System Development ProcessSystem Development Process

Lecture 9BSIT-2nd (M+E)

Outline

• System Development Process

• Two Forms of System Development Process

(Waterfall & Iterative)

• System Planning for Process Optimization

• System Analysis & Design

• Good System Design

• System Construction, Installation, Testing

• System Deployment & Maintenance

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System Development Process

Plan System

Conduct System Analysis

DesignSystem

ConstructSystem

Deploy & MaintainSystem

Install & TestSystem

__________________Focus on___________:

Organizational goals & plans

Org. processes and data As-is vs. To-be

System solutions to problems in org. processes & data

Result of IS Analysis & Design are system requirements*

Programming, purchasing software & hardware; also called “implementation”

Reality check

Fine-tuning the system

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System Development Model:1- Waterfall Model

• System development steps can be run on the entire system sequentially in defined periods. This is Waterfall methodology.

• Linear, no turning back to previous step.

• Inflexible: once defined system requirements are fixed.

• If development time longer, system may be obsolete at time of release.

Plan System

Conduct System Analysis

DesignSystem

ConstructSystem

Deploy & MaintainSystem

Install & TestSystem

years

0

1

2

X

X

X

4

2- Iterative ModelSystem Part A

System Part B

System Part C

System Part ...

One run of Plan-to-Test is called iteration.* Some system parts can take more than 1 iteration. Even previously developed and tested parts could be revised later in the iterative developing process.

Plan System

Conduct System Analysis

DesignSystem

ConstructSystem

Install & TestSystem

time

Deploy & MaintainSystem

All

More parts?NY

5

.

.

Information Systems for Management 6Information Systems for Management 6

Iterative Methodology

Strengths Weaknesses

Rapid, savings (people, time, $) Less suitable for large, complex systems due to system integration issues

Useful when system requirements are less certain due to dynamic business

May neglect details in analysis, documentation and testing

Involves users in process, not at the end only

• An alternative to sequential development of systems• Methodology:

• Break whole system into smaller pieces that functionally build on each other.

• For example: Focus on one system function. Develop software for it as well as a part of database and part of user interface for it.

• Analyze, design and construct a piece quickly; test it on users, revise, and move on to next function.

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Business goals and plans to be accomplished with new system:

Optimize process design*Improve process performance**Define new processes***What are the costs and financial returns expected from the process/IS changes?

How does IS in planning can help to accomplish the above?

Plan System

Your IS What you

need

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• The goal is to understand the existing (present) business and systems (As-is) in order to create improvements (To-be).

• Focus on the present:

– Analysis of present organizational processes (design, performance) - interview end-users & managers.

– Analysis of present data as part of organizational processes - collect business documents, analyze communications

• Focus on the future:

– Business plans & goals

– Analysis of informing needs: What data is needed, what system outputs are needed, who/when/where needs them.

Perform System Analysis

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Design System

• Designing system is about creating a new IS or a major upgrade of an existing IS.

• The data model is created or changed in case of upgrade.

• The processing of data in the system is defined according to the model of organizational process resulting from the System Analysis step.

• User Interface is designed (content and look of screens, & their sequence).

• User interface is the point of connection between User and System, and thus it determines expenditures of users’ time and effort – productivity factors.

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Good System Design - User PerspectiveWell-designed information system needs to:

1.Do the work it is planned to support – fit with business processes

2.Be easy to learn and use - user interface quality, menu design:

– intuitive screen items (labels, buttons) $

– screens reasonably complex (but remember SAP?)

– letting users know where they are (navigation* aspect)

– allows for easy tracking and correction of errors

1.Support quick execution of tasks - user interface & technical aspects (fast hardware, fast data transfer, well-designed application software). Impacts on process performance (timing, costs).

Drop-down menu design

Tab menu design

See Footnote

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Construct System• A system is physically made based on the design created (data

diagrams, and process diagrams that determine what software should do – how the data should be processed).

• This includes several activities:

– Write application software (computer programming)

– Buy application software (off-the-shelf software)

– Purchase computer and other electronic hardware

Paired rather than individual programming is often practiced today as part of rapid IS development. Quality of software may benefit.

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Install & Test System

• Installation: Software is mounted on hardware, cabling completed, and facilities prepared. This may happen gradually in iterative development.

• Testing: Evaluating the performance of a developed system.

• Kinds of tests run based on moving from small to large :

1. Unit testing (experts test an individual function a system performs; e.g., set a credit limit for a customer, create a customer order, test relationship between the order amount & credit limit). Test two related units, and keep adding new ones.

2. System testing (experts test all functions; also, how much load can an IS take).

3. Acceptance testing (final testing performed by users; includes all components).

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System Deployment Methods1. Direct deployment

- New system completely replaces old one - Higher risk, lower cost

1. Parallel deployment– Old and new system used until the new proves reliable– Lower risk, higher cost

OLD IS NEW IStime

Old out/New in

NEW IS

OLD IS

time

New in Old out

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System Deployment Methods (cont.)

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3. Phased deployment

- New system introduced in stages part by part.

- Optimizing risk & cost.

OLD IS

time

replace

New part in/Old part out……………..

Once a System is Deployed…

1 2

3 But…

Funny wayof showing…

… what may happen in reality!

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Maintain System in Production Stage

• IS is used in organizational operations (use period or production stage).

• IS is evaluated (how many employees use it, how well it supports work, costs, business benefits).

• As IS is used and managed, its development continues in small; this is called system maintenance.

• System maintenance is incremental development performed in the use period of an IS. It includes:

– De-bugging software (correcting errors in software)*

– IS modifications based on business needs (e.g., larger data storage needed or reports answering new business questions)

– Adding new software and hardware driven by vendors or technological trends.

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S u m m a r y

• System development process takes activities of planning, analysis, designing, constructing, installing, testing, and deploying, and maintaining an IS.

• Systems are developed in two ways – waterfall and iterative.

• Plan for new IS can aim at optimizing process design, improving process performance, and creating new processes.

• System Analysis focuses on both business and existing IS (if any) to understand how work is done and how it should be.

• Well-designed IS should perform work needed, be easy to learn and use, and enable efficient (quick ) work.

• IS construction implements IS design, where software can be created in different ways.

• There are 3 methods of IS testing and 3 deployment strategies.

• System maintenance continues throughout the system use period.

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