Reference Architecture

Reference Architecture

1. The purpose of a reference architecture is mainly to provide guidance for the development, standardization and evolution of systems architctures

2. Definition of reference architecture

   • A reference architecture is, in essence, a predefined architectural pattern, or set of patterns, possibly partially or completely instantiated, designed and proven for use in particular business and technical contexts, together with supporting artifacts to enable their use.
   • Reuse od knowledge about software development in a given domain
   • Reference architecture versus refence model
     • A reference model mapped onto software elements and the data flows between them can be considered a reference architecture
   • Reference Architecture versus product line arcgitecture
     • Product line architecture
       • A special of software architecture used to build a prodcut line; it explicitly dexcribes commonality and variability and is the basis for the architectures of all product line members
     • Reference architectures are generally on a higher level of abstraction compared to product line architectures

3. A model for reference architecture

   • RAModel
     • Providing information on the elements and their relationships tha could be contained in the reference architecture
     • Domain
       • Information of the space of human real world
     • Application
       • Capabilities and limitations. Also elements related to the business rules
     • Infraestructure
       • The elements that can be used to build the software
     • Crosscutiong elements
       • Set of elements that are usually spread with elements of the other three groups
   • Analysis of reference architecture
     • we have to analyse the elements of the architecture reference between RAModel because sometimes we should be inserted these elements into these architectures
   • Comparative analysis of reference architectures
     • The RAModel can be used as a guideline to observe which elements each reference architecture contains
       • It can be used to better understand each architecture

4. Reference Architecture Engineering

   • Ad hoc approach
   • ProSA-RA
     • Is a process that systematizes the desing, representation and evaluation of reference architecture
     • Scope is first
     • Only four steps
       • 1. Information sources investigation
         • These sources must be provide information about the processes, activities and task
         • People
           • Customers, users, reearchers and system development
             • Interviews and questionnaires
             • Needs and limitations
         • Software Systems
           • The main system related to the domain are selected and investigated throught their use
         • Publications
           • Information related to the processes, activities and tasks
             • Articles, books and technical reports
         • Domain Ontologies
           • Represent the domain terminology, concepts, terms
             • Vocabularies
             • Taxonomies
             • Thesauri
             • Concept maps
           • facilitate understanding
       • 2. Architectural requirements establishment
         • Based on the selected sources
         • Information related to the application domain is identified
         • Identification of the system requirements
           • Funtional and non funtional requirements
         • Establishment of the reference architecture requirements
           • Based on the system requirements
             • A set of arcgitectural requirements are established
             • One or more system requirements will be aggredated in an architectural requirement
           • Higher abstraction level
         • Identification of the domain concepts
           • Each architectual requirement is mapped to a domain concept
           • More than one requirement can be mapped to a unique concept
         • Domain experts and system analysts
         • Concepts related to the business rules
       • 3. Reference architecture design
         • Adequately design and represent reference architectures
         • Representation of reference architectures, their description, in order to make them understandable for wid variety of stakeholders
         • Architectural views can also be adopted to describe reference architectures
         • Enterprise view, computational view and information view
         • UML diagrams
           • Case diagram
           • Component diagram
           • Class diagram
           • Deployment diagram
         • MVC
         • Module View
           • Structure of the system
             • Packages, classes, containment and relationships
         • Runtime View
           • It show the behavior of all the systems derived from the architecture in a higher level of abstraction
         • Deployment view
           • It describes de Hardware
         • Conceptual view
           • Vocabularies, taxonomies and concept maps
       • 4. Reference architecture evaluation
         • Quality in reference architecture refers to a set of quality attribites, such as completeness, applicability and understandability
         • FERA
           • Checklist-based
             • composed for 78 miltiple choice questions, whose have to answered by 8 types of stakeholders
             • Vary from fully satisfactory to totally unsatisfactory
         • Defects in the documents
         • Provide general information
         • Adequate set of architectural viewpoints, views and models
         • Interoperability, security and scalability
         • Software architects and testers
   • Information source investigation

5. Uses of refence architecture

   • Building software systems
     • Reading and understandinf the documentation
       • Selecting the whole architecture or their parts that are interesting
         • Refining and adapting the architecture or their parts, using the specification of the software system
           • Documenting the architectural instance
             • Evaluating the architectural instace
               • Concreting the architectural instance through implementation
   • Domain Standarization
     • Reference architectures have promoted internal and extenal interoperability in software systems
     • Reference architectures jave also standardised the internal structure of software systems
   • Evolution of existing software systems
     • The selection of one or more reference architectures
       • The study pd related documentation
         • The investigation of parts and elements contained
           • The instantiation of these part and elements
             • The implementation
   • Deriving new reference architectures
     • Existing reference architectures can be used as a basis to derive new reference architectures
     • A reference architecture that has as a basis a specific architectural style can be derived to an architecture that has the service-oriented architectural style
   • Supporting the building of SPL
     • In particular, the use of existing reference architectures as the basis of SPL can be explored.
     • Reusing knowledge contained in these architectures can contribute to reduce the effort requitred to build SPL artifacts
     • ProSA-RA2PLA
       • One or more reference architectures are first identified and selected
       • Higher level structure of the reference architectures
       • This process selects and prioritizes the elements contained
     • Top- Down interative approach of planning

6. Future perspectives of reference architecture

7. Final remarks

   • The evolution of this area is extremely important as software systems, technologies and development approaches are constanly changing

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