lecture 2 sa

8/12/2019 Lecture 2 SA

http://slidepdf.com/reader/full/lecture-2-sa 1/14

Lecture 2 July 6, 2011

Hatley Pirbhai TemplateBy

Mangesh R. WanjariAsst. Professor, Department of CSE

RKNEC, Nagpur



6/6/2014 2

Overview of the talk

Introduction to design method

according to Hatley and Pirbhai

Two types

overview of the requirements model

Further reading

References



6/6/2014 3

Introduction

The requirements

model of the Hatley and

Pirbhai method is dividedinto two parts: A process

part and a control part



6/6/2014 4

Introduction



6/6/2014 5

Introduction

1. Hatley-Pirbhay modeling is an extension of the concept that every computersystem can be modeled through the usage of an input-processing-output model

by including the two additional features of user interface process and

maintenance/self testing.

2. These 5 components are added to a system model template to allow for

modeling of the system which allows for proper assignment to the processingregions.

3. The templates components are User Interface, Input, System Function and

Control, Output and Maintenance/Self Test.

4. This modeling technique allows for creation of a hierarchy of detail of which thetop level of this hierarchy should consist of a System Context Diagram.The

developed system context diagram serves the purpose of, "establish[ing] the

information boundary between the system being implemented and the

environment in which the system is to operate.”



6/6/2014 6

THE REQUIREMENTS METHOD

1. This method merges into a unified whole the well-established

Structured Analysis (SA) method, and finite-state machine theory

2. Data processing is represented by conventional data flow diagrams

(DFDs), and the flow of control information is carried in a parallel

structure of control flow diagrams (CFDs).

3. Between these two are control specifications (CSPECs), containing the

finite state (FS) machine structures. These FS machines are used to

control the behavior of the processes in the DFDs, thus adding an

important dimension lacking in basic SA.

4. Input-to-output timing relationships are represented in a timing

specification (TSPEC), and all data and control information is defined in

a requirements dictionary.



6/6/2014 7

1. This method models the physical realization of the system, and is anextension and formalization of the familiar engineering block

diagram.

2. Its principal graphical components are architecture flow diagrams

(AFDs) and architecture interconnect diagrams (AIDs).

3. The modules, flows, and channels are all rigorously defined in textualmodule and interconnect specifications, and in an architecture

dictionary.

4. The method includes an architecture template, which is used as a

guide in adding derived requirements to the requirements model,

and in allocating requirements to the architecture components.

5. The allocation of requirements to architecture is represented

graphically using Superbubbles on enhanced DFDs, and is further

recorded through Traceability Matrices.

THE ARCHITECTURE METHOD



6/6/2014 8




6/6/2014 9




6/6/2014 10


The

Steps



6/6/2014 11




6/6/2014 12

Features and benefits



6/6/2014 13

Features and benefits

• Another advantage of a simulation-

based approach using H-P can be seen

by reference to the figure.

• As system development proceeds

down the left side of the “Vee” the

models developed provide the

foundation and guidance for the steps

as integration proceeds up the right side

of the “Vee”.

• It should noted that the “Vee” model

has been demonstrated to be consistent

with spiral development



6/6/2014 14

Questions???

Thanks for Patient Listening…!!!

lecture 2 sa

Documents