1. DESIGN OF SOFTWARE ARCHITECTURE
Instructor: Dr. Hany H. Ammar
Dept. of Computer Science and Electrical Engineering, WVU

2. Ouline What is Software Architecture? Software Architecture Styles
UML Development – Overview
The Requirements, Analysis, and Design Models
What is Software Architecture?
Software Architecture Elements
Software Architecture Styles
A Simple Example of Software Architecture
Design of Software Architecture
Examples

3. UML Development - Overview
ACTORS
USE CASES
REQUIREMENTS
ELICITATION
Time
SCENARIOS D
SEQUENCE
DIAGRAMS A T A
ANALYSIS
CLASS DIAGRAM(S)
ANALYSIS
Specify Domain
Objects
StateChart
DIAGRAMs D I
OPERATION CONTRACTS C T
Architectural Design
Include
Design Objects I
SUBSYSTEM CLASS/
OR COMPONENT
DIAGRAMS
DESIGN SEQUENCE DIAG.
DEPLOYMENT DIAGRAM O N
DESIGN DIAGRAMS A
Detailed DESIGN R Y
Object
Design
IMPLEMENTATION
CHOICES
IMPLEMENTATION
Activity DIAGRAMS
IMPLEMENTATION
PROGRAM

4. The Requirements, Analysis, and Design Models
Elicitation
Process
Use Case Diagrams/
Sequence Diagrams
(the system level)
Functional/
Nonfunctional
Requirements
- Analysis Class Diagrams
- State Diagrams/
Refined Sequence
Diagrams (The object
level)
Static Analysis
Dynamic Analysis
The Analysis
Process
Design Class Diagrams and
Components Diagrams
Design Sequence Diagrams
The Design
Process
Static Architectural
Design
Dynamic Design

5. Ouline What is Software Architecture? Software Architecture Styles
UML Development – Overview
The Requirements, Analysis, and Design Models
What is Software Architecture?
Software Architecture Elements
Software Architecture Styles
A Simple Example of Software Architecture
Design of Software Architecture
Examples

6. What is Software Architecture?
A simplified Definition
A software architecture is defined by a configuration of architectural elements--components, connectors, and data--constrained in their relationships in order to achieve a desired set of architectural properties.

7. Software Architecture Elements
A component is an abstract unit of software instructions and internal state that provides a transformation of data via its interface
A connector is an abstract mechanism that mediates communication, coordination, or cooperation among components.

8. Standard Satellite Control Segment Reference Architecture
Software Architecture Elements
A datum is an element of information that is transferred from a component, or received by a component, via a connector.
A configuration is the structure of architectural relationships among components, connectors, and data during a period of system run-time.
An architectural style is a coordinated set of architectural constraints that restricts the roles/features of architectural elements and the allowed relationships among those elements within any architecture that conforms to that style.
Detailed example:
Standard Satellite Control Segment Reference Architecture

9. Ouline What is Software Architecture? Software Architecture Styles
UML Development – Overview
The Requirements, Analysis, and Design Models
What is Software Architecture?
Software Architecture Elements
Software Architecture Styles
A Simple Example of Software Architecture
Design of Software Architecture
Examples

10. Software Architectural Styles
An architectural style is a class of architectures characterized by:
Components types: are component classes characterized by either SW packaging properties or functional or computational roles within an application.
Communication patterns between the components: the communication protocols between the component types.
Semantic constraints, indicating the behavioral properties of the components individually, and in the context of their interactions.
A set of connectors, SW artifacts that enable us to implement the communication between the components in a way that satisfies the semantic constraints.
Software Architectures Course Overview

11. Example of an Architecture Style
Embedded Systems example architecture
<<Interface>>
Input_devices
or actors
Monitors
Monitor sensors
Controllers
Generate
controls
Schedulers
Schedule
controllers
<<Interface>>
Output_devices
or actors

12. Example of an Architecture Style
The Layered Architecture
e.g computer network
Services architecture
Application Layer
Presentation Layer
Session Layer

13. Layered Architectural styles Example of a Layered Application Architecture

14. Example of an Architecture Style: The Layered Architecture
Interactive Electronic Technical Manuals (IETMs) for Technicians to use for repairing complex systems
Business Services
User Services
Data Services

15. Ouline What is Software Architecture? Software Architecture Styles
UML Development – Overview
The Requirements, Analysis, and Design Models
What is Software Architecture?
Software Architecture Elements
Software Architecture Styles
A Simple Example of Software Architecture
Design of Software Architecture
Examples

16. Information Available At Architectural Design
The Requirements model
Use cases, Use case Diagram, system sequence diagrams
The Analysis model
Analysis class diagram,
stateCharts for multi-modal classes, and
Domain Object sequence diagrams

17. Artifacts Developed at Architectural Design
Subsystems + their public interfaces (APIs)
Subsystem dependencies
Subsystems class diagrams. A class diagram for each subsystem
Requirements
And
Analysis models
Design
Class
Diagrams
Architecture design

18. The Process of Designing Software Architectures
Define overall structure of the system into components or subsystems, or classes
Define Component interfaces and interconnections separately from component internals (defined during details design)
Each subsystem performs major service
Contains highly coupled objects
Relatively independent of other subsystems
May be decomposed further into smaller subsystems
Subsystem can be an aggregate or a composite object

19. Step 1 - Subsystem/Components Structuring Criteria
Decompose the system into subsystems or classes such that each performs a specific function or task to maximize cohesion and minimize coupling, the following are typical examples of subsystems or classes
Controllers
Subsystem controls a given aspect of the system (e.g., Cruise cont. Fig )
Coordinators/Schedulers
Coordinates several control subsystems (e.g., Cruise cont Fig 20.45,20.46)
Data Collectors/Monitors
Collects data from external environment (e.g., Cruise cont Fig )•
Data analyzers
Provides reports and/or displays (e.g., Cruise cont Fig )
Servers
Provides service for client subsystems (e.g., MyTrip example)
User/Device Interface
Collection of objects supporting needs of user (e.g., Cruise cont Fig )

20. Another way of forming subsystems
Aggregate into the same subsystem
Objects that participate in the same use case (functional cohesion)
Objects that have a large volume of interactions (e,g, Control object & objects it controls) or share common data or file structures (communicational cohesion)
Object that execute in the same time (temporal cohesion)

21. Example: MyTrip System, uses a Global Positioning System to locate and coordinate a trip for a driver in an automobile software system The Analysis Class Diagram
Location
Segment
Crossing
Direction
Destination
Trip
RouteAssistant
PlanningService
We can imagine that in reality there would be more details in the class diagram but it is not relevant here
PlanningService is an boundary class interfacing with another external system, a web server, that can supply a trip linking a number of destinations in the form of a sequence of crossings and segments

22. Design Class Diagram MyTrip Subsystems
Location
Segment
Crossing
Direction
Destination
RoutingSubsystem
PlanningSubsystem
Trip
RouteAssistant
PlanningService
Only one association crossing subsystem boundaries
The Trip object group is shared and used for communicating information from one subsystem to another. We can either create a new subsystem to accommodate them or assign them to the subsystem that creates these objects (we retained the latter solution above).

23. MyTrip Deployment Diagram
Components must be associated with a processor node in
the deployment diagram
:RoutingSubsystem
:PlanningSubsystem
:OnBoardComputer
:WebServer
We select here, for the myTrip system, a hardware configuration and a platform
RoutingSubsystem runs on the OnBoardComputer while PlanningSubsystem runs on a WebServer.
Let’s assume we select a UNIX machine as the virtual machine for the :webserver and the web browsers Netscape and Internet Explorer as the virtual machines for the :OnBoardComputer

24. New Classes and Subsystems
Trip
Location
PlanningService
Segment
Crossing
RouteAssistant
Direction
Destination
TripProxy
SegmentProxy
PlanningSubsystem
Message
Connection
CommunicationSubsystem
RoutingSubsystem
The assignment of objects and subsystems to nodes often triggers the identification of new objects and subsystems, e.g., for transporting data among nodes
In the myTRIP system, subsystems need to communicate via a wireless modem using some communication protocol
New subsystem to support communication: CommunicationSubsystem – responsible for transporting objects from the PlanningSubsystem to the RoutingSubsystem
Connection: A Connection represents an active link between the PlanningSubsystem and the RoutingSubsystem. A Connection object handles exceptional cases associated with loss of network services
Message: A Message represents a Trip and its related Destinations, Segments, Crossings, and Directions, encoded for transport.

25. MyTrip Data Storage RoutingSubsystem PlanningSubsystem
MapDBStoreSubsystem
TripFileStoreSubsystem
RoutingSubsystem
CommunicationSubsystem
Subsystem decomposition of MyTrip after deciding on the issue of data stores (UML class diagram, packages collapsed for clarity).
Current trip is saved on a small removable disk in order to allow the recovery of the Trip in case the driver shuts off the car before reaching the final Destination. Using a file is the simplest and most efficient solution in this case, given that the RoutingSubsystem will only store complete trips to the file before shutdown and load the file at start-up. In the PlanningSubsystem all trips will be stored in a Database. All trips will be managed by this subsystem, for many drivers, as well as the maps needed to generate trips. It will allow us to perform complex queries using, for example, a Relational Database Management system and a language like SQL.

26. Example: Cruise Control
And Monitoring System
Class Diagram of the
Cruise Control
Subsystem

27. Example: Cruise Control System;
The Monitoring Subsystem

28. Example: Aggregating classes into a subsystem using temporal cohesion

29. Example: aggregating classes
Using functional cohesion

30. Step 2 - Define Subsystem Interfaces
The set of public operations forms the subsystem interface or Application Programming Interface (API)
Includes operations and also their parameters, types, and return values
Operation contracts are also defined (pre- and post-conditions) and accounted for by client subsystems – they can be considered part of the API

31. Subsystem Interfaces Interfaces can be methods such as Notify, update,
Or can be classes such context.

32. Ouline What is Software Architecture? Software Architecture Styles
UML Development – Overview
The Requirements, Analysis, and Design Models
What is Software Architecture?
Software Architecture Elements
Software Architecture Styles
Design of Software Architecture
Examples

33. A Simple Example of Software Architecture
EXAMPLE: SATELLITE CONTROL SYSTEM

34. A Simple Example of Software Architecture Using UML2
SATELLITE CONTROL SYSTEM Architecture

35. A Simple Example of Software Architecture Using UML2
SATELLITE CONTROL SYSTEM Architecture

36. A Simple Example of Software Architecture
SATELLITE CONTROL SYSTEM Architectural behavior
Interactions between components of the architecture for a given scanrio

37. A complete Example: A Digital Sound Recorder From Requirements-to-Analysis-to-Design
The main function of the DSR is to record and playback speech.
The messages are recorded using a built-in microphone and they are stored in a digital memory.
The DSR contains an alarm clock with a calendar. The user can set a daily alarm. The alarm beeps until the user presses a key, or after 60 seconds.

38. Digital Sound Recorder:A Complete Example From Requirements-to-Analysis-to-Design

39. Digital Sound Recorder: A Complete Example

40. Digital Sound Recorder: A Complete Example
System
Sequence
Diagram

41. Digital Sound Recorder: A Complete Example

42. Digital Sound Recorder: A Complete Example

43. Digital Sound Recorder: A Complete Example
Analysis
Class Diagram

44. Digital Sound Recorder: A Complete Example
Design
Class
Diagram:
Designing
The
Subsystems,
The names of
subsystems
Should be
improved

45. Digital Sound Recorder: A Complete Example
Operation
Details
Are defined
Using
Design
Sequence diagrams

46. Digital Sound Recorder: A Complete Example

47. Digital Sound Recorder: A Complete Example

48. Digital Sound Recorder: A Complete Example