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Reference Architecture Reference Architecture and Agile Developmentand Agile Development
Presentation to NASA Standards Process Group Reference Presentation to NASA Standards Process Group Reference Architecture workshop at Architecture workshop at
the ESIP Federation Meetingthe ESIP Federation Meeting
George Percivall
OGC Chief Architect
22 July 2010
Copyright © 2010, Open Geospatial Consortium, Inc. Copyright © 2010, Open Geospatial Consortium, Inc.
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Reference Architecture and Agile DevelopmentReference Architecture and Agile Development
• Architecting
• Reference Architectures
• Agile Development
• Some examples
Copyright © 2010, Open Geospatial Consortium, Inc.
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Architecture and ArchitectingArchitecture and Architecting
• Architecture
– Organization of a system embodied in its components, their relationships to each other and to the environment and principles guiding its design and evolution (IEEE P1471)
• Architecting Approaches
– Heuristics: Rule of thumb
– Stakeholders: Process
– Normative: Standards
Systems Architecting, Eberhardt Rechtin, Prentice Hall, 1991
Copyright © 2010, Open Geospatial Consortium, Inc.
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Architecting HeuristicsArchitecting Heuristics
• The greatest leverage in system architecting is at the interfaces - Eberhard Rechtin
• Look for misfits with context and design to minimize them - Christopher Alexander
• Running code wins - IETF• Solutions should be as simple as possible, but no simpler –
Albert Einstein• Simple ain’t easy – Thelonious Monk
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Reference Architecture StandardsReference Architecture Standards
• IEEE 1471
– General process. Requires viewpoints but does not define any.
• RM-ODP
– Reference Model for Open Distributed Processing
– Enterprise, Informational, Computational, Engineering, Technology
– Viewpoint languages coordination with UML
• OASIS Reference Model for Service Oriented Architecture
– Focused on Services
• Others: DODAF, TOGAF, Zachman
Copyright © 2010, Open Geospatial Consortium, Inc.
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SUMMARY OF ARCHITECTURE STANDARDSSUMMARY OF ARCHITECTURE STANDARDS
Source: GST Interoperability Group, 2002
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SUMMARY OF ARCHITECTURE STANDARDSSUMMARY OF ARCHITECTURE STANDARDS
• Maintenance organization – what organization is responsible for establishing, updating and distributing the standard.
• Architecting products defined? – Does the standard define what items, e.g., views, shall be used to define an architecture?
• Architecting process defined? – Does the standard define the steps that an organization shall perform in order to develop an architecture?
• Standards Category Model? – Does the standard provide an outline for organizing standards that shall be used to define architectures. (These categories are the basis for a Standards Technical Reference Model)
• Required standards listed? – Does the standard provide specific standards that shall be used to be compliant to the architecture standard?
• Standards Development Process? – Does the standard define a process for developing or adopting standards?
• The Zachman Framework is not included in the evaluation as it is a proprietary approach not allowing for comparison.
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RM-ODP Viewpoints – Separation of ConcernsRM-ODP Viewpoints – Separation of Concerns
“GIGAS Methodology for comparative analysis of information and data management systems” OGC Best Practice, 10‑028r1
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Examples of Reference Architecture for Examples of Reference Architecture for Evolutionary DevelopmentEvolutionary Development
• OGC Reference Model (ORM)– Overview of OGC Standards Baseline– Resource for defining architectures for specific applications
• GEOSS Architecture Implementation Pilot
– System of Systems based on Interoperability Arrangements
– Process of iterative development while refining an architecture
– AIP Architecture using RM-ODP
• http://www.ogcnetwork.net/AIpilot
Copyright © 2010, Open Geospatial Consortium, Inc.
GEOSSClearinghouse
s
GEO Web Portals
GEOSS Common Infrastructure
Components & Services
Standards andInteroperability
Best PracticesWiki
User Requirements
Registries
Main GEOWeb Site
CSW WMS
CSW
Registered Community Resources
Community Portals
Client Applications
Client Tier
Business Process Tier
CommunityCatalogues
AlertServers
WorkflowManagement
ProcessingServers
Access Tier
GEONETCastProduct Access
ServersSensor Web
ServersModel Access
Servers
Test Facility
MediationServers
CSW WMS CSW W*S
WMS WFS WFS SOS SAS SPS W*S
CSW
WPS
Engineering Viewpoint
OGC 13
ISO 19101-2 – Geographic Information – Reference Model – ImageryISO 19101-2 – Geographic Information – Reference Model – Imagery
Engineering viewpoint - NodesEngineering viewpoint - Nodes
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Prototyping Versus SpecifyingPrototyping Versus Specifying
• “Prototyping Versus Specifying: A Multiproject Experiment”
1) Prototyping yielded products with roughly equivalent performance, but with about 40 percent less code and 45 percent less effort.
2) The prototyped products rated some what lower on functionality and robustness, but higher on ease of use and ease of learning.
3) Specifying produce produced more coherent designs and software that was easier to integrate.
– BARRY W. BOEHM, TERENCE E. GRAY, AND THOMAS SEEWALDT, IEEE TRANSACTIONS ON SOFTWARE ENGINEERING, VOL. SE-10,NO. 3,MAY 1984
• See also Michael Schrage, e.g., Serious Play and “Cultures of Prototyping” in Bringing Design to Software
Copyright © 2010, Open Geospatial Consortium, Inc.
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Agility and ArchitectureAgility and Architecture
• Use agile development to get to a good architecture by appropriately applying suitable combinations of – architectural functions
• (such as communication, quality attributes, and design patterns) and
– architectural skills at four points in the development life cycle. • (up-front planning, storyboarding, sprint, and working
software)
• http://www.computer.org/cms/Computer.org/ComputingNow/homepage/2010/0410/T_SW_AgileArchitectureInteractions.pdf
Copyright © 2010, Open Geospatial Consortium, Inc.
GEO AIP Evolutionary Development Process
DevelopmeDevelopmentnt
ActivitiesActivities
Kick-offKick-offWorkshoWorksho
pp
Call for Call for ParticipationParticipation
ConceptConceptDevelopmeDevelopme
ntnt
PersistentPersistentOperationOperation
ss(AR-07-(AR-07-
01)01)
Participation
Participation
Participation
Participation
ParticipationArchitectureArchitectureDocumentationDocumentation
Updates for each step
Baseline
AR-07-02 Architecture Implementation Pilot
Evolutionary Development Process
Operational Baseline and Lessons Learned for next evolutionary spiral
Continuous interaction with external activities
4.Deployment
Plan
4.Deployment
Plan
1. SBA
Scenarios
1. SBA
Scenarios
2.Enterprise
Models
2.Enterprise
Models
3. Engineering
Design
3. Engineering
Design
Component Types
Information Framework
Optimize
Specify
AIP: Using the Architecture Views in the Evolutionary Development Process
Use Cases
Services
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David Byrne: David Byrne: How Architecture helped music evolveHow Architecture helped music evolve
• http://www.ted.com/talks/david_byrne_how_architecture_helped_music_evolve.html
• He asks: Does the venue make the music? – From outdoor drumming to Wagnerian operas to arena rock, Byrne
explores how context has pushed musical innovation.
• Model for creation (at 13:45 in talk)
– We make music primarily in a form to fit the context and we make art to fit museum walls
– We write software to fit existing operating systems. Its evolutionary, its adaptive.
– This is a reverse view from the traditional romantic view: first comes the outpouring of emotion and then somehow it gets shaped into something.
– The passion is still there, but the vessel that it is going to be injected into and poured in to is instinctively and intuitively created first.
Copyright © 2010, Open Geospatial Consortium, Inc.
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For Details on OGC Standards…For Details on OGC Standards…
• OGC Standards– Freely available– www.opengeospatial.org/standards
• OGC Reference Model (ORM)– Overview of OGC Standards Baseline– Resource for defining architectures for specific
applications– www.opengeospatial.org/standards/orm
George Percivall, gpercivall at opengeospatial.org
Copyright © 2010, Open Geospatial Consortium, Inc.