SeLeNe Architecture

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SeLeNe - Architecture
THE UNIVERSITY OF CYPRUS

• George Samaras
• Kyriakos Karenos
• Larnaca April 2003

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Presentation Preview

• Introduction Service-based Approach
• SeLeNe Proposed Services
• Authorities
• Service Availability
• Simple Scenarios
• Alternatives C-B-P model

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Introduction

• Service-based Approach
• The Grid Architecture made up of services
• Semantic Grid for eScience
• Using Services Examples
• Tools
• JXTA (p2p)
• Globus (grid)
• Web Services
• RMI, CORBA

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Proposed Services (I)

• Classification Core\Appended
• Relevance to OGSA and Semantic Grid

Application
Collective
Resource
Connectivity
Fabric
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Proposed Services (II)

• Core Services
• Information Service
• LO Metadata
• Services
• Storage Service
• Content (LOs)
• Metadata physical files
• Indices (known sites)
• Communication Service
• Available Protocols (TCP\IP,)

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Proposed Services (III)

• Appended Services
• Registration
• Search
• Uses the information Service
• Schema heterogeneity issues Clusters?
• Access
• Allow local and remote access to heterogeneous
  LOs via a common API
• Caching
• Local and Remote
• Content, Service and Message caching

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Proposed Services (IV)

• Appended Services
• Replication
• File copying and Transferring (Access Serv)
• Single Owner
• Update Propagation
• Object Lookup logical-to-physical
• Security
• On local data
• Third party
• Collaboration
• Possibly available Services (Blackboards, Message
  Boards) managed by high level service

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Proposed Services (V)

• Appended Services
• Integration Service
• Transparent integration mechanism
• Authoring
• Create and visualize
• Trail Management
• Knowledge Layer
• The most difficult to design at this point
  (requires lower level services)

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Authorities

• Super-peer like
• Reliable service provision
• Static participation
• Provide persistent services including
  Collaboration, Caching, Registration,
  Integration
• Roles
• Mediators (handle ontology diversion)
• Coordinators (e.g. maintain Collaboration state,
  manage Integration process)
• Third party (security, pricing)

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Service Availability

• Basic services are made core.
• Reliable sites (authorities) provide
  popular/demanding services
• Service replication
• Break services to smaller components
• Remote service starting to save resources
• Predictable service shutdown

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Example (I)
C
A
D
B
E
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Example (II)
an individual author creating a new derived LO
and its associated metadata from other LOs

• C Uses Search service
• identifies sites A and D
• Integration service at site B used user-view
• Access service at site A
• Saved at the local cache
• Replication Service at B Replicate locally a
  part
• Information service new interconnections/
  relationships between LOs.

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Alternatives (I)

• Maintain the Service-based focus
• Create sets of services
• Consumer services, Brokering services and
  Producer services
• Two different Setups presented later

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Alternatives (II)

• Views to the C-B-P architecture

Producer
Super-Peer like
Grid Like
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Alternatives (II)

• Setup 1
• Define strict roles to each site
• Producer Services Repositories
• Consumer Services Client
• Brokering Services Brokers
• Analogy to Database Users

Repositories
Brokers
Clients
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Alternatives (III)

• Setup 2
• Allow Consumer\Producer services to be co-located
  at sites i.e. LOs stored at any site
• May require site collaboration
• Local Services (more independent)

Brokers
Consumer
Producer
Consumer\Producer
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Comparison (I)

• Distribution of Services
• Pure Grid Heavy, weight on servers
• Grid\P2P more flexible, site of various
  resources
• C-B-P Somewhere in the Middle
• Dynamic
• Pure Grid Low. Server site must remain up and be
  static but highly available
• Grid\P2P and C-B-P highly dynamic but no quality
  of service can be dealt with!
• Dynamic nature Vs Availability Trade-offs

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Comparison (II)

• Managerial Ease
• Pure Grid and C-B-P Highly Manageable- strict
  service specification
• P2P\Grid Difficult to manage, independent sites.
  More supported services (powerful) - autonomy Vs
  Light but dependent

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Thank you