Building and using REST information
services
Rion Dooley
Outline
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What is REST?
Why REST?
Designing RESTful services
Accessing RESTful services
Example
Demo
Questions
What is REST?
• Stands for REpresentational State Transfer
• Defined by Roy Felding (Day Software, cofounder of Apache Software Foundation)
"Representational State Transfer is intended to evoke an image of
how a well-designed Web application behaves: a network of web
pages (a virtual state-machine), where the user progresses through an
application by selecting links (state transitions), resulting in the next
page (representing the next state of the application) being transferred
to the user and rendered for their use.” – Roy Felding
What is REST?
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It’s a way of thinking about your enterprise.
A concept, not a protocol
Applies web architecture to web services.
Model each document and process as a
resource (noun) with a unique URI
• Use standard HTTP actions (verbs) to interact
with a resource.
What is REST?
• GET: Retrieve a resource. No modification
should be done. No side effects allowed.
• DELETE: Remove a resource
• POST: Create or update a resource
• PUT: Update a resource
Why REST?
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Scalable
Human and machine usable
Language agnostic
Globally accessible resources
Intuitively understandable URIs, resources,
and actions.
Designing RESTful Services
• Implementing a style, not a protocol
– Resources rather than services
– Nouns rather than verbs
• Resource oriented design (ROD)
• What the enterprise is instead of what the
enterprise does.
• Don’t reinvent the wheel!!
Accessing RESTful Services
• REST is meant for interoperability.
• Built on same technology as the internet.
• Can be consumed in many different ways
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Web browser
Web services
Lightweight clients
Command line (curl, wget)
• May be used by components of an SOA, but
need not be a component in an SOA.
Designing RESTful Services
• Key Principals
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Everything gets an ID
Link resources together
Use standard methods
Resources have multiple representations
Communicate statelessly
Example
• Simple User VO service
– Authenticated
– Gives user-specific information about a user’s
profile, resources, accounts and jobs.
– Output HTML and XML responses
Example
Everything gets an ID
• A Resource has a unique URI.
• Sample endpoints may be:
- /profiles
- /resources/id
- /profiles/id
- /accounts
- /resources
- /accounts/id
• These are human-friendly for the example,
but no real need for them to be so.
Example
Use standard
methods
/profiles
GET – list all user profiles
PUT – unused
POST – add a new user profile
DELETE – unused
/profiles/id
GET – get user profile details
PUT – update user profile
POST – unused
DELETE – delete user profile
/resources
GET – list all resources
PUT – unused
POST – add resource
DELETE – unused
/resources/id
/accounts
/accounts/id
GET – get resource details
PUT – update resource information
POST - unused
DELETE – delete resource
GET – list all accounts
PUT – unused
POST – add account
DELETE - unused
GET – get account details
PUT – update account details
POST - unused
DELETE – delete account
Example
Representation based on request type
• Request for XML output
GET /resources/forte HTTP/1.1
Host: example.com
Accept: application/xml
• Request for HTML output
GET /resources/forte HTTP/1.1
Host: example.com
Accept: text/html
• Could be any format you wish to support.
Example
Resources link together
<resource self='http://example.com/resources/forte’>
<name>forte</amount>
<hostname>forte.example.com</hostname>
<status>up</status>
<account ref='http://example.com/accounts/1212’>1212</account>
<username ref='http://example.com/profiles/jdoe’>jdoe1</username>
</resource>
Example
• Language and implementation details are
up to the developer.
• Frameworks and APIs available in most
popular languages
• REST is an architectural design, not a
protocol, so work within your skill zone.
DEMO
Links
• Roy Felding’s dissertation
– http://www.ics.uci.edu/~fielding/pubs/dissertati
on/top.htm
• SOAP vs REST comparison paper
– http://www.jopera.org/docs/publications/2008/r
estws
• Security for REST web services
presentation by Mark O’Neill of Vordel
– http://www.vordel.com/downloads/rsa_conf_20
06.pdf
Links
• Popular REST Frameworks in Java
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Restlet (http://www.restlet.org)
Axis 2.0 (http://ws.apache.org/axis2/0_94/rest-ws.html)
Jboss RESTEasy (http://www.jboss.org/resteasy/)
Apache CXF (http://cxf.apache.org/)
• Popular REST Frameworks in other lang.
– Ruby on REST(http://rubyforge.org/projects/rubyrest/)
– Rest in Python (http://lukearno.com/projects/rip/)
– .NET
Links
• Familiar RESTful services
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TeraGrid Info Services (http://info.teragrid.org/web-apps/html/index/)
Amazon Web Services (http://aws.amazon.com/)
Yahoo! Web Services (http://developer.yahoo.com/everything.html)
Google Web Services (http://code.google.com/apis/ajax/)
• Accessing REST services
– Python: http://developer.yahoo.com/python/python-rest.html
Questions
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Building and using REST information services