18 documenting 4 plus one notes 2 (PDF)

Documenting Software Architecture
4+1 view model continue…

TDT4240 Software Architecture,

www.idi.ntnu.no/emner/tdt4240 Email: alfw@idi.ntnu.no Slide - 19 -

4+1 View model

TDT4240 Software Architecture,

www.idi.ntnu.no/emner/tdt4240 Email: alfw@idi.ntnu.no Slide - 20 -

The Process View: Integrators
√  Focus on non-functional requirements:
–  Performance (scalability)
–  Availability

√  Addresses issues like:
– 
– 
– 
– 

Concurrency and distribution
System integrity
Fault tolerance
Execution threads

√  From logical view:
–  How main abstractions fit with processing architecture

TDT4240 Software Architecture,

www.idi.ntnu.no/emner/tdt4240 Email: alfw@idi.ntnu.no Slide - 21 -

The Process View: Abstractions
√  Abstraction levels of the process view:
–  Logical networks of independently executing Processes:
• 
• 
• 
• 

Distributed across hardware resources connected by LAN/WAN
Process is grouping of tasks that form an executable unit.
Processes can be tactically controlled.
Processes can be replicated for improved performance and
availability.

–  Software is partitioned into a set of independent Tasks:
•  Separate thread of control.
•  Can be individually scheduled on one processing node.
•  Major tasks: Architectural elements that can be uniquely
addressed
•  Minor tasks: Introduced for implementation reasons.
TDT4240 Software Architecture,

www.idi.ntnu.no/emner/tdt4240 Email: alfw@idi.ntnu.no Slide - 22 -

Notation for Processing View (UML)

ActionState1

State1

TDT4240 Software Architecture,

Initial State

Control Flow

Final State

Object Flow

Action State

Decision

State

Transition

www.idi.ntnu.no/emner/tdt4240 Email: alfw@idi.ntnu.no Slide - 23 -

Notation for Processing View (Booch)

TDT4240 Software Architecture,

www.idi.ntnu.no/emner/tdt4240 Email: alfw@idi.ntnu.no Slide - 24 -

Process view: Example of Phone control

TDT4240 Software Architecture,

www.idi.ntnu.no/emner/tdt4240 Email: alfw@idi.ntnu.no Slide - 25 -

Process view (UML): Example of Phone
control
Controller process
Terminal process

Terminal process

Controller task High rate

Controller task Low rate

Message1
Message2
Message3
Message4

Message5
Message6

Message7

TDT4240 Software Architecture,

www.idi.ntnu.no/emner/tdt4240 Email: alfw@idi.ntnu.no Slide - 26 -

4+1 View model

TDT4240 Software Architecture,

www.idi.ntnu.no/emner/tdt4240 Email: alfw@idi.ntnu.no Slide - 29 -

The Development View: Programmers
√  Focus on actual software module organization:
–  Subsystems with export/import relationships.

√  Software packaged in small chunks:
–  Subsystems can be developed by
developers.
–  Subsystems are organized
in hierarchy of layers.
–  Each layer provides well-defined
interface to layers above.

one or few

√  Rules for Development view:
–  Partitioning, grouping, visibility.

√  Development view should ease development:
–  Software management, reuse, commonality, constraints imposed by toolset
or programming language.
–  Foundation for organization, cost planning, monitoring etc.
TDT4240 Software Architecture,

www.idi.ntnu.no/emner/tdt4240 Email: alfw@idi.ntnu.no Slide - 30 -

Notation for Development View (UML)
*
Package1

Package

-End1
-End2

Communication

*

Component1

Component

1

-End3
-End4

Composition

*

ComponentInstance1

Node1

TDT4240 Software Architecture,

Component
Instance

Dependence

Node

www.idi.ntnu.no/emner/tdt4240 Email: alfw@idi.ntnu.no Slide - 31 -

Notation for Development View (Booch)

TDT4240 Software Architecture,

www.idi.ntnu.no/emner/tdt4240 Email: alfw@idi.ntnu.no Slide - 32 -

Development View Example (Layered):
Air Traffic System

TDT4240 Software Architecture,

www.idi.ntnu.no/emner/tdt4240 Email: alfw@idi.ntnu.no Slide - 33 -

Development View Example (UML):
Air Traffic System
CAATS,
MAATS, etc

Man-Machine Interface/External systems: Offline tools, test hardness
{Customer specific}
HATS
Components

ATC Functional areas: Flight management,
Sector Management, etc.
{Domain specific}
ATC Framework

Aeronautical classes ATC classes

{Common ATC code}

Distributed
Virtual Machine

Support Mechanisms: Communication, Time,
Storage, Resource management etc.

{Domain independent}

Basic elements

Common utilities: Bindings, Low-level
services

Hardware,
OS, COTS

TDT4240 Software Architecture,

www.idi.ntnu.no/emner/tdt4240 Email: alfw@idi.ntnu.no Slide - 34 -