Event Based Communication for Computational Collaboratories

1
Event Based Communication for Computational
Collaboratories
2
Event Based Communication for Computational
Collaboratories

• Outline for the talk
• Recap
• Event models
• Requirements and architecture of event based
  system for computational collaboratories.

3
Recap

• What are event based systems.
• Salient features.
• Decoupled architecture.
• Reduced network traffic.
• Comparison with time based systems.
• Various players of the event system and their
  communication mechanisms.

4
Event Models

• An event model describes the various entities and
  the relationship between them
• Corba event and notification services
• Java delegation and distributed models
• Jedi
• Siena

5
CORBA Event Models

• CORBA event service
• Supplier-consumer entities
• Event channel for decoupling
• No provision for filtering, Qos
• Corba notification service
• Multiple instances of admin objects for
  hierarchical filtering
• Provision for Qos parameters, structured events

6
Java Event Models

• Delegation event model
• Event sources and event listeners
• Use of event adapters asynchrony and partial
  decoupling
• Distributed event model
• Event generators and remote event listeners
• Use of third party event adapters for decoupling,
  application specific functionality

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JEDI

• Active Objects and Event Dispatcher
• Centralized and Distribute ED
• Hierarchical Distributed ED configuration
• Event Patterns
• Mobility of Reactive Objects

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Distributed JEDI ED
DS
DS
DS
Event subscriptions and events
DS
DS
DS
DS
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SIENA

• Distributed event service similar to JEDI
• Advertisements, subscriptions and publications
• Mobility of applications
• Native
• Transparent use network level mechanisms to
  transparently manage mobility
• External

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Scalable Server Topologies

• Hierarchical overloading of higher end servers
• Acyclic P2P no fault protection without
  redundant servers
• Generic P2P possibility of cycles due to
  multiple paths
• Hybrid mixture of the above

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Requirements for the Event Model

• Discovery of dynamically changing interfaces
• Publishing and subscribing of events
• Client authentication and access control
• Event filtering and pattern-matching

12
Architecture
cluster
Gateway Event Servers
Federation of Event servers
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Architecture Contd..

• Application interface discovery using traders
• The authentication and access control using
  gateway ES
• Event publication and subscription with
  forwarding filters
• Event correlation at the federated ES