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Posts tagged ‘ERD’

Dream getaway assignment requirements

Charts/ diagrams needed

  • Organization chart to show who is involved in DG
  • ID and describe info gathering techniques that could be used to gather info needed for DG project
  • Use case diagram for procedures and functions at DG
  • Use case description for booking a vacation at DG
  • Activity diagram for booking a vacation at DG
  • Use above three to construct an entity relationship model, should include all  required entities, relationships between entities and attributes I believe they should contain using the paper based forms

Analysis report

Requirements fall into five categories: Outputs, inputs, processes, timings and controls. ID requirements for each category for attached scenario.

Investigation items

  • Intro
  • Systems request summery
  • Findings
  • Scope statement
  • Feasibilty study
  • Recommendations (we go ahead with report and need a data base)
  • Project roles
  • Time and cost estimates
  • Expected benefits

**Using UML and ERD for report

Preliminary investigation report

  • Booking
  • Suppliers
  • Customers/ clients

Scope statement

  • Things you will definately do
  • Things you will definately not do
  • Things you may do if you have time
  • Different options/ costs

The team needs:

  • An analyst
  • A team manager
  • Hardware
  • Software
  • Other stakeholders, owners etc

Info gathering

Organisation chart for the business

Techniques used:

Interviews

JAD sessions

Documentation

Design

Use cases for all functionalities eg. Making bookings, get reports, update suppliers

Design use case descriptions for bookings:

  • What is the use case for
  • What tasks/ steps are needed
  • Use parts of the use case diagram to help

Activity diagrams

These are based on the use cases

ERD’s

  • Entities
  • Relationships
  • Cardinality/optionality
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Modelling types

Data flow diagrams (DFD)

O-O modelling

Uses UML (a case tool), attributes, methods, messages, classes and instances.

Each object needs a parent object

DFD has different levels as follows:

  • Context level diagram
  • Level 0 DFD
  • Level 1 DFD
  • Level 2 DFD

There should be no more than four levels, (the context level diagram counts as a level even though it doesn’t have a number)

Context level diagram contains:

  • The processes of a system
  • External entities
  • Data flow in and out of the system
  • The relationship between dataflows

Level 0 DFD contains:

  • Processes of the system
  • External entities
  • Data flows
  • Data stores
  • Sub processes

Level 1 DFD contains:

  • Subprocesses of the level 0 DFD

Level 2 ERD (Entity Relationship Diagram) contains:

  • Entities
  • Relationships
  • Cardinality – The closest option to the box
  • Optionality – May have this, option furtherest away from the box

Cardinality

0 – Zero

1 – One

<-   – Many (more like an E)

Optionality

0 – Zero

1 – One

*ERD’s should have the cardinalities and optionalities written out for both directions

The context level provides each item/process, in level 0 these are numbered eg 1. 2. 3. etc

In level one each subprocess is numbered off of its original process eg. 1.1, 2.1, 3.2 etc

In level two these processes are broken down again eg 1.1.1, 2.1.3, 3.2.2

UML

Unified modelling language used mostly for o-o

Contains a super class, a class and a subclass

Visual modelling is a UML

UML diagrams use:

  • A use case diagram
  • Activity diagrams
  • Sequence diagrams
  • Class diagrams
  • State transitional diagrams

Objects are held within the classes Eg.

Class

| Object

| Object

| Object

| Object

————

The relationship is the information the objects need to know about each other, or how they relate.

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