Systems Analysis and Design

Overview of Current Methodologies

CT026-1 Systems Analysis and Design Overview of current methodologies Slide 2 (of 43)

Topic & structure of the lesson

Overview of current methodologies and their suitability for application domains SSADM Object-oriented RAD

CT026-1 Systems Analysis and Design Overview of current methodologies

Methodologies

Software development methodology structured method based on life cycle model

Why do we need a methodology?

CT026-1 Systems Analysis and Design Overview of current methodologies

Methodologies

Different methodologies Process oriented methodologies

STRADIS (Gane and Sarson)

YSM (Yourdan)

Blended methodologies SSADM

Information Engineering

CT026-1 Systems Analysis and Design Overview of current methodologies

Methodologies

Different methodologies OO methodologies

OO Analysis

Rational Unified Process (RUP)

Rapid development methodologies

People-oriented methodologies

Organizational methodologies

CT026-1 Systems Analysis and Design Overview of current methodologies

Structured Systems Analysis and Design (SSADM)

A “baseline” for comparison and evaluation of other methodologies and for themes in systems development

The true successor to the traditional SDLC approach with new techniques and tools developed since the 1970s

CT026-1 Systems Analysis and Design Overview of current methodologies

Structured Systems Analysis and Design (SSADM)

supported by CASE tools clearly defined deliverables quality checkpointsWaterfall can be classified as this kind of

methodology. vulnerable to any business changes that

happen while the development is still on the way, as it is extremely difficult to go backwards

CT026-1 Systems Analysis and Design Overview of current methodologies

SSADM

forces the developers to well identify and understand system requirements long time before the implementation phase begins.

lack of ability to go backwards makes it unaccommodating to changes as the project proceeds.

system being built can not be presented until it is completely done at the end of the implementation phase.

CT026-1 Systems Analysis and Design Overview of current methodologies

SSADM

Major tools Logical Data Modeling

Logical Data Structure ER Model - Entities & Relationships Documentation

Data Flow Modeling Data Flow Diagrams Documentation

Entity / Event Modelling Entity Life History Documentation

CT026-1 Systems Analysis and Design Overview of current methodologies

SSADM

Version 4 in 1990 has 7 stages1. Feasibility

2. Investigation of current environment

3. Business system options

4. Requirements Specifications

5. Technical system options

6. Logical design

7. Physical design

CT026-1 Systems Analysis and Design Overview of current methodologies

Object Oriented Analysis & Design (OOAD)

different approaches and methodologies Booch Coad and Yourdon Martin and Odell Rumbaugh et al

CT026-1 Systems Analysis and Design Overview of current methodologies

OOAD

OO life cycle analysis design implementation

Deliverables diagrams repository description

CT026-1 Systems Analysis and Design Overview of current methodologies

OOAD

uses a tool called UML (Unified Modeling Language), which is a set of standard in diagramming and modeling techniques invented by three OO champions, Grady Booch, Ivar Jacobson, and James Rumbaugh

CT026-1 Systems Analysis and Design Overview of current methodologies

Comparison between SSADM and OOA

blend of data and process models used

programming code separate from data

maybe waterfallprocess modelexplicitly shows data

flowsshows data store

objects used

code and data bundled in an object

incremental and iterativeuse case implies data flowhas no equivalent to data

store

Structured OO

CT026-1 Systems Analysis and Design Overview of current methodologies

Similarities

show functions required by user may be leveled according to detail strongly related to how information is storedshow external agents interacting with the systempartition functionalities into small partsindicate how data may be storedrefer to attributes

CT026-1 Systems Analysis and Design Overview of current methodologies

Rapid Application Development (RAD)

Introduced code generators and the visual fourth-generation (4G) programming languages such as Microsoft Visual Basic and Borland Delphi

Iterative model allowing back tracking “Working model is worth a thousand pictures” High level of user involvement

CT026-1 Systems Analysis and Design Overview of current methodologies

Phases in RAD

1. Requirements Planning phase

2. User design phase

3. Construction phase

4. Cutover phase

Compared with traditional methods, the entire process is compressed. As a result, the new system is built, delivered, and placed in operation much sooner.

CT026-1 Systems Analysis and Design Overview of current methodologies

RAD Methodology

CT026-1 Systems Analysis and Design Overview of current methodologies

RAD

Some part of the system (the core functioning) is developed quickly to be delivered to the users

However as the system can be delivered quickly, users tend to change their expectations of what the system can do, thus the requirements tend to change and expand.

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Follow Up Assignment

List and explain the differences between SSADM and Object-oriented in terms of the activities and phases involved.

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Summary of Main Teaching Points

Overview of current methodologies and their suitability for application domains SSADM Object-oriented RAD

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Question and Answer Session

Q & A

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Next Session

Introduction to OO Concepts