introducing rest

Introducing RESTIntroducing REST

Dong LiuDept. of Computer ScienceUniv. of Saskatchewandong.liu@usask.ca

http://blogs.usask.ca/dong_notes/

Jan. 8 2008Jan. 8 2008 Dong LiuDong Liu

AgendaAgenda

� What is REST � RESTful services� Comparing RESTful and SOAP-based approaches

� Useful resources

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RESTREST

� Representational State Transfer � The term comes from Roy Fielding’s PhD work� More practical than theoretical

� It is an architectural style, not a technology, nor an architecture � Software architecture = {Elements, Constraints, Rationale} *

� An architectural style abstracts elements and constraints from various specific architectures *

� Analogy: designs and design pattern

* Perry & Wolf "Foundations for the study of software architecture," SIGSOFT Softw. Eng. Notes. ACM, vol. 17, pp. 40-52, 1992.

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Deriving RESTDeriving REST

from Roy T. Fielding "Architectural styles and the design of network-based software architectures," University of California, Irvine, 2000.

RR: replicated repository$: cache CS: client-server LS: layered system S: stateless VM: virtual machine COD: code on demand U: uniform interface

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Uniform interfaceUniform interface

� Resources are identified by ONE resource identifier mechanism

� Access methods are the same for all resources

� Resources are manipulated by exchanging representations

� Representations are in self-descriptive messages

� Hypermedia acts as the engine of application state

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REST rationaleREST rationale

� Maximize reuse� Minimize coupling � Eliminate partial failure condition � Scale without bound� Simplify

from Roy T. Fielding "The Rest of REST," RailsConf Europe, 2007.

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Generic process to design RESTful servicesGeneric process to design RESTful services

1. Identify resources2. Design URIs3. Expose a subset of the uniform interface 4. Design the representations from and to the

client5. Integrate this resource into existing

resources, using hypermedia links and forms6. Consider typical flows 7. Consider error conditions A revised version of P216 in Leonard Richardson & Sam Ruby "RESTful Web Services," O'Reilly, 2007.

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RESTful design of del.icio.us services (1)RESTful design of del.icio.us services (1)

The example comes from Leonard Richardson & Sam Ruby "RESTful Web Services," O'Reilly, 2007.

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RESTful design of del.icio.us services (2)RESTful design of del.icio.us services (2)

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RESTful design of del.icio.us services (3)RESTful design of del.icio.us services (3)

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WS stackWS stack

from http://www.innoq.com/resources/ws-standards-poster/

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Interoperability?Interoperability?

Support for the Basic Profile is the baseline for interoperable Web services. Customers should demand that all of their Web services-enabled technology be compliant with the Basic Profile, and that in turn will lay the foundation for Web services to fulfill their promise and provide technology independentinteroperability.

Dan Sholler, Gartner from http://www.ws-i.org/Default.aspx

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WSWS--BabelBabel

from http://www.flickr.com/photos/psd/1805565187/in/set-72157602805227511/

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WSWS--AddressingAddressing

from http://www.flickr.com/photos/psd/406077535/in/set-72157602131510927/

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The Web is agreement The Web is agreement

from http://www.archive.org/details/TheWebIsAgreement

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Two mustTwo must--readread’’ss

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The communityThe community

� Yahoo rest-discuss group � Steve Vinoski � Paul Downey� Sam Ruby� Bill de hÓra � Joe Gregorio� Mark Nottingham� Pete Lacey� Stefan Tilkov� Stuart Charlton� Mark Baker � …

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