Building a Swift Web API and Application Together

Transcript

1. 1.

   Building a Swift Web API and Application Together Kyle Fuller

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   Agenda —API Design —Building API in Swift —Deploying API in

   Swift in production
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   API Design

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   What makes a good API?

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   What makes a good API? —Decoupled from implementation details —Able

   to evolve without breaking existing clients
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   Example: Pagination

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   GET /posts

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   GET /posts{?page}

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   GET /posts?page=2

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    None
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    None
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    ! How can we solve?

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    GET /posts{?before}

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    GET /posts?before=44

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    How do we introduce changes to our API?

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    Versioning APIs

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    /v1/posts{?page} /v2/posts{?before}

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    /posts{?page} /posts{?before}

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    API is coupled to implementation details

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    API is coupled to implementation details

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    What happens when you version an API?

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    What happens when you version an API?

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    How can we design the API without exposing implementation details?

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    REST Representational State Transfer

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    Anticipating change is one of the central themes of REST

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    Evolvability

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    Tight Coupling

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    "You can’t have evolvability if clients have their controls baked

    into their design at deployment"
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    "Controls have to be learned on the fly. That’s what

    hypermedia enables"
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    Hypermedia

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    Web Linking RFC 5988

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    GET /posts Link: </posts?before=30>; rel="next", </posts?before=120>; rel="last"

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    GET /posts?before=120 Link: </posts?before=90>; rel="prev", </posts>; rel="first"

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    WebLinking.swift https://github.com/kylef/WebLinking.swift

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    WebLinking: Checking for next link if let link = response.findLink(relation:

    "next") { print("We have a next link with the URI: \(link.uri).") }
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    WebLinking: Introspecting Available Links for link in response.links { print("Relation:

    \(link.relationType)") print("URI: \(link.uri)") }
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    application/hal+json

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    Blog Post { "title": "My First Blog Post", "body": "Lorem

    Ipsum" }
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    Blog Post (Next Link) { "title": "My First Blog Post",

    "body": "Lorem Ipsum", "_links": [ { "href": "/posts/2", "relation": "next" } ] }
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    Blog Post (Self) { "title": "My First Blog Post", "body":

    "Lorem Ipsum", "_links": [ { "href": "/posts/1", "relation": "self" }, { "href": "/posts/2", "relation": "next" } ] }
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    Blog Post (Comments) { "title": "My First Blog Post", "body":

    "Lorem Ipsum", "_links": [ { "href": "/posts/1", "relation": "self" }, { "href": "/posts/2", "relation": "next" }, { "href": "/posts/1/comments", "relation": "comments" }, ] }
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    Blog Post (Embedded Comments) { "_embed": { "comments": [ {

    "author": "Kyle", "body": "That's a really interesting post!" "_links": [ { "href": "/posts/1/comments/1", "relation": "self" } ] } ] } }
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    application/ vnd.siren+json

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    Delete Post { "properties": { "title": "My First Blog Post",

    "body": "Lorem Ipsum", }, "actions": [ { "name": "delete", "method": "DELETE", "href": "/posts/1" } ] }
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    Delete Post { "properties": { "title": "My First Blog Post",

    "body": "Lorem Ipsum", }, "actions": [ { "name": "delete", "method": "DELETE", "href": "/posts/1" } ] }
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    Create Comment { "properties": { "title": "My First Blog Post",

    "body": "Lorem Ipsum", }, "actions": [ { "name": "comment", "method": "POST", "href": "/posts/1/comments", "fields": [ { "name": "author", "type": "string" }, { "name": "message", "type": "string" } ] } ] }
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    Create Comment (Logged in) { "properties": { "title": "My First

    Blog Post", "body": "Lorem Ipsum", }, "actions": [ { "name": "comment", "method": "POST", "href": "/posts/1/comments", "fields": [ { "name": "message", "type": "string" } ] } ] }
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    Hypermedia —Remove implementation details from interface —Keep business logic on

    back-end, not front-end
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    Building an API in Swift

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    Web Frameworks

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    Web Frameworks —Frank —IBM Kitura —Vapor

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    Frank vs Kitura vs Vapor

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    Frank get("users", *) { (request, username: String) in return "Hello

    \(username)" }
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    Server APIs Working Group

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    Server APIs Working Group

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    Useful Tools —Templating Languages —Stencil —Data Persistence —Redis (Redbird) —PostgreSQL

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    Testing

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    XCTest class PersonTests: XCTestCase { let person = Person(name: "Kyle")

    func testPersonName() { XCTAssertEqual(person.name, "Kyle") } func testPersonDescription() { XCTAssertEqual(person.description, "Kyle") } }
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    extension PersonTests: XCTestCaseProvider { var allTests : [(String, () throws

    -> Void)] { return [ ("testPersonName", testPersonName), ("testPersonDescription", testPersonDescription), ] } } XCTMain([ PersonTests(), ])
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    Dredd https://github.com/apiaryio/dredd

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    API Blueprint # GET /hello + Response 200 (application/json) {

    "name": "Kyle" }
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    Dredd Testing $ dredd \ apidescription.apib \ https://localhost:8080 ✔ GET

    /hello ✔ API Matches API Description
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    Deployment

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    https://github.com/kylef/heroku-buildpack-swift

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    $ cat Package.swift import PackageDescription let package = Package( name:

    "Hello", dependencies: [ .Package(url: "https://github.com/nestproject/Frank.git", majorVersion: 0, minor: 3), ] )
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    $ cat Sources/main.swift import Frank get { _ in return

    "Hello World" } get(*) { (_, username: String) in return "Hello \(username)" }
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    $ cat Sources/main.swift import Frank get { _ in return

    "Hello World" } get(*) { (_, username: String) in return "Hello \(username)" }
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    $ cat .swift-version 3.0.2

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    $ cat .swift-version 3.0.2

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    $ swift build $ .build/debug/Hello [INFO] Listening at http://0.0.0.0:8000 (48827)

    [INFO] Booting worker process with pid: 48828
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    $ cat Procfile web: Hello

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    $ heroku create --buildpack https://github.com/kylef/heroku-buildpack-swift.git $ git push heroku master

    remote: -----> Swift app detected remote: -----> Installing 3.0.2 remote: -----> Installing clang-3.7.0 remote: -----> Building Package remote: -----> Copying binaries to 'bin'
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    None
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    None
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    None
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    Manual Deployment

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    Monitoring

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    Logging

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    print("ERROR: Connection to database failed \(error)")

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    Papertrail

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    None
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    None
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    Conclusion —API Design —Swift Web Services —Tools & Frameworks —Testing

    —Deployment —Monitoring
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    Conclusion —API Design —Swift Web Services —Tools & Frameworks —Testing

    —Deployment —Monitoring
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    kylefuller https://fuller.li/talks