Information Technology and Systems (MB231) : January 2004 Suggested Answers Section B and C

Section B : Caselets
1. A relational database consists of a collection of tables each of which is assigned a unique name. Each row in a
table represents a relationship among a set of values. Since a table is a collection of such relationships, there is a
close correspondence between the concept of table and the mathematical concept of relation, from which the
relational database has evolved. The goal of a relational DBMS is to make data easy to store and retrieve. A
modern relational system has several useful tools. Input screens allow users to enter data. Reports can be created
by laying out data, text and graphics on the screen without programming. You can get answers to questions with
a query language or even by pointing to tables and data on the screen. Security can be ensured by allowing or
denying access to some portions of the data. Most systems include an application generator that can tie input
screens, queries and reports together with a menu system. A complex application can be created by typing a few
titles on the screen, without writing a single line of traditional program code.
Relational databases are specifically designed to allow many tables to be created and then combined in
interesting ways. As most of the business problems involve data stored in different tables, the relational
database system would provide the necessary report for the query given.
DESIGNING A RELATIONAL DATABASE
The important step in designing any relational database is the initial definition where one decides exactly what
columns to put in each table. The table fits together the columns and enables the user to get any combination of
the needed data. It is also easy to make additions and changes to the tables if the tables are defined correctly.
However, getting answers to certain questions is difficult if the tables are not defined correctly. Redefining
tables and reports to fix such problems can be time consuming.
Data Definition
The first step in defining tables is to identify the information that one will need to make decisions. The input
forms and reports that will be used must be collected and designed. Then the data items displayed on these
forms and reports are organized into tables. Each table must obey certain rules. First, every table must have a
primary key, which is one or more columns that uniquely identify each row. Often, an ID number serves as a
primary key. Second, there must be only one value stored in each cell. If there is a column for numbers, it
cannot hold a home phone number and a business phone number at the same time. The solution in this case is to
create two columns: Home phone and Workplace phone.
The process of defining tables is called data normalization. An important rule here is that every non-key column
must depend on the primary key and nothing but the key. This means each table should refer to only one object
or concept.
Data Input Screens
Data is rarely entered into the database tables directly. Instead, input forms are generally used to enter some
data which makes the process easy. Input screens can also be used to perform calculations such as taxes. Longer
descriptions and help screens can be included to make it easier for the user to remember what goes in each column.
Colors and boxes are also used to make the screen easier to read.
These input screens look like existing paper forms. Most input forms begin as a screen that is empty except for
a menu line or some other help message. Three types of information can be placed on an input screen: (1)
simple text, (2) input blanks or (3) data retrieved from the database. A Windows-based DBMS can also include
pictures, graphs, sound and video.
Most database systems automatically enter some types of data, such as the current date. If necessary, users can
change the date, but it saves time by enabling them to press ENTER to accept the displayed value. The same
situation holds for sequential items like order numbers, where the DBMS can automatically generate each
unique order number.
Data entry boxes should be filled once the basic tables are filled. For instance, move the screen cursor to a
position next to the Date label, then tell the DBMS to enter data at that point. You can also specify the default
values. In the case of the date, the DBMS will let you enter a name like date( ) that will display the current date.
You can control the way the data is displayed by using a format command. A date might be displayed as
08/29/77 by entering the format MM/DD/YY. You can also enter this in the sales table, which is connected to
the orders table by the order number. Type in the column names for item #, description, price and quantity. The
DBMS input form will define this part of the table as a scrolling region or sub form. This allows the user to see
several rows at a time, and the appropriate keys (or the mouse) will move the screen cursors up and down as
users enter data into any row.
The only items entered in the sales table are the item # and the quantity ordered. The description and price can
be found by creating a look-up in the items tables. Once the item number is typed in, the description and the
price will appear. With a good DBMS, it is possible to define a pop-up form or combo box in case the user dues
not know the number. This way, a table listing each item # and description will be displayed in a window on the
screen. You can then scroll through the list to find a particular item.
Reports
To create a report, one should tell the DBMS what the report should include. You can type in the titles and
format the report however you want; the DBMS report-writer will do the job of creating the reports.
Application generators are the tools that enable one to combine various features into a single application. The
resulting application can be used by selecting choices from a menu, much like users do with commercial
software. The important design feature is that one can create the entire application without writing any
programming commands
DATA DICTIONARY
A relational database system needs to maintain data about the relations, such as the schema, the schema of the
relations. This information is called the data dictionary, or system catalog. The system must store names of the
relations, names of the attributes of each relation, domains and lengths of attributes, names of views defined on
the database, and definitions of those views, and integrity constraints (key constraints).
In addition to this, many systems keep the names of authorized users and ‘accounting information’ about them.
Data about the database is generally stored in the database itself. By using the database to store system data, the
overall structure of the system is simplified and allows full power of the database to be used to permit fast
access to system data.
Data dictionaries can be queried by the database administrator to report the status of any particular aspect of a
firm’s data. The administrator can make changes to the definitions of selected data elements to incorporate any
new requirements. Some data dictionaries automatically enforce standard data element definitions whenever end
users and application programs access an organization’s databases. For example, an active data dictionary
would not allow a data entry program to use a nonstandard definition of a customer record, nor would it allow a
data entry operator to enter a name that exceeds the defined size of that data clement.
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2. Microsoft Windows NT is a 32-bit graphical-user interface (GUI) operating system specifically designed for
client/server systems. To support client/server computing, Windows NT has two components: the NT
workstation and Windows NT server.
The Windows NT workstation module is designed for individual desktop computers and is faster than Windows
95 and Windows 98. The real benefits of the Windows NT workstation are in a networked corporate
environment, where NT desktops link to servers running the Windows NT server.
Windows 95 runs only on CISC computer systems, whereas Windows NT runs on both RISC and CISC
computer systems.
Moreover, Windows NT supports multi-user, multitasking and multiprocessing capabilities, other than built-in
networking capabilities.
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3. Yes, I think that Scott Realtors could have built an adequate system using off-the-shelf software.
Nowadays, very user-friendly off-the-shelf softwares are available, offering a variety of features. e.g., the team
had purchased a visual modeling tool that enabled them to specify the data and relationships as diagrams, which
were then converted into a complete database specification. But proper customization of the software is
required, taking into account the existing business processes and the future requirements.
The costs of trying this approach are as follows:
(i) The database design might not serve the right purpose.
(ii) It might have lots of mistakes in it.
(iii) It might not be compatible with all types of computer systems.
(iv) It might not be scalable to handle future demand.
The benefits of trying this approach are as follows:
(i) It saves the firm from having to pay hefty fees to outside consultants. e.g., McCoy estimated that the team
saved $20,000 by not having to pay for approximately 200 hours of time from outside consultants.
(ii) It saves the firm valuable time, as this approach enables completion of database design, much faster.
(iii) There is no fear of leakage of confidential information of the firm to outsiders.
(iv) It enables the employees to get very conversant with the system and they themselves can solve the
problems arising any time, since the database is designed by them.
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4. The potential security problems that exist with the network are as follows:
(i) Excessive data traffic on the network at times, resulting in crashing of routers.
(ii) Unauthorized hacking by hackers into the network.
(iii) Attack of viruses and worms.
(iv) Defrauding the department out of long-distance toll charges.
(v) Theft of routers and Fiber-optic Cables.
(vi) Terrorist attacks.
(vii) Malicious damage by dissatisfied employees.
(viii) Industrial espionage.
The major types of controls that will be needed to ensure quality and security of such an information system are
as follows:
Information System Controls
These are methods and devices that try to ensure the accuracy, validity and propriety of information system
activities. Controls must be developed to ensure proper data entry, processing techniques, storage methods and
information output. Input Controls are usually set in the form of login passwords and other security codes,
formatted data entry success, appropriate error signals etc.
Processing controls are developed to identify errors in arithmetic calculation and logical operations. They also
ensure that data is not lost, or that it does not go unprocessed. Process controls can be either hardware controls
or software controls.
Output controls are developed to ensure that information products are correct and complete, and are available to
authorized users in a timely manner. Access to online output of computer networks is typically controlled by
security codes that identify which users can receive what type of output. ‘Pre numbered output forms’ is
another method that can be employed to check the loss of important output documents.
Many firms also use backup file systems wherein duplicate files of data or programs are created and stored at a
different location. These files can be used if the current files are destroyed.
Procedural Controls
Procedural controls are methods that specify how an organization’s computer and network resources should be
operated for maximum security. They help to ensure the accuracy and integrity of computer and network
operations and systems development activities.
Facility Control
These controls protect an organization’s computing and network facilities from loss or destruction. Computer
networks and other hardware are subject to such hazards as accidents, natural disasters, sabotage, industrial
espionage, destruction or theft. Various safeguards and control procedures are necessary to protect the hardware,
software, network and vital data resources of an organization.
Network security: Specialized system software packages known as system security monitors provide security for
a network. These are programs that monitor the use of computer systems and networks and protect them from
unauthorized use, fraud or destruction. Two most commonly used methods in network security are encryption
and firewalls.
A network firewall is a ‘gate keeper’ that protects computer networks from intrusion. It serves as a filter and safe
transfer point for access to and from the Internet and other networks. In some cases a firewall may allow access
only from trusted locations on the Internet to particular computers inside the firewall. Or it may allow only safe
information to pass. For example, a firewall may permit users to read email from remote locations, but not to run
certain programs.
Biometric Controls include security measures that measure the physical traits that make each individual unique.
Such measures include voice verification, fingerprints, hand geometry, retina scanning, face recognition and
genetic pattern analysis. Biometric control devices use special sensors to measure and digitize a biometric
profile of an individual’s fingerprints, voice or some other physical trait.
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5. The various types of transmission cables used in telecommunication networks are:
(i) Twisted-Pair Cable
It consists of copper wire twisted into a pair, and it is the most widely used media for telecommunications
today. Such a cable can transmit both voice and data.
(ii) Coaxial Cable
Coaxial Cable consists of a sturdy copper or aluminum wire wrapped with spacers to insulate and protect
it. This insulation minimizes the chance of interference from other signals, and distortion of the signals
that the cable carries. It allows high-speed data transmission and is used as an alternative for Twisted-Pair
cable in high-service metropolitan areas, for cable TV systems.
(iii) Fiber-optic Cable
Fiber-optic Cable consists of one or more hair thin filaments of glass fiber wrapped in a protective jacket.
It can conduct light pulses generated by lasers at transmission rates as high as 30 billion bits per second.
This type of cable provides substantial size and weight reductions as well as increased speed and greater
carrying capacity. As it does not generate, and is not affected by electromagnetic radiation, multiple fibers
can be placed in the same cable. The only disadvantage is the difficulty of splicing the cable to make
connections. This, however, is a security advantage and limits line tapping.
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6. As the salesperson of the company, I would choose Microsoft's PowerPoint software, as it includes almost all
the features for making interesting and effective presentations.
Presentation graphics software, like other top-selling productivity programs, uses a visual metaphor, i.e., a
simulation of the media (a slide or transparency) that is used in making presentations. Each page of a
presentation is called a slide.
The salient features of a presentation graphics software are as follows:
(i) Output options
With most presentation graphics program, one has the following output options:
􀂃 On-screen show
􀂃 Transparencies
􀂃 35-mm slides
􀂃 Audience handouts
􀂃 Speaker notes
(ii) Templates
Presentation graphics software would not have contributed to the increase of one's productivity if every slide
had to be designed from scratch. That is why popular presentation graphics softwares come with templates,
ready-made designs, that include an overall layout, font and font-size choices, a color scheme, and other design
elements. The most popular programs come with tens or hundreds of templates, enabling the presenter to choose
the best one that suits the occasion. Even designing of a new template is possible, but unless a graphic artist
does it, it would suffer on counts of visual effectiveness and legibility.
(iii) View options
Most presentation graphics allow one to view the presentation in different ways. In Microsoft PowerPoint, one
can choose from the following options
􀂃 Slide view
􀂃 Outline view
􀂃 Slide sorter view
􀂃 Notes view
􀂃 Slide show view
(iv) Slide Options
Varying slide options are also available, which would bring variety into otherwise monotonous presentation
methods. These are:
􀂃 Two-column bulleted list
􀂃 Table
􀂃 Chart
􀂃 Text and Chart
􀂃 Text and Clipart
􀂃 Multimedia
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7. In order to hold conferences during every new product introduction, without having to bring every salesperson
back to the home office, I would like to adopt the technology of 'Group Support Facilities and Systems'. The
various applications are as under:
Teleconferencing
Teleconferencing is an important group support facility, in which sessions are held in real time where major
participants are televised, while participants from remote areas may take part with voice input of questions and
responses. It can also be done using closed-circuit television to reach multiple small groups instead of using
television broadcasting to reach large groups at multiple sites.
Data Conferencing
It is a method where a Groupware Package connects two or more PCs over the Internet or Intranets, so that a
team can share, mark up and revise a white board of drawings, documents and other material displayed on their
screens. It is also known as White Boarding.
Audio/video Teleconferencing
This enterprise collaboration tool enables real-time video/audio conferences among (1) networked PCs, known
as desktop video conferencing or (2) participants in conference rooms or auditoriums in different locations. In
either case, team and enterprise collaboration can be enhanced with a full range of interactive video, audio,
document, and white board communications, among the online participants. Desktop videoconferencing today
takes place over the Internet, Intranets, Extranets, as well as over the public telephone and other networks.
White Pine’s CU-See Me and Intel's Proshare are the two market leaders in Desktop Videoconferencing
software.
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Section C: Applied Theory
8. The various types of user-defined functions in C programming language are briefly explained below:
(i) Functions with no arguments and no return values
When a function has no arguments, it does not receive any data from the calling function. When the
called function does not return a value, the calling function does not receive any data. Therefore,
there is no data transfer between the calling function and the called function. As there is nothing to
be returned, the return statement is optional.
(ii) Functions with arguments but no return values
In this category, the calling function reads data from the terminal and passes it to the called
function.
For example,
printline (ch)
value (p, r, n)
are the two functions that have arguments called ch, p, r and n. These are called formal arguments.
The calling function can send values to these arguments using function calls containing appropriate
arguments. For example, the function call
value (200, 0.215, 7)
would send the values 200, 0.215 and 7 to the function value (p, r, n) and assign 200 to p, 0.215 to r
and 7 to n. These values 200, 0.215 and 7 are called actual arguments. They become the values of
formal arguments inside the called function.
The actual and formal arguments should match with each other in number, type and order. The
values of arguments are assigned to the formal arguments on a one-to-one basis, starting with the
first argument.
(iii) Functions with arguments and return values
Here, two way communication takes place between the calling program and the called program. The
values of arguments are passed to the calling function and the function result is passed back to the
called function. The following program illustrates this point.
main( )
{
float p, ir, a;
int period;
printf("Enter principal amount, interest rate and period");
amount = value (p, ir, period);
printf(" \n %f \ + %d \ + %f \n", p, ir, period, amount);
}
value(prn, r, n)
int n;
float prn, r;
{
int year;
float sum;
sum = p; year = 1;
while(year ≤ n)
{
sum = sum * (1 - r);
year = year + 1;
}
return(sum);
}
The following events occur when the function call
amount = value (p, ir, period);
is executed.
a. The call function transfers the control along with the values of actual arguments to the function
value where the formal arguments prn, r and n are assigned the values of p, ir and period.
b. The called function, value, is executed till the return (sum); statement is encountered. The value
of sum is passed back to the function call in main ( ).
c. The calling statement is executed and the returned value is assigned to amount.
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9. The roles of 'Shell' as a 'Command Interpreter' and as a 'Programming Language' are explained below:
SHELL AS A COMMAND INTERPRETER
The shell can be considered as the Sleeping beauty of the system, even though it acts as an interpreter when
one tries to interact with the machine. When the user issues an instruction (command), the shell acquires it
first. Before executing the command, it sees whether the command line is in a form which the system can
understand. If it is not, then it processes the request to recreate a simplified command line. After having
found a correct instruction, it leaves the jobs of command execution to the Kernel.
The shell after all is nothing but a Unix command — a program that starts when a person logs in, and
truncates when he or she logs out. The only difference here is that unlike other Unix commands, the shell is
there all the time, indicating its presence by the familiar $ prompt. Shell resembles the role played by
command.com in MS-DOS, though the capabilities of the shell far outweigh those of command.com. The
unique thing about the shell is that while it is technically a Unix command in itself, its main job is to accept
and interpret user requests. i.e., other Unix commands.
Many commands require complex interaction with the hardware like opening and closing of files,
starting a tape drive unit, skipping a page on the printer, etc. The shell does not interact with the hardware
directly. Instead it works hand in hand with its agent, the kernel, which communicates directly with the
hardware, and takes care of all the complex processes that go on. Since the kernel interacts directly with
the shell, users can afford to remain ignorant of the complex internal processes that take place between the
kernel and the hardware. This transparency is one of the most wonderful aspects of the Unix design
philosophy.
One of the functions of the Shell is to wait for input from the user. The commands keyed in through the
keyboard and at the $ prompt are actually the input to the shell program. Having received the inputs from
the user, the shell performs a series of processing tasks, interacting with the kernel when necessary. After
the job is complete it returns to its waiting role, to start the next 'Cycle'. The Shell typically performs the
activities mentioned below, in each cycle:
(i) First it issues the $ prompt and waits for the user command.
(ii) After receiving the command, the shell scans the command line for some special characters, and then
rebuilds the command line, after the processing is complete.
(iii) The command is passed on to the kernel for execution and the shell waits for its completion.
(iv) The $ prompt appears again, after completing the task and providing the result.
The shell is said to be sleeping when there is no input from the user at the $ prompt. It wakes up whenever
a user enters some characters through the keyboard and presses the key. The productive work of
the shell begins only after it has accepted the characters that are keyed in.
SHELL AS A PROGRAMMING LANGUAGE
In the preceding section, the role played by the shell in processing a command line was explained. But the
shell’s work is not restricted to command interpretation alone; it does much more than that. The shell also
has rudimentary programming features, which coupled with the use of Unix commands, or other programs,
make it an extremely useful programming language.
The scope of shell programming often goes beyond the limits of conventional languages. In addition to
external commands like grep, sed etc., one can use the entire set of the shell’s internal commands inside a
shell program. These internal commands can be stringed together as a language with its own variables,
conditions and loops. What makes shell programs powerful is that an external command can be used as a
control command for any of the shell's constructs. The language has features borrowed from C, though
most of its constructs are compact and simpler to use than those in C. Shell’s built-in commands are
usually termed statements.
One can learn how to develop professional grade applications using the programming features of the shell.
One can design menus, data entry or validation routines, and other useful scripts, which take care of daily
chores. However, shell programs run slower than those written in higher level languages and the shell is
often used as an intermediate platform to finally code the program in C. But if speed is not a hurdle, or if
one has a shell compiler installed in the system, the shell is a fascinating language which every serious
Unix user must know.