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Lecture notes on various computer applications, Essays (high school) of Computer Applications

Preston University, Pakistan Campus (PUPC)Computer Applications

Lecture notes on various computer applications

Typology: Essays (high school)

2014/2015

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Lecture Notes on Various Computer Applications

By Dr. Vincent A. Ssembatya.

University of Florida and Makerere

University

"Technology is far ahead of the law"

(textbook)

Database Programs

Database programs are applications. Database programs can be thought of as a

computerized file cabinet. Database programs are designed to maintain databases-

collections of information stored on a computer disk.

A database is?

• An information manager.

• Databases make it possible to store, organize and retrieve information in ways

that otherwise would not be possible.

• Databases come in all sizes and shapes from mainframe applications that run

multi-national corporations to appointment calendars in PDAs.

• Just about any collection of information can be turned into a database.

The good:

• Easy access to information makes life easier and more efficient.

The bad:

• Easy access to information can lead to erosion of privacy.

Why databases?

•Databases make it easy to store large quantities of information. The larger the

mass of information, the bigger the benefit of using a database.

• Databases make it easy to retrieve information quickly and flexibly.

• Databases make it easy to organize and reorganize information. You can

quickly switch between schemes.

• Databases make it easy to print and distribute information in a variety of ways.

Discover Essays (high school) of Computer Applications Preston University, Pakistan Campus (PUPC)

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Lecture Notes on Various Computer Applications

By Dr. Vincent A. Ssembatya.

University of Florida and Makerere

University

"Technology is far ahead of the law"

(textbook)

Database Programs

Database programs are applications. Database programs can be thought of as a computerized file cabinet. Database programs are designed to maintain databases- collections of information stored on a computer disk. A database is?

An information manager.
Databases make it possible to store, organize and retrieve information in ways that otherwise would not be possible.
Databases come in all sizes and shapes from mainframe applications that run multi-national corporations to appointment calendars in PDAs.
Just about any collection of information can be turned into a database. The good:
Easy access to information makes life easier and more efficient. The bad:
Easy access to information can lead to erosion of privacy. Why databases?
(^) Databases make it easy to store large quantities of information. The larger the mass of information, the bigger the benefit of using a database.
Databases make it easy to retrieve information quickly and flexibly.
Databases make it easy to organize and reorganize information. You can quickly switch between schemes.
Databases make it easy to print and distribute information in a variety of ways.

Nuts and bolts of a database.

Databases have a specialized vocabulary.
A database is a collection of information stored in an organized form in a computer.
A database program is a software tool for organizing storage and retrieval of that information.
Many of the terms that describe the computer come from the file cabinet terminology of the office.
For databases, the term file means a data file that is a part of a database.
A record is the information relating to one person, item or event.
Each discreet chunk of information in a record is called a field.
There are different types of fields. Field types include a text fields that contain text, a numeric fields which contain only numbers and date fields which contain only dates. Other field types can include other types of data including graphics, photos, sounds or even videos. Computed fields contain formulas similar to spreadsheets.
Most database programs have more than one way that data can be viewed. For example, form views show one record at a time and list views which show several records at a time. Database operations
Most database programs can easily import or receive data in the form of text files created with word processors, spreadsheets or other databases.
You can browse through these information records just as you would if they were paper records in a notebook.
You can make an information request from the database called an information query.
A query may be a simple search for or a specific record or a search for a group of records that meet defined criteria.
A sort command allows you to arrange records in alphabetic or numeric order based on values in one or more fields.
Reports are the most common types of database printouts.
Many database programs don't print themselves; they export data or transport selected records to word processing programs with mailmerge capabilities. Queries
Queries may be simple or complex, but like most computer operation parameters, they must be precise and unambiguous.
The exact method for making a query depends on the computer's user interface.
Some types require the user to use a special query language that is more specific than English.
Most modern database programs support SQL which is the standard for programming complex queries.
Users are often shielded from the complexities of the query language by graphical user interfaces that allow point-and-click queries.

Databases used to consist solely of mainframe computers, which kept data in one central mainframe called a data warehouse. Now, with client/server computing, information can be spread over many geographically separate computers. This model is called a distributed database. ERP (Enterprise Resource Planning) software
This type of software looks at the data processing needs of a whole company (commonly called an enterprise .) It provides the company with a modular approach to data processing that is integrated. ERP software creates one process for each activity, eliminates all duplications and redundant processes thus increasing efficiency.
SAP R/3 is the big player in ERP (Systems, Applications and Products in data processing. The "R" stands for real time. The three means it is the third version, the client/server version, of SAP.)
SAP has 44% of ERP market. Peoplesoft is major competitor.
SAP is a big company with a product in huge demand. Their 3rd quarter revenue was up 82 percent in 97.
An SAP implementation changes the way a corporation does business.
There are 12 jobs for every person trained and experienced in SAP.
SAP software alone costs corporations $500K. The Future?
Object-oriented database capabilities are being incorporated into relational databases. Object-oriented databases may come to dominate. In these types of databases rather than just storing records in tables, databases may store objects that contain procedures or instructions along with data.
Multimedia technology is changing the way users interact with data, especially over the Internet. Privacy
The price we pay for convenience of information access is the loss of privacy.
Data is one of the currencies of our time.
Marketing databases are the tip of the iceberg.
There is a sea of information out there we have little control over. Sources of information include: credit, banking, voter registration, warranty registration, magazine and newsletter subscriptions, DMV, airline reservations, census data, arrest records, etc.
With networked computers it is easy to link information.
Record matching is easy and quick using social security, drivers license and other identification numbers that can be transformed into key fields.
Data is often wrong.
Data can become immortal.
Data is often insecure.
Technology is far ahead of the law.

Connectivity and Networking

A computer network is any computer system that links two or more computers. Telecommunications

Samuel Morse invented the telegraph in 1844
Alexander Bell invented the telephone in 1876
Telecommunications today means long-distance electronic communications in a variety of forms, including networks Networks
Hardware, networks allow people to share hardware
Software, networks allow people to share data and software
People, networks allow people to work together in ways that were impossible before Networks extend the reach of computers
Networks allow computers to communicate their binary electrical signals beyond the confines of the local system
Users connect to a network, either directly through a network card or through a phone based connection via a modem People connect to networks:
With a modem (either internal or external)
With a network interface card (NIC) Network Interface Cards (NICs)
Add a serial port to a system
Connect directly to the network
Converts the computers low power internal signals to higher powered signals that can be transmitted over the network
Are measured in speeds rated in megabits per second

LANs and WANs (Local Area Networks and Wide Area Networks)

This is a WAN:

LANs, and a single user remote site, are shown here connected in a WAN. The networks in San Francisco and San Jose are LANs. The whole network, with all sites considered, constitute a WAN. Communication Software

Computers need communication software to interact
Computers on a network must follow the same protocol - a set of rules for the exchange of data between nodes
Many communications on the network are taken care of by the Network Operating System (NOS)
Most medium sized or larger LANs are set up following the Client-Server model
Some small LANs follow a peer-to-peer model Client-Server Networks: This is the type of network used in this lab. Drives physically located on the server can be mapped to appear as local drives on the local computer. Files saved on these mapped drives are actually saved on the remote server. (Note: Mapped drives appear when you open the "my computer" icon on your computer's desktop. Without mapping only drives physically located on the computer would appear. This mapping is done by the network administrator.) Client-server
This is a hierarchical model where some computers are servers and others are clients
Typical networks using this approach are Novell and NT based networks (there are others, including Appleshare File Servers)
The server computers fulfils requests from client computers for data and other resources
There can be many types of servers, including file servers, mail servers, print servers and web servers

In a client-server LAN the bulk of the NOS exists on the servers Peer-to-peer
The nodes on the network serve as both clients and servers
Every user can make files available to other users on the LAN
One problem is that resources go away when users turn off their workstations
Modern Windows and MacOS computers have this ability built in Hybrid Networks
The most common type of network
Combines client-server and peer-to-peer Terminal emulation software
Terminal emulation software allows a personal computer to function as a terminal of a larger and/or more sophisticated computer, typically a mainframe
This larger computer is called the host Network advantages
Since resources are shared peripherals can be more sophisticated and standardized, such as expensive laser printers
(^) Servers allow users to share files and/or software that's stored in a central location where it's available for everyone
Software is licensed. Copyright issues must be respected and addressed!
Networks make it possible for users of different kinds of systems to share data
Data can be sent between remote sites very quickly
Using GroupWare multiple users can work on the same documents at the same time (Lotus Notes is a very popular type of GroupWare) Interpersonal Computing Email
Proprietary systems for Email used to be common, but these have been eclipsed by Internet savvy Email packages
(^) Each Email user has a mailbox
Everybody can send mail to the mailbox but only the owner of the mailbox can open it Teleconferencing
A teleconference is a real-time on-line meeting between two or more people
Give and take format
Often called Chat and Talk
Chat rooms tend to be chaotic Delayed teleconference
In effect users share a mailbox to discuss a topic of common interest
Usenet newsgroups are a good example of this "E" vs. "snail" mail
Email is faster and cheaper
Email doesn't depend on location

Email and teleconferencing vs. meetings

Participants nave time to think about topics and decisions can evolve over time
Long distance meetings are possible without travel
Emphasize the idea over the messenger. You can't see who is sending the message. "Everyone is the same on the internet." Downsides of Email (and similar technologies)
Junk Email is even easier and cheaper to send than junk snail mail
Email is easily lost and/or forgotten. It is often impossible to know if it was even delivered.
Email can be read by others
Email can be faked, difficult to verify!
Email works only if everyone is connected and reads their mail
Email can be dehumanising and closes the door to many types of human interaction
(^) Email shifts the communication advantage away from the physically attractive ones and the good orators, toward the good writers and those who know the technology the best. Is everyone really the same on the Internet?

Dial-up services Electronic bulletin board systems (BBSs)

(^) An electronic place for posting messages and reading messages posted by others
Most are small operations
Many divide messages into categories called SIGs, for special interest groups
Often used to download and upload files and software
Runs unattended with the sysop, or system operator, needed only to maintain the system On-line databases
Place to get instant answers to very specific questions
Most for very specific information for customers with specific information needs
Most, like Dow Jones News Retrieval Service, by subscription only Commercial on-line services
On-line information services like America Online, CompuServe etc.
Allow users to send and receive information like BBSs do
Able to handle large volume of information and users
Services include: news, research databases, shopping, banking, games, bulletin boards, communications
Most offer connections to the Internet Worth noting
Use of on-line services can be addictive and expensive

They have changed the way many people meet and relate to each other, there have been many on-line marriages (and divorces)
Heavy users of computer dial-up networking include telecommuters. (Many are working parents or people who care for invalid family members.)
(^) For a growing percentage of our population networks and on-line services are as an important part of their lives (or more important) as TV and phones!
Some people spend hours on-line each day Facsimile transmission (fax)
The sending fax machine scans each page, converts the scanned image into a series of analog pulses and sends those signals, via built in modem, over the phone lines
The receiving machine uses that signal to construct a facsimile (a fax, a copy) of the original document
A computer can also use a fax modem to receive and send a fax Voice mail & computer telephony
(^) Voice mail is a sophisticated computer based system for taking messages and routing phone calls
Often too many layers to go through to speak to a human
Telephony software allows calls to be handled by computers sometimes over the computer network Video teleconferencing
Combines video and computer technology to allow people to communicate face to face over long distances
Expensive, but cheaper and more convenient than travel Electronic Funds Transfer EFT
Money is just another form of information
(^) Automated teller machine (ATM), is a specialized computer terminal hooked up via a computer network to a banks mainframe computer
ATMs are not needed for EFTs to happen, can be handled automatically or via telephone or user logging in personal computer Personal Digital Assistants (PDAs)
Can meet many communication requirements
A PDA can combine cell phone, fax and other communication equipment in a light weight wireless box

The Internet

A technology.
A tool.
A culture. The Internet is:
(^) An interconnected network of thousands of networks linking academic, research, government, commercial institutions and other organizations and individuals.
The Internet was originally written by and for computer scientists.
The Internet is not centrally controlled. It is in a sense, massive anarchy built around common protocols. Internet services include:
Electronic mail (E-mail), Internet users can send mail messages, data files and software programs to other users.
Remote login (telnet), users on one system can access and log into a host system across the Internet with just a handful of commands.
File transfer (File Transfer Protocol, "FTP") , some internet servers house vast archives of shareware, public domain software, pictures, literary works and other files. Users can download this stuff from these servers to their own computers.
Newsgroups (Usenet) the Usenet is the home of thousands of Usenet newsgroups that are ongoing discussion groups on every imaginable topic.
The World Wide Web, a collection of multimedia documents that are linked in a hypertext web.

"Browser: An application that downloads HTML files from a Web server and

displays the formatted file. Also called a client."

How big is it? The Internet's costs are shared by the thousands of organizations that are connected to it.

Growing too fast to track, 2 million new users per month!
Too decentralized to quantify.
Does not have hard boundaries. Transmission Control Protocol/Internet Protocol (TCP/IP)
TCP/IP is an open standard, not owned by anybody.
Hidden in software, generally invisible. TCP protocols, for packet routing
Information on the Internet is broken down into packets.
Each packet contains an address, like letters going through the post office, each packet has all the information it needs to reach its destination.
Different packets might take different routes.
When the packets reach their destination they are reassembled into the original message.

This follows a packet-switching model that is flexible and robust. IP protocols, for addressing
Every host computer on the Internet has a unique IP address.
In the current version of IP (IPv4), the IP address is 4 bytes.
The binary address is represented by four decimal numbers separated by dots that might look like 123.23.168.
Every packet includes the IP address of the sending (server) computer and the receiving (client) computer.
To further confuse you (and because they are running out of IP addresses) there is another, longer, IP protocol coming out called IPv6. 3 ways to access the Internet
Direct connection , a full time connection on a LAN.
Dial-up, terminal emulation, via modem your remote computer is functioning as a terminal on a host computer that has a direct connection.
Full-access dial-up connection. Via SLIP (Serial Line Interface Protocol) or PPP (Point to Point Protocol) the remote computer has temporary full access to the internet. It is a part of the Internet while it is connected. Various levels of access
Internet Service Providers (ISP's) generally offer different levels of connection at different prices.
In some areas free access is available, "freenet."
Many computer networks, bulletin board systems and on-line services are separate systems connected to the Internet via gateways -computers connected to two networks - and are sometimes called "outernets." Intranets
Self-contained networks built around Internet protocols and/or standards.
(^) A typical Intranet offers Internet services, but not all of these services are available to users outside the organization.
Intranets are generally separated from the outside world with firewalls. Internet applications are different
Based on the client/server model.
The distributed nature of the Internet.
Various connections and types of clients. Internet users see things different The same content presented in a variety of ways to users. As a designer of Internet content, you need to keep in mind that only so much can be controlled. UNIX
The dominant operating system on the Internet, an Internet fact of life.
UNIX has long been the choice for workstations and mainframes in research and academia.
There are many flavors of UNIX, available for most types of computers.
UNIX, like DOS, is character based, (sometimes with a graphical shell.)

Make a contribution, help others! Information on the Net
The most popular use of the Internet is getting information.
The Internet is a giant global library with nobody in charge.

Telnet

Remote login protocol
Sometimes need an account, but many systems allow you to login as a guest. File Transfer Protocol (FTP)
Allows users to transfer (usually compressed) files from remote sites (FTP severs) to their computers.
FTP and Telnet often used as verbs. Other Data Mining Tools
Gopher, (the proto web), character and menu based.
Archie, checks FTP servers and updates an Archie sever database.
Veronica and Jughead, do what Archie does, but for Gopher servers.
Wide Area Information Server (WAIS), specialized database system spread among computers that contain specific information in databases spread across the Net. The World Wide Web
Introduced in 1993 at CERN.
(^) The killer application of the Internet?
The heart of the Web is the concept of hypermedia. The Web is a giant hypermedia document created by unrelated authors and spread over thousands of computers around the world.
Web browsers are client programs that allow you to explore web (Internet Explorer, Navigator/Communicator.)
Links to other pages appear seemingly at random.
Content often can be stale (cobwebs) or be removed with old links remaining.
Browsers include tools for keeping personal lists of favorite sites (bookmarks and/or favorites.)
(^) Search engines facilitate searching for content.
Web addresses are Uniform Resource Locators (URLs). A typical URL
http://jmcweb.sjsu.edu/sloan/apsc101/home.htm
The first part (http:) is the protocol. Note: A "protocol" is an agreed upon way, a set of rules, that computers use to exchange information with each other.
The second part (jmcweb.sjsu.edu) is the address of the host containing the resource.
the third part (sloan/apsc101/home.htm) describes the path, the nesting of directories, to the file that is the resource (home.htm).

"In this age of advanced technology, thick walls and locked doors cannot

guard our privacy or safeguard our personal freedom"

Computer security Computers and crime

Computers have an ever increasing role in fighting crime.
Law enforcement facing an ever increasing amount of computer crime.
Most computer crimes undetected.
Most of those that are detected are not reported.
(^) Computer crimes cost billions of dollars each year. Types of computer crimes
Use of computers to steal goods, money, information, software and services.
Use and creation of Trojan horses, viruses, worms, logic bombs, etc. to sabotage systems. Hackers
The myth is that hackers are responsible for most computer crimes.
Actually, they are responsible only for a small proportion.
Typical crimes committed by trusted employees.
Software piracy is the most common form of computer crime. Security
Badges and keys, traditional forms of security, are not enough.
Passwords, encryption, shielding and audit-control software are used to secure data.
Backups are critical!
Security measures can be oppressive to the point of threatening individual rights. Other threats
Computer systems also threatened by bugs and glitches.
Increasingly, lives depend on performance of computers.
As systems become more complex likelihood of bugs grows Military applications
Reliability issues are especially important.
Humans are being squeezed out of decision-making loop.
The debate over high-tech weaponry is bringing security issues to public's attention.

"It's impossible to make anything foolproof, because fools are so

ingenious."

Systems Design and Development

Today's PC software is so sophisticated that it is almost invisible to the user. But underneath the virtual environment that is your computer is an incredibly complex software substructure. The programming process Like problem solving, the programming process is a four step process.

Defining the problem.
Defining, refining and testing the algorithm.
Writing the program.
Testing and debugging the program. Control structures
Logical structures that control the order in which instructions are carried out. Three basic control structures
Sequence
Selection
Repetition Coding
(^) Statements in the algorithm translate directly into lines of code in whichever programming language best fits the programmer's needs.
The program needs to be entered into the computer's memory, saved as a disk file and needs to be translated into the computer's native machine language before it can be executed, or run.
Because it's a computer program, every word, symbol, and punctuation mark has an exact, unambiguous meaning.
To enter code into computer, programmers use a text editor - like a word processor without formatting features.
Once it is coded it is translated into machine language using an interpreter or a compiler. Programming Languages
There are many types of programming languages.
Assembly languages (low level languages) are very similar to machine languages and are used a lot with programs that have to relate to hardware.
High level languages are more independent of hardware and more transportable between platforms.
High level programs often are designed for different types of applications.
Modern programming languages often referred to as fourth generation languages (4GL's). Structured Programs
(^) Previous programs required a lot of "go to" statements that were used to transform control to other parts of programs.
Structured programs are built from modules and submodules. Object-oriented programming (OOP)
Similar to multimedia and hypermedia.

Lecture notes on various computer applications, Essays (high school) of Computer Applications

Related documents

Partial preview of the text

Download Lecture notes on various computer applications and more Essays (high school) Computer Applications in PDF only on Docsity!

Lecture Notes on Various Computer Applications

By Dr. Vincent A. Ssembatya.

University of Florida and Makerere

University

"Technology is far ahead of the law"

Database Programs

This is a WAN:

"Browser: An application that downloads HTML files from a Web server and

displays the formatted file. Also called a client."

"In this age of advanced technology, thick walls and locked doors cannot

guard our privacy or safeguard our personal freedom"

"It's impossible to make anything foolproof, because fools are so

ingenious."