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Scalable Internet Event Notification Architectures

Explore the scalability and functionality of the SIENA system for event observation, notification, and dissemination on the Internet. Learn about event patterns, notification models, simulation studies, and future design choices.

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Scalable Internet Event Notification Architectures

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  1. Internet-Scale Interoperability ICS 123 Richard N. Taylor and Eric M. Dashofy* UC Irvine http://www.isr.uci.edu/classes/ics123s02/ * With the usual thanks to David Rosenblum

  2. Distributed Applications on the Internet

  3. Example:An Arbitrage Application Yen Traderin Zurich 125.92 per $ Arbitrageur inNew York 125.90 per $ Yen Traderin London

  4. Technologies for Event-Based Interaction

  5. Some Statistics from Network Wizards (www.nw.com) • January 2002: • 147,344,723 hosts in DNS • 236 active level 1 domains (e.g., .edu) • Top 10: .com (24,863,331), .net (18,853,655), .edu (6,085,137), .jp, .uk, .us, .mil, .de, .ca, .au • 2,867,326 level 2 domains (e.g., .uci.edu) • 35,967,238 level 3 domains (e.g., .ics.uci.edu) • This probably does not include all the “hidden” hosts on the internet (I.e. those behind firewalls or with a 10.x.x.x address) • These numbers are • Almost 100% higher than the January 2000 numbers, which are: • nearly 75% higher than the January 1999 numbers • more than 2 times the January 1998 numbers • about 4.5 times the January 1997 numbers

  6. Eight Fallacies of Distributed Computing (Peter Deutch) • 1. The network is reliable • 2. Latency is zero • 3. Bandwidth is infinite • 4. The network is secure • 5. Topology doesn't change • 6. There is one administrator • 7. Transport cost is zero • 8. The network is homogeneous Discuss: Why were people able to make such assumptions with relatively little risk in the past?

  7. Attributes of Internet Scale

  8. Some Warning Signs That a Technology Is Not Scalable

  9. Event Observation and Notification Terminology interested party@ New York invoker object of interest@ Zurich 120.92 per $ notification pattern ofevents 120.90 per $ object of interest@ London Event Service invoker

  10. Event Observation and Notification Activities 1. Making a class of events observable 2. Expressing interest in a pattern of events 3. Occurrence of an event 4. Observing an event 5. Relating observations with each other 6. Notifying an interested party 7. Receiving a notification 8. Responding to a notification

  11. Event Notification Service SIENA: Scalable Internet Event Notification Architectures Advertise Publish Subscribe Service Access Points Notifications

  12. Goals of SIENAResearch Project • SIENA provides an event observation and notification service... • Scalability • vast dimensions, scarce connectivity, heterogeneity, openness, decentralization • Expressiveness • flexible data modeling • accurate selection • aggregation of events

  13. Interface of SIENA • SIENA: • publish(notificationn) • subscribe(URI subscriber, patternp) • unsubscribe(URI subscriber, patternp) • advertise(URI publisher, filterp) • unadvertise(URI publisher, filterp) • Interested party: • notify(notificationn)

  14. Notification Model in SIENA • A notification is a list of attributes attribute=(type,name,value)

  15. Filters • A filter is a list of attribute filters attribute filter=(type,name,operator,value)

  16. Patterns • A pattern is an algebraic expression whose basic elements are filters and then

  17. Some Design Choices

  18. Simulation Studies

  19. Distributed Servers

  20. Centralized Server Architecture Server

  21. Hierarchical Architecture … … … … …

  22. General Graph Architecture

  23. Sample Simulation Outputs • Cost per Service: total cost of all messages involved in a single service request • Delay per Service: time delay between departure of first message and arrival of last one for a single service request • Cost per Site: total cost of all messages handled by a site • Cost per Link: total cost of all messages passing through one link Both averages and totals computed for metrics

  24. Hierarchical Architecture with Subscription Forwarding … … …

  25. Hierarchical Architecture with Advertisement Forwarding … … …

  26. Side Topic: Delivery without Routing • We have had large-scale information delivery without routing for ~100 years. Where? How?

  27. Side Topic: Delivery without Routing • We have had large-scale information delivery without routing for ~100 years. Where? How? Rabbit Ears

  28. What About Event Delivery Over Wireless Networks? • Routing and distribution greatly simplified • No need for sophisticated routing algorithms • No need for carefully-designed server topology • But reliability may become greatly complicated • Simple wireless handheld devices, such as pagers • One-way communication • No guarantee of delivery • Need sophisticated broadcast algorithms

  29. Approximate State Synchronization

  30. Approximate State Synchronization

  31. Approximate State Synchronization

  32. Approximate State Synchronization

  33. Approximate State Synchronization

  34. Wasted explicit addressing in IP Redundant, unused routing information in DNS Implicitly-addressed, content-based routing (CBR) Hardware routers with CBR routing tables and algorithms Middleware vs.Network Infrastructure Today:Siena over TCP/IP Future:Siena alongside TCP/IP SIENA Client SIENA Client SIENA TCP/IP CBR TCP/IP

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