ICEBERG/SAHARA Brainstorming session on service composition
18 May 2001, Friday

Composable services

- Storage service
- Web/Streaming media server
- Name/lookup service (distributed indexing)
- Preference filtering (user specific)
- Redirection service
- Format conversion services
- Gateway service (protocol conversion)
- Billing/accounting service

Service:

Find favourite song ---> translate ---> download into cell-phone for
customized ring

Centralizing services versus distributing them: what is the take on
this from an industry stand point?

Billing service:

Value Added Service 1 ----+
                          |
Value Added Service 2 ----+----> Billing system <----> User
                          |
Value Added Service 3 ----+

iMode works this way...

Third party services versus implementing your own.  What are the
reasons for going for third party services:

- business model
- maintenance hassles are lesser with 3rd party services
(Is there a technical argument?)

Babelfish translator: example of a third party service used by a lot
of different services

What are the services that can be close to the edges of the network?
- Location sensitive services
- User interface download

Think of a generic compute cycle service...

Choice of service instance (when there are multiple providers)
- depends on security service
- circumventing things like packet filtering
- administrative domain constraints

Issues:
centralized vs distributed

Centralized:
- easier to manage
- economies of scale
- business model argument: managed large-scale services like
  search-engines

Distributed:
- good for latency senstive apps
- compute intensive services
- security/trust issues
- smaller scale services, light weight (codecs for example)

Industry is focussed on large-scale centralized services mostly, while
there is a lot of research on small-scale services.  Would be
interesting to know where they meet.

Dynamic versus static service composition:
The path could be a tree -- decided statically
Which branch of the tree is chosen could be decided dynamically.
For instance, a redirection service that redirects video to a user's
PDA or desktop PC depending on where the user is.

How many services can be there in the data-stream?
- The data source
- Caching
- Transcoding
- Redirection
- Billing/Accounting
- Gateway service