Service composition scenarios

Day in the life of a student:

Bus to school: check bus schedule from bus-stop:

Web service with bus schedule and fare

Traffic conditions on bus route

GPS service to get user’s location

SMS gateway to send message to user’s cell-phone

Pay bus-fare electronically using cell-phone:

Authentication service to check for student discount

Online banking service for payment

Steaming music on cell-phone/PDA

Streaming media server

Gateway service to go from cell-phone network to the Internet

Online personal preference service to find new favorite music

One or more trans-coding services for data transformation

Online CD store to extract price of CD with that song

Proxy service to display CD price and purchase information on PDA while music is playing

Important email pushed to cell-phone

Email service like yahoo

Personal preference registry to give list of important email senders (student’s prof)

Text-to-speech service to convert email to speech

Additional codecs if any

Gateway service to access cell-phone network

(Prof’s email says that class has been moved to an alternate location)

Notes in class

Student downloads lecture notes from local web-server (web-mirror service) onto laptop

Starts-up media-board application and opens the lecture notes (media-board proxy) -- shares notes with study-group

Local storage service stores marked-up notes periodically

Streaming video on handheld

On the way back from school, student views missed lecture

School’s streaming video server

Preference service to extract student’s handheld’s capabilities

Transcoding service to adapt content

Redirection service

When student gets off the bus, and walks to home, the video session is switched to the PC at home

The redirection service handles this

Online gaming on home PC

Video from game server

Compose with email service or news service that inserts text into the bottom of the game screen

Types of services:

Location service (GPS)

Storage services

Registry/preference

File

Database

Caching service

Security/authentication service, Billing service

Redirection service

Transformation agents

Trans-coding

Rate-adaptation

Adding content (text to the bottom of video, or ads)

Text-to-speech

Gateway services

Sources

Web server

Streaming media server

Game server

Access patterns

Session-oriented (long-lived session) versus short-access

Transaction-oriented versus no-transaction access

Read-only (request-reply) kind of access