Service Composition: Breakout Session Summary

lilactruckInternet and Web Development

Dec 4, 2013 (3 years and 10 months ago)

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Service Composition: Breakout
Session Summary

Randy Katz

David Culler

Summary: Bhaskaran Raman

Discussion topics


Background


Emerging Internet service model


Confederated vs. Overlay model


Issues:


Granularity of composition


Growth trends: copious bandwidth


Service economics

Background


Emerging Internet service model


Structure
-
less cloud


Structured, with Internet data
centers


Portal service built out of pieces


Portal


Appln infra service


Appln specific servers


Overlay networks


Physical topology


Confederated vs. Overlay model


At the network layer


At the service layer

Granularity of services


Heavy
-
weight pieces


E.g., search engines


Light
-
weight pieces


E.g., transformation agents


Yahoo portal is an example of heavy
-
weight
composition


Ninja paths: light
-
weight composition

Composition: beyond functionality


Service composition: flexibile


Can a composed service be robust?


Can we build in a negative feedback loop into the system?


With an event queue based approach to composition?


Can such a mechanism work across machines, across the
network?


How to compute reliability of a composed service?


Who to blame when something breaks?


SLAs for services: complex


Yahoo/Google have legal SLA document

Design for decomposition


Design for decomposition: how to design a service
so that it can be built from pieces meaningfully


End
-
2
-
End argument in service composition:


If we want to have admission control at the end, how to
effect this when the bottleneck is in the middle?


How to design protocols to allow for composition?


Expose more information


E.g., HTTP/1.0 has little support for caches, HTTP/1.1
has a lot of support

Internet Growth Trends


Optical technology being deployed in a big way


1.6 Tb/s


24 Tb/s in the backbone


Where to place services, and how many service
instances?


Does it matter, if backbone bandwidth is free and
infinite?


What about the people cost of managing distributed
instances?


In storage management, people cost is 3
-
4 times more than
system cost


Network access cost dropping: can buy optical link for $2K
a month

Service distribution vs. Centralization


Might depend on granularity


Hard to distribute search engine


Easier to distribute Akamai servers: soft
-
state


People cost:


HP: 50,000 node computer network


$10K per server


One person can manage 10 servers


Service in the telephone network are distributed


Might be related to the way the telephone network
evolved, and its architecture

Service distribution vs. Centralization


Latency/server
-
load might be a reason to
distribute a service


There are congested parts of the Internet today


Trans
-
oceanic links


Public
-
peering points


Distribution:


Over
-
provisioning may be easier if there are many sites

Service Economics


Composition: economics meets engineering


SLAs are an important part


Trust relations


Management tools for services


What are the ones required for composed services


Diagnose and isolate problems


Composition by user (dynamic) vs. composition by
service providers (less dynamic)