Transcript Document Control

Document Control
Versio
n
Details
Changed
Date
0.1
Initial Revision
BC
28/Feb/2007
Copyright
This document is protected by copyright and the information contained herein is confidential. The document may not be copied and the information herein
may not be disclosed except by the written permission of, and in a manner permitted by the proprietors, Westinghouse Rail Systems Australia Limited, 2007.
Application Integration
A five-ten minute presentation by
Benjamin Carlyle
The two Webs?


The World-Wide-Web
Enterprise Web Services
3
The two many Webs!






The World-Wide-Web
My Industry’s Web
My Supply Chain’s Web
My Enterprise’s Web
…
Thousands of them!
4
Each with…

Hierarchy/Overlap


Special interaction patterns



Components may participate in several Webs
Special protocols, document types and methods
More than just request/response message exchanges?
Separate application of Metcalfe’s law



A particular web can be defined as a set of components that
implement the same uniform interface
Components that can’t understand each other don’t get
network effects
Smaller Web = Lower Intrinsic Value.
5
Web Services are too Low-Level





HTTP is an application-level protocol
SOAP needs a specific WSDL added to be an
application-level protocol
Each new WSDL = A new web
How to we minimise the number of WSDL?
How do we see WSDLs evolving?
6
REST Covers many of these issues

If a parent web has an appropriate interaction
pattern, use it
 No web-specific code needs to be written
 Avoid proliferation of webs – text/plain

If a parent web has a nearly-appropriate interaction
pattern, embrace and extend
 Add new methods as required – SUBSCRIBE
 Add new content types – purchase order, train list.

Evolution by different webs influencing each other
 What is special today might not be tomorrow
7
Each web needs

A registry of
 Methods,
 return codes,
 content types,
 other interaction-affecting features
 All of which are understood when appropriate by all
components


References to parent web registries
Can WSDL or WADL help make this machine
readable: Reduce cost of low-value webs.
8
Recommendation

WS-*/HTTP/WAKA/whatever?
 In the short term, use bridges to make everything talk
 Define a high-fidelity “HTTP” WSDL that services can
implement
 In the longer term, a single protocol should rule them
all
 HTTP has enough momentum to see any challenger
wash away. Can it be extended, rather than replaced?

Focus on content-type development and filling in
missing features such as pub/sub, HA, and MOM
features
9