Lecturer : Mr. Tri Djoko Wahjono, Ir., M.Sc
Name : Agatha Virgitia Darmawan
Student ID : 1701338122
1.
What Is System Development, and What Are
the System Development Phases?
A system is a set of components that
interact to achieve a common goal. You use, observe, and interact with many
systems during daily activities. You drive a highway system to reach a
destination. You use a programmable thermostat to regulate your heating and
cooling systems to save energy. You use the decimal number system to calculate
an amount due.
An information system (IS) is a collection
of hardware, software, data, people, and procedures that work together to
produce quality information. An information system supports daily, short-term,
and long-range activities of users. As time passes, the type of information
that users need often changes. A sales manager may want the weekly summary
report grouped by district today and by product tomorrow. When information
requirements change, the information system must meet the new requirements. In
some cases, the members of the system development team modify the current
information system. In other cases, they develop an entirely new information
system.
System development is a set of activities
used to build an information system. Some system development activities may be
performed concurrently. Others are performed sequentially. Depending on the
type and complexity of the information system, the length of each activity
varies from one system to the next. In some cases, some activities are skipped
entirely.
System development activities often are
grouped into larger categories called phases. This collection of phases
sometimes is called the system development life cycle (SDLC). Many SDLCs
contain five phases:
1.
Planning
2.
Analysis
3.
Design
4.
Implementation
5.
Operation, Support, and Security.
2.
What Are Guidelines for System Development?
System development should follow three general
guidelines: group activities into phases, involve the users, and define
standards.
1.
Group activities or tasks into phases:
Many SDLCs contain the same phases. Others have more or fewer phases.
Regardless, all SDLCs have similar activities. Some SDLCs separate these
activities in an additional phase called Construction and Testing. Other
differences among SDLCs are the terminology they use, the order of their
activities, and the level of detail within each phase.
2.
Involve users:
Users include anyone for whom the system is being built. Customers,
employees, students, data entry clerks, accountants, sales managers, and owners
all are examples of users. You, as a user, might interact with an information
system at your bank, library, grocery store, fitness center, work, and school.
The system development team members must remember they ultimately deliver the
system to the user. If the system is to be successful, the user must be
included in system development. Users are more apt to accept a new system if
they contribute to its design.
3.
Define standards:
Standards are sets of rules and procedures an organization expects
employees to accept and follow. Standards help people working on the same
project produce consistent results. For example, one programmer might refer to
a product number in a database as a product ID. Others may call it a product
identification number, product code, and so on. If standards are defined, then
every- one involved uses the same terms, such as product number. Standards
often are implemented by using a data dictionary.
3.
Why Are Project Management, Feasibility
Assessment, Documentation, and Data and Information Gathering Techniques
Important?
Project management is the process of planning,
scheduling, and then controlling the activities during system development. The
goal of project management is to deliver an acceptable system to the user in an
agreed-upon time frame, while maintaining costs. For larger projects, project
management activities often are separated between a project manager and a
project leader. Some organizations use extreme project management. The project
leader identifies the scope of the project, required activities, time
estimates, cost estimates, the order of activities, and activities that can
take place simultaneously. The project leader records this information in a project
plan. Feasibility is a measure of how suitable the development of a system will
be to the organization. A systems analyst typically uses four tests to evaluate
feasibility of a project: operational feasibility, which measures how well the
proposed system will work; schedule feasibility, which measures whether
established project deadlines are reasonable; technical feasibility, which
measures whether the organization has or can obtain the hardware, software, and
people to deliver and then support the system; and economic feasibility, also called cost/benefit
feasibility, which measures whether the lifetime benefits of the proposed system
will be greater than its lifetime costs.
Documentation is the collection and summarization of data and
information and includes reports, diagrams, programs, or other deliverables. A
project notebook contains all documentation for a single project. To gather
data and information, systems analysts and other IT professionals review
documentation, observe, survey, interview, participate in joint-application
design (JAD) sessions, and research.
4.
What Activities Are Performed in the Planning
Phase?
The planning phase for a project begins
when the decision-making body for the organization, called the steering
committee, receives a project request. During the planning phase, four major
activities are performed: (1) review and approve the project requests, (2)
prioritize the project requests, (3) allocate resources such as money, people,
and equipment to approved projects, and (4) form a project development team for
each approved project.
5.
What Is the Purpose of Activities Performed in
the Analysis Phase?
The planning phase for a project begins
when the steering committee receives a project request. As mentioned earlier in
this chapter, the steering committee is a decision- making body for an organization.
This committee usually consists of five to nine people. It typically includes a
mix of vice presidents, managers, non-management users, and IT personnel.
During the planning phase, four major activities
are performed:
(1) review and approve the project
requests; (2) prioritize the project requests; (3) allocate resources such as
money, people, and equipment to approved projects; and (4) form a project
development team for each approved project.
The projects that receive the highest priority
are those mandated by management or some other governing body. These requests
are given immediate attention. The steering committee evaluates the remaining
project requests based on their value to the organization. The steering
committee approves some projects and rejects others. Of the approved projects,
it is likely that only a few will begin system development immediately. Others
will have to wait for additional funds or resources to become available.
6.
What Are Tools Used in Process Modeling?
Process modeling, sometimes called structured
analysis and design, is an analysis and design technique that describes
processes that transform inputs into outputs. Tools used for process modeling
include the following. An entity-relationship diagram (ERD) graphically shows
the connections among entities in a system. An entity is an object in the
system that has data. A data flow diagram (DFD) graphically shows the flow of
data in a system. Key elements of a DFD are a data flow, which shows the input
or output of data or information; a process, which transforms an input data
flow into an output data flow; a data store, which is a holding place for data
and information; and a source, which identifies an entity outside the scope of
the system. The project dictionary, sometimes called the repository, contains
all the documentation and deliverables of a project. Techniques used to enter
items in the project dictionary include structured English, a decision table
and/or a decision tree, and a data dictionary.
7.
What Are Tools Used in Object Modeling?
Object modeling, sometimes called
object-oriented (OO) analysis and design, combines the data with processes that
act on the data into a single unit, called an object. Object modeling can use the same tools as
those used in process modeling, but the UML (Unified Modeling Language) has
been adopted as a standard notation for object modeling and development. Two
common tools in the UML are the use case diagram and the class diagram. A use
case diagram graphically shows how actors interact with the information system.
An actor is a user or other entity, and the use case is the function that the
actor can perform. A class diagram graphically shows classes and one or more lower
levels, called subclasses, in a system. Lower levels (subclasses) contain
attributes of higher levels (classes) in a concept called inheritance.
8.
What Activities Are Performed in the Design
Phase?
The design phase consists of two major
activities: (1) if necessary, acquire hardware and software and (2) develop all
of the details of the new or modified information system. Acquiring necessary
hardware and software involves identifying technical specifications, soliciting
vendor proposals, testing and evaluating vendor proposals, and making a
decision. Detailed design includes developing designs for the databases,
inputs, outputs, and programs. During detailed design, many systems analysts
use a prototype, which is a working model of the proposed system.
Computer-aided software engineering (CASE) products are tools designed to
support one or more activities of system development.
9.
Why Is Program Development Part of System
Development?
During the design phase, an organization
can purchase packaged software, which is mass-produced, copyrighted, prewritten
software. If suitable packaged software is not available, however, a company
may opt for custom software, which is application software developed at the
user’s request to match the user’s requirements exactly. Programmers write
custom software from the program specification package created during the
analysis phase, following an organized set of activities known as the program
development life cycle.
10.
What Activities Are Performed in the
Implementation Phase?
The purpose of the implementation phase is
to construct, or build, the new or modified sys- tem and then deliver it to the
users. Members of the system development team perform four major activities in
this phase:
(1)
develop programs,
If the organization purchases packaged software and no modifications to
the software are required, the development team may skip this activity. For
custom software or packaged software that requires modification, however,
programs are developed or modified either by an outside firm or in-house.
Programmers write or modify programs from the program specification package created
during the analysis phase. Just as system development follows an organized set
of activities, so does program development. These program development
activities are known as the program development life cycle. The program
development life cycle follows these six steps: (1) analyze the requirements,
(2) design the solution, (3) validate the design, (4) implement the design, (5)
test the solution, and (6) document the solution. Chapter 13 explains the
program development life cycle in depth. An important concept to understand is
that the program development life cycle is a part of the implementation phase,
which is part of the system development life cycle.
(2)
install and test the new system,
If the organization acquires new hardware or software, someone must
install and test it. The systems analysts should test individual programs. They
also should be sure that all the programs work together in the system. Systems
analysts do not want errors in the system after it is delivered to the users.
Systems analysts and users develop test data so that they can perform various
tests. The test data should include both valid (correct) and invalid
(incorrect) data. When valid test data is entered, the program should produce
the correct results. Invalid test data should generate an error. Tests performed
during this step include unit tests, systems tests, integration tests, and
acceptance tests. A unit test verifies that each individual program or object
works by itself. A systems test verifies that all programs in an application
work together properly. An integration test verifies that an application works
with other applications. An acceptance test is performed by end-users and
checks the new system to ensure that it works with actual data.
(3)
train users, and
According to a recent study, poor user training is one of the top ten
reasons why system development projects fail. Users must be trained properly on
a system’s functionality. Training involves showing users exactly how they will
use the new hard- ware and software in the system. Other organizations use
Web-based training, which is a self-directed, self-paced online instruction
technique. Whichever method is used, it should include hands-on sessions with
realistic sample data.
(4)
convert to the new system
The final implementation activity is to change from the old system to the
new system. This change can take place using one or more of the following
conversion strategies: direct, parallel, phased, or pilot. With direct
conversion, the user stops using the old system and begins using the new system
on a certain date. The advantage of this strategy is that it requires no
transition costs and is a quick implementation technique. Some systems analysts
call this technique an abrupt cutover. The disadvantage is that it is extremely
risky and can disrupt operations seriously if the new system does not work
correctly the first time. Parallel conversion consists of running the old
system alongside the new system for a specified time. Results from both systems
are compared. If the results are the same, the organization either terminates
the old system abruptly or phases it out. The advantage of this strategy is
that you can fix any problems in the new system before you terminate the old
system. The disadvantage is that it is costly to operate two systems at the
same time. Larger systems that have multiple sites often use a phased
conversion. With a phased conversion, each location converts at a separate
time. For example, an accounting system might convert its accounts receivable,
accounts payable, general ledger, and payroll sites in separate phases. Each
site can use a direct or parallel conversion. With a pilot conversion, only one
location in the organization uses the new system — so that it can be tested.
After the pilot site approves the new system, other sites convert using one of
the other conversion strategies. At the beginning of the conversion, existing
data must be made ready for the new system. Converting existing manual and
computer files so that the new system can use them is known as data conversion.
11.
What Activities Are Performed in the
Operations, Support, and Security Phase?
The purpose of the operation, support, and
security phase is to provide ongoing assistance for an information system and
its users after the system is implemented. The operation, sup-port, and
security phase consists of three major activities: (1) perform maintenance activities,
(2) monitor system performance, and (3) assess system security. Information
system maintenance activities include fixing errors in, as well as improving, a
system’s operations. To determine initial maintenance needs, the systems
analyst should meet with users. The purpose of this meeting, called the
post-implementation system review, is to discover whether the information
system is per- forming according to the users’ expectations. Sometimes users
identify errors in the system. Problems with design (logic) usually are the
cause of these errors. For example, the total of a column might be incorrect.
These types of errors return the analyst to the planning phase to perform
corrective maintenance, which is the process of diagnosing and correcting
errors in an information system. Sometimes, users have enhancements or
additional requirements that involve modifying or expanding an existing
information system. Adaptive maintenance is the process of including new
features or capabilities in an information system. To perform adaptive
maintenance, the analyst returns to the planning phase. During this phase, the
systems analyst monitors performance of the new or modified information system.
The purpose of performance monitoring is to determine whether the system is
inefficient or unstable at any point. If it is, the systems analyst must
investigate solutions to make the information system more efficient and reliable,
a process called perfective maintenance — back to the planning phase. Most
organizations must deal with complex computer security issues. All elements of
an information system — hardware, software, data, people, and procedures — must
be secure from threats both inside and outside the enterprise. For example,
users should be allowed access only to the data and information for which they
are authorized, which typically is limited to the amount necessary to do their
job. Data should be secure so that intruders cannot alter, damage, or steal data.
Networks need safeguards to prevent them from being compromised. If any vulnerabilities
are detected, the analyst returns to the planning phase to investigate
techniques to safeguard the information system. Organizations today often have
a chief security officer (CSO) who is responsible for physical security of an
organization’s property and people and also is in charge of securing computing
resources. It is critical that the CSO is included in all system development projects
to ensure that all projects adequately address information security. The CSO
uses many of the techniques discussed in Chapter 11 to maintain confidentiality
or limited access to information, ensure integrity and reliability of systems,
ensure uninterrupted availability of systems, ensure compliance with laws, and
cooperate with law enforcement agencies.
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