Transcript Web Services Advanced Topics

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IBM Software Group
IBM Position
W3C Enterprise Web Services WS
Christopher Ferris
Senior Technical Staff Member
© 2003 IBM Corporation
Feb, 2007
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IBM Software Group | WebSphere software
Debunking the Myth
 Many “RESTafarians” have taken the position that REST and Web
services are somehow incompatible with one another
 Fact: recent versions of SOAP and WSDL have been designed
specifically to enable more RESTful use of Web services
 SOAP1.2
SOAP1.2 Response MEP
Web Method
 WSDL2.0
HTTP binding permits assigning verbs (GET, POST, etc.) on a peroperation basis
Attribute to mark an operation as safe
 Unfortunately, the implementations of Web services runtimes and
tooling have made RESTful use of Web services difficult
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IBM’s Vision
“… a single scalable stack, offering the best of the Web in simple
scenarios, and scaling gracefully to SOAP based Web services with
the addition of optional extensions when more robust quality of service
features are required. We believe that the right steps have been taken
in the development of some of the more recent WS-* specifications to
enable this vision to become reality.”
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URI vs EPR
 A URI is an identifier
http://www.weather.com/outlook/travel/businesstraveler/local/01534
 An EPR is not (supposed to be) an identifier
 May carry reference parameters (similar to HTTP Cookies)
 No defined means of equivalence comparison
 EPR Address (URI) is the “address” of the service
<wsa:EndpointReference>
<wsa:Address>http://www.weather.com/weatherService/</wsa:Address>
<foo:ZipCode>01534</foo:ZipCode>
</wsa:EndpointReference>
 Some uses of EPR reference parameters treat the EPR as if it were an
identifier
 WS-Naming
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Uniform Interface
 Web services don’t expose a uniform interface
 (although, this is changing a bit with the emergence of WSResourceTransfer and WS-MetadataExchange)
 WSDL is used to provide a description of the service interface that
clients may use to interact with that service
 This means that deploying a new Web service requires socialization of the
specifics of its interface before any prospective client may interact with that
service
 Uniform interface lowers the barrier to entry of new services
 In contrast, new HTTP-based services can be made available without
the need to upgrade everyone’s browser
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Choose Wisely, Grasshopper
 It is important to note that REST and Web services are not mutually
exclusive architectural styles. There may be many circumstances in
which an application will want to take advantage of both styles.
 Examples
 Electronic Manufacturing
 RosettaNet RAE and Web services bindings
 Automotive
 When dealing with smaller supply-chain partners, they have need to
expose an interface that is more accessible (e.g. web based)
 Financial
 Web-based (portal) access for individuals, Web services for enterpriselevel interactions, some leveraging the same functions
 Others…
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When it makes sense to use “REST”
 To leverage direct integration with the Web
 Caching of resource representations for scalability and to mitigate
against transient failures
 Streaming of large amounts of data
 Direct access to the resource representation from a Web browser
 Manipulate the same resource interactively (e.g. using HTML forms)
and programmatically (e.g. via SOAP or POX over HTTP)
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When it makes sense to use WS-*
 Message-level security, such as when you need permanent total or
partial encryption of message content, or when you need to have the
authentication credentials bound to the message content
 Multi-protocol exchanges (e.g. HTTP to WebSphere MQ)
 Intermediation of message content between original sender and
ultimate recipient such as an XSLT transformation to or from a
standardized representation of the message content
 Integration into an automated business processes orchestration
engine using a standard such as WS-BPEL
 Additional quality of service capabilities such as reliable messaging,
transactions and advanced security capabilities
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IBM Software Group | WebSphere software
Thank You!
Thanks for listening.
[email protected]
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