REST & ActiveResource

REST & ActiveResourceRyan Daigle

ALTERthought

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Overview

• What is REST?

• How do I use ActiveResource?

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REST

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We Are Guilty of Poor Grammar

• Think of REST as a sentence

• HTTP Methods are verbs

• URIs are nouns

• This grammar is currently being abused

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Grammar Abused

• Action implied in the URI

• Implied action conflicts with HTTP method

Conflicting

GET http://addressbook/contacts/destroy/1

What’s wrong with this?

Embedded verb

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Proper Structure

DELETE http://addressbook/contacts/1

PUT http://addressbook/contacts/1

GET http://addressbook/contacts/1

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HTTP Verbs

• 4 (Main) Request Methods

• POST

• *GET

• PUT

• DELETE

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Verb Similarities

HTTP Method CRUD SQL Action

Post Create Insert Create

Get Read Select Show

Put Update Update Update

Delete Delete Delete Destroy

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Nouns

• Represent Resources with URIs (Uniform Resource Identifier)

• ‘contacts’ = http://addressbook/contacts

• Different representations of the same resource (html, xml, json)

• contacts.html, contacts.xml etc...

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Sentences

“View the XML representation of all contacts”GET http://addressbook/contacts.xml

“Get the vCard representation of the contact with id 1”GET http://addressbook/contacts/1.vcd

“Create a new contact”POST http://addressbook/contacts.xml

“Update the contact with id 1”PUT http://addressbook/contacts/1

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Surely This Can’t Be It?

• REST’s simplicity is not a limitation

• Think in terms of properly structured sentences

• Build upon this foundation

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Non-CRUD Actions

• How invoke non create/show/update/destroy actions?

• Use Rails practices for consistent service addressing

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Example“Get the XML representation of all contacts whose first name starts with the letter ‘r’ ”

GET http://addressbook/contacts.xml

Action name

;search

Query parameters

?first=r

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ActiveResourceConsuming REST services

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ActiveResource (ARes)

• ActiveRecord for REST

• O-O abstraction to remote services

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ActiveResource

Network(Scary)

(Your) Model

Remote REST Service

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Howto Implement ARes?

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What You Get For Free

Finders

Create/update

Destroy

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What ARes Does For You

• Form request URI

• Send RESTful request w/ XML body

• Process response

• O-O access to response details

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‘Create’ Request

HTTP Request:

ARes:

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Successful ‘Create’Http Response:

ARes Usage:

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Http Response:

ARes Usage:

Errors on ‘Create’

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ARes Not Tied to Rails

• Send/receive XML data

• Proper response codes & headers

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Nested Resources

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Nested Resources

• Nested != Inherited

• has_many relationships often represented w/ nesting

• Nesting specified via URIhttp://addressbook/users/1/contacts.xml

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Nested ARes Models

Containing model:

Nested model:

uri prefix

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Nested Model Initialization

• 2nd parameter hash is uri prefix (used to populate nesting entities in URI)

uri prefix parameters

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Nested RequestsARes:

Nested HTTP Request:

nesting entity parameters

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Nested URI Formation

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Non-CRUD Scenarios

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Non-CRUD Scenarios

• Access underlying connection

• Build custom URI

• e.g. ‘Register’ different from ‘Create’

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What We WantARes:

Http Request:

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How We Get It

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Remember the Basics

• ARes builds URIs

• ARes sends and receives XML

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Authentication

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Basic HTTP Authentication

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Token-Based Authentication

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ARes Positives

• Very simple framework

• Not explicitly tied to Rails remote service

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ARes Caveats

• Very raw

• No caching

• No ActiveRecord-like DSL

• Not officially part of Rails (just kind of hanging out in their repository)

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Play Timehttp://contactsapi.com

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