Architectural style in terms of pattern

1. ARCHITECTURAL STYLES - 2
An architectural style defines a family of Systems in terms
of a pattern of structural Organization. It determines:
–The vocabulary of components and connectors
– A set of constraints on how they can be
combined.
Dr Reeja S R
Professor
CSE Dept
SJECVamanjoor, Mangalore

2. ARCHITECTURAL STYLES - 2
Layered systems
Repositories
interpreters

3. Layered Systems

4. Layered Systems
 Components – layers
 Connectors – procedure calls
 Each layer acts as a
 Server: service provider to layer “above”
 Client: service consumer of the layer “below”

5. Examples
Networking protocols
Operating System

6. Layered pattern - variant
Closed architecture Open architecture

7. Advantages
 Support design based on increasing levels of abstraction – thereby
partitioning a complex problem into a sequence of incremental
steps
 Supports enhancement since changes to one layer affects at the
most 2 adjacent layer
 Supports reuse - since different implementations (with identical
interfaces) of the same layer can be used interchangeably

8. Disadvantages
 All systems cannot be structured in a layered fashion
 It is quite difficult to get the right level of abstraction.
 The system may suffer lower performance

9. REPOSITORIES

10. Repositories

11. Repositories Architectural Style
 Components
 A central data structure representing the current state of the
system.
 A collection of independent components that operate on the
central data structure.
 Connectors
 Procedure calls or direct memory accesses.

12. Variants
1. Type of transactions in an input stream trigger
selection of process to execute
2. Current state of the central data structure is the
main trigger for selecting processes to execute.
Ex: Blackboard

13. Blackboard
Typically used for AI systems and in applications requiring complex
interpretations of signal processing, such as speech and pattern recognition.

14. Distance
Object Location …
Visual
Processor
Motion
System
Voice
Synthesizer
Blackboard
Object Location …
o1 L1
o2 L2

15. Distance
Object Location …
o1 L1
o2 L2
10
Visual
Processor
Motion
System
Voice
Synthesizer
Blackboard
If(dist >=3)

16. Distance
Object Location …
o1 L1
o2 L2
8
Visual
Processor
Motion
System
Voice
Synthesizer
Blackboard
If(dist >=3)

17. Distance
Object Location …
o1 L1
o2 L2
6
Visual
Processor
Motion
System
Voice
Synthesizer
Blackboard
If(dist >=3)

18. Distance
Object Location …
o1 L1
o2 L2
4
Visual
Processor
Motion
System
Voice
Synthesizer
Blackboard
If(dist >=3)

19. Distance
Object Location …
o1 L1
o2 L2
2
Visual
Processor
Motion
System
Voice
Synthesizer
Blackboard
If(dist < 3)

20. Repositories
 Advantages
 Efficient way to store large amounts of data.
 Centralized management for backup, security and
concurrency control
 Disadvantages
 Must agree on a data model a priori.
 Data evolution is expensive

21. INTERPRETERS
Suitable for applications in which the most appropriate
language or machine for executing the solution is not
directly available

22. Interpreter
 An interpreter takes a program written in one
language and interprets it to another language

23. Interpreter

24. Interpreter
 An interpreter has 4 Components:
 “Program” being executed and its data
 Interpretation engine and its state
 Connectors
 procedure calls and shared state.

25. Interpreter Examples
 Programming Language Compilers: Java, Smalltalk
 Rule Based Systems: Prolog, Coral
 Scripting Languages: Awk, Perl