Internet-Scale Interoperability

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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
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Distributed Applications on the Internet
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ExampleAn Arbitrage Application
Yen Traderin Zurich
125.92 per
Arbitrageur inNew York
125.90 per
Yen Traderin London
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Technologies for Event-Based Interaction
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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

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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?
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Attributes of Internet Scale
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Some Warning Signs That a Technology Is Not
Scalable
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Event Observation and Notification Terminology
interested party_at_ New York
invoker
object of interest_at_ Zurich
120.92 per
notification
pattern ofevents
120.90 per
object of interest_at_ London
Event Service
invoker
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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
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SIENA Scalable Internet Event Notification
Architectures
Advertise
Publish
Subscribe
Service Access Points
Notifications
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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

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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)

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Notification Model in SIENA

• A notification is a list of attributes

attribute(type,name,value)
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Filters

• A filter is a list of attribute filters

attribute filter(type,name,operator,value)
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Patterns

• A pattern is an algebraic expression whose basic
  elements are filters

and then
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Some Design Choices
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Simulation Studies
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Distributed Servers
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Centralized Server Architecture
Server
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Hierarchical Architecture





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General Graph Architecture
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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
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Hierarchical Architecture with Subscription
Forwarding



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Hierarchical Architecture with Advertisement
Forwarding



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Side Topic Delivery without Routing

• We have had large-scale information delivery
  without routing for 100 years. Where? How?

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Side Topic Delivery without Routing

• We have had large-scale information delivery
  without routing for 100 years. Where? How?

Rabbit Ears
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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

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Approximate State Synchronization
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Approximate State Synchronization
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Approximate State Synchronization
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Approximate State Synchronization
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Approximate State Synchronization
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Middleware vs.Network Infrastructure
TodaySiena over TCP/IP
FutureSiena alongside TCP/IP
SIENA Client
SIENA Client
SIENA
TCP/IP
TCP/IP
CBR

• 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