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 [email protected] Context Boundaries
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
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