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GraphQL with .NET Core
- 2. @MarkLechtermann What‘s wrong with REST?
- 3. @MarkLechtermann Architectural Styles and the Design of Network-based Software Architectures DISSERTATION DOCTOR OF PHILOSOPHY Roy Thomas Fielding 2000
- 8. @MarkLechtermann The internet in the year 2000
- 15. @MarkLechtermann Web 2019 I want JSON! I want HTML! I want JS! I want IOT data! I want a stream!
- 16. @MarkLechtermann Web 2019 I want JSON! I want HTML! I want JS! I want IOT data! I want a stream!
- 17. @MarkLechtermann Again: What‘s wrong with REST?
- 19. @MarkLechtermann Over-fetching GET http://example.com/api/v1/whiskys/1 { "name":"ArdbegTEN", "strength":46, "distillery":"Ardbeg", "size":"700 ml", "prize":45.00, … } But all I wanted was the prize!
- 20. @MarkLechtermann Under-fetching GET http://example.com/api/v1/whiskys "items":[ "http://example.com/api/v1/whiskys/1" "http://example.com/api/v1/whiskys/2" … ] GET http://example.com/api/v1/whiskys/1 GET http://example.com/api/v1/whiskys/2 ...
- 21. @MarkLechtermann Under-fetching GET http://example.com/api/v1/whiskys "items":[ "http://example.com/api/v1/whiskys/1" "http://example.com/api/v1/whiskys/2" … ] GET http://example.com/api/v1/whiskys/1 GET http://example.com/api/v1/whiskys/2 ... But all I wanted was a list of names!
- 22. @MarkLechtermann REST Properties ● Performance ● Reliability ● Simplicity ● Scalability ● Modifiability ● Portability
- 23. @MarkLechtermann REST Benefits ● Performance (with HTTP2) ● Well-established ● Media types ● Decoupling server and client
- 24. @MarkLechtermann The problem with REST ● Difficult to implement correctly ● Tooling for clients ● API description format – Swagger, RAML, API Blueprint, Odata...? ● It's not a Standard
- 25. @MarkLechtermann We call it a "REST"-API
- 26. @MarkLechtermann Richardson Maturity Model HATEOAS HTTP Verbs Resources Swamp of POX
- 28. @MarkLechtermann But what about OpenAPI/Swagger?
- 30. @MarkLechtermann Nobody stops us from using the endpoint directly!
- 31. @MarkLechtermann REST without Hypermedia is CRUD over HTTP!
- 32. @MarkLechtermann
- 33. @MarkLechtermann
- 34. @MarkLechtermann react.js conf 2015 not only for React!
- 36. @MarkLechtermann Spec ● https://graphql.github.io/graphql-spec/ ● Latest stable version – June 2018
- 37. @MarkLechtermann Let's build an App
- 40. @MarkLechtermann Whisky +Name : string +Age : uint +Strength: float + Size: uint Distillery +Name : string +Owner : string +SpiritStills : uint +WashStills : uint +Capacity : uint64 +Region : string 0..1 * WhiskyApp
- 41. @MarkLechtermann
- 42. @MarkLechtermann
- 50. @MarkLechtermann
- 51. @MarkLechtermann A query language for your API
- 52. @MarkLechtermann GraphQL Feature ● Query ● Mutation ● Subscription
- 54. @MarkLechtermann Schema schema { query: WhiskyRootQuery mutation: WhiskyRootMutation }
- 55. @MarkLechtermann Scalar Types type Whisky { MyField1 : ID // unique identifier String MyField2 : Int MyField3 : Float // signed double-precision MyField4 : String // UTF-8 MyField5 : Boolean }
- 56. @MarkLechtermann Type type WhiskyRootQuery { whiskys: [Whisky] whisky(id: ID): Whisky }
- 57. @MarkLechtermann Lists and Non-Null type WhiskyRootQuery { whiskys: [whisky!]! whisky(id: ID!): whisky }
- 58. @MarkLechtermann Interfaces interface Drink { id: ID! name: String! }
- 59. @MarkLechtermann Implements Interface type Whisky implements Drink { region: WhiskyRegion }
- 60. @MarkLechtermann Enumerations enum WhiskyRegion { LOWLANDS HIGHLANDS SPEYSIDE CAMPELTOWN ISLAY THE ISLANDS }
- 62. @MarkLechtermann Query query { whiskys { id name } } "data" { "whiskys" : [ { "id" : "1", "name": "Ardbeg Ten" } ] }
- 63. @MarkLechtermann Query { whiskys { id name } } "data" { "whiskys" : [ { "id" : "1", "name": "Ardbeg Ten" } ] }
- 64. @MarkLechtermann Query with Arguments { whisky(id: "1") { id name } } "data" { "whisky" : { "id" : "1", "name": "Ardbeg Ten" } }
- 65. @MarkLechtermann Alias { first : whisky(id:"1") { name } second : whisky(id:"2") { name } } { "data": { "first": { "name": "Ardbeg TEN" }, "second": { "name": "Ardbeg Uigeadail" } } }
- 66. @MarkLechtermann Fragments { first : whisky(id:"1") { ...myFields } second : whisky(id:"2") { ...myFields } } fragment myFields on WhiskyType{ name id strength } { "data": { "first": { "name": "Ardbeg TEN", "id": "1", "strength": 46 }, … } }
- 67. @MarkLechtermann Variables query Compare($a: ID!, $b: ID!){ first : whisky(id:$a) { ...myFields } second : whisky(id:$b) { ...myFields } } fragment myFields on WhiskyType { name id strength } { "data": { "first": { "name": "Ardbeg TEN", "id": "1", "strength": 46 }, … } }
- 68. @MarkLechtermann Directives - include query GetWhisky($id: ID!, $dInfo: Boolean = false) { whisky(id:$id) { id name destillery @include(if: $dInfo) { name } } } {"id": "1", "dInfo": true} { "data": { "whisky" : { "id" : "12, "name" : "Ardbeg TEN" "destillery" : { "name" : "Ardbeg" } } } }
- 69. @MarkLechtermann Directives - skip query GetWhisky($id: ID!, $dInfo: Boolean = false) { whisky(id:$id) { id name destillery @skip(if: $dInfo) { name } } } {"id": "1", "dInfo": true} { "data": { "whisky": { "id": 1, "name": "Ardbeg TEN", } } }
- 71. @MarkLechtermann mutation mutation { deleteWhisky(id: "1") } { "data" : { "deleteWhisky" : true } }
- 72. @MarkLechtermann mutation mutation { addWhisky( destilleryId : "1" whisky : { name : "MyWhisky" age : 0 size : 70 strength : 40 } ) { id name } } { "data" : { "addWhisky" : { "id" : "123", "name" : "MyWhisky", } } }
- 73. @MarkLechtermann Let‘s start with .NET Core
- 74. @MarkLechtermann .NET Libraries ● graphql-dotnet/graphql-dotnet (~3000) ● ckimes89/graphql-net ( ~700) ● ChilliCream/hotchocolate ( ~300)
- 77. @MarkLechtermann $ dotnet new webapi $ dotnet add package GraphQL $ dotnet add package GraphQL.Server.Transports.AspNetCore # Optional: $ dotnet add package GraphQL.Server.Ui.GraphiQL $ dotnet add package GraphQL.Server.Ui.Playground $ dotnet add package GraphQL.Server.Ui.Voyager Create a new project
- 78. @MarkLechtermann public class WhiskyType : ObjectGraphType<WhiskyEntity> { public WhiskyType() { Field<NonNullGraphType<IdGraphType>>().Name("id"); Field(entity => entity.Name).Description(""); } } Add Types
- 79. @MarkLechtermann public class WhiskyQuery : ObjectGraphType { public WhiskyQuery() { this.Field<WhiskyType>( name: "whisky", resolve: context => new WhiskyType()); } Add Query
- 80. @MarkLechtermann public class WhiskyAppSchema : Schema { public WhiskyAppSchema(IDependencyResolver resolver) : base(resolver) { Query = resolver.Resolve<WhiskyQuery>(); Mutation = ... } } Add a Schema
- 81. @MarkLechtermann public void ConfigureServices(IServiceCollection services) { services.AddScoped<WhiskyType>(); services.AddScoped<WhiskyQuery>(); services.AddScoped<ISchema, WhiskyAppSchema>(); services.AddScoped<IDependencyResolver>( s => new FuncDependencyResolver(s.GetRequiredService)); services.AddSingleton<IDocumentExecuter, DocumentExecuter>(); services.AddSingleton<IDocumentWriter, DocumentWriter>(); services.AddGraphQL(); } Add Services
- 82. @MarkLechtermann app.UseGraphQL<ISchema>("/graphql"); // Optional: app.UseGraphiQLServer(new GraphiQLOptions()); app.UseGraphQLPlayground(new GraphQLPlaygroundOptions()); app.UseGraphQLVoyager(new GraphQLVoyagerOptions()); Add Middleware
- 83. @MarkLechtermann N + 1 Problem and Batching!
- 86. @MarkLechtermann public WhiskyType( IDataLoaderContextAccessor accessor) { … Field<DestilleryType, DestilleryEntity>() .Name("destillery") .ResolveAsync(context => { var loader = accessor.Context.GetOrAddBatchLoader<string, DestilleryEntity>("whisky_destillery", ... ); return loader.LoadAsync(context.Source.Id); }); } DataLoader
- 87. @MarkLechtermann Pro GraphQL ● Easy to learn ● Vendor agnostic ● Pragmatic ● Contract ● Introspection
- 88. @MarkLechtermann Contra GraphQL ● Content negotiation ● Media type support ● Caching ● "Only" POST – What about GET, DELETE, PUT?
- 89. @MarkLechtermann API Gateway REST JSON over HTTP OData gRPC
- 90. @MarkLechtermann What are the alternatives?
- 93. @MarkLechtermann OData @ Build 2019 ● Microsoft PowerApps – https://docs.microsoft.com/en-us/powerapps/developer/common-data-service/webapi/overview ● Build2019: Microsoft Graph powers the Microsoft 365 platform – https://developer.microsoft.com/en-us/office/blogs/build-2019-microsoft-graph-powers-the-microsoft-365-platform/ ● Graph Explorer – https://developer.microsoft.com/en-us/graph/graph-explorer ● Expamples: – https://graph.microsoft.com/v1.0/me/?$select=givenName – https://graph.microsoft.com/v1.0/me?$select= displayName, skills
- 94. @MarkLechtermann Contra OData ● Strong coupling with the database ● Query only with GET – Long and complex URL
- 95. @MarkLechtermann docker run -p 5000:5000 marklechtermann/whiskygraphqlapp Docker Image