Post on 02-Apr-2015
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Chapter 14
Construct, Deliver, and Maintain Systems Projects
Accounting Information Systems, 5th editionJames A. Hall
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SDLC major phases
1. Systems strategy2. Project initiation3. In-house development4. Commercial packages5. Maintenance & support
Chapter 14
Chapter 13
Systems Development Life Cycle
1. Systems Strategy - Assessment - Develop Strategic Plan
1. Systems Strategy - Assessment - Develop Strategic Plan
2. Project Initiation - Feasibility Study - Analysis - Conceptual Design - Cost/Benefit Analysis
2. Project Initiation - Feasibility Study - Analysis - Conceptual Design - Cost/Benefit Analysis
3. In-house Development - Construct - Deliver
3. In-house Development - Construct - Deliver
4. Commercial Packages - Configure - Test - Roll-out
4. Commercial Packages - Configure - Test - Roll-out
5. Maintenance & Support - User help desk - Configuration Management - Risk Management & Security
5. Maintenance & Support - User help desk - Configuration Management - Risk Management & Security
System Interfaces, Architecture and User Requirements
Business Requirements
High Priority Proposals undergo Additional Study and Development
Feedback:User requests for New Systems
Selected System Proposals go forward for Detailed Design
New and Revised Systems Enter into Production
Business Needs and Strategy
Legacy Situation
Feedback:User requests for System Improvements and Support
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Ch14 Ch14
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Overview of Phases 3, 4 and 5
Phase 3 - In-House Development appropriate when organizations have
unique information needs steps include:
analyzing user needsdesigning processes and databasescreating user viewsprogramming the applicationstesting and implementing the completed
system
Overview of Phases 3, 4 and 5
Phase 4 - Commercial Packages when acceptable, most organizations will
seek commercial software package advantages:
lower initial costshorter implementation timebetter controlsrigorous testing by the vendor
risks:must adequately meet end users’ needsmust be compatible with existing systems
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
Phase 3In-house Development
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3 problems that account for most system failures…
1. Poorly specified systems requirementscommunication problemstime pressures
2. Lack of user involvement in systems
development/selection 3. Ineffective development
techniques(for internally developed systems)
systemsdeveloper
enduser
PrototypingProvides preliminary working version
of the systemBuilt 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.
Computer-Aided Software Engineering (CASE)
CASE technology uses 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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PERT charts
Used to show relationship among key activities of a systems project
Probably used more for in-house development (than commercial software acquisition)
A
DG
B
C
F
H
I
Purch
ase E
quipm
ent
Install and Test Equipment
Design Data Model Create Data Structures
E
Design Process
Code Programs Test
Prog
ram
s
Prepare
Doc
umen
tation
Convert Data Files
Test System
Train Personnel
Cut Over
to N
ew Syste
m
A-D 3
Wee
ks
A-B 4 Weeks
A-C 4 Weeks
D-F 2 Weeks
B-F 5 Weeks
C-E 5 Weeks E-F
3 W
eeks
F-G 3
Wee
ks
F-I 3 Weeks
F-H 4 Weeks
H-I 4 W
eeks
G-I 3 Weeks
Construct Phase Deliver Phase
Project Evaluation and Review Technique (PERT)
PERT charts show the relationship among key activities that constitute the construct and delivery process.
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 (not necessary to study DFDs)
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
Data Modeling
Formalizes data requirements of the business process as conceptual model
Entity-relationship diagram (ERD) primary tool for data modeling used to depict the entities or data objects
in systemEach entity in ER diagram is a
candidate for a conceptual user view that must be supported by database.
Normalization
User views in 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 that the data requirements
of all users have been properly specified in the data model
The resulting databases will support multiple user views
More detail in chapter 9 about data normalization
Physical User Views: Output Views
Output is the information produced by the system to support user tasks and decisions.
Output attributes:-relevant-summarization-except orientation
-timely-accurate-complete-concise
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.
Designing System ControlsThe last step in the detailed design phaseNeed 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
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 auditors
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SY STE M
The Delivery
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Delivering a system
Appropriate for commercial software or in-house development Test entire system Document the system
Designer/Programmer documentation (in-house)
Operator documentation (more centralized than distributed)
User documentationAccountant/Auditor documentation
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Conversion of databases
Appropriate for commercial software or in-house development Transfer of data from old system to
new system Validate data before conversion Reconcile data after conversion Keep backup copies of old data!
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Converting to New System
Three approaches:Cold turkey cutover (“Big Bang”) - firm
switches to new system on particular day and simultaneously terminates old system. Riskiest approach.
Phased cutover - modules are implemented in piecemeal fashion. Risk of devastating failure can be reduced.
Parallel cutover - old system and new system are run simultaneously. Safest, yet costliest, approach.
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Role of Accountants in Construct & Deliver Phases
Accountant should: Provide technical expertise re:
GAAP, GAAS, SEC regulations, SoX, IRS code.
Specify documentation standards
Verify control adequacy
Phase 4Commercial Packages
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4. Commercial Software
Four factors have stimulated growth of commercial software: relatively low cost prevalence of industry-specific
vendors growing demand by small businesses trend of organizational downsizing and
distributed data processing
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Types of Commercial Software
Turnkey systems: completely finished and tested systems -- ready for implementation.
Backbone systems: provide basic system structure on which to build.
Vendor-supported systems: custom-developed and maintained by vendor for customer.
ERP systems are difficult to classify because they have characteristics of all of the above.
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Commercial Software
Advantages Implementation time Cost Reliability
Disadvantages Dependence on vendors Need for customized systems Maintenance
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Steps in Choosing a Commercial Package
1. Needs analysis2. Send out Request for Proposals (RFP)
to prospective vendors to serve as comparative basis for initial screening.
3. Gather facts about each vendor’s system using multiple sources and techniques.
4. Analyze findings and make final selection.
Phase 5Maintenance and Support
Maintenance and Support
Approximately 80% of the life and costs of SDLC
Can be outsourced or done in-houseEnd 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
The Iceberg Effect
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