Abstraction Layers

1
Abstraction Layers

• Why do we need them?
• Protection against change
• Where in the hourglass do we put them?
• Computer Scientist perspective
• Expose low-level services
• Use SOAP as a wire protocol?
• Working Scientist perspective
• Want high-level services
• Use C/C/Java APIs
• Opaque Service Interaction Handles

2
What Services / Abstractionsdo we need?

• Look at some projects
• CLRC e-Science Centre
• AstroGrid
• MyGrid
• ICENI
• OGSA

3
CLRC e-Science Centre

• Single sign-on authentication
• Security service
• Authorisation
• Additional user services (including local user
  management)
• Resource discovery service
• Workspace creation service
• 3rd party file transfer facility
• XML parser service
• Query generation
• Replication

• Data source discovery
• Results collation
• Dynamic resource monitoring
• Event handling services
• Messaging service
• Job submission
• Job monitoring
• Visualisation
• Computational steering
• Thesaurus service
• Ontology service.

4
AstroGrid
VOVirtual Observatory
5
MyGrid Architecture
6
MyGrid Services

• User Agent Repository
• Notification
• Workflow Personalisation, Resolution, Enactment
  Serialisation
• Databases Distributed Query
• Job Scheduling Resource Management
• Information Extraction
• Authentication
• Service Directory
• User, Group Roles Directory
• Workflow Provenance Repository
• Ontologies Service function metadata

7
ICENI

• Low-level services
• Computational
• Storage
• Software
• Networking
• High-level services
• Application composition to define workflow
• Scheduling (mapping components to resources)
• Throughput (resource brokering)

8
OGSA (17/2/02)

• Is a Grid Service also a Web Service?
• YES as it has ports (described in WSDL) for
• Grid Service (Introspection termination)
• Notification Source Sink
• Registration of Grid Service Handles
• Service creation (factory)
• Primary Key (map key to GSH)
• Mapping (map GSH to GSR)
• BUT can only be deployed in an OSGA compatible
  hosting environment
• Is a Web Service also a Grid Service?
• NO as it misses out on the extra capability
• BUT can be deployed within an OGSA environment

9
OGSA Services

• Low-level services
• Execution, file transfer service meta-data (?)
• Higher-level services
• Distributed Data Management
• Work flow
• Auditing
• Instrumentation monitoring
• Problem determination (e.g. dump, trace log)
• Security protocol mapping

10
Common Requirements?

• Low-level
• Security
• Execution
• Database Access
• Data movement
• Service Management
• High-level
• Workflow management (Scheduling)
• Usage Access Policy
• Notification (Events Messaging)