Beyond Documentation with OpenAPI (PHP Central Europe 2018)

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BEYOND DOCUMENTATION WITH OpenAPI

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GET /SPEAKERS/BOYAN Boyan Yordanov @specter_bg PHP Varna and VarnaJS organizer VarnaLab member Developer@ShtrakBG

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WHO LIKES WRITING DOCUMENTATION?

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DOCUMENTATION THAT IS: "too long to read" "totally useless" "not updated"

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JUST BORING

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API SPECIFICATIONS machine readable easy to write more than documentation

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- me I still have to write it, though.

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- also me (a couple of months later) I can do so many cool things with this de nition.

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WHY BOTHER WITH AN API SPECIFICATION?

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HAVE YOU BEEN THIS PERSON? http://www.commitstrip.com

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HOW ABOUT THIS?

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OUR PROCESS HAS FAILED US

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1. LITTLE UPFRONT DESIGN WORK

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2. UNANNOUNCED OR MISCOMMUNICATED CHANGES

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WASTED TIME AND A LOT OF FRUSTRATION

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COMMON PROBLEMS changes aren't properly tested clients constantly wait for the API documentation and code don't match SDKs have another opinion

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https://blog.apisyouwonthate.com/why-do-people-dislike-json- a7d67c8d38c1

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WHAT CAN WE DO?

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SPECIFICATION FIRST Nothing gets implemented until the API is de ned

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SPECIFICATIONS AS CONTRACTS verify that the API does what it says

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GAME PLAN 1. produce the API speci cation 2. generate docs and mock API 3. re ne the speci cation 4. use it in integration tests 5. work on the actual server code

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POTENTIAL BENEFITS

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1. THE SPEC IS THE SINGLE SOURCE OF TRUTH FOR OUR DESIGN

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2. ALWAYS UP TO DATE DOCUMENTATION AND TESTS

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3. WORK ON BACKEND AND CLIENTS INDEPENDENTLY

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API SPECIFICATION FORMATS

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API BLUEPRINT markdown based development is open on GitHub it's quite mature there's tooling for the most essential things mostly documentation oriented

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RAML RESTful API Modeling Language yaml based syntax is quite similar to the OpenAPI Speci cation covers the whole design/development process

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JSON SCHEMA not entirely fair to include it here json based focused only on the data model great for validation and tests includes syntax for describing hypermedia controls

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formerly known as Swagger don't call it that please yaml or json based very actively developed very active community

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HOW TO WRITE AN OPENAPI SPECIFICATION read the spec at swagger.io/speci cation

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BASIC STRUCTURE openapi: “3.0.0” info: # ... servers: # ... paths: # ... tags: # ... components: # ...

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LET'S BUILD A SIMPLE OPENAPI SPECIFICATION

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BASIC INFORMATION ABOUT THE API info: description: > *Imaginary* API for managing meetups. Imagined for this **PHPCE 2018** talk. version: '0.1' title: Meetups Are Awesome API contact: email: [email protected] name: Boyan Yordanov url: 'https://boyanyordanov.com' license: # ...

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HOW CAN USERS ACCESS THE API servers: url: 'https://imaginarymeetups.com/api' description: Imaginary API for managing Meetups url: 'https://staging.imaginarymeetups.com/api' description: Staging server for the imaginary AP url: 'http://localhost:8080' description: Development version of the API

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it also supports templating servers: url: https://{username}.apiserver.com/api/ description: User specific URLs variables: username: default: demo description: assigned upon registration

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WHAT CAN THE API DO

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Just a list of paths and the possible requests and responses paths: /meetups # ... /meetups/{id} # ... /meetups/{id}/events # ...

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A path description /meetups: summary: meetups description: Meetups resource tags: # .. parameters: # .. get: # ... post: # ..

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DESCRIBING PARAMETERS /meetups: # ... parameters: name: city in: query / path / header description: Filter meetups based on city schema: type: string

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handling array parameters /meetups: # ... parameters: name: technologies in: query description: Filter meetups based on city schema: type: array items: type: string style: form explode: false

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Result ?technologies=php,apis,javascript

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POSSIBLE RESPONSES /meetups/{id} get: responses: '200': content: application/json: schema: # ... '404': content: application/problem+json: # ...

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SCHEMA OBJECTS "extended subset" of JSON Schema draft 5 support references in future will support current drafts of JSON Schema and other formats

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example schema schema: type: object properties: id: type: string format: uuid name: type: string startingdate: type: string format: date

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nullable elds city: description: either a string or null type: string nullable: true

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other schema formats still a proposal schema: xoasdraftalternativeSchema: type: jsonSchema location: ./realjsonschema.json https://github.com/OAI/OpenAPI-Speci cation/issues/1532

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REFERENCE OBJECT object with $ref property reference objects in the same document reference external documents replace inline de nitions for most OpenAPI components

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Replace almost anything in the spec schema: $ref: '#/components/schemas/Meetup' # ... responses: '200': $ref: 'MeetupsListResponse.yaml'

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COMPONENTS components: schemas: # ... responses: # ... parameters: # ... requestBodies: # ... headers: # ... examples: #

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WE HAVE AN OPENAPI SPECIFICATION WHAT DO WE DO WITH IT?

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EASY PICKINGS HTML DOCUMENTATION

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Swagger UI - least favorite

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Widdershins + Slate / Shins.js

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REDOC

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LINTER - SPECCY https://github.com/wework/speccy lints your speci cation supports rulesets docs preview with ReDoc resolve spec in one le supports external references written in json-schema

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EDITORS everything supporting yaml

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VSCode with openapi-lint extention validates and lints converts Swagger/OpenAPI 2.0 to OpenAPI 3.0 intellisense for both formats

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Swagger Editor

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Apicurio

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OpenAPI GUI

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SENYA EDITOR https://senya.io PhpStorm (JetBrains) plugin free for the time being smart completion live linting handles $refs well preview in Swagger UI ¯\_( ツ)_/¯

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CODE GENERATION OPENAPI GENERATOR

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community supported fork of swagger-codegen supports OpenAPI 3.0 Updated templates for different languages and frameworks

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JANE-PHP/JANE-PHP generates PSR-7 compatible SDKs can use different clients based on HTTPlug supports json-schema and OpenAPI OpenAPI v3 support was added recently https://github.com/janephp/janephp

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MOCK SERVERS APISprout SwaggerHub Stoplight.io

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POSTMAN COLLECTIONS Apimatic.io upload/download or use API transform to and from OpenAPI lots of formats including Postman 2.0 Collections

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OPENAPI / JSON SCHEMA CONVERSION https://github.com/mikunn/openapi2schema https://github.com/wework/json-schema-to-openapi- schema

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WHY CONVERT? BEST OF BOTH WORLDS (sort of)

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EXAMPLE TEST https://github.com/swaggest/php-json-schema /** @test */ public function it_tests_with_swaggest_json_schema() { $schema = $this>loadSchema('events'); $response = $this>get('/events'); $this>assertValidResponse($schema, $response); }

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EXAMPLE ASSERTION https://github.com/swaggest/php-json-schema protected function assertValidResponse( $schema, $response ){ $validator = Schema::import($schema); try { $data = json_decode($response>getContent()); $validator>in($data); $this>assertTrue(true, 'Something went wrong.') } catch (InvalidValue $e) { $this>fail($e>getMessage()); } }

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WORKING WITH THE SPECIFICATION Parse OpenAPI speci cation Generate from code Nice PHP API to work with the spec Supports other speci cations as well https://github.com/apioo/psx-api

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PROOF OF CONCEPT TIME https://github.com/boyanyordanov/php-openapi-testing class ApiTest extends TestCase { use OpenAPITestTools\OpenAPIAssertions; /** @dataProvider getApiTestCases */ public function test_it_runs_openapi_based_tests( $path, $resource ) { $this>assertValidContract($path, $resource); }

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//... public function getApiTestCases(): array { $provider = new OpenAPITestTools\SpecDataProvide __DIR__ . '/../../openapi.yaml' ); return $provider>getTestCases(); } }

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MORE TOOLS thanks to Phil Sturgeon and Matthew Trask OPENAPI.TOOLS

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THANK YOU! QUESTIONS? https://joind.in/talk/17ec9

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RESOURCES Speci cation: - issues / PRs - books/blog/slack https://swagger.io/speci cation https://github.com/OAI/OpenAPI-Speci cation https://apisyouwonthate.com https://philsturgeon.uk https://apihandyman.io https://apievangelist.com http://json-schema.org http://www.commitstrip.com/en/2018/02/26/its-good-to-have- experience/