Architectural Specification Principles & Foundation Piero Corte, Engineering Ing. Inf. NEXOF-RA.

Architectural Specification Principles & Foundation

Piero Corte, Engineering Ing. Inf.NEXOF-RA

Topics

1. The NEXOF Reference Architecture2. Principles: RA specification properties3. Foundation: RA specification

mechanisms

Valencia, 12 and 13 April 2010 NESSI Projects Summit

Service-Based Software Systems


Main Design Concerns for the platform and the infrastructure


ServiceService

MessageMessage

DiscoveryDiscovery

ProcessProcess

AnalysisAnalysis

PresentationPresentation

Management

Management

Security

Security

ResourcesResources

• Encaspsulation of functionalities (+automation): ServiceService

• Open interfaces and smooth machine-to-machine interaction (+interoperability): MessagesMessages

• Dynamic software configuration and service composition (+flexibility): ProcessProcess, DiscoveryDiscovery

Structure of the NEXOF Reference Architecture


It is a CLASS of architectures

• It does not provide the specification of a single and complete software system

• It provides “pieces” of well-organized architectural specification

• It is based on “variation points”: providing alternatives to be taylored and meet different contexts


It is used to derive specific service-based system architectures


Reference Architecture

System Architecture Description

Service-Based Software System

(describes property of)

DesignActivity

Requirements, needs,

demands(produces)

Principles: Specification Properties

• Modularity• Layering• Partitioning• Reuse• Extesibility


… that is• The NEXOF-RA Specification is constituted of

parts (modularity)• These parts are related (layering,

partitioning)• These parts are reusable to produce new

parts of the specification• The overall specification results highly

extensible

“Which kind of parts we are using?”


Foundation: Specification Mechanisms

Constructional Patterns !• Patterns:

– They provides the description of architectural design solutions of a “whole” or a “part” of a software system

• Constructional:– They are first-class compose-able design

elements


Pattern Template


Pattern ID-Card

Problem Description

Functional Requirements

Assumptions

Solution

Non-Functional Qualities

Relationships to other Patterns

Relationships to Components Catalogue

Relationships to Standards Catalogue

Application Examples

References

Design Problem Statement

Architectural Solution

Quality AttributesTrade-off Evaluation

… meeting MODULARITY

• Constructional Patterns are our specification modules

• Each pattern is developed– to provide an architectural solutions in

terms of highly-coupled (strong cohesion) components/subsystems

– to be loosely-coupled to other patterns


… meeting LAYERING

• Constructional Patterns can be related by means of refinement relationships:– extends– isPartOf

• These mechanisms enable the organization of patterns in a layered-tree of architectural design refinements


… meeting PARTITIONING

• Patterns are classified according with:– The functionality of the (sub)system they

design (functional concerns)– The quality attributes they intend to

affects (design goals)


… meeting REUSE

• Constructional Patterns are first-class compose-able design elements, i.e. they are conceived this way exactly for the “reuse” purpose.

• You can design new patterns by refining, composing and transforming other patterns: inheriting some aspects and overriding others


… meeting EXTENSIBILITY

• The complete NEXOF-RA Specification results into a set of “Constructional Patterns”.

• The adoption of “Constructional Patterns” will make possible and economic to add new patterns that enlarge and refine the specification


Conclusions

• The principles and the foundations adopted to develop the NEXOF-RA are very important.

• We consider them fundamental to sustain the development and evolution of the specification beyond the project life-time.


Thank you!


Architectural Specification Principles & Foundation Piero Corte, Engineering Ing. Inf. NEXOF-RA.

Documents

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