How to use OpenAPI 3 for API developer RubyKaigi 2019 ota42y (FiNC Technologies)

Today’s Topic • Introduce OpenAPI 3 and explain why it is necessary • The OpenAPI 3 specification • How to use OpenAPI 3 • Request / response validation • A story about how to implement OpenAPI 3 feature • Other OpenAPI 3 tools

about me • @ota42y (github/twitter) • Server side engineer at FiNC Technologies • I maintain request/response validation gem using OpenAPI 3

2F

Introduce OpenAPI 3 and explain why it is necessary

OpenAPI 3 • programming language-agnostic definition for REST API • OpenAPI 3 means OpenAPI specification version 3 • previously known as Swagger so Swagger 2 == OpenAPI 2 https://www.openapis.org/

Definition of OpenAPI 3 • It’s machine-readable API definition rule • Definition of OpenAPI 3 is described in YAML or JSON formats • We can use it as interactive document generation, validation, mock-server, client library, etc…(I’ll talk about it later)

Sometimes the machine-readable API schema is important • When we create many APIs • When we want to do schema-first development • etc…

When we create many APIs • Backend API server for iOS/Android/Web(SPA) • We have many JSON APIs
 (We use microservices architecture so 1000 over endpoints ) • API schema is very important for interface documentation

Schema first development • Schema first development • Define API schema • Client-side and server-side implement according it • Integration test • Without Schema first development, 
 we can’t start client-side implement until server side implement finished Reference: RubyKaigi 2017 API Development in 2017 https://www.youtube.com/watch?v=a28jJ62ZfZM Rails Developers Meetup 2019: 
 https://speakerdeck.com/aeroastro/rails-meets-protocol-buffers-for-schema-first-development

Definition and implementation must be always same • If there are difference we can’t trust API schema • Even if we passed unit test, we gets bug on integration test • But it’s difficult to avoid making mistakes

The machine-readable API schema is important • We can find mistakes API automatically using the schema • So always the schema and definition is matched • We can use schema to generate human-readable docs, client library, etc…

OpenAPI 3

OpenAPI is one of the definition method • JSON Hyper-Schema • It defines hypermedia specifications, and it can also be used to define REST API too • GraphQL • Query language and runtime • The response can be specified in the query sent from the client

OpenAPI is one of the definition method • gRPC • RPC framework using protocol buffers and HTTP/2 • It generates code from interface definition and do almost all communication processing

OpenAPI extends REST API • OpenAPI is just a YAML/JSON rule • Actual processing is just REST API • OpenAPI 3 takes full advantage of existing RESTful frameworks and insights • Since REST is a web best practice at the time, various mechanisms such as HTTP cache, monitoring system can also be used

The OpenAPI 3 specification

Example API get "/apps" do content_type :json # page should be Integer page = params["page"] [page, (page*10)].map(&:to_s).to_json end

get "/apps" do content_type :json # page should be Integer page = params["page"] [page, (page*10)].map(&:to_s).to_json end • GET /apps returns application/json Example API

get "/apps" do content_type :json # page should be Integer page = params["page"].to_i [page, (page*10)].map(&:to_s).to_json end • GET /apps returns application/json • This API requires `page` parameter and must be Integer Example API

get "/apps" do content_type :json # page should be Integer page = params["page"].to_i [page, (page*10)].map(&:to_s).to_json end • GET /apps returns application/json • This API requires `page` parameter and must be Integer • Succeed response includes string array Example API

Example API to OpenAPI 3 definition openapi: 3.0.0 info: title: Sample API version: 0.1.0 paths: "/apps": get: parameters: - name: page in: query required: true schema: type: integer responses: '200': description: example content: 'application/json': schema: type: array items: type: string

Example API to OpenAPI 3 definition • GET /apps openapi: 3.0.0 info: title: Sample API version: 0.1.0 paths: "/apps": get: parameters: - name: page in: query required: true schema: type: integer responses: '200': description: example content: 'application/json': schema: type: array items: type: string

Example API to OpenAPI 3 definition • GET /apps returns application/json openapi: 3.0.0 info: title: Sample API version: 0.1.0 paths: "/apps": get: parameters: - name: page in: query required: true schema: type: integer responses: '200': description: example content: 'application/json': schema: type: array items: type: string

Example API to OpenAPI 3 definition • GET /apps returns application/json • `page` parameter required and it’s integer openapi: 3.0.0 info: title: Sample API version: 0.1.0 paths: "/apps": get: parameters: - name: page in: query required: true schema: type: integer responses: '200': description: example content: 'application/json': schema: type: array items: type: string

Example API to OpenAPI 3 definition • GET /apps returns application/json • `page` parameter required and it’s integer • Succeed response includes string array openapi: 3.0.0 info: title: Sample API version: 0.1.0 paths: "/apps": get: parameters: - name: page in: query required: true schema: type: integer responses: '200': description: example content: 'application/json': schema: type: array items: type: string

Example API to OpenAPI 3 definition • GET /apps returns application/json • `page` parameter required and it’s integer • Succeed response includes string array openapi: 3.0.0 info: title: Sample API version: 0.1.0 paths: "/apps": get: parameters: - name: page in: query required: true schema: type: integer responses: '200': description: example content: 'application/json': schema: type: array items: type: string

OpenAPI 3 structure JOGP QBUIT TFSWFST DPNQPOFOUT TFDVSJUZ UBHT FYUFSOBM%PDT required

OpenAPI 3 structure JOGP QBUIT TFSWFST DPNQPOFOUT TFDVSJUZ UBHT FYUFSOBM%PDT required Metadata for this definition API definitions Target server setting Schema objects Security settings Tags External document url

OpenAPI 3 structure JOGP QBUIT TFSWFST DPNQPOFOUT TFDVSJUZ UBHT FYUFSOBM%PDT required Metadata for this definition API definitions Target server setting Schema objects Security settings Tags External document url

openapi: 3.0.0 info: title: Sample API version: 0.1.0 paths: "/apps": get: parameters: - name: page in: query required: true schema: type: integer responses: '200': description: example content: 'application/json': schema: type: array items: type: string Paths Object • API definitions are written in this section • There is path string key and 
 Path Item Object • We can write definition in Path Item Object Path string Path Item Object

openapi: 3.0.0 info: title: Sample API version: 0.1.0 paths: "/apps": get: parameters: - name: page in: query required: true schema: type: integer responses: '200': description: example content: 'application/json': schema: type: array items: type: string Path Item Object • Define request/response parameter 
 per HTTP method Path Item Object

Path Item Object • Define request/response parameter 
 per HTTP method • We can define request parameter openapi: 3.0.0 info: title: Sample API version: 0.1.0 paths: "/apps": get: parameters: - name: page in: query required: true schema: type: integer responses: '200': description: example content: 'application/json': schema: type: array items: type: string

Path Item Object • Define request/response parameter 
 per HTTP method • We can define request parameter and 
 response parameter schema openapi: 3.0.0 info: title: Sample API version: 0.1.0 paths: "/apps": get: parameters: - name: page in: query required: true schema: type: integer responses: '200': description: example content: 'application/json': schema: type: array items: type: string

OpenAPI 3 structure JOGP QBUIT TFSWFST DPNQPOFOUT TFDVSJUZ UBHT FYUFSOBM%PDT required Metadata for this definition API definitions Target server setting Schema objects Security settings Tags External document url

Security Scheme Object • We can define security schema for all API or specific API

Security Scheme Object • We can define security schema for all API or specific API • We can use HTTP authentication type: http scheme: basic type: http scheme: bearer bearerFormat: JWT JWT basic

Security Scheme Object • We can define security schema for all API or specific API • We can use HTTP authentication, API key (like header, query) type: http scheme: basic type: apiKey name: api_key in: header type: http scheme: bearer bearerFormat: JWT JWT API key basic

Security Scheme Object • We can define security schema for all API or specific API • We can use HTTP authentication, API key (like header, query), 
 OAuth2, OpenID Connect type: http scheme: basic type: apiKey name: api_key in: header type: http scheme: bearer bearerFormat: JWT JWT API key basic type: oauth2 flows: implicit: authorizationUrl: https://example.co... scopes: write:pets: modify pets read:pets: read your pets OAuth2

OpenAPI 3 structure JOGP QBUIT TFSWFST DPNQPOFOUT TFDVSJUZ UBHT FYUFSOBM%PDT required openapi: 3.0.0 info: title: Sample API version: 0.1.0 paths: "/apps": get: parameters: - name: page in: query required: true schema: type: integer responses: '200': description: example content: 'application/json': schema: type: array items: type: string

How to use OpenAPI 3

OpenAPI is definition • It’s just a rule in YAML/JSON file, so it alone does nothing • It is effective by combining it with peripheral tools • request/response validation, interactive document generation, mock-server, client library, etc…

Request / Response validation
 using OpenAPI 3

We need validation • We make mistakes when implementing the API

We need validation • We make mistakes when implementing the API • OpenAPI is programming language-agnostic definition

We need validation • We make mistakes when implementing the API • OpenAPI is programming language-agnostic definition • So we need a tool to check differences between implementation and definition

We need validation • We make mistakes when implementing the API • OpenAPI is programming language-agnostic definition • So we need a tool to check differences between implementation and definition • This will ensure the credibility of the schema

committee gem • Request/Response validation gem

committee gem • Request/Response validation gem • This gem works as Rack middleware and performs validation if requested URL is in definition 3BDL
 "QQMJDBUJPO $MJFOU "QQMJDBUJPO Request validation Response validation committee

Request validation using committee require "sinatra" require "committee" use Committee::Middleware::RequestValidation, schema_path: 'schema.yaml' use Committee::Middleware::ResponseValidation, schema_path: 'schema.yaml' get "/apps" do content_type :json # page should be Integer page = params["page"].to_i [page, (page*10)].map(&:to_s).to_json end

require "sinatra" require "committee" use Committee::Middleware::RequestValidation, schema_path: 'schema.yaml' use Committee::Middleware::ResponseValidation, schema_path: 'schema.yaml' get "/apps" do content_type :json # page should be Integer page = params["page"].to_i [page, (page*10)].map(&:to_s).to_json end Request validation using committee committee returns error without `page` parameter % curl -X GET "http://localhost:4567/apps" {"id":"bad_request","message":"required parameters page not exist in #/paths/~1apps/get”}

Request validation using committee % curl -X GET "http://localhost:4567/apps" {"id":"bad_request","message":"required parameters page not exist in #/paths/~1apps/get”} % curl -X GET "http://localhost:4567/apps?page=1" ["1","10"] When `page` parameter exists, get correct response require "sinatra" require "committee" use Committee::Middleware::RequestValidation, schema_path: 'schema.yaml' use Committee::Middleware::ResponseValidation, schema_path: 'schema.yaml' get "/apps" do content_type :json # page should be Integer page = params["page"].to_i [page, (page*10)].map(&:to_s).to_json end

% curl -X GET "http://localhost:4567/apps?page=1" ["1","1111111111"] require "sinatra" require "committee" # use Committee::Middleware::RequestValidation, schema_path: 'schema.yaml' # use Committee::Middleware::ResponseValidation, schema_path: 'schema.yaml' get "/apps" do content_type :json # page should be Integer page = params["page"] [page, (page*10)].map(&:to_s).to_json end Coerce request parameter Normally, request parameters don’t have type and are always string

% curl -X GET "http://localhost:4567/apps?page=1" ["1","10"] Coerce request parameter But committee converts class using definition type (optional feature) require "sinatra" require "committee" use Committee::Middleware::RequestValidation, schema_path: 'schema.yaml' use Committee::Middleware::ResponseValidation, schema_path: 'schema.yaml' get "/apps" do content_type :json # page should be Integer page = params["page"] [page, (page*10)].map(&:to_s).to_json end

Coerce request body and other convert % curl -X POST -H "Content-Type: application/json" -d '{"measured_at":"2016-04-01T16:00:00+09:00"}' “http://localhost:4567/apps" {"class":"DateTime"} post: requestBody: content: application/json: schema: type: object properties: measured_at: type: string format: date-time responses: '201': description: no content content: 'application/json': schema: type: object properties: class: type: string • committee coerce parameter in request body • When string in date-time format, 
 committee converts it to DateTime class

Response validation using committee require "sinatra" require "committee" use Committee::Middleware::RequestValidation, schema_path: 'schema.yaml' use Committee::Middleware::ResponseValidation, schema_path: 'schema.yaml' get "/apps" do content_type :json # page should be Integer page = params["page"].to_i [page, (page*10)].to_json end This API returns string array but when returns integer array (we should call `map(&:to_s)` )

require "sinatra" require "committee" use Committee::Middleware::RequestValidation, schema_path: 'schema.yaml' use Committee::Middleware::ResponseValidation, schema_path: 'schema.yaml' get "/apps" do content_type :json # page should be Integer page = params["page"].to_i [page, (page*10)].to_json end We get error response from committee And we can change to write log and return the response Response validation using committee % curl -X GET "http://localhost:4567/apps?page=1" {"id":"invalid_response","message":"1 class is Integer but it's not valid string in #/paths/~1apps/get/responses/200/content/application~1json/schema/items"}

Test Assertions describe "GET /apps" do it "conforms to schema" do get '/apps?page=1' assert_schema_conform end end % bundle exec ruby committee_test.rb Run options: --seed 62877 # Running: E Finished in 0.023367s, 42.7954 runs/s, 0.0000 assertions/s. 1) Error: Committee::Middleware::Stub::GET /apps#test_0001_conforms to schema: Committee::InvalidResponse: don't exist status code definition in #/paths/~1apps/get/responses • committee provides response format checker for test • When there’re difference, test will fail

committee secures the reliability • Committee supports request/response validation • We can check if it’s a valid request and response by unit test or integration test • So we can trust that the interface is correctly implemented along with the schema

How to implement 
 request/response validator using OpenAPI 3

Inside committee • The committee initially supported only JSON Hyper-Schema and OpenAPI 2 validation • So I added new validation feature using OpenAPI 3 to committee

Tight coupling with JSON Hyper- Schema • committee converted OpenAPI 2 to JSON Hyper-Schema so committee validated one schema only • Validator was strongly coupled to JSON Hyper-Schema

• OpenAPI 3 structure is different from JSON Hyper-Schema and • OpenAPI 3 have many new features (like security) • I decided to refactoring and implement a new validator for OpenAPI 3 Implement new validator

Refactoring in committee • The committee does three steps

Refactoring in committee • The committee does three steps • Rack layer processing SBDLNJEEMFXBSF

Refactoring in committee • The committee does three steps • Rack layer processing • Find the schema from the request SBDLNJEEMFXBSF +40/)ZQFS4DIFNB 4DIFNB URL + HTTP method

SBDLNJEEMFXBSF Refactoring in committee • The committee does three steps • Rack layer processing • Find the schema from the request • Validation using schema +40/)ZQFS4DIFNB 7BMJEBUPS validate 4DIFNB QBSBNFUFS

SBDLNJEEMFXBSF Refactoring in committee • The committee does three steps • Rack layer processing • Find the schema from the request • Validation using schema +40/)ZQFS4DIFNB 7BMJEBUPS validate 4DIFNB QBSBNFUFS Depends on 
 JSON Hyper-Schema

Refactoring schema finder SBDLNJEEMFXBSF +40/)ZQFS4DIFNB 4DIFNB URL + HTTP method • Rack middleware pass URL and HTTP method to definition and get schema so don’t need to know detail of definition

Abstracted schema definition • So I create abstracted schema class and made rack middleware depend on it URL + HTTP method %FpOJUJPO SBDLNJEEMFXBSF

Abstracted schema definition +40/)ZQFS4DIFNB URL + HTTP method %FpOJUJPO SBDLNJEEMFXBSF • So I create abstracted schema class and made rack middleware depend on it • The middleware don’t care it’s JSON Hyper-Schema or OpenAPI 3

0QFO"1* Abstracted schema definition URL + HTTP method %FpOJUJPO SBDLNJEEMFXBSF • So I create abstracted schema class and made rack middleware depend on it • The middleware don’t care it’s JSON Hyper-Schema or OpenAPI 3

Refactoring validator • Rack middleware validate using schema object from definition and request/response data from rack • But middleware don’t need to know more about schema SBDLNJEEMFXBSF 7BMJEBUPS validate 4DIFNB QBSBNFUFS +40/)ZQFS4DIFNB %FpOJUJPO

SBDLNJEEMFXBSF Abstracted validator • I create abstracted validator which include schema definition • The middleware gets it from definition URL + HTTP method %FpOJUJPO "CTUSBDUWBMJEBUPS 4DIFNB +40/)ZQFS4DIFNB +40/)ZQFS4DIFNB

Abstracted validator • The middleware passes parameter to the validator for validation %FpOJUJPO "CTUSBDU7BMJEBUPS 4DIFNB +40/)ZQFS4DIFNB +40/)ZQFS4DIFNB QBSBNFUFS validate SBDLNJEEMFXBSF

Abstracted validator • The middleware passes parameter to the validator for validation • So rack middleware don’t need to know the definition is OpenAPI 3 or JSON Hyper-Schema %FpOJUJPO "CTUSBDU7BMJEBUPS 4DIFNB 0QFO"1* 0QFO"1* QBSBNFUFS validate SBDLNJEEMFXBSF

Abstracted validator • The middleware passes parameter to the validator for validation • So rack middleware don’t need to know the definition is OpenAPI 3 or JSON Hyper-Schema %FpOJUJPO "CTUSBDU7BMJEBUPS 4DIFNB 0QFO"1* 0QFO"1* QBSBNFUFS validate SBDLNJEEMFXBSF

openapi_parser gem • OpenAPI 3 parser is separated gem
 https://github.com/ota42y/openapi_parser • So we can implement another gem for OpenAPI 3 validation
 (e.g. more Ruby on ̋̋̋̋̋ friendly validator) • OpenAPI 3 parser is separated gem
 https://github.com/ota42y/openapi_parser • So we can implement another gem for OpenAPI 3 validation
 (e.g. more Ruby on ̋̋̋̋̋ friendly validator)

Inside openapi_parser gem • OpenAPI 3 parser has 3 feature • Mapping definition data to Ruby object • Finding schema from path and HTTP method • Validating parameter using schema

Mapping OpenAPI definition to object • OpenAPI 3 definition have many object openapi: 3.0.0 info: title: Sample API version: 0.1.0 paths: "/apps": get: parameters: - name: page in: query required: true schema: type: integer responses: '200': description: example content: 'application/json': schema: type: array items: type: string

Mapping OpenAPI definition to object • OpenAPI 3 definition have many object • Definition is YAML/JSON file so 
 ruby loads it as Hash objects • openapi: 3.0.0 info: title: Sample API version: 0.1.0 paths: "/apps": get: parameters: - name: page in: query required: true schema: type: integer responses: '200': description: example content: 'application/json': schema: type: array items: type: string

Mapping OpenAPI definition to object • openapi_parser map definition data to Ruby object using DSL • I implemented few methods to these classes module OpenAPIParser::Schemas class Parameter < Base openapi_attr_values :name, :in, :description, :req openapi_attr_value :allow_empty_value, schema_key: openapi_attr_value :allow_reserved, schema_key: :a def validate_params(params, options)

Inside openapi_parser gem • OpenAPI 3 parser has 3 feature • Mapping definition data to Ruby object • Finding schema from path and HTTP method • Validating parameter using schema

%FpOJUJPO "CTUSBDU7BMJEBUPS 4DIFNB 0QFO"1* 0QFO"1* QBSBNFUFS validate SBDLNJEEMFXBSF URL + HTTP method

openapi: 3.0.0 info: title: Sample API version: 0.1.0 paths: "/apps": get: parameters: - name: page in: query required: true schema: type: integer responses: '200': description: example content: 'application/json': schema: type: array items: type: string • Schema is defined separately for each HTTP method in Path Item Object Find schema from URL Path Item Object Path string

openapi: 3.0.0 info: title: Sample API version: 0.1.0 paths: "/apps": get: parameters: - name: page in: query required: true schema: type: integer responses: '200': description: example content: 'application/json': schema: type: array items: type: string • Schema is defined separately for each HTTP method in Path Item Object Find schema from URL Path Item Object

openapi: 3.0.0 info: title: Sample API version: 0.1.0 paths: "/apps": get: parameters: - name: page in: query required: true schema: type: integer responses: '200': description: example content: 'application/json': schema: type: array items: type: string • Schema is defined separately for each HTTP method in Path Item Object • So we should find Path Item Object from requested URL Find schema from URL Path Item Object Path string

OpenAPI 3 support path parameter paths: "/pets/mine": … Requested path Definition path /pets/mine -> "/pets/mine" 


OpenAPI 3 support path parameter paths: "/pets/mine": … "/pets/{petId}": … Requested path Definition path /pets/mine -> "/pets/mine" /pets/1 -> "/pets/{petId}" /pets/2 -> "/pets/{petId}" 


OpenAPI 3 support path parameter paths: "/pets/mine": … "/pets/{petId}": … "/pets/0": … Requested path Definition path /pets/mine -> "/pets/mine" /pets/1 -> "/pets/{petId}" /pets/2 -> "/pets/{petId}" /pets/0 -> "/pets/0" 
 /pets/1/food -> "/pets/{petId}/food" /pets/0/food -> "/pets/0/food/" • If there are both with and without parameters, the one without parameters takes precedence

OpenAPI 3 support path parameter paths: "/pets/mine": … "/pets/{petId}": … "/pets/0": … Requested path Definition path /pets/mine -> "/pets/mine" /pets/1 -> "/pets/{petId}" /pets/2 -> "/pets/{petId}" /pets/0 -> "/pets/0" 
 /pets/1/food -> "/pets/{petId}/food" /pets/0/food -> "/pets/0/food/" • If there are both with and without parameters, the one without parameters takes precedence • So we should find Path Item Object according this rule

Support many API • If we are using JSON Hyper-Schema in committee, do the same thing but it was a full search • But we have many API ( One server had up to 500 APIs) • So we want to more efficient data structure

• Patricia tree is space-optimized trie tree • All nodes have string value and child node have parent’s prefix Patricia tree Patricia trie.svg: Claudio Rocchini CC-BY 2.5

Patricia tree for path string

• Divide defined path by `/` and create node Patricia tree for path string users /users/meals/me me meals

• Divide defined path by `/` and create node • Build tree Patricia tree for path string users /users/meals/me me meals

• Divide defined path by `/` and create node • Build tree Patricia tree for path string users meals me

• Divide defined path by `/` and create node • Build tree • Add new path’s nodes Patricia tree for path string users /users/meals/{id} {id} meals users meals me

• Divide defined path by `/` and create node • Build tree • Add new path’s nodes • If there is same node, skip it and use shared node Patricia tree for path string users meals me users {id} meals

• Divide defined path by `/` and create node • Build tree • Add new path’s nodes • If there is same node, skip it and use shared node Patricia tree for path string users meals me users {id} meals

• Divide defined path by `/` and create node • Build tree • Add new path’s nodes • If there is same node, skip it and use shared node Patricia tree for path string users users meals me {id} meals

• Divide defined path by `/` and create node • Build tree • Add new path’s nodes • If there is same node, skip it and use shared node Patricia tree for path string users users meals me {id} meals

• Divide defined path by `/` and create node • Build tree • Add new path’s nodes • If there is same node, skip it and use shared node Patricia tree for path string users {id} meals users meals me

• Divide defined path by `/` and create node • Build tree • Add new path’s nodes • If there is same node, skip it and use shared node • Add all paths Patricia tree for path string users {id} meals users meals me

Find defined path from patricia tree lunch {id} users meals me steps lunch public root

lunch • Divide requested URL by `/` too • Find node from root {id} users meals me steps lunch /users/meals/42/lunch public root Find defined path from patricia tree

lunch • Divide requested URL by `/` too • Find node from root Find defined path from patricia tree {id} users meals me steps lunch /users/meals/42/lunch public root

lunch • Divide requested URL by `/` too • Find node from root Find defined path from patricia tree {id} users meals me steps lunch /users/meals/42/lunch public root

lunch • Divide requested URL by `/` too • Find node from root Find defined path from patricia tree {id} users meals me steps lunch /users/meals/42/lunch public root

lunch • Divide requested URL by `/` too • Find node from root • If there isn’t matched node, 
 use parameter node (OpenAPI 3 definition) Find defined path from patricia tree {id} users meals me steps lunch /users/meals/42/lunch public root

lunch • Divide requested URL by `/` too • Find node from root • If there isn’t matched node, 
 use parameter node (OpenAPI 3 definition) Find defined path from patricia tree {id} users meals me steps lunch /users/meals/42/lunch public root

lunch • Divide requested URL by `/` too • Find node from root • If there isn’t matched node, 
 use parameter node (OpenAPI 3 definition) Find defined path from patricia tree {id} users meals me steps lunch /users/meals/42/lunch public root

lunch • Divide requested URL by `/` too • Find node from root • If there isn’t matched node, 
 use parameter node (OpenAPI 3 definition) Find defined path from patricia tree {id} users meals me steps lunch /users/meals/42/lunch public root

lunch • Divide requested URL by `/` too • Find node from root • If there isn’t matched node, 
 use parameter node (OpenAPI 3 definition) Find defined path from patricia tree {id} users meals me steps lunch /users/meals/{id}/lunch public root

lunch • Divide requested URL by `/` too • Find node from root • If there isn’t matched node, 
 use parameter node (OpenAPI 3 definition) • Get Path Item Object from matched Find defined path from patricia tree {id} users meals me steps lunch /users/meals/{id}/lunch public root

%FpOJUJPO "CTUSBDU7BMJEBUPS 4DIFNB 0QFO"1* 0QFO"1* QBSBNFUFS validate SBDLNJEEMFXBSF URL + HTTP method

• When we find a schema, we can validate the parameter • OpenAPI 3 schema is subset of the JSON Schema Specification Wright Draft 00 Parameter validation

schema: type: object nullable: false properties: nickname: type: string string, boolean, integer • There are few types of schema in JSON Schema Parameter validation schema: type: string format: email schema: type: array items: type: object required: - id properties: id: type: integer object array

• JSON Schema has `string`, `boolean`, `integer` type • These can be mapped same Ruby class so it’s easy to check Standard validation schema: type: string format: email

• JSON Schema has `object` type Object validation schema: type: object nullable: false properties: nickname: type: string

• JSON Schema has `object` type • This type has `properties` which has property name and schema Object validation schema: type: object nullable: false properties: nickname: type: string

• JSON Schema has `object` type • This type has `properties` which has property name and schema • This type can be mapped to Hash in ruby 
 and property name is represented as hash key Object validation schema: type: object nullable: false properties: nickname: type: string

• JSON Schema has `object` type • This type has `properties` which has property name and schema • This type can be mapped to Hash in ruby 
 and property name is represented as hash key Object validation schema: type: object nullable: false properties: nickname: type: string schema.properties.each do |name, child_schema| child_schema.validate(parameter[name]) end

• The `array` type in JSON Schema which can be mapped Array Array validation schema: type: array items: type: object required: ...

• The `array` type in JSON Schema which can be mapped Array • The `array` type has items schema definition Array validation schema: type: array items: type: object required: ...

• The `array` type in JSON Schema which can be mapped Array • The `array` type has items schema definition • Check all item in array is according to schema Array validation schema: type: array items: type: object required: ... array_parameter.all? do |item| items_schema.validate(item) end

openapi_parser include these methods • These feature is implemented in openapi_parser
 and it’s separated from committee

openapi_parser include these methods • These feature is implemented in openapi_parser
 and it’s separated from committee # load OpenAPI 3 definition root = OpenAPIParser.parse(YAML.load_file('open_api_3/schema.yml'))

openapi_parser include these methods • These feature is implemented in openapi_parser
 and it’s separated from committee # load OpenAPI 3 definition root = OpenAPIParser.parse(YAML.load_file('open_api_3/schema.yml')) # get schema from HTTP method (POST) and path (/validate) op = root.request_operation(:post, '/validate')

openapi_parser include these methods • These feature is implemented in openapi_parser
 and it’s separated from committee # load OpenAPI 3 definition root = OpenAPIParser.parse(YAML.load_file('open_api_3/schema.yml')) # get schema from HTTP method (POST) and path (/validate) op = root.request_operation(:post, '/validate') # validate request body ret = op.validate_request_body('application/json', params)

openapi_parser include these methods • These feature is implemented in openapi_parser
 and it’s separated from committee • So if you want to create OpenAPI 3 tool, this gem help for you # load OpenAPI 3 definition root = OpenAPIParser.parse(YAML.load_file('open_api_3/schema.yml')) # get schema from HTTP method (POST) and path (/validate) op = root.request_operation(:post, '/validate') # validate request body ret = op.validate_request_body('application/json', params)

Other OpenAPI 3 tools

Client library generation

OpenAPI Generator • Generate API client and Server stub from OpenAPI definition • Many language and framework supported (OpenAPI Generator is a folk of Swagger Codegen)

Generate Ruby gem • This generator generates API client library as gem • You can try this command (using docker) % docker run --rm -w /local -v ${PWD}:/local openapitools/openapi-generator-cli \ generate \ -i schema.yaml \ -g ruby \ -o output_dir

Generated gem • One method is created for one HTTP method definition api_instance = OpenapiClient::DefaultApi.new page = 56 result = api_instance.apps_get(page)

Generated gem • One method is created for one HTTP method definition api_instance = OpenapiClient::DefaultApi.new page = 56 result = api_instance.apps_get(page) GET /apps

Generated gem • One method is created for one HTTP method • If you want to divide by namespace, use tags in OpenAPI 3
 (OpenAPI 3 allow add tag per HTTP method) api_instance = OpenapiClient::DefaultApi.new page = 56 result = api_instance.apps_get(page) users_api = OpenapiClient::UsersApi.new limit = 10 users_api.blogs_get(limit)

Document Included • OpenAPI 3 supports markdown description for many objects • OpenAPI Generator convert request / response parameter as method argument and return value and outputs these as YARD style comments with description # get app names by array # @param page specific page setting # @param [Hash] opts the optional parameters # @return [Array] def apps_get(page, opts = {})

Generete type definition…? • I think we can generate type definition (.rbi) class DefaultApi def apps_get: (page: Integer) -> Array end

Generete type definition…? • I think we can generate type definition (.rbi) • And we can generate server side code like Hanami with .rbi class DefaultApi def apps_get: (page: Integer) -> Array end module Web module Controllers module Home class Index include Web::Action def call(params) end end

Interactive Document • Swagger UI provide 
 interactive document 
 (but no Ruby… ) • It provides human-readable
 documents and the ability to
 try out a request

Interactive Editor • Swagger Editor provide interactive editor

If there is time, I’m going to demo

Convert OpenAPI 2 to OpenAPI 3 • There is OpenAPI 2 to OpenAPI 3 converter • https://mermade.org.uk/openapi-converter

JSON Hyper-Schema to OpenAPI 3 • I created JSON Hyper-Schema to OpenAPI 3 • https://github.com/ota42y/json_hyperscheme_to_openapi3

JSON Hyper-Schema to OpenAPI 3 • I created JSON Hyper-Schema to OpenAPI 3 • https://github.com/ota42y/json_hyperscheme_to_openapi3 • But we need additional data to convert

JSON Hyper-Schema to OpenAPI 3 • I created JSON Hyper-Schema to OpenAPI 3 • https://github.com/ota42y/json_hyperscheme_to_openapi3 • But we need additional data to convert • We need path parameter as additional data "/pets/{id}": get: parameters: - name: id in: path schema: type: integer

Other tools • Mock server • Definition converter (e.g. OpenAPI 3 to protocol buffers) • Please see OpenAPI.Tools site
 (https://openapi.tools/)

Summary

Summary • We can use OpenAPI 3 to define API schema • OpenAPI 3 has various tools • Request/Respones validation • Client library generation • Interactive document • If you want to create new OpenAPI tool, it’s not so difficult

Summary • We can use OpenAPI 3 to define API schema • OpenAPI 3 has various tools • Request/Respones validation • Client library generation • Interactive document • If you want to create new OpenAPI tool, it’s not so difficult

Summary • We can use OpenAPI 3 to define API schema • OpenAPI 3 has various tools • Request/Respones validation • Client library generation • Interactive document • If you want to create new OpenAPI tool, it’s not so difficult

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Additional slides
 (I added after the end 
 There is answers for Q&A)

Do you use committee in production? • Yes • We use request validator and coerce all value in production • But we don’t use response validator in production, we use staging only • Because if we implement request/response by correct in staging, we don’t need check in production • committee has parameter coercer so we use request validation in production

Committee is slow? • It is a benchmark result • Small benchmark have 1 query parameter • Big benchmark have 2600 objects • Check enable/disable committee and request 1000 times • I don’t check response validation benchmark because we don’t use it in production • Benchmark script is here
 https://gist.github.com/ota42y/3ed68a2cb0dc7c98122bdfd1a696ab72

Small result • 1000 times request • So committee need 0.2 milliseconds in every request VTFS TZTUFN UPUBM SFBM /PU6TF 6TF

Big result • Validate 2600 objects by 6 milliseconds
 ( In many cases, it is about 100 at most, so I think that there is no problem) VTFS TZTUFN UPUBM SFBM /PU6TF 6TF