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Chapter 13
The Systems Development Process, Part I: Introduction to the Systems Development Life Cycle
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Objectives for Chapter 13 Identify the seven stages in the SDLC Common problems that can lead to failure in the SDLC
process Use of prototyping and computer-aided software
engineering in the SDLC Importance of strategic planning for systems What transpires during systems analysis Basic features of both the structured and object-oriented
approaches to systems design How accountants participate in the SDLC activities
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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.
The Seven Stages of the SDLC
SystemsPlanning
SystemsAnalysis
ConceptualDesign
SystemSelection
DetailedDesign
SystemImplementation
Maintenance
New Systems Development
SYSTEMS DEVELOPMENT LIFE CYCLE
ProjectProposals &Schedules
SystemsAnalysisReport
MultipleConceptualDesigns
SystemSelectionReport
DetailedSystemDesign
FullyDocumentedSystem
Required Documentation
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Participants in Systems Development
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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Why Are Accountants Involved with SDLC?
The creation of an information system consumes significant resources and has financial resource implications.
The quality of accounting information systems and their output rests directly on the SDLC activities that produce them.
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How are Accountants Involved with the SDLC?
Accountants are users and must provide a clear picture of their problems and needs.
Accountants are members of the development team.
Accountants are involved in systems development as auditors to ensure the system is designed with appropriate computer audit techniques.
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Up to 25% of all systems projects fail! Why?
Poorly specified systems requirements communication problems time pressures
Ineffective development techniques paper, pencils, templates, erasers
instead of software tools, such as CASELack of user involvement in systems
development
systemsdeveloper
enduser
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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
IdentifyConceptualUserSpecifications
DevelopPrototype
PresentPrototypeto Users
ObtainUserFeedback
ChangePrototypePer UserFeedback
DevelopPrototypeinto FinishedSystem
Discard Prototypeand DevelopSystem UnderTraditionalSDLC 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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Uses of CASE Tools
define user requirementscreate physical databases from
conceptual user viewsproduce system design specifications automatically generate program code facilitate the maintenance of
programs created by both CASE and non-CASE techniques
CASE Spectrum of Support Tools for the SDLC
SystemsPlanning
SystemsAnalysis
ConceptualDesign
SystemSelection
DetailedDesign
SystemImplementation
Maintenance
New Systems Development
SYSTEMS DEVELOPMENT LIFE CYCLE
Analysis ToolsModelingTools
DesignTools
CodingTools
MaintenanceTools
FRONT END, UPPER CASE TOOLS BACK END, LOWER CASE TOOLS
Overview of CASE System
CentralRepository
DFDModel
PrototypeModel
DesignModel
CodingModel
MaintenanceModel
CASESystem
User Workstations
DatabaseStructures
ProgramCode
StructureDiagrams
PrototypeScreens
Context DFD
IntermediateDFD
ElementaryDFD
Upper CASE Models Lower CASE ModelsCASE Outputs
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Data Flow Diagrams (DFDs)
DFDs are used to represent multiple levels of detail.
Context-level DFDs are used to present an overview model of the business activities and the primary transactions processed by the system.
It does not include a detailed definition of data files and specific procedures.
Advantages of CASE
Reusable program code and documentation
Increased flexibility
Reduced system complexity and maintenance cost
Promotion of user involvement
Capacity to review alternative designs
Benefits
Quicker development process
CostsProgram efficiency
Start-up time
and cost
Product cost
Incompatible CASE tools
Disadvantages of CASE
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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
BusinessPlan
SystemsPlan
SystemsProjects
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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: 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 FeasibilityTechnical 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 SDLCAll 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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The Accountant’s Role in Systems Planning
Accountants are often called on to provide expertise in evaluating the feasibility of projects during the planning process.
As auditors, accountants must routinely examine the systems planning phase of the SDLC since careful systems planning helps to prevent unnecessary development costs.
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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 symptomsDisadvantages
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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The Accountant’s Role in Systems Analysis
The accountants’ expertise makes them important players in the design of a good, well-controlled system: internal control standards audit trail requirements external reporting requirements
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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
Characteristics of an Inventory Object
Part Number DescriptionQuantity on Hand Reorder Point Order Quantity
Inventory
Reduce ReviewQuantity
Reorder Replace
Attributes
Object
Operations
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Classes and Instances
An object class is a logical grouping of individual objects that share the same attributes and operations.
An instance is a single occurrence of an object within a class.
Inventory
Wheel Bearing Alternator Water Pump
ObjectClass
Instance
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Inheritance
Inheritance means that each object instance inherits the attributes and operations of the class to which it belongs.
Object classes may also inherit from other object classes.
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The Role of the Accountant in Conceptual Design
Accountants are responsible for the conceptual system, and the systems professionals are responsible for the physical system.
If important accounting considerations are not conceptualized at this point, they may be overlooked and expose the organization to potential financial loss.
The auditability of a system depends in part on its design characteristics.