GraphQL for .NET - Subscription Transport WebSockets

WARNING: not tested in heavy production use! That said if you are using this in production drop me a line to tell me how's it working for you. Maybe I can take this disclaimer off.

Transport compatible with Apollo subscription protocol.

Getting started

For just the HTTP middleware:

dotnet add package GraphQL.Server.Transports.AspNetCore

For the WebSocket subscription protocol (depends on above) middleware:

dotnet add package GraphQL.Server.Transports.WebSockets

For the UI middleware/s:

dotnet add package GraphQL.Server.Ui.GraphiQL
dotnet add package GraphQL.Server.Ui.Playground
dotnet add package GraphQL.Server.Ui.Voyager

Configure

public void ConfigureServices(IServiceCollection services)
{
    services.AddSingleton<ChatSchema>();

    // Add GraphQL services and configure options
    services.AddGraphQL(options =>
    {
        options.EnableMetrics = true;
        options.ExposeExceptions = this.Environment.IsDevelopment();
    })
    .AddWebSockets() // Add required services for web socket support
    .AddDataLoader(); // Add required services for DataLoader support
}

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    // this is required for websockets support
    app.UseWebSockets();

    // use websocket middleware for ChatSchema at path /graphql
    app.UseGraphQLWebSockets<ChatSchema>("/graphql");

    // use HTTP middleware for ChatSchema at path /graphql
    app.UseGraphQL<ChatSchema>("/graphql");

    // use graphiQL middleware at default url /graphiql
    app.UseGraphiQLServer(new GraphiQLOptions());

    // use graphql-playground middleware at default url /ui/playground
    app.UseGraphQLPlayground(new GraphQLPlaygroundOptions());
    
    // use voyager middleware at default url /ui/voyager
    app.UseGraphQLVoyager(new GraphQLVoyagerOptions());
}

UserContext and resolvers

UserContext of your resolver will be type of MessageHandlingContext. You can access the properties including your actual UserContext by using the Get<YourContextType>("UserContext") method. This will read the context from the properties of MessageHandlingContext. You can add any other properties as to the context in IOperationMessageListeners. See the sample for example of injecting ClaimsPrincipal.

Sample

Samples.Server shows a simple Chat style example of how subscription transport is used with GraphiQL integration.

Here are example queries to get started. Use three browser tabs or better yet windows to view the changes.

Subscription 1

Query:

subscription MessageAddedByUser($id:String!) {
  messageAddedByUser(id: $id) {
    from { id displayName }
    content
  }
}

Variables:

{
  "id": "1"
}

Subscription 2

subscription MessageAdded {
  messageAdded {
    from { id displayName }
    content
  }
}

Mutation

Query:

mutation AddMessage($message: MessageInputType!) {
  addMessage(message: $message) {
    from {
      id
      displayName
    }
    content
  }
}

Variables:

{
  "message": {
    "content": "Message",
    "fromId": "1"
  }
}