MECOSIG Adapted to the Design of Distributed GIS

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MECOSIG Adapted to the Design of Distributed GIS

• F. Pasquasy, F. Laplanche, J-C. Sainte J-P.
  Donnay
• Unit of Geomatics, University of Liège, Belgium
• http//www.geo.ulg.ac.be

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MECOSIG

• A method devoted to GIS design and implementation
  published in 1996 considering
• GIS as an Information System (IS) where IS ?
  Organization (systemic approach)
• Organization as the core of the method
• The method has been progressively improved (last
  decade)
• Emergence of distributed GIS involved
• reassessment of the methodology
• new concerns and tools (fitting the requirements
  of distributed environments) identified

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MECOSIG - Design protocol

• Method covering the complete GISs lifecycle
• using specific tools at different abstraction
  levels
• Descriptive to Logical-Physical level...
• Design protocol is summarized into a monitoring
  matrix
• every cell relates to
• specific tools (formalisms, models, prototyping
  )
• semantic concerns (metadata, documentation )
• Main concerns are
• Organization, Data, Data flows, Processes
• MECOSIG suggested to go twice through the
  monitoring matrix
• analysis stage (not anymore taken into account
  because of redundancy with the descriptive level
  in conception step)
• conception step

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MECOSIG - Monitoring Matrix
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Adaptations - Descriptive level

• Group of actors of the organization(s) must be
  identified
• Actors have their own
• set of privileges
• specific use cases
• More often a specialization relationship exists
  between them

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Adaptations - Descriptive level

• Concerning processes (in particular crossed
  processes in distributed GIS), interactions
  between groups of actors and the System are
  identified in terms of
• textual descriptions
• UML use cases
• Data are identified according to use cases
• Data are described in a catalogue and quality
  must be analysed
• Use of standards (ISO 19110 19115) is
  recommended
• Further agreements must be achieved in order to
  incorporate semantic rules in spatial data domain
  (interoperability requirements )

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MECOSIG - Monitoring Matrix
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Adaptations - Conceptual level

• UML class diagram used to design Data (original
  formalism proposed in MECOSIG - CONGOO is
  substituted)
• is internationally admitted as standard (System
  modelling)
• offers more than only one diagram
• design can combine serial of models to depict a
  context
• Specificity of spatial data in UML
• objects geometry
• a lot of studies e.g. COMOSIG Workshops ER2004,
  Bédard al., 2004 dealt with
• stereotypes or tagged values allow to adapt UML
• topological relationships
• concept of topological matrix (originally from
  CONGOO) is added and adapted
• two kinds of topological matrix are available
• the traditional matrix and the strong one

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Adaptations - Conceptual level
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Adaptations - Conceptual level

• Every use case is extracted from the descriptive
  level and detailed using UML activity diagrams
• Sequence diagrams are used to conceptualize
  specific scenarios of activity diagrams

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MECOSIG - Monitoring Matrix
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Adaptations - Organizational level

• Facing the implementation of a distributed
  infrastructure, important organisational
  constraints must be met
• missions of all actors should be assessed and
  possibly redefined
• new tasks are introduced in order to guarantee
• maintenance, permanent working and growth of the
  distributed System
• new data flows are generated and others have to
  be adapted
• data exchange must be performed easily and in a
  transparent way for all users
• access to metadata ISO standards - particularly
  metadata related to quality (data usability and
  appraisal of final results)
• some data / services access can be restricted or
  subject to authorization(s)

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Adaptations - Organizational level

• From these purposes
• coming up representatives committees in charge
  of coordination tasks
• formalization can also be introduced to depict
  their tasks (UML use cases, activity sequence
  diagrams, )

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MECOSIG - Monitoring Matrix
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Adaptations - Logical-Physical level

• Roles and tasks of all actors should be clearly
  specified
• key is to associate all actors in the new System
  which will be set up
• e.g.
• sensitizing and training sessions to facilitate
  the understanding of the re-engineered system
• possible reallocation of human resources
• Constitution of the representatives committees
  in charge of coordination tasks
• competent and representative of the various
  departments or organizations
• receiving the ability to act decisively
• Managerial economies and economies of scale could
  be achieved
• Acquisition of common reference data
• Globalisation of software licenses

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Adaptations - Logical-Physical level

• A technical study must be completed
• to guarantee the required degree of
  interoperability
• to identify precisely
• add-on hardware and software
• distributed system components
• systems for cross-relating items of information
  across multiple sources
• Modelling process is to design objects which must
  be deployed in a distributed System
• e.g. data storage structure (components and
  deployment UML diagrams)
• previous activity and sequence diagrams
  (conceptual level) are improved
• by adding objects dealing with data flows,
  procedures and processes according to GIS
  software, tools and DBMS specificities...

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Adaptations - Logical-Physical level
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Adaptations - Logical-Physical level

• Whole of the logical-physical level is integrated
  into a evolutionary project pilot

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Thank youQ / A ?

• http//www.geo.ulg.ac.be