Defining System and

SOPHIST GmbH

Vordere Cramergasse 13

90478 Nürnberg

Tel.:+49 (0)911 40 900 - 0

Fax:+49 (0)911 40 900 - 99

www.sophist.de

heureka@sophist.de

Defining System and

Context Boundaries

2.2

System & System Context

2.1

2.3

Defining System

and Context Boundaries

System & Context

Boundaries

2.2

Documentingthe System

Context

2.3

� Purpose of the

System Context

� Aspects within the

System Context

System & System Context

System Context

� Definition

System & System Con

text

Purpose of the System Context

1. Which aspects pertain to the system,

which do not?

Which questions answer thoughts about the system context?

aspects that mustbe specified

System & System

1. Which aspects stand in a direct relation to the

system?

aspects that don‘t haveto be specified

aspects that must be consideredduring specification

SOPHIST GmbH Defining System and System Context 2.1 – page 4

System & System Con

text

DefinitionSystem Context

The system context is the part of the system

environment that is relevant for the definition as

well as for the understanding of the

requirements of a system to be developed.

System & System

requirements of a system to be developed.

SOPHIST GmbH Defining System and System Context 2.1 – page 6

� Considering

Boundaries

� Definition

� Gray Zones

System and Context Boundaries

� Gray Zones

Con

text

Bou

ndaries

Considering Boundaries

System

System context

Irrelevant environment

Context boundary

Considering Boudaries during system developmentSystem & Con

text

System Context boundary

System boundary

SOPHIST GmbH Defining System and System Context 2.2 – page 8

Con

text

Bou

ndaries

DefinitionSystem Boundary

The system boundary separates the

system to be developed from its

environment; i.e. it separates the part

of the reality that can be modified or

System & Con

text

SOPHIST GmbH Defining System and System Context 2.2 – page 9

altered by the development process

from aspects of the environment that

cannot be changed or modified by the

development process.

Con

text

Bou

ndaries

DefinitionContext Boundary

The context boundary separates the

relevant part of the environment of a

system to be developed from the

System & Con

text

SOPHIST GmbH Defining System and System Context 2.2 – page 10

irrelevant part, i.e., the part that does

not have to be considered during

requirements engineering.

Con

text

Bou

ndaries

Gray Zones

System

aspects that have not been assigned to the system or the system context lie in the gray zone

Gray zones of the definition of system and context boundariesSystem & Con

text

System

gray zones

SOPHIST GmbH Defining System and System Context 2.2 – page 11

� A Simple Example

� Data Flow Diagram

� Use Case Diagram

Documenting the System Context

� Use Case Diagram

Kap

itelnam

eSystem Con

text

Data Flow DiagramWhich data flows back and forth?

receipt,

library card,

rental object

customer

library

Kap

itelnam

eDocum

enting

the

SOPHIST GmbH Defining System and System Context

order confirmation,

rental object

identification,

research,

reservations,

address

orders

shipping

system

library

system

2.3 – page 14

... often called context diagram.

Kap

itelnam

eSystem Con

text

Use Case DiagramWho or what is involved in which use cases?

uc Library System

Library System

reserve rental object

«actor»

Kap

itelnam

eDocum

enting

the

SOPHIST GmbH Defining System and System Context 2.3 – page 15

customer

object

order rental object

manage customer

data

«actor»versand

Any further questions?

SOPHIST GmbH Defining System and System Context page 16

References - Pictures

� Title: Rückspiegel (Rear-view Mirror)

• Source: -

• Author: Chris Rupp

� Title: Genau betrachtet (Looked at more closely)

• Source: aboutpixel.de

• Author: -

SOPHIST GmbH Defining System and System Context page 17

� Title: Schattenspiel Industriebau neutral (Shadow Play Industrial Building neutral)

• Source: aboutpixel.de

• Author: Rainer Sturm