Building Resilient API Clients

Transcript

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   Building!Resilient!API!Clients !KyleFuller

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   Building!Resilient!API!Clients

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    How$does$it$work?

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    GET /questions

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    DELETE /questions/{id}

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    GET /questions/{id}

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    POST /questions/{id}/choices/{choice_id}

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    POST /questions

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    Applica'on*was*built*from*an*out3 of3band*specifica'on

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    Tight&Coupling

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    We#want#to#change#something.

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    /v1

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    /v2

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    Move%Fast%and%Break&Things

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    Move%Fast%and%Break%Things

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    "Each&version&will&remain&for&at&least& 2&years&from&release."

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    Eventually*have*to*switch

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    API$Team$maintains$legacy$API

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    Move%Fast%and%Break&Nothing

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    REST

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    What%is%REST?

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    “An$cipa$ng*change*is*one*of*the* central*themes*of*REST”

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    REST%is%not... • CRUD • Pre)y+URLs • JSON • HTTP+"Verbs" •

    Rou9ng
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    It’s%not%about%exposing%your% database%via%an%API

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    These%are%implementa)on%details

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    Representa)onal,State,Transfer

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    Transfer(State(from(Server(to(Client?

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    Ques%on(Resource

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    HATEOAS

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    Hypermedia*as*the*Engine*of* Applica6on*State

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    Ques%ons • create • list

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    Ques%on • delete • choices

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    Choice • vote

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    Teaching)the)client)the)seman.c) meaning)of)the)domain

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    Without'knowledge'about'the' implementa3on'details

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    Root questions

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    Ques%on delete

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    Choice vote

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    Ques%on create • ques&on • choices

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    Why$are$we$not$doing$this?

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    Hyperdrive

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    One$Does$Not$Simply$Use$JSON

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    HAL$+$Siren

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    HAL Hypertext(Applica.on(Language

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    HAL { "_links": { "self": { "self": "/questions/1" } }

    }
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    HAL { "_embedded": { "choices": [ { "_links": { "self":

    { "self": "/questions/1/choices/1" } }, "choice": "Swift", "votes": 2048 } ] } }
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    Siren { "actions": [ { "name": "vote", "href": "/questions/1/choices/3", "method":

    "POST" } ] }
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    Siren { "actions": [ { "name": "create", "fields": [ {

    "name": "question", "type": "text", "title": "Question" }, { "name": "choices", "type": "array[text]", "title": "Choices" } ], "method": "POST", "type": "application/json", "href": "/questions" } ] }
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    API$Blueprint$+$Hyperdrive

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    apiblueprint.org

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    hyperdrive.enter("https://polls.apiblueprint.org/") { result }

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    representor

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    representor • a#ributes • transi,ons

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    representor • a#ributes • transi,ons • representors

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    if let questions = representor.transitions["questions"] { }

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    hyperdrive.request(questions) { result in }

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    if let questions = representor.representors["questions"] { map(questions, viewQuestion) }

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    } else { println("Looks like there are no questions yet.")

    }
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    func viewQuestion(question:Representor<HTTPTransition>) { println(question.attributes["question"]) if let choices = question.representors["choices"] {

    map(choices, viewChoice) } else { println("-> This question does not have any choices.") } if let delete = question.transitions["delete"] { // User may delete this question } }
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    func viewChoice(choice:Representor<HTTPTransition>) { let text = choice.attributes["choice"] let votes =

    choice.attributes["votes"] println('-> \(text) (\(votes))') if let vote = choice.transitions["vote"] { // User may vote on this choice } }
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    hyperdrive.request(vote)

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    if let create = questions.transitions["create"] { // We may create

    a new question for attribute in create.attributes { // Creation takes `attribute.name` } } else { // Gracefully handle the lack of being able to create a question }
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    Why?

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    Change'business'rules

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    Remove&transi-ons

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    Add#transi*ons

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    Coupling

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    TaaS Toaster(as(a(Service

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    Toaster(Applica.on

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    Demo

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    How$does$API$Blueprint$work?

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    ## Questions Collection [/questions] ### List All Questions [GET] +

    Relation: questions + Response 200 (application/json) + Attributes (array[Question])
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    ### Create a New Question [POST] + Relation: create +

    Request (application/json) + Attributes + question (string, required) - The question + choices (array[string]) - A collection of choices. + Response 201 (application/json) + Attributes (Question)
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    ## Question [/questions/{question_id}] + Attributes + question: `Favourite programming language?`

    (string, required) + published_at: `2014-11-11T08:40:51.620Z` (string) - An ISO8601 date when the question was published + choices (array[Choice], required) - An array of Choice objects
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    { "id": 1, "question": "Favourite programming language?", "choices": [ {

    "id": 1, "choice": "Swift", "votes": 128 }, { "id": 2, "choice": "Objective-C", "votes": 2 } ] }
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    ### Delete a Question [DELETE] + Relation: delete + Response

    204
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    ## Choice [/questions/{question_id}/choices/{choice_id}] + Attributes + choice: Swift (string, required)

    + votes: 0 (number, required)
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    ### Vote on a Choice [POST] This action allows you

    to vote on a question's choice. + Relation: vote + Response 201
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    Conclusion • Move&Faster • Write&Less&Code • Don't&Break&Things • Embrace&Change

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     Move%Fast,%Break%Nothing

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     the$hypermedia$project!/!Hyperdrive the$hypermedia$project!/!representor*swi- !apiaryio!/!polls'app apiaryio!/!polls'api

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     Ques%ons?

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     fuller.li/slides !KyleFuller