PHP London: API Contracts using Open API

Transcript

1. API Contracts using
   Open API
   Billie Thompson
   @PurpleBooth
   https://github.com/PurpleBooth/book-store
   

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2. Contents
   1. Why are some APIs terrible?
   2. API Contracts: Your Options
   3. How to write OpenAPI Specifications
   4. A Practical Example
   5. Conclusion
   

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3. Why do some APIs
   terrible?
   Even though they don't have
   downtime, or bugs
   

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4. Conway's Law
   

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5. "organizations which design
   systems ... are constrained to produce
   designs which are copies of the
   communication structures of these
   organizations"
   — M. Conway
   

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6. "If you have four groups working on a
   compiler, you'll get a 4-pass compiler"
   — Eric S Raymond
   

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7. Changing
   communication
   between stakeholders
   

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8. Sit in a room with the
   stake holders
   And write down the results
   (In a computer readable document)
   

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9. The Why!
   » Learn about requirements
   » Share Expectations
   » Humanising teams creates respect
   » Living Documentation
   

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10. A Contract
    Options for defining one
    

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11. Things to consider
    (It's got to do these in PHP)
    » Generate Clients
    » Validate Standard
    » Documentation Generation
    » Pleasant Editor
    

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12. Your Options
    » RAML
    » API Blueprint
    » OpenAPI/Swagger (JSON Schema + Operations)
    

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13. RAML
    

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15. RAML
    » Generate Clients: Yes, roughly 1 choice per language
    » Validate Standard: No (not in PHP anyway)
    » Documentation Generation: Yes, loads
    » Pleasant Editor: Yes
    Note: Weird split between version 0.8, 1.0.
    

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16. API Blueprint
    

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18. API Blueprint
    » Generate Clients: Yes, roughly 2 generators (poor generally)
    » Validate Standard: Yes
    » Documentation Generation: Yes, 3 or 4 things
    » Pleasant Editor: Yes
    Note Blueprint was sponsored by Apiary, who have now thrown
    themselves behind OpenAPI Specification
    

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19. OpenAPI Specification
    

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21. OpenAPI Specification
    » Generate Clients: Yes, lots for PHP and other languages
    » Validate Standard: Yes
    » Documentation Generation: Yes, loads
    » Pleasant Editor: Yes, lots
    

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23. Some History
    » ~2011 - Swagger Released based on JSON Schema
    » ~2014 - v2 Released
    » January 1st 2016 - Swagger becomes OpenAPI Specification
    

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24. Swagger is awesome but:
    » Don't use swaggers YAML format.
    » Inheritance Doesn't work well
    » Nulls aren't well supported
    (It's still pretty awesome though)
    

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25. How to write Open API
    Specifications
    

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26. {
    "swagger": "2.0",
    "info": { },
    "paths": { },
    "definitions": { }
    }
    

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27. {
    "swagger": "2.0",
    "info": {
    "version": "1.0.0",
    "title": "Swagger Petstore",
    "description": "A sample API that uses a petstore as an example",
    "termsOfService": "http://swagger.io/terms/",
    "contact": {
    "name": "Swagger API Team"
    }
    },
    "consumes": [
    "application/json"
    ],
    "produces": [
    "application/json"
    ],
    

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28. {"paths": {
    "/pets": {
    "get": {
    "description": "Returns all pets from the system that the user has access to",
    "produces": [
    "application/json"
    ],
    "responses": {
    "200": {
    "description": "A list of pets.",
    "schema": {
    "type": "array",
    "items": {
    "$ref": "#/definitions/Pet"
    }
    }
    }
    }
    }
    }
    },
    

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29. {"definitions": {
    "Pet": {
    "type": "object",
    "required": [
    "id",
    "name"
    ],
    "properties": {
    "id": {
    "type": "integer",
    "format": "int64"
    },
    "name": {
    "type": "string"
    },
    "tag": {
    "type": "string"
    }
    }
    }
    }
    

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30. A Practical Example
    Mandatory Symfony Example
    

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31. Demo Checklist
    » The swagger file for this Example
    » Generating Clients
    » The Implementation
    » Validating the Spec
    » The Documentation UI
    

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32. The tooling rocks!
    

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33. What to take away
    

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34. Questions?
    @PurpleBooth
    » https://github.com/PurpleBooth/book-store
    » http://apievangelist.com/2016/09/16/a-look-at-the-state-of-api-
    documentation-solutions/
    » https://github.com/janephp/openapi
    » https://github.com/fitbug/guzzle-swagger-validation-middleware
    » https://github.com/OAI/OpenAPI-Specification
    » http://swagger.io/swagger-ui/
    » http://editor.swagger.io/
    

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