Chapter 13

transcript

Chapter 13

The Systems Development Process, Part I: Introduction to the Systems Development Life Cycle

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

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

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.

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.

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.

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

PrototypingPrototyping 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.

Prototyping Techniques

IdentifyConceptualUserSpecifications

DevelopPrototype

PresentPrototypeto Users

ObtainUserFeedback

ChangePrototypePer UserFeedback

DevelopPrototypeinto FinishedSystem

Discard Prototypeand DevelopSystem UnderTraditionalSDLC Procedures

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.

Uses of CASE Toolsdefine 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

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

BenefitsQuicker development process

CostsProgram efficiency

Start-up time

and cost

Product cost

Incompatible CASE tools

Disadvantages of CASE

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.

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

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

Strategic Systems Planninginvolves 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

Project Planningallocates resources to individual

applications within the framework of the strategic plan

includes: recognizing the problem defining the problem specifying system objectives determining project feasibility

Specifying System ObjectivesThe 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.

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?

Systems Project ProposalA 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.

Project Schedulespresent management’s commitment

to the projectcontain a budget of the time and

costs for all phases of the SDLC

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.

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.

Stage 2: Systems AnalysisA 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

The Survey StepFacts 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

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

The Analysis StepThe 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

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

Conceptual Systems DesignAn 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.

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

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.

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.

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

Classes and InstancesAn 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

InheritanceInheritance 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.

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.

Chapter 13

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