can speed the process and make transmission more effective and efficient
Reliability
In addition to accuracy of delivery, network reliability is measured by frequency of failure. The time it takes a link to recover from a failure network`s robustness in a catastrophe.
§ Frequency of the failure: All networks fail occasionally. A network that fails often, however, is of little value to a user.
§ Recovery time of a network after a failure: How long does it to take restore service? A network that recovers quickly is more useful than one that does not.
§ Catastrophe: Networks must be protected from catastrophic events such as fire, earthquake, or not theft. One protection unforeseen damage is reliable system to back up network software.
Security
A network security issues include protecting data from unauthorized access and viruses.
§ Unauthorized access: For a network to be useful, sensitive data must be protected from unauthorized access .protection can be accomplished at a number of levels. At the lowest levels are user identification codes and passwords .At a higher levels are encryption techniques
§ Viruses: Because a network is accessible from many points it can be susceptible to computer viruses. A good network is protected from viruses by hardware and software designed Applications. In the short time they have been around , data communication networks have become an indispensable part of business industry and entertainment. Some of the network application in different fields are the following:
§ Marketing and sales: Computer networks are used extensively in both marketing and sales organization .Marketing professionals use them to collect exchange and analyze data relating to customer needs and product development cycles. sales application including teleshopping, which uses order-entry computers or telephones connected to an order –processing network, and on-line reservation services for hotels airlines and so on
§ Financial services: Today`s financial services are totally dependent on computer networks. Application include credit history searches foreign exchange and investment services , and electronic funds transfer (EFT),which allows a user to transfer money without going into a bank .
§ Manufacturing: Computer networks are used today in many aspects of manufacturing including the manufacturing process itself. Two applications that use networks to provide essential services are computer –assisted design(CAD) and computer –assisted(CAM),both of which allow multiple users work on project simultaneously.
§ Electronic messaging: Probably the most widely network application is electronic mail(e-mail)
§ Directory services: Directory services allow lists of files to be stored in a central location to speed worldwide web search operations.
§ Information services: Network information services include bulletin boards and data banks. A world wide web site offering the technical specification for a new product is an information service.
§ Electronic data interchange(EDI):EDI allows business information(including documents such as purchase order and invoices ) to be transferred without using paper
§ Teleconferencing: Teleconferencing allows conferences to occur without participants being in the same place .Applications include simple text conferencing ,voice conferencing and video conferencing.
§ Cellular telephone: In the past two parties wishing to use the services of the telephone company had to be linked by a fixed physical connection. Today`s cellular networks make it possible to maintain wireless phone connections even while traveling over larger distances.
§ Cable television: Future services provided by cable television networks may include video on request , as well as the same information, financial, and communications services currently provided by the telephone companies and computer networks.
DONE BY
NAME: SAIPRIYA.S
CLASS: III BCA
