Basta Fall 2019 OpenAPI

This session shows how to document your ASP.NET Core Web API using Swashbuckle Swagger, enrich the resulting document, use that to automatically generate client code for API usage and postman collections for testing.

Sample code can be found at: https://github.com/thinktecture/basta-fall-2019-openapi

Transcript

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2. Advanced ASP.NET Core Web APIs
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   Advanced ASP.NET Core Web APIs
   

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4. Advanced ASP.NET Core Web APIs
   

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5. Advanced ASP.NET Core Web APIs
   Target audience
   

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   Advanced ASP.NET Core Web APIs
   

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7. Advanced ASP.NET Core Web APIs
   

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8. Advanced ASP.NET Core Web APIs
   

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9. 10
   Advanced ASP.NET Core Web APIs
   OpenAPI Initiative
   Linux Foundation
   TL;DR;
   OpenAPI = Specification
   Swagger = Tooling
   

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10. 11
    Advanced ASP.NET Core Web APIs
    IL-Code
    Meta data
    Swagger.json
    Documentation
    Webserver with Swagger UI
    

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11. Advanced ASP.NET Core Web APIs
    

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12. 13
    • dotnet new webapi
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    • /api/weatherForecast
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    • /weatherForecast, /health, /article
    • /weatherForecast (paged), /health, /article (paged)
    • /health, /article (paged)
    Advanced ASP.NET Core Web APIs
    

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13. 14
    • Document methods / endpoints
    • Document model / schema information
    • Enrich this as much as possible
    • Exclude certain endpoints from documentation
    • Enable AuthN & AuthZ with Swagger UI
    • Combine with API Versioning
    • Customize documentation UI
    • Generate client code to consume our API
    • Test our API
    Advanced ASP.NET Core Web APIs
    

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14. Advanced ASP.NET Core Web APIs
    

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15. Advanced ASP.NET Core Web APIs
    

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    • Why we need Web API documentation
    • What is OpenAPI and Swagger
    • Swashbuckle.Swagger can automatically generate that for us
    • Swagger UI enables developers to explore our API interactively
    • The document can be used to generate client code
    • The document can be used to generate test boilerplates
    • We don’t have to do that manually and safe a lot of tedious work & time
    Advanced ASP.NET Core Web APIs
    

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17. Advanced ASP.NET Core Web APIs
    

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    • OpenAPI
    • Formerly Swagger Specification & Tools by Smartbear Software
    • Open Source as well as commercial / closed source components
    • Smartbear Software & other companies (Google, IBM & Microsoft) started the
    Open API Initiative in Nov. 2015 under the umbrella of the Linux Foundation
    • Smartbear contributed its Swagger specification to the initiative
    • The initiative released the official OpenAPI specification 3.0 in Oct. 2017
    • Smartbear Software continues to maintain their Swagger toolings
    (Swagger Editor, Swagger CodeGen, Swagger UI, etc.)
    • TL;DR;
    • OpenAPI = Specification
    • Swagger = Tooling
    Advanced ASP.NET Core Web APIs
    

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    • Documentation
    • Endpoints and data structures / schemas
    • Example data, example calls
    • Understandable
    • Explorable
    • Searchable
    • Ideally as much automated as possible
    • Ideally as multi-purpose as possible
    Advanced ASP.NET Core Web APIs
    

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    • .NET (luckily) offers a lot of metadata at runtime
    • Tooling is capable of automatically extracting a lot of
    documentation-relevant data directly from our IL code
    • Swashbuckle.Swagger for .NET (Core) projects
    • From Richard Morris (Getty Images, not Smartbear)
    • Automatically generates an OpenAPI document (swagger.json)
    using a custom Swagger Generator
    • Automatically displays a web page with our Web API documentation
    using Swagger UI from Smartbear
    Advanced ASP.NET Core Web APIs
    

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    • To be able to use a Web API, you need some sort of client
    • Web API clients usually consist of a ton of boilerplate code
    • They only differ in parameters, body format, http method and response format
    • All of that is known and documented
    • All information in available in our OpenAPI 3.0 document (swagger.json)
    • We can use that to automatically generate clients
    Advanced ASP.NET Core Web APIs
    

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    • When we write endpoints, we want to make sure they really work as expected
    • Postman helps in manual & automated testing
    • Setting up all the requests manually is tedious
    • Postman can import our swagger.json to pre-fill most of our requests
    • Postman tests use
    • Chai Assertion Library
    • tv4 (Tiny Validator for v4 JSON Schema) (marked as deprecated)
    • Ajv (Another JSON Schema Validator) (still needs manual import)
    Advanced ASP.NET Core Web APIs
    

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23. 24
    • https://github.com/thinktecture/basta-fall-2019-openapi
    • https://speakerdeck.com/phoenixhawk/basta-fall-2019-openapi
    • https://www.openapis.org/
    • https://swagger.io/
    • https://github.com/domaindrivendev/Swashbuckle.AspNetCore
    • https://github.com/microsoft/aspnet-api-versioning
    • https://github.com/swagger-api/swagger-codegen
    • https://www.getpostman.com/
    • https://www.npmjs.com/package/newman
    Advanced ASP.NET Core Web APIs
    

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24. @phoenixhawk
    sebastian.gingter@thinktecture.com
    https://github.com/thinktecture/basta-fall-2019-openapi
    https://speakerdeck.com/phoenixhawk/basta-fall-2019-openapi
    

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