ICS 123 InternetScale Interoperability ICS 123 Richard N

ICS 123 Internet-Scale Interoperability ICS 123 Richard N. Taylor and Eric M. Dashofy* UC Irvine http: //www. isr. uci. edu/classes/ics 123 s 02/ * With the usual thanks to David Rosenblum

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

Example: An Arbitrage Application 125. 92 per $ Topic 15 Internet-Scale Interoperability ICS 123 Yen Trader in Zurich Arbitrageur in New York 125. 90 per $ 3 Yen Trader in London

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

Some Statistics from Network Wizards (www. nw. com) Topic 15 Internet-Scale Interoperability ICS 123 • 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 5

Eight Fallacies of Distributed Computing (Peter Deutch) • 1. • 2. • 3. • 4. • 5. • 6. • 7. • 8. Topic 15 Internet-Scale Interoperability ICS 123 The network is reliable Latency is zero Bandwidth is infinite The network is secure Topology doesn't change There is one administrator Transport cost is zero The network is homogeneous Discuss: Why were people able to make such assumptions with relatively little risk in the past? 6

Attributes of Internet Scale 7 Topic 15 Internet-Scale Interoperability ICS 123

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

Event Observation and Notification Terminology interested party @ New York object of interest @ Zurich Topic 15 Internet-Scale Interoperability ICS 123 invoker 120. 92 per $ notification pattern of events 120. 90 per $ Event Service 9 object of interest @ London invoker

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 10 8. Responding to a notification Topic 15 Internet-Scale Interoperability ICS 123

SIENA: Scalable Internet Event Notification Architectures Advertise Publish 11 ICS 123 Subscribe Event Notification Service Access Points Topic 15 Internet-Scale Interoperability Notifications

Goals of SIENA Research Project Topic 15 Internet-Scale Interoperability ICS 123 • 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 12

Interface of SIENA • SIENA: – – – 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) 13 Topic 15 Internet-Scale Interoperability ICS 123

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

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

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

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

Simulation Studies 18 Topic 15 Internet-Scale Interoperability ICS 123

Distributed Servers 19 Topic 15 Internet-Scale Interoperability ICS 123

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

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

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

Sample Simulation Outputs Topic 15 Internet-Scale Interoperability ICS 123 • 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 23

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

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

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

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

What About Event Delivery Over Wireless Networks? Topic 15 Internet-Scale Interoperability ICS 123 • Routing and distribution greatly simplified – No need for sophisticated routing algorithms – No need for carefully-designed server topology • But reliability may become greatly complicated – – 28 Simple wireless handheld devices, such as pagers One-way communication No guarantee of delivery Need sophisticated broadcast algorithms

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

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

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

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

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

Middleware vs. Network Infrastructure Today: Siena over TCP/IP Topic 15 Internet-Scale Interoperability ICS 123 Future: Siena alongside TCP/IP SIENA Client SIENA TCP/IP CBR • Wasted explicit addressing in • • 34 IP Redundant, unused routing information in DNS • TCP/IP Implicitly-addressed, contentbased routing (CBR) Hardware routers with CBR routing tables and algorithms