Tools Of Structure Analysis 2003

Tools Of Structured Analysis

Group Members

Introduction  Traditional

tools have some limitations. So to overcome these limitations structured tools are used.  Structured tools such as a Data Flow Diagram(DFD), Data dictionary & Structured English, provide alternative ways of designing a candidate system.

What is Structure Analysis? 

Definition : it’s a set of techniques and graphic tools that allow the analysis to developed a new kind of system specification that are easily understandable to the user.  Goals : 4. Use graphic whenever possible. 5. Differentiate between logical and physical system. 6. Build a logical system.

Tools Of Structure Analysis Data

Flow Diagram Data Dictionary Structured English Decision Tree Decision Table



Data Flow Diagram (DFD)

Data flow diagram supports 4 main activities: • Analysis: DFD used to determine requirements of users • Design: DFD used to map out plan and illustrate solutions to analysts and users while designing a new system • Communication: DFD is simple and easy to understand to analysts and users; • Documents: DFD used to provide special description of requirements and system design.

Main components of data flow diagram •

• • • •

Process Flow Storage External factors Internal factors.

 You

can construct DFD of system with the following guidelines: •

Choose meaningful names for processes, flows, stores, and terminators. • Number of processes. • Re-draw the DFD many times . • Avoid overly complex DFD.

Data Flow Diagrams Symbols 

DFD Symbols DFDs use four basic symbols that represent processes, data flows, data stores, and entities Gane and Sarson symbol set Yourdon symbol set



Advantage & Disadvantage

Advantage : 1.Its shows a minimum contents of data stores. 2.Its a quite effective, to clear the design to the user. 3.Its analyst to use the national language for communication.  Disadvantage : 1.It required the large number of iterations, that often are required to arrive at the most accurate and complete solution.

Library Management System

Readers Management

Doc uments Management

New reader receiving

Documents Classifying

Dept_no Checking

New books Inserting

New department register Reader_no allocating

New magazines inserting

Doc uments Lookin g up Books looking up Magazines looking up

B/R ticket Management

System Reports

B/R ticket Receiving

Document Report

Checking

Department Report

Replying

Function Hierarchy Diagram

Overdue Readers

Data Dictionary o In DFD we give name to data flow,

process , data store. o Although the names are descriptive of the data, the do not give detail. o So a structured place is build to keep the detail, this place is called data dictionary. o It’s a regorous definition of all DFD.

Advantages of Data Dictionary  It’s

works as a valuable reference.  It improves the communication between analysis and user.  it can be use to compare the data description.  Data dictionary can be use for cross referenced.  It’s used in building a database.

Logical Data Description Hierarchy

Decision Tree  Decision

Trees

Graphical representation of the conditions,

actions, and rules found in a decision tree. Whether to use a decision table or tree it is a matter of personal preference.

Structured English  Structured

English

Might look familiar to programming students

because it resembles pseudo code

Decision Tables 

Decision Tables  It define problems and action that has to be taken.  It’s a relationship between condition and action.  It has two parts: stub and entry. Stub has two parts, Entry has two parts, 1.Condition Stub 1.Condition Entry 2.Action Stub 2.Action Entry

Decision Tables

Summary 

Data and process modeling involves five main tools: Data Flow Diagrams(DFD), a Data Dictionary, Structure English, Decision Tree and Decision Table.  Data flow diagrams (DFDs) graphically show the movement and transformation of data in the information system.  The data dictionary is the central documentation tool for structured analysis.

Thank You