process oriented approaches n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Process-oriented approaches PowerPoint Presentation
Download Presentation
Process-oriented approaches

Loading in 2 Seconds...

play fullscreen
1 / 11

Process-oriented approaches - PowerPoint PPT Presentation


  • 148 Views
  • Uploaded on

Process-oriented approaches. Colin Potts Georgia Tech. Process-oriented philosophy. A system is what it does so model it as a hierarchy of functions Functional decomposition for description but not necessarily for deriving the description Requirements drive the decomposition process

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Process-oriented approaches' - plato


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
process oriented approaches

Process-oriented approaches

Colin Potts

Georgia Tech

process oriented philosophy
Process-oriented philosophy
  • A system is what it does
    • so model it as a hierarchy of functions
  • Functional decomposition for description
    • but not necessarily for deriving the description
  • Requirements drive the decomposition process
    • but decomposition furthers understanding of the requirements
overview structured analysis
Overview: Structured Analysis
  • Structured Analysis
    • Functional decomposition based on data flow
    • Widely used
    • Intuitively simple
mapping the system s context
Mapping the system’s context
  • Describe system’s interfaces to its environment

Alarm

notificn

Security

company

Sensor

Time

Status

signal

Burglar alarm

system

Clock

Alarm cmd

Settings

Tone

generator

Security

code

Warning

tone cmd

Householder

team exercise context mapping
Team exercise: Context mapping
  • In teams of 2-3
    • Think about the system described in the requirements document
    • Draw a context diagram for the system
  • As a class
    • Discuss insights gained into the system’s requirements
data flow diagrams

Alarm

cmd

Security

code

Alarm

notificn

Settings

Set

alarm

Raise

alarm

Active

sensors

    • Non-
  • inhibited
  • alarm

Alarm

signal

Determine

alarm

conditions

Monitor

sensors

Warning

tone cmd

Intruder

signal

Time

Data flow diagrams
  • Define sub-functions & essential internal data flows
layered dfds
Layered DFDs
  • Functional architecture is hierarchical
    • System is a collection of interacting functions which may be decomposed further
    • Net inputs and outputs should be consistent across levels
structured system specification
Structured Analysis has recommended document structure

Data flow diagrams form core models

Data dictionary

Process specs.

B

D

A

P

Q

C

E

R

  • Data element
  • Definition
  • A
  • Integer*
  • Integer, Float
  • B
  • Process P
    • Find sum of elements
    • Find mean of elements
Structured system specification
detailed specification
Data dictionary

Definitions of data elements that flow along data flows

Backus-Naur Form

Settings ::= Out | In | Off

Security_Code ::= Digit Digit Digit Digit

Security_Code ::= Digit*

Alarm_Notificn ::= Time House_Id Sensor_Id

Process specs

Data flow diagram decomposition

Sub-diagram with consistent I/O

Pseudo-code defs

Detailed specification
structured analysis evaluation
Advantages

Basic ideas and notations are simple

Many organizations have major investment in SA

Widespread tool support for notations and analyses

Limitations

Top-down decomposition is better for explaining than for deriving

Essential architecture and implementation architecture often different

Document maintenance

Significant ambiguities

Serious for RT systems

Structured Analysis: Evaluation
how to find out more structured specification
How to find out more: Structured specification
  • Methodology-specific textbook
    • De Marco: Structured Analysis & System Specification
  • Book on methods, incl. SA
    • Wieringa: Requirements Engineering