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Unit 3. System Life Cycle
51
The hardware and the relevant software required for running the system
must be made fully operational before implementation. The conversion is also
one of the most critical and expensive activities in the system development life
cycle. The data from the old system needs to be converted to operate in the new
format of the new system. During this phase, all the programs of the system are
loaded onto the user’s computer. After loading the system, training of the user
starts. After the users are trained about the computerized system, working has to
shift from manual to computerized working. The process is called ‘Changeover’.
The documentation of the system is also one of the most important activity in the system development life cycle. The user documentation is a complete
description of the system from the users point of view detailing how to use or
operate the system. The system documentation contains the details of system design, programs, their coding, system flow, data dictionary, process description,
etc. This helps to understand the system and permit changes to be made in the
existing system to satisfy new user needs.
Maintenance
Maintenance is necessary to eliminate errors in the system during its
working life and to tune the system to any variations in its working environments.
It has been seen that there are always some errors found in the systems that must
be noted and corrected. It also means the review of the system from time to time.
If a major change to a system is needed, a new project may have to be set up to
carry out the change. The new project will then proceed through all the above
life cycle phases [5].
VOCABULARY IN USE
11. Replace the italicized words with the equivalents from the box.
reexamination study repetitive bugs
correspond to possible applied
1. The detailed investigation of the system is carried out in accordance
with the objectives of the proposed system.
2. Systems analysis is an iterative process that continues until a preferred
and acceptable solution emerges.
3. The output of the test run should match the expected results.
System analyses and control
52
4. It has been seen that there are always some errors found in the systems
that must be noted and corrected.
5. It also means the review of the system from time to time.
6. The system design needs to be implemented to make it a workable
system.
7. Systems analysis is a process of collecting factual data, understand the
processes involved, identifying problems and recommending feasible suggestions for improving the system functioning.
12. Complete with the word combinations from the box.
the system functioning computer instructions the expected results
to satisfy new user needs the cost effectiveness removing the bugs
coordinate the data movements
1. The feasibility study is basically the test of the proposed system in the
light of its workability, meeting user’s requirements, effective use of resources
and ____________________.
2. Systems analysis is a process of collecting factual data, understand the
processes involved, identifying problems, and recommending feasible suggestions for improving _____________________.
3. This is also called the programming phase in which the programmer
converts the program specifications into_________________, which we refer to
as programs.
4. The programs ______________________ and control the entire process
in a system.
5. Before actually implementing the new system into operation, a test run
of the system is done for _______________________.
6. The output of the test run should match _______________________.
7. This helps to understand the system and permit changes to be made in
the existing system _________________________________.
COMPREHENSION CHECK
13. Decide whether the following statements are true or false (T/F) by
referring to the information in the text. Then make the necessary changes
so that the false statements become true.
Unit 3. System Life Cycle
53
1. Preliminary system study is the last stage of system development life
cycle.
2. The detailed system study involves the preparation of a ‘System Pro-
posal’
3. The detailed investigation of the system is carried out in accordance
with the objectives of the proposed system.
4. Interviews, on-site observation, and questionnaire are the tools used
for testing.
5. Based on the user requirements and the detailed analysis of the exist-
ing system, the new system must be designed.
6. The hardware coordinates the data movements and controls the entire
process in a system.
7. The output of the test run should match the expected results.
8. Coding is the stage of a project during which theory is turned into
practice.
9. During the Feasibility Study, all the programs of the system are loaded
onto the user’s computer.
10. After loading the system, training of the user finishes.
11. After the users are trained about the computerized system, working has
to shift from manual to computerized working.
12. Maintenance is necessary to eliminate errors in the system during the
system design.
14. Answer the questions.
1. What is System life cycle?
2. Who prepares the system proposal?
3. What are the tools used for detailed system study?
4. Is Systems analysis an iterative process?
5. What is done during the Preliminary or General Design?
6. When do we move to the detailed design stage?
7. What is done during the Structured or Detailed Design?
8. What is done in the design stage?
9. What is the programming phase?
10. What do the programs do?
11. What is a test run of the system done for?
System analyses and control
54
12. What is the conversion?
13. When does training of the user start?
14. What is ‘Changeover’?
15. What is the user documentation? What does it contain?
16. Why is Maintenance necessary?
SPECIALIST READING
TEXT B
SYSTEM DEVELOPMENT MODELS
15. Read the text, make up a plan of the main content and write out
key words for every point of your plan.
points
key words
System and product development approaches generally follow four commonly used models or hybrids. The most common models include the: 1) Waterfall Development Model, 2) Spiral Development Model, 3) Incremental Development Model, and 4) Evolutionary Development Model.
The waterfall model is a popular version of the systems development life
cycle. The waterfall model describes a development method that is linear and
sequential. Waterfall development has distinct goals for each phase of development. Once a phase of development is completed, the development proceeds to
the next phase and there is no turning back. Each phase of development proceeds
in strict order, without any overlapping or iterative steps. The Waterfall model is
the most simple and widely followed model, but like any other system, Waterfall
model does have its own pros and cons.
Spiral Model for software development was designed in order to overcome the disadvantages of the Waterfall Model. This model proposed by Barry
Bohem in 1988, attempts to combine the strengths of various models. It also takes
into account the risk assessment whose outcome determines taking up the next
phase of the designing activity. Unlike all other models which view designing as
a linear process, this model views it as a spiral process. This is done by representing iterative designing cycles as an expanding spiral.
Unit 3. System Life Cycle
55
Typically, the inner cycles represent the early phase of requirement analysis along with prototyping to refine the requirement definition, and the outer
spirals are progressively representative of the classic designing life cycle. At
every spiral there is a risk assessment phase to evaluate the designing efforts and
the associated risk involved for that particular iteration. At the end of each spiral
there is a review phase so that the current spiral can be reviewed and the next
phase can be planned.
Advantages
1. It facilities high amount of risk analysis.
2. It is more suitable for designing and managing large projects.
3. The system is produced early in the system life cycle.
Disadvantages
1. Risk analysis requires high expertise.
2. It is costly model to use
3. Not suitable for smaller projects.
4. There is a lack of explicit process guidance in determining objectives,
constraints and alternatives.
5. This model is relatively new. It does not have many practitioners unlike
the waterfall model.
System analyses and control
56
The incremental build model is a method of software development where
the model is designed, implemented and tested incrementally (a little more is
added each time) until the product is finished. It involves both development and
maintenance. The product is defined as finished when it satisfies all of its requirements. This model combines the elements of the waterfall model with the
iterative philosophy of prototyping.
The product is decomposed into a number of components, each of which
are designed and built separately (termed as builds). Each component is delivered to the client when it is complete. This allows partial utilization of product
and avoids a long development time. It also creates a large initial capital outlay
with the subsequent long wait avoided. This model of development also helps
ease the traumatic effect of introducing completely new system all at once.
The Evolutionary Development Model is based on the premise that a system’s capabilities evolve over time via a series upgrades. The EVO development
model divides the development cycle into smaller, incremental waterfall models
in which users are able to get access to the product at the end of each cycle. The
users provide feedback on the product for the planning stage of the next cycle
and the development team responds, often by changing the product, plans, or
process. These incremental cycles are typically two to four weeks in duration and
continue until the product is shipped [6].
16. Read text B. Choose words and phrases to describe development
models.
The waterfall model
in a series of small amounts, straight, consecutive, requires a high level of knowledge or
skill, easy to understand or do, massive projects,
sequential, break down, User-Developer interaction, comforting, expensive,
risk examination, a gradual process of
change and development, gradual, incomplete,
start using quickly.
Spiral Model
The incremental model
The Evolutionary Development
Model
SPEAKING
17. Identify three types of systems or system upgrades that may be
ideal candidates for a Spiral Development Model strategy.
Unit 3. System Life Cycle
57
18. Identify three types of systems or system upgrades that may be
ideal candidates for a Waterfall Development Model strategy.
19. Identify three types of systems or system upgrades that may be
ideal candidates for Incremental Development Model.
20. In your own words and experiences, pick a system and describe
how any of the following approaches might apply for someone who is
unfamiliar with the methods?
(a) Waterfall Approach
(b) Evolutionary Approach
(c) Incremental Approach
(d) Spiral Approach
21. What does system modeling mean? The Supplementary reading
section may help you to answer this question.
SUPPLEMENTARY READING
SOFTWARE ENGINEERING SYSTEM MODELING
System modeling is the process of developing abstract models of a system, with each model presenting a different view or perspective of that system.
It is about representing a system using some kind of graphical notation, which is
now almost always based on notations in the Unified Modeling Language
(UML). Models help the analyst to understand the functionality of the system;
they are used to communicate with customers.
Models can explain the system from different perspectives:
− An external perspective, where you model the context or environment
of the system.
− An interaction perspective, where you model the interactions between a
system and its environment, or between the components of a system.
− A structural perspective, where you model the organization of a system
or the structure of the data that is processed by the system.
− A behavioral perspective, where you model the dynamic behavior of the
system and how it responds to events.
Five types of UML diagrams that are the most useful for system modeling:
System analyses and control
58
− Activity diagrams, which show the activities involved in a process or in
data processing.
− Use case diagrams, which show the interactions between a system and
its environment.
− Sequence diagrams, which show interactions between actors and the
system and between system components.
− Class diagrams, which show the object classes in the system and the
associations between these classes.
− State diagrams, which show how the system reacts to internal and ex-
ternal events.
Models of both new and existing system are used during requirements
engineering. Models of the existing systems help clarify what the existing system
does and can be used as a basis for discussing its strengths and weaknesses. These
then lead to requirements for the new system. Models of the new system are used
during requirements engineering to help explain the proposed requirements to
other system stakeholders. Engineers use these models to discuss design proposals and to document the system for implementation.
Context models are used to illustrate the operational context of a system –
they show what lies outside the system boundaries. Social and organizational
concerns may affect the decision on where to position system boundaries.
System boundaries are established to define what is inside and what is
outside the system. They show other systems that are used or depend on the system being developed. The position of the system boundary has a profound effect
on the system requirements. Context models simply show the other systems in
the environment, not how the system being developed is used in that environment. Process models reveal how the system being developed is used in broader
business processes.
Interaction models. Types of interactions that can be represented in a
model:
− Modeling user interaction is important as it helps to identify user re-
quirements.
− Modeling system-to-system interaction highlights the communication
problems that may arise.
− Modeling component interaction helps us understand if a proposed
system structure is likely to deliver the required system performance and dependability.
Unit 3. System Life Cycle
59
Structural models of software display the organization of a system in
terms of the components that make up that system and their relationships. Structural models may be static models, which show the structure of the system design, or dynamic models, which show the organization of the system when it is
executing. You create structural models of a system when you are discussing and
designing the system architecture.
Behavioral models are models of the dynamic behavior of a system as it
is executing. They show what happens or what is supposed to happen when a
system responds to a stimulus from its environment. Two types of stimuli: some
data arrives that has to be processed by the system; some event happens that
triggers system processing. Events may have associated data, although this is not
always the case [7].
Unit 2. General Systems Theory (GST)
60
UNIT 4
DECISION MAKING
“Once you make a decision,
the universe conspires to make it happen.”
Ralph Waldo Emerson
LEAD IN
1. Decisions are a part of daily life. Let’ s discuss how you make
decisions.
Do you rely on the cold hard facts or your gut feeling? Choose one of the
options and explain your choice.
1. How would you go about making an important decision between two
equally good things?
a. I would just flip a coin.
b. I would consider all the pros and cons of each before making a decision.
c. I would ask for everyone's opinions and go with the most popular one.
d. I will just try and go with my "gut feeling".
2. How long does it take you to make a big decision?
a. It's immediate and spontaneous.
b. It can take a while, but I hate stretching things out for too long.
c. It can be immediate, or it can take a long while, it depends on how
long it takes me to figure out how I am really feeling.
d. I can mull over it for so long that I never come to a decision.
3. You are working in a team on a big project. In the final hour, you
discover a big problem in what you have been working on. How do you deal
with this?
a. Just leave it and hope no one else will notice.
b. Try and fix it on my own without alerting my team mates so as not to
worry them.
c. Hope someone else has also noticed the problem and has come up
with a solution.
d. Assign everyone tasks of what to do so we can fix the problem ASAP.
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