11 Jan 2011

Systems Development Life Cycle (SDLC)

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Resits for Christmas MCQ

• This coming Friday 14th Jan at 10am.Venue room 3.85 (3rd floor o'Rahilly Builiding).

CORE ACTIVITY DESCRIPTION

Systems analysis Identify problem(s)Specify solutionsEstablish information requirements

Systems design Create design specifications

Programming Translate design specifications into code

Testing Unit testSystems testAcceptance test

Conversion Plan conversionPrepare documentationTrain users and technical staff

Production and maintenance

Operate the systemEvaluate the systemModify the system

Summary of Systems Development ActivitiesSummary of Systems Development ActivitiesOverview of Systems Development

This slide is from notes in first term

Systems Development Life Cycle (SDLC)

• Many approaches to systems development

• Sequential versus Iterative Development– Understanding the difference between these two

approaches is essential

• Traditional Approach – Waterfall Model

Systems Development Life Cycle (SDLC)

• Traditional Approach is sequential

• Each phase of development is completed before the next phase begins

• Waterfall Model is a common example of a sequential approach

6

Initiation

Analysis

Investigation

Implementation

Design

Maintenance

NO FEEDBACK!!!!

SDLC - Waterfall Model

SDLC - Waterfall Model

• What are the limitations of this approach? – This is now regarded as the “hard” systems approach

because of its rigid demarcation between phases

– Cannot correct defects from previous stages

– No Feedback

– Expensive – Spending long time in each phase

Example

• Existing System – Analysis stage– Extensive problem analysis and Requirements

gathered

• Move to next stage – Design stage– Create design based on previous analysis stage

• What happens if something changes

9

Initiation

Analysis

Investigation

Implementation

Design

Maintenance

NO FEEDBACK!!!!

SDLC - Waterfall Model

SDLC – Waterfall Model

• Limitations of sequential approach has lead to the emergence of a more iterative approach

• Iterative approach involves a more flexible approach allowing for the movement back and forth between stages of the lifecycle

• What are the advantages of this?

Iterative approach to SDLC

• Advantages– Flexibility – allows for changing requirements

– Feedback from different stages – refinement

– Maintains communication between systems analyst and the technical team• Why is this communication important?

Business People

Technical People

Business Solution

Technical Solution

Gap Between Business and

Technical

Iterative Approach to SDLC

• Phases are generally the same as the waterfall model

• However, there can be several iterations back and forth between these phases

• Essentially this is an incremental approach

14

Initiation

Analysis

Investigation

Implementation

Design

Maintenance

Phase 1: Project Planning & Initiation

• Project planning and initiation essential

• Aims: To establish whether the project is feasible and to ensure that the project will be successful

• Initiation team must be developed– Why?

Phase 1: Project Planning & Initiation

• Key Initiation Activity – Developing a project charter– Short document for both internal and external

stakeholders of the project– Providing high level overview of project

• Why do this? Remember – IS not just a technical issue!

Phase 1: Project Planning & Initiation

• Project Charter – typically contains:– Project title, start date, prj manager, contact info– Customer details – key stakeholders– Project timeline (projected)– Key stakeholders (internal and external) • Responsibilities

– Project Objectives and Description– Assumptions

Phase 1: Project Planning & Initiation

• Activities of project planning– Project scope– Feasibility and alternative options– Creating project tasks• Deliverables – start time; completion; responsibilities

– Resource Requirements– Project Constraints

Phase 2: Investigation

• Investigation of the functional requirements of the existing system (if it exists) and whether these requirements can be achieved

• The requirements of the new system

Phase 2: Investigation• Interviewing - Individuals and groups of users is usually the

most helpful technique for establishing and verifying information

• Questionnaires - Used where large amounts of information needs to be obtained from a large number of respondents or from remote locations

• Observation - Can be a useful insight into existing work problems

• Documentation – Analysing existing documents within the system

• An organisation chart showing the reporting structure of people in a company or department

• Various Flowcharts, which help the analyst to trace the flow of documents in the department. It is possible to include in the flowchart the processes that are applied to each document. These processes could include for example the checking and error correction procedures.

21

Documentation Aids

• Discussion records on which the notes taken at interviews could be recorded.

• Grid charts, showing how different components of the system such as people and machines interact with each other.

22

Documentation Aids

End of Lecture Notes

Tutorials

• Low attendance in labs today

• Attendance is mandatory – will be taken into account when correcting in-class exams and final year exams

• Tutorial material in this term is extremely important!