Chapter 14 Construct, Deliver, and Maintain Systems Projects

Hall, Accounting Information Systems, 7e

©2011 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Accounting Information Systems, 7eJames A. Hall

Chapter 14Construct, Deliver, and Maintain

Systems Projects

Hall, Accounting Information Systems, 7e©2011 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.

Objectives for Chapter 14 Be able to identify the sequence of events that constitutes the in-

house development phase of SDLC. Be familiar with tools used to improve the success of systems

construction and delivery activities including prototyping, CASE tools, and the use of PERT and Gantt charts.

Understand the distinction between structured and object-oriented design approaches.

Understand the use of multi-level DFDs in the design of business processes.

Be familiar with the different types of systems documentation and the purposes they serve.

Recognize the role of accountants in the construction and delivery of systems.

Understand the advantages and disadvantages of the commercial software option and be able to discuss the decision-making process used to select commercial software.

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System Development Life Cycle

3

Figure 14-1


Overview of Phases 3, 4 and 5 Phase 3. In-House Development

appropriate when organizations have unique information needs

steps include: • analyzing user needs• designing processes and databases• creating user views• programming the applications• testing and implementing the completed system

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Overview of Phases 3, 4 and 5 Phase 4. Commercial Packages

When acceptable, most organizations will seek a pre-coded commercial software package.

advantages: • lower initial cost• shorter implementation time• better controls• rigorous testing by the vendor

risks:• must adequately meet end users’ needs• compatible with existing systems

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Overview of Phases 3, 4 and 5 Phase 5. Maintenance and Support

acquiring and implementing the latest software versions of commercial packages

making in-house modifications to existing systems to accommodate changing user needs

may be relatively trivial, such as modifying an application to produce a new report, or more extensive, such as programming new functionality into a system

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Phase 3Systems Strategy


Why Up to 25% of All 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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Prototyping A technique for providing a preliminary

working version of the system Built quickly and relatively inexpensively with

the intention it will be modified End 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

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Figure 14-2


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 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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CASE Spectrum of Support Tools for the SDLC

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1

27

3

4

6

8

9

Purcha

se Equ

ipmen

t

Install and Test Equipment

Design Data Model Create Data Structures

5

Design Process

Code Programs Test

Prog

rams

Prepare

Docu

mentation

Convert Data Files

Test System

Train Personnel

Cut Over

to New

System

A = 3 Week

s

B = 4 Weeks

C = 4 Weeks

D = 2 Weeks

E = 5 Weeks

F = 5 Weeks G = 3

Wee

ks

H = 3 Week

s

I = 3 Weeks

J = 4 Weeks

L = 4 Week

s

K = 3 Weeks

Construct Phase Deliver Phase

PERT Chart for In-House Development Project

PERT charts show the relationship among key activities that constitute the construct and delivery process.

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Figure 14-4


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Gantt Chart

Figure 14-5


Structured Design Approach

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 data flow diagrams (DFDs) and structure diagrams

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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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Characteristics of an Inventory Object

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Figure 14-8


Classes and Instances An object class is a logical grouping of

individual objects that share the same attributes and operations.

An object instance is a single occurrence of an object within a class.

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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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Systems Design Follows a logical sequence of events:

model the business process and design conceptual views

design normalized database tables design physical user views (output and input

views) develop process modules specify system controls perform system walkthroughs

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Data Modeling Formalizes the data requirements of the

business process as a conceptual model Entity-relationship diagram (ERD)

the primary tool for data modeling used to depict the entities or data objects in

the system Each entity in an ERD is a candidate for

a conceptual user view that must be supported by the database.

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Normalization User views in the data model must be

supported by normalized database tables. Normalization of database tables:

A process of organizing tables so that entities are represented unambiguously

Eliminates data redundancies and associated anomalies

Depends on the extent to which the data requirements of all users have been properly specified in the data model

REA modeling facilitates normalization by identifying entities at their most fundamental levels

The resulting databases will support multiple user views

Described in more detail in chapter 9.24


Physical User Views: Output Views

Output is the information produced by the system to support user tasks and decisions.

Output attributes:-relevance-summarization-exception orientation

-timeliness-accuracy-completeness-conciseness

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Output Reporting Techniques

Different users prefer different styles of output… tables, matrices, charts, and graphs

…and modes of output. hard copy vs. display screen.

Systems designers must identify these styles and provide output in the desired style.

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Physical User Views: Input Views Input views are used to capture the relevant

facts in business processes and transactions (e.g., via REA model): Resources Events Agents

Input may be either hard copy input documents or electronic input.

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Designing Hard Copy Input

Items to Consider: How will the document be handled? How long will the form be stored and in

what type of environment? How many copies are required? What size form is necessary?

• Non-standard form can cause printing and storage problems.

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Designing Electronic Input Input may be from either hardcopy or electronic

Figure 14-14


Data Entry Devices Point-of-sale terminals Touch screens Mouse Magnetic ink character recognition

devices Optical character recognition devices Voice and touch-tone recognition

devices30


Designing Process Modules Begins with the DFDs produced in the

general design phase First, decompose the existing DFDs to

a degree of detail that will serve as the basis for creating structure diagrams

Structure diagrams provide the blueprints for writing the actual program modules

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Data Flow Diagrams (DFDs) Used to represent multiple levels of

detail. Can represent system physically or logically

Context-level DFDs represent an overview of the business activities and the primary transactions processed by the system. Do not include detailed definitions of data

files and specific procedures. Decompose high-level DFDs into more

detailed lower-level DFDs.32


DFD for Purchases and Cash Disbursements System

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Figure 14-15


Lower Level DFD for AP Process I.4

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Figure 14-16


The Modular Approach Each module performs a single task. Correctly designed modules possess two

attributes: loosely coupled - low amounts of exchange

of data between modules strongly cohesive - small number of tasks

performed in each module

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Designing System Controls The last step in the detailed design phase Need to consider:

computer processing controls data base controls manual controls over input to and output from the

system operational environment controls

Allows the design team to review, modify, and evaluate controls with a system-wide perspective that did not exist when each module was being designed independently

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Systems Walkthrough Usually performed by the development

team Ensure that design is free from conceptual

errors that could become programmed into the final system

Some firms use a quality assurance (QA) group to perform this task. An independent group of programmers,

analysts, users, and internal auditors37


Program Application Software If the organization intends to develop

software in-house, then a programming language must be selected: procedural languages or 3GLs COBOL event-driven languages Visual Basic object-oriented languages Java

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The Modular Approach to Programming

Promotes programming efficiency modules can be both programmed and

tested independently Promotes maintenance efficiency

small modules are easier to analyze and change

Promotes greater control modules are less likely to contain material

errors of fraudulent logic39


Deliver the System:Testing Programs must be thoroughly tested

before being implemented. All logic procedures should be tested.

Test individual modules with test data containing both “good” and “bad” data.

After testing individual modules, the entire system should tested as a whole.

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Deliver the System:Documenting Describes how the system works Documentation should be provided for:

designers and programmers - comment lines in programs, system flowcharts, and program flowcharts

operator documentation - run manuals user documentation - instructions on how to

use the system, tutorials, and help features accountants and auditors - all of the above as

well as document flowcharts

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Deliver the System:Converting the Databases The transfer of data from its current form

to the format or medium required by the new system

Control risks with the following procedures: validation – inspect old database before

conversion reconciliation – reconcile the new converted

database against the original backup - keep copies of the original files against

discrepancies in the converted data42


Deliver the System:Converting the Databases

Three data conversion cutover approaches: Cold turkey - switch to the new system all at once

and simultaneously terminate the old system. riskiest approach

Phased - modules are implemented in a piecemeal fashion. reduces risk of a devastating failure

Parallel operation - the old system and new system are run simultaneously for a while. safest, yet costliest, approach

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Deliver the System:Post-Implementation Review Objective: measure the success of the new

system. do after initial problems have been addressed

Assess: system design adequacy accuracy of time, cost, and benefit estimates

Provides feedback to improve future systems development projects, including changes to the current system

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Deliver the System:The Role of Accountants

Most system failures are due to poor design and improper implementation.

Accountants should provide their expertise to help avoid inadequate systems by: providing technical expertise for financial

reporting requirements specifying documentation standards for auditing

purposes verifying control adequacy in accordance with

SAS 7845




Phase 4Commercial Packages


The Purchase of Commercial Systems Packages Four factors have stimulated the growth

of commercial software: relatively low cost prevalence of industry-specific vendors growing demand by small businesses trend toward downsizing and distributed data

processing

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Trends in Commercial Packages Turnkey systems - completely finished and

tested systems ready for implementation Backbone systems - provide a basic

system structure on which to build. Vendor-supported systems - customized

and maintained by a vendor for a customer ERP systems - difficult to classify since

they have characteristic of all of the above. See chapter 11 for more details on ERP systems.

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Pros and Cons of Commercial Packages

Advantages: decreased implementation time decreased cost reduced probability of program errors

Disadvantages: dependent on the vendor for maintenance less flexibility in system greater difficulty in modifying the system as needs

change over time

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Four Steps in Choosing a Commercial Package

1. Analyze needs and develop detailed specifications of the system requirements.

2. Send out the request for proposals to all prospective vendors to serve as a comparative basis for initial screening.

3. Gather the facts about each vendor’s system using multiple sources and techniques.

4. Analyze the findings and make a final selection.

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Phase 5Maintenance and Support


Maintenance and Support Approximately 80% of the life and costs of

SDLC Can be outsourced or done in-house

resources End user support is a critical aspect of

maintenance that can be facilitated by: knowledge management - method for gathering,

organizing, refining, and disseminating user input group memory - method for collecting user input

for maintenance and support

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The Iceberg Effect

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Figure 14-29

Documents

Chapter 14 Construct, Deliver, and Maintain Systems Projects