Final Presentation of Tools and Techniques of Structure Analysis (1) (1)

7/31/2019 Final Presentation of Tools and Techniques of Structure Analysis (1) (1)

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Tools and TechniquesOf

Structured Systems Analysis and Design

(SSAD)

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MEMBERS ROLL NO

o Himanshu ojha 011098

o Rohan naik 011179

o Ajay nandkumar 011158

o Manvir singh sohal 011106

o Rohan yadav 011172

o Sukesh nagurkar 011072

o Nishant jadhav 011079

o

Gurpreet singh Jhuman 01119211/7/2012 002


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Acknowledgement

We would like to thank M/s Priya Vij for giving us

this opportunity.

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Structured Systems Analysis and Design

Structured Systems Analysis and Design (SSAD) is a systems

approach to the analysis and design of information systems. SSAD

was produced for the CCTA, a UK government office concerned

with the use of technology in government, from 1980 onwards.

System design methods are a discipline within the software

development industry which seek to provide a framework for

activity and the capture, storage, transformation and disseminationof information so as to enable the economic development of

computer systems that are fit for purpose.

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Objectives

Improvements in communication.

Ensure the maintainability of the system to be analyzed.

Useful tools for representing the system.

Must be able to effectively partition a complex problem.

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Benefits of SSAD

Usability

Respond to changes in the business environment

Effective use of skills

Better quality

Improvement of productivity

Cuts costs

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Disadvantages of SSAD

SSAD puts special emphasis on the analysis of the system and its

documentation. This causes the danger of over-analysing, which can

be very time and cost consuming.

Due to various types of description methods, checks of consistencecannot be carried out.

Especially with large systems, the outline diagram can become very

unclear, because all relevant data flows have to be included.

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SSADM Tools

Data Flow Diagram (DFD).

Data Dictionary.

Structured English.

Decision Trees.

Decision Tables.

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Data Flow Diagram:

Data Flow Diagram(Bubble Chart) is a graphical representation ofthe logical flow of data.

It help in expressing the systems requirements in a simple andunderstandable form the and Contains 4 graphic symbols.

It clarify the system requirement and indentify majortransformations that will become program in system design .

Still used today to document business and/or other processes.

Data flow refers to the movement of data through a system fromentry to destination

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Data Flow Diagram: Signs1.Symbol: Square

Meaning: External Agent. Description: A source/destination of system data

2.Symbol:Arrow

Meaning: Data Flow

Description: Pipeline through which the data flows.

3.Symbol: Oval

Meaning: Process

Description: A series of one or more steps that converts inputs to outputs

4.Symbol: Openrectangle

Meaning: Data Store.

Description: Data at rest, usually a file or database table

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Rules for drawing the DFD:

Process should be named and numbered .

Name should represent the process .

The direction of flow is from top to bottom and from left to right .

Sources cannot leak data directly to a data store .

The name of data stores, sources and destinations are written in capital

letter . Process and data flow names have the first letter capitalized.

cont..

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Levels Of DFD

Thelevel-0 partitions the entire system. It has only one process (the

system), and from it, the data flows to/from the external agents.

The level 1 diagram-decomposes the system into 3processes: Schedule Courses ,Enrol Student, and Product Class List.

The level 2 diagram -decomposes the Schedule Course process into

3 sub-process.

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DATA DICTIONARY

Meaning

Data dictionary also is known as Meta data which is data about data

It contains accurate definition of all DFDs, data elements & data structure

and data base

A data dictionary contains a list of all files in the database, the number of

records in each file, and the names and types of each field.

Data dictionaries uses tables

Data Dictionary have proper format

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Example of data dictionary

Sr no Student Roll no Students name Students age Students marks

1 Integer(123 Varchar(abc) Integer (123) Integer(123

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Features Of Data Dictionary:

Structured repository of data

Support Documentation

Describe Interrelationship

Improves Communication

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Data Dictionary Contains Mainly Three Items:

Data element

Data structure

Data Base

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Structured English

Structured English is the use of the English language with the

syntax of structured programming.

structured English aims at getting the benefits of both the

programming logic and natural language. Program logic helps to

attain precision while natural language helps in getting the

convenience of spoken languages.

cont..

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Structured English consists of the following elements:

Operation statements written as English phrases executed from the

top down

Conditional blocks indicated by key words such as IF, THEN, and

ELSE

Repetition blocks indicated by key words such as DO, WHILE, andUNTIL

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Guidelines when writing Structured English

Statements should be clear and unambiguous.

Use one line per logical element.

All logic should be expressed in operational, conditional, and

repetition blocks.

Logical blocks should be indented to show relationship.

Keywords should be capitalized.

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Example

If customer purchase > Rs 1000

Then give 10% discount

Else do not provide any discount End- if

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Decision tree

A decision tree is a decision support tool that uses a tree-like graph

or model of decisions and their possible consequences.

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A Decision Tree Consists of 3types of Nodes:-

1. Decision nodescommonly represented by squares.

2. Chance nodes - represented by circles.

3. End nodes - represented by triangles.

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Advantages

Are simple to understand and interpret.

Have value even with little hard data.

Can be combined with other decision techniques.

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Decision table

Decision table are a precise yet compact way to model complicated

logic. Decision tables, like if-then-else and switch-case statements,

associate conditions with actions to perform.

A Decision table represents all possible conditions, actions. The

table is divided into columns which contain the conditions, actions

and rules.

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Decision table Structure

The four quadrants

Conditions

Condition alternatives Actions

Action entries

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SSADM Techniques

The 3 most important techniques that are used in SSADM are:

Logical Data Modelling.

Data Flow Modelling.

Entity Behaviour Modeling.

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Data Flow Modelling

This is the process of identifying , modelling and documenting how data

moves around an information system . Data Flow Modeling examines

processes (activities that transform data from one form to another), data

stores(the holding areas for data), external entities (what sends data into a

system or receives data from a system), and data flows (routes by which

data can flow).

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Entity Behaviour Modelling

This is the process of identifying , modelling and documenting the events

that affect each entity and the sequence in which these events occur.

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How is SSADM Structured

SSADM consists of 5 main modules , which are in turn broken

down into a complex hierarchy of stages, steps and tasks.

Feasibility Study.

Requirements Analysis.

Requirements Specification.

Logical System Specification.

Physical Design.

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Documents

Final Presentation of Tools and Techniques of Structure Analysis (1) (1)