Matakuliah
Tahun
: A0294/Audit SI Lanjutan
: 2009
Metodologi
Pengembangan Sistem Aplikasi
Pertemuan 23-24
Learning Outcomes
Pada akhir pertemuan ini, diharapkan mahasiswa
akan mampu :
• Menjelaskan tahapan-tahapan atau prosedur pengembangan sistem aplikasi
• Menjelaskan pengorganisasian proyek pengembangan sistem aplikasi
• Menjelaskan berbagai metoda pengembangan sistem aplikasi
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Outline Materi
•
•
•
Materi 1: Tahapan-tahapan atau prosedur pengembangan sistem aplikasi
Materi 2: Pengorganisasian proyek pengembangan sistem aplikasi
Materi 3: Berbagai metoda pengembangan sistem aplikasi.
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The Systems
Development Process
Audit
Systems Development Life Cycle
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The Systems Development Life Cycle (SDLC)
• A logical sequence of activities used to identify new systems needs and to
develop new systems to support those needs.
• The SDLC model may be understood as consisting of two major phases
comprising seven stages.
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7 Tahap SDLC
SYSTEMS DEVELOPMENT LIFE CYCLE
Systems
Planning
New Systems Development
Conceptual System
Systems
Design
Selection
Analysis
Systems
Project
Proposals & Analysis
Schedules Report
Multiple
System
Conceptual Selection
Designs
Report
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Required Documentation
Detailed
Design
Detailed
System
Design
System
Maintenance
Implementation
Fully
Documented
System
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Pihak Terkait
• Systems Professionals - gather and analyze facts about problems with the current
system and formulate a solution
– systems analysts
– systems designers
– programmers
• End Users - the primary users’ needs are solicited
• Stakeholders - individuals who have an interest in the system but are not end
users.
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Bagaimana Keterlibatannya?
• Users must provide a clear picture of their problems and
needs.
• User perlu terlibat aktif, bahkan sebagai members of the
development team.
• User are involved in systems development as auditors to
ensure the system is designed with appropriate computer
audit techniques.
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>25% systems projects fail!
•
•
•
Poorly specified systems requirements
– communication problems
– time pressures
Ineffective development techniques
– paper, pencils, templates, erasers instead of
software tools, such as CASE
Lack of user involvement in systems development
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systems
developer
end
user
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Prototyping
• Prototyping is a technique for providing users a preliminary
working version of the system.
• It is built quickly and relatively inexpensively with the intention it
will be modified.
• As the users work with the prototype and make suggestions for
changes, a better understanding of the true requirements of the
system is achieved.
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Prototyping Techniques
Identify
Conceptual
User
Specifications
Develop
Prototype
Present
Prototype
to Users
Obtain
User
Feedback
Change
Prototype
Per User
Feedback
Develop
Prototype
into Finished
System
Discard Prototype
and Develop
System Under
Traditional
SDLC Procedures
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Computer-Aided Software Engineering
(CASE)
• CASE technology involves the use of computer systems
to build computer systems.
• CASE tools are commercial software products consisting of
highly integrated applications that support a wide range of
SDLC activities.
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Menggunakan CASE Tools
•
•
•
•
•
define user requirements
create physical databases from conceptual user views
produce system design specifications
automatically generate program code
facilitate the maintenance of programs created by both CASE
and non-CASE techniques
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Dukungan CASE pada SDLC
SYSTEMS DEVELOPMENT LIFE CYCLE
New Systems Development
Systems
Planning
Systems
Analysis
Analysis Tools
Conceptual System
Design
Selection
Modeling
Tools
FRONT
END, UPPER CASE TOOLS
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Detailed
Design
Design
Tools
System
Maintenance
Implementation
Coding
Tools
Maintenance
Tools
BACK END, LOWER CASE TOOLS
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Overview of CASE System
CASE Outputs
Upper CASE Models
DFD
Model
Prototype
Model
Lower CASE Models
Design
Model
Coding
Model
Context DFD
Maintenance
Model
Intermediate
DFD
Elementary
DFD
Prototype
Screens
Central
Repository
CASE
System
Structure
Diagrams
Program
Code
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User Workstations
Database
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Structures
Advantages of CASE
Reduced system
complexity and maintenance cost
Increased flexibility
Capacity to review
alternative designs
Benefits
Reusable program code
and documentation
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Promotion of
user involvement
Quicker
development
process
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Disadvantages of CASE
Product cost
Program
efficiency
Costs
Start-up
time
and cost
Incompatible CASE tools
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Joint Application Development (JAD)
• JAD employs CASE technology and prototyping to facilitate end user
involvement in systems development.
• JAD uses time efficiently and effectively to reduce the user-analyst
communications barrier.
• A typical JAD session is conducted in a conference room equipped with
a CASE workstation and a JAD coordinator.
• End users actively participate in the development process.
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Stage 1: Systems Planning
• The objective of systems planning is to link individual systems projects or
applications to the strategic objectives of the firm.
STRATEGIC OBJECTIVES OF THE FIRM
Business
Plan
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Systems
Plan
Systems
Projects
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Systems Steering Committee
• The steering committee provides guidance and reviews the status of
systems projects and typically includes the CEO, CFO, CIO, senior
management from user areas and computer services, and an internal
auditor.
• Typical responsibilities are:
–
–
–
–
–
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resolving conflicts
reviewing projects and assigning priorities
budgeting funds
reviewing the status of projects
determining whether projects should be continued
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Strategic Systems Planning
• involves the allocation of systems resources at the macro level for a time
frame of 3 to 5 years
• is important because:
– it charts the path the firm will follow to reach its information systems goal
– it reduces the crisis component in systems development
– it provides authorization control for the SDLC
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Project Planning
• allocates resources to individual applications within the framework of the strategic plan
• includes:
–
–
–
–
recognizing the problem
defining the problem
specifying system objectives
determining project feasibility
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Specifying System Objectives
• The strategic objectives of the firm and the operational objectives of the
information systems must be compatible.
• At this point, the objectives only need to be defined in general terms.
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Preliminary Project Feasibility
•
•
•
•
Technical feasibility - is the technology necessary available?
Economic feasibility - are the funds available and appropriate for the system?
Legal feasibility - does the system fall within legal boundaries?
Operational feasibility - can procedural changes be made to make the system
work?
• Schedule feasibility - can the project be completed by an acceptable time period?
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Systems Project Proposal
• A systems project proposal provides management with a basis for deciding
whether or not to proceed with the project.
• It summarizes the findings of the study and makes a general recommendation.
• It outlines the linkage between the objectives of the proposed system and
the business objectives of the firm.
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Project Schedules
• present management’s commitment to the project
• contain a budget of the time and costs for all phases of the SDLC
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Announcing the New System Project
• The most delicate aspect of the SDLC
• All users need to be made to understand the objectives of the new system.
• End user managers who view the new system as a potential benefit to their jobs,
rather than a threat to their personal well-being, are more likely to comply and
cooperate with the project team’s objectives.
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Stage 2: Systems Analysis
• A business problem must be fully understood before
a solution can be formulated.
– A defective analysis will lead to a defective solution.
• System analysis is a
two-step process
– survey of the current system
– an analysis of the users’ needs
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The Survey Step
• Facts must be gathered regarding:
– data sources and data stores; users; processes; data flows; controls;
transaction volumes; error rates; resource costs; bottlenecks and redundant
operations
• Fact-gathering techniques:
– JAD sessions; observation; task; participation; personal interviews; reviewing
key documents
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Survey of Current System
• Advantages
– allows aspects of the old system which should be kept to be identified
– aids in planning the implementation of the new system
– may allow conclusive determination of the cause of the reported problem
symptoms
• Disadvantages
– can stifle new ideas
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The Analysis Step
• The systems analysis is an intellectual process that is commingled with fact
gathering.
• A formal systems analysis report, prepared and presented to the steering
committee, contains:
– reasons for system analysis
– scope of study
– problem identified with current system
– statement of user requirements
– resource implications
– recommendations
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Conceptual Systems Design
• An objective of this phase is to reach consensus between users and systems
professionals on plausible alternative designs for the new system.
• JAD sessions are an effective mechanism for achieving this objective.
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The Structured Design Approach
• is a disciplined way of designing systems from the top down
• starts with the “big picture” of the proposed system and gradually decomposes it
into greater detail so that it may be fully understood
• utilizes DFD and structure diagrams
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Structured Design Level of Detail
• The systems designs during the conceptual phase should be general.
• The designs should identify all the
– inputs
– outputs
– processes
– special features
• It is necessary to distinguish one alternative from another.
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Object-Oriented Design Approach
• It builds information systems from reusable standard components or objects.
• Once created, standard modules can be used in other systems with similar needs.
• A library of modules can be created for future use.
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Elements of the Object-Oriented Approach
• Objects - equivalent to nouns
– vendors, customers, inventory, etc.
• Attributes - equivalent to adjectives
– part number, quantity on hand, etc.
• Operations - equivalent to verbs
– review quantity on hand, reorder item
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Application Systems Development Audits
• Systems development audits are directed at the activities of the systems analyst
and programmers.
• Controls governing the systems development process directly affect the reliability
of the application programs that are developed.
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Application Systems Development Audits
•
There are three general areas of audit concern in the systems development
process:
1.
2.
3.
•
Systems development standards
Project management
Program change control
What are systems development standards?
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Application Systems Development Audits
• Systems development standards are the documentation governing the design,
development, and implementation of application systems.
• What is project management?
• It consists of project planning and project supervision.
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Application Systems Development Audits
• What is the objective of program change controls?
• It is to prevent unauthorized and potentially fraudulent changes from being
introduced into previously tested and accepted programs.
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Audit Systems Development Approaches
•
•
•
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Concurrent audit
Post-implementation audit
General audit
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