Building better clients

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BUILDING BETTER CLIENTS

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BEN LONGDEN CTO Inviqa Enterprise open source

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@BLONGDEN

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There are two types of client

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MACHINE DRIVEN

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HUMAN DRIVEN

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WHAT'S THE PROBLEM?

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We're getting quite good better at building RESTful API's on the server side.

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But what about our clients?

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Do they allow the API to change?

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Consider the web browser.

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What would the browser do? — Brian Sletten

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Supports the most common media types.

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application/x-shockwave-flash

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Versioning

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HTML

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We're not building a web browser

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But we can be inspired

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CONTENT NEGOTIATION (CONNEG)

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Send what your client will accept

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Accept: application/hal+json, text/plain

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Check what the server sends back

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Content-Type: application/hal+json

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Allow clients to support new media types when they become available

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Accept: application/hal+json, application/ vnd.error+json, text/plain;q=0.9

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USE AN HTTP CLIENT

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CACHEING

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URLS

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Remember that any GET request can be bookmarked by a client

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But also that it could result in a redirect

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GUZZLE ▸ Cacheing ▸ Logging ▸ Oauth

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HYPERMEDIA CONSTRAINT

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Hypermedia is deﬁned by the presence of application control information embedded within, or as a layer above, the presentation of information — Roy Fielding

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LINK RELATIONS POSSIBLE STATES

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CONTEXT

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{ "_links": { "self": { "href": "/comment/3864362" } }, "content": "lol" }

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{ "_links": { "edit": { "href": "/comment/3864362" }, "self": { "href": "/comment/3864362" } }, "content": "lol" }

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No content

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CLIENT CAN EVOLVE INDEPENDENTLY

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Futureproof?

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DESIGN OF EVERYDAY THINGS

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Form a goal

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Intention to act

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Sequence of actions

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Execution of the sequence of action

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Perceive the state of the world

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Interpret the perception

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Evaluate the outcome

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No content

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Why am I talking about this?

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A hypermedia client works in much the same way

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Let the server be in control

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Use content negotiation to allow clients to evolve

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Use an HTTP client and turn on cacheing

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Drive human interaction through hypermedia controls

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No content

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QUESTIONS! (or ask me at the bar later)