1. ICS 123 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. ICS 123 2 Topic 15 Internet-Scale Interoperability Distributed Applications on the Internet

3. ICS 123 3 Topic 15 Internet-Scale Interoperability Example: An Arbitrage Application Yen Trader in Zurich Yen Trader in London Arbitrageur in New York 125.92 per $ 125.90 per $

4. ICS 123 4 Topic 15 Internet-Scale Interoperability Technologies for Event- Based Interaction

5. ICS 123 5 Topic 15 Internet-Scale Interoperability 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. ICS 123 6 Topic 15 Internet-Scale Interoperability 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. ICS 123 7 Topic 15 Internet-Scale Interoperability Attributes of Internet Scale

8. ICS 123 8 Topic 15 Internet-Scale Interoperability Some Warning Signs That a Technology Is Not Scalable

9. ICS 123 9 Topic 15 Internet-Scale Interoperability Event Observation and Notification Terminology invoker object of interest @ London object of interest @ Zurich Event Service pattern of events invoker notification 120.92 per $ 120.90 per $ interested party @ New York

10. ICS 123 10 Topic 15 Internet-Scale Interoperability 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. ICS 123 11 Topic 15 Internet-Scale Interoperability SIENA: Scalable Internet Event Notification Architectures Event Notification Service AdvertisePublishSubscribe Service Access Points Notifications

12. ICS 123 12 Topic 15 Internet-Scale Interoperability Goals of S IENA Research Project S IENA 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. ICS 123 13 Topic 15 Internet-Scale Interoperability Interface of S IENA S IENA : –publish(notification n) –subscribe(URI subscriber, pattern p) –unsubscribe(URI subscriber, pattern p) –advertise(URI publisher, filter p) –unadvertise(URI publisher, filter p) Interested party: –notify(notification n)

14. ICS 123 14 Topic 15 Internet-Scale Interoperability Notification Model in S IENA A notification is a list of attributes attribute=(type,name,value)

15. ICS 123 15 Topic 15 Internet-Scale Interoperability Filters A filter is a list of attribute filters attribute filter=(type,name,operator,value)

16. ICS 123 16 Topic 15 Internet-Scale Interoperability Patterns A pattern is an algebraic expression whose basic elements are filters and then

17. ICS 123 17 Topic 15 Internet-Scale Interoperability Some Design Choices

18. ICS 123 18 Topic 15 Internet-Scale Interoperability Simulation Studies

19. ICS 123 19 Topic 15 Internet-Scale Interoperability Distributed Servers

20. ICS 123 20 Topic 15 Internet-Scale Interoperability Centralized Server Architecture Server

21. ICS 123 21 Topic 15 Internet-Scale Interoperability Hierarchical Architecture … … … … …

22. ICS 123 22 Topic 15 Internet-Scale Interoperability General Graph Architecture

23. ICS 123 23 Topic 15 Internet-Scale Interoperability 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. ICS 123 24 Topic 15 Internet-Scale Interoperability Hierarchical Architecture with Subscription Forwarding … … …

25. ICS 123 25 Topic 15 Internet-Scale Interoperability Hierarchical Architecture with Advertisement Forwarding … … …

26. ICS 123 26 Topic 15 Internet-Scale Interoperability Side Topic: Delivery without Routing We have had large-scale information delivery without routing for ~100 years. Where? How?

27. ICS 123 27 Topic 15 Internet-Scale Interoperability Side Topic: Delivery without Routing We have had large-scale information delivery without routing for ~100 years. Where? How? Rabbit Ears

28. ICS 123 28 Topic 15 Internet-Scale Interoperability 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. ICS 123 29 Topic 15 Internet-Scale Interoperability Approximate State Synchronization

30. ICS 123 30 Topic 15 Internet-Scale Interoperability Approximate State Synchronization

31. ICS 123 31 Topic 15 Internet-Scale Interoperability Approximate State Synchronization

32. ICS 123 32 Topic 15 Internet-Scale Interoperability Approximate State Synchronization

33. ICS 123 33 Topic 15 Internet-Scale Interoperability Approximate State Synchronization

34. ICS 123 34 Topic 15 Internet-Scale Interoperability Middleware vs. Network Infrastructure 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 Today: Siena over TCP/IP Future: Siena alongside TCP/IP S IENA S IENA Client TCP/IP S IENA Client TCP/IPCBR