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WebLanguages

Part II Advanced Topics

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The J ourney till now

suppliercustomer

SOAP-based

middleware

SOAP-

basedmiddlewareSOAP messages

(invoke)

UDDI registry

SOAP-basedmiddleware

SOAP messages

(publish)SOAP messages

(bind)

WSDL interfaces

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Part II Approach to designing service-oriented systems

Properties of the interaction

Secure

Reliable

Routing

Policies

Coordination

Business Protocols

Transactions

Service Bus

Composition and Mashups

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Part II - Project

Develop a useful service combining buildingblocks

Publish them as web services and make them

available as Web pages

Adopt interface-first approach

BPEL

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A note oninterfaces

The art ofKISSing

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Quality of code (and of interfaces)

http

://www.osn

ews.com/sto

ry/19266/WTFs_m

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good code (and interfaces)

Despite deadlines, take time to write goodcode.

Good code does not help only for doing

maintenance next year, it will help you doingmaintenance in a couple of hours.

LeBlancs law: later equals never

Robert Martin: Take the time to go fast

Poor code will slow you down even before thedeadline

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Characteristics of good code Stroustrup: elegant, straightforward (make it hard for

bugs to hide)

Thomas: can be read and enhanced by somebodyelse. Includes testing. Minimal dependencies,

Featers: looks like written by someone who cares Booch: re a d s lik e we ll-w ritte n p ro se

(from Clean Code, by Robert Martin. Read also effectivejava, by J oshua Bloch)

Minimal API

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Google Big Table

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What about Web servicesinterfaces

The same, but with MORE emphasis on simplicity

SERVICE DESCRIPTION AND INTERFACES SPECSARE WRITTEN FOR OTHERS TO READ. THINK ABOUT

THE READER

If the specs are not clear, its your fault

If the specs are not clear, your service does notget used

REMEMBER THE HOW TO

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Dynamics of the ecosystem Constant growth since programmableweb.com went

online (over 600 days) [by Michael Weiss, Carleton University]

Number of APIs Number of mashups

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Some figures(programmableweb.com)

Most popularcategories ofmashups

Most popularweb APIs

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Protocol usage by APIs

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Compositionand Mashups

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A B

C

P

Choreography vsComposition

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Business Process

Service composition

WAS.net

CICS

Web service

Legacy integration

WS-BPEL def i nes a model and a gr ammar f or descr i bi ng t he behavi or of abusiness pr ocess based on int eract i ons bet ween t he pr ocess and i t s pa r t ner s.

The int er act ion w it h each par t ner occurs t hrough Web Servi ce int er f aces.

Web serviceWeb service

Web service

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(Enterprise) Application

Integration

18

Business Process

WAS.net

CICS

SOAP

RMI/IIO

P

MQSeries

MQSeries

Delivery

channels

Legacy

integration