INFO SYS ANALYSIS & DESIGN

Why are failed systems abandoned?

analysts tried to build wonderful system w/o understanding the organization

Primary goal

create value for the organization

Systems Analyst

• Analyzing the business

• Identifying opportunities for improvement

• designing information systems to implement these ideas

Systems Analyst Skills

• Technical skills

• Business skills

• Analytical skills

• Interpersonal

• Management

• Ethical

Technical Skills

existing environment and the new system’s tech foundation and the way both can be fit into an integrated technical solution

Business Skills

how IT can be applied to business processes and to ensure that IT delivers real business value

Analytical skills

put to test regularly in both project and organizational level

Interpersonal Skills

Communicate effectively

Management

manage the pressure and risks associated with unclear situations

Ethically

fairly and honestly

Systems Development Life Cycle

Planning

• Why build the system?

Analysis

• Who, what, when, where will the system be?

Design

• How will the system work?

Implementation

• System delivery

Planning

• Identifying business value

• Analyze feasibility

• Develop work plan

• Staff the project

• Control and direct project

Analysis

• Info gathering

• Process modeling

• Data modeling

Design

• Physical design

• Architectural design

• Interface design

• Database and file design

• Program design

Implementation

• Construction

• Installation

Methodology

formalized approach or series of steps

SDM Categorization

• Process centered

• Data centered

• Object oriented

Structured Design

Moves methodically from one to the next step

• Waterfall

• Parallel

Waterfall Development

Pros

• identifies systems requirements long before programming begins

Cons

• design must be specified on paper before programming begins

• long time between system proposal and delivery of new systems

Parallel Development

Rapid Application Development

Phased development

• A series of versions

Prototyping

• System prototyping

Throw-away prototyping

• Design prototyping

Critical elements of rapid application development

• CASE tools

• JAD sessions

• Fourth generation/visualization programming languages

• Code generators

Prototyping

Throw-away Prototyping

Object Oriented Systems Analysis and Design (OOSAD)

Use Case Driven

• use cases as primary modelling tools

Architecture Centric

• requirements focus on software architecture for a more cost effective approach

Iterative and Incremental

Benefits of OOSAD

• modularity

Iterative and Incremental Development

Agile

Individuals & Interactions over Process & Tools

Working Software over Comprehensive Documentation

Customer Collaboration over Contract Negotiation

Responding to Change over Following a plan

Extreme Programming

Communication - rapid feedback

Simplicity - KISS
Feedback - incremental changes

Courage - quality first mentality

Scrum

• Ideas for features

• Items managed by product owner

• Product owner develops and manages a prioritized feature list

Product backlog

to-do list

Sprints

the development cycles in Scrum development process

DevOps & Custom Methodologies

Inclusion of operations personnel with the dev team

Continuous deployment

Selecting the Appropriate Methodology

• Clarity of User Requirements

• Familiarity with Tech

• System Complexity

• System Reliability

• Short Time Schedules

• Schedule Visibility

Unified Process Phases

• Inception

• Elaboration

• Construction

• Transition

Unified Process Workflows

• Engineering workflow

• Business modelling workflow

• Requirements workflow

• Design workflow

• Implementation workflow

• Testing workflow

• Deployment workflow

Unified Modeling Language

• Object Management Group

• Structure Diagrams

• Behavior Diagrams

• Version 2.5 of the UML defines a set of 15 diagramming techniques

Why OOS?

• Managing code

• Maximize Reuse

• Build on other’s work

• Modularity

• No need to start from scratch

• Combines both process and structure oriented

Basic Characteristics of OOS

• Classes and objects

• Methods and Messages

• Encapsulation and Information Hiding

• Inheritance

• Polymorphism and Binding

Class

template to define specific instances or objects

Object

Instantiation of a class

Attributes

Describes the object

Behaviors

specify what object can do

Method

implement an object’s behavior

Message

sent to trigger methods

Encapsulation

combination of data and process into an entity

Information Hiding

only the info required to use a software module is published to the user.

Internal workings are hidden

Superclass

general class are at the top of a hierarchy of classes

Subclasses

inherit attributes and methods from classes higher in the hierarchy

Abstract Class

cannot be instantiated directly

Concrete Class

can be instantiated

Polymorphism

message can be interpreted differently by different classes of objects - method overriding

Dynamic Binding

Run Time

Late binding
Overriding

• method that is actually called is not chosen by the object-oriented system until the system is running

• Polymorphism is made possible through dynamic binding

Static Binding

Compile Time

Early binding

Overloading

• developer has to choose which method should be called instead of allowing the system to do it

Use Case Driven

allows developers to focus on how users interact with the system

Encapsulation

Hiding the content of the object

Communication only through the object’s methods

Key to reusability

Polymorphism

• same message triggers diff methods in diff objects

• dynamic binding means specific method is selected at run time

• implementation of dynamic binding is language specific

• need to be very careful about run time errors

• need to ensure semantic consistency

Inheritance

singe inheritance - one parent class

multiple inheritance - multiple parent classes

redefinition and inheritance conflict

most inheritance conflicts are due to poor classification