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

Topics 1.The NEXOF Reference Architecture 2.Principles: RA specification properties 3.Foundation: RA specification mechanisms Valencia, 12 and 13 April 2010NESSI Projects Summit

Service-Based Software Systems Valencia, 12 and 13 April 2010NESSI Projects Summit

Main Design Concerns for the platform and the infrastructure Valencia, 12 and 13 April 2010NESSI Projects Summit Service Message Discovery Process Analysis Presentation Management Security Resources Service Encaspsulation of functionalities (+automation): Service Messages Open interfaces and smooth machine-to- machine interaction (+interoperability): Messages ProcessDiscovery Dynamic software configuration and service composition (+flexibility): Process, Discovery

Structure of the NEXOF Reference Architecture Valencia, 12 and 13 April 2010NESSI Projects Summit

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 Valencia, 12 and 13 April 2010NESSI Projects Summit

It is used to derive specific service- based system architectures Valencia, 12 and 13 April 2010NESSI Projects Summit Reference Architecture System Architecture Description Service-Based Software System (describes property of) Design Activity Requirements, needs, demands (produces)

Principles: Specification Properties Modularity Layering Partitioning Reuse Extesibility Valencia, 12 and 13 April 2010NESSI Projects Summit

… 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?” Valencia, 12 and 13 April 2010NESSI Projects Summit

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 Valencia, 12 and 13 April 2010NESSI Projects Summit

Pattern Template Valencia, 12 and 13 April 2010NESSI Projects Summit 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 Attributes Trade-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 Valencia, 12 and 13 April 2010NESSI Projects Summit

… 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 Valencia, 12 and 13 April 2010NESSI Projects Summit

… 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) Valencia, 12 and 13 April 2010NESSI Projects Summit

… 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 Valencia, 12 and 13 April 2010NESSI Projects Summit

… 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 Valencia, 12 and 13 April 2010NESSI Projects Summit

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. Valencia, 12 and 13 April 2010NESSI Projects Summit

Thank you! Valencia, 12 and 13 April 2010NESSI Projects Summit