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System Development Life Cycle

Linked Together

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Detail of the SDLC

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Systems Development Life Cycle - PHASE 1: PLANNING

Primary planning activities include

1. Identify and select the system for development

2. Assess project feasibility3. Develop the project plan

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Planning phase – involves establishing a high-level plan of the intended project and determining project goals

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PLANNING 1: Identify and Select the System for Development

Organizations use different forms of evaluation criteria to determine which systems to develop

◦ Critical success factor (CSF) – a factor that is critical to an organization’s success

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PLANNING 1: Identify and Select the System for Development

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PLANNING 2: Assess Project Feasibility

Feasibility study – determines if the proposed solution is feasible and achievable from a financial, technical, and organizational standpoint

Different types of feasibility studies◦ Economic feasibility study◦ Operational feasibility study◦ Technical feasibility study◦ Schedule feasibility study◦ Legal and contractual feasibility study

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PLANNING 3: Develop the Project Plan

Developing the project plan is a difficult and important activity

The project plan is the guiding force behind on-time delivery of a complete and successful system

Continuous updating of the project plan must be performed during every subsequent phase during the SDLC

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SDLC – PHASE 2: ANALYSIS Analysis phase – involves analyzing end-user business

requirements and refining project goals into defined functions and operations of the intended system

Primary analysis activities include:1. Gather business requirements2. Create process diagrams3. Perform a buy vs. build analysis

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ANALYSIS 1: Gather Business Requirements

Business requirements – the detailed set of business requests that the system must meet in order to be successful

Different ways to gather business requirements

◦ Joint application development (JAD) session – where employees meet to define or review the business requirements for the system

◦ Interviews◦ Questionnaires◦ Observations◦ Review business documents

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ANALYSIS 1: Gather Requirements The system users review the

requirements definition document and determine if they will sign-off on the business requirements

◦ Requirements definition document – contains the final set of business requirements, prioritized in order of business importance

◦ Sign-off – the system users’ actual signatures indicating they approve all of the business requirements

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ANALYSIS 2: Create Process Diagrams

Process modeling – graphically representing the processes that capture, manipulate, store, and distribute information between a system and its environment

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Common process modeling diagrams include

Data flow diagram (DFD) – illustrates the movement of information between external entities and the processes and data stores within the system

Computer-aided software engineering (CASE) tools –automate systems analysis, design, and development

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ANALYSIS 3: Perform a Buy vs. Build Analysis An organization faces two primary choices when

deciding to develop an information system

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1. Buy the information system from a vendor– Commercial off-the shelf (COTS) –

software package or solution that is purchased to support one or more business functions and information systems

– SCM, CRM, and ERP solutions are typically COTS

2. Build the information system itself

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ANALYSIS 3: Perform a Buy vs. Build Analysis

Organizations must consider the following when making a buy vs. build decision:

◦ Are there any currently available products that fit the needs?

◦ Are there features that are not available and important enough to warrant the expense of in-house development?

◦ Can the organization customize or modify an existing COTS to fit its needs?

◦ Is there a justification to purchase or develop based on the acquisition cost?

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ANALYSIS 3: Perform a Buy vs. Build Analysis

Three key factors an organization should also consider when contemplating the buy vs. build decision

1. Time to market2. Availability of corporate resources3. Corporate core competencies

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Systems Development Life Cycle – PHASE 3: DESIGN Design phase – involves describing the desired

features and operations of the system including screen layouts, business rules, process diagrams, pseudo code, and other documentation

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Primary design activities include:

1. Design the IT infrastructure

2. Design system models

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DESIGN 2: Design System Models Modeling – the activity

of drawing a graphical representation of a design

Different modeling types include:

◦ Graphical user interface (GUI)

◦ GUI screen design◦ Data model◦ Entity relationship

diagram (ERD)Slide: 16

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Systems Development Life Cycle – PHASE 4: DEVELOPMENT

Development phase – involves taking all of the detailed design documents from the design phase and transforming them into the actual system

Primary development activities include:

1. Develop the IT infrastructure2. Develop the database and programs

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Systems Development Life Cycle – PHASE 5: TESTING

Testing phase –

involves bringing all the project pieces together into a special testing environment to test for errors, bugs, and interoperability, in order to verify that the system meets all the business requirements defined in the analysis phase

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Primary testing activities include:

1. Write the test conditions2. Perform the system testing

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TESTING 2: Perform the System Testing

Different types of testing◦ Unit testing – tests each unit of code

upon completion◦ Application (or system) testing –

verifies that all units of code work together

◦ Integration testing – exposes faults in the integration of software components or units

◦ Backup and recovery testing – tests the ability of an application to be restarted after failure

◦ Documentation testing – verifies instruction guides are helpful and accurate

◦ User acceptance testing (UAT) – tests if a system satisfies its acceptance criteria

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Unit Testing System Testing

Integration Testing

Backup and Recovery Testing

Documentation Testing

User Acceptance

Testing

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Systems Development Life Cycle – PHASE 6: IMPLEMENTATION Implementation phase – involves

placing the system into production so users can begin to perform actual business operations with the system

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Primary implementation activities include:1. Write detailed user documentation2. Determine implementation method3. Provide training for the system

users

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IMPLEMENTATION 1: Determine Implementation Method

Four primary implementation methods 1. Parallel implementation

2. Plunge implementation

3. Pilot implementation

4. Phased implementation

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Using both old and new systems until it is evident the new system works

Completely discarding old system and immediately start using new system

Only a small group uses new system until it is evident that it works

Implementing a new system in phases

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Systems Development Life Cycle – PHASE 7: MAINTENANCE

Maintenance phase – involves performing changes, corrections, additions, and upgrades to ensure the system continues to meet the business goals

Primary maintenance activities include:1. Build a help desk to support the system users2. Perform system maintenance3. Provide an environment to support system changes

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MAINTENANCE 1: Perform System Maintenance Maintenance – fixing

or enhancing an information system

Different types of maintenance include:

◦ Adaptive maintenance ◦ Corrective maintenance ◦ Perfective maintenance ◦ Preventative maintenance

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AdaptiveIncreases system functionality

CorrectiveRepairs defective systems

PerfectiveEnhances

systems

PreventativeReduces chances

of failure