Microsoft.Azure.WebPubSub.AspNetCore

Azure Web PubSub service middleware client library for .NET

Azure Web PubSub Service is a service that enables you to build real-time messaging web applications using WebSockets and the publish-subscribe pattern. Any platform supporting WebSocket APIs can connect to the service easily, e.g. web pages, mobile applications, edge devices, etc. The service manages the WebSocket connections for you and allows up to 100K concurrent connections. It provides powerful APIs for you to manage these clients and deliver real-time messages.

Any scenario that requires real-time publish-subscribe messaging between server and clients or among clients, can use Azure Web PubSub service. Traditional real-time features that often require polling from server or submitting HTTP requests, can also use Azure Web PubSub service.

This library can be used to do the following actions. Details about the terms used here are described in Key concepts section.

• Parse upstream request under CloudNative CloudEvents
• Add validation options for upstream request
• API to add user defined functionality to handle different upstream events

Source code | Package | API reference documentation | Product documentation | Samples |

Getting started

Install the package

Install the client library from NuGet:

dotnet add package Microsoft.Azure.WebPubSub.AspNetCore --prerelease

Prerequisites

• An Azure subscription.
• An existing Azure Web PubSub service instance.

Authenticate the client

In order to interact with the service, you'll need to create an instance of the WebPubSubServiceClient class. To make this possible, you'll need the connection string or a key, which you can access in the Azure portal.

Create a WebPubSubServiceClient

var serviceClient = new WebPubSubServiceClient(new Uri(endpoint), "some_hub", new AzureKeyCredential(key));

Key concepts

For information about general Web PubSub concepts Concepts in Azure Web PubSub

WebPubSubHub

WebPubSubHub is an abstract class to let users implement the subscribed Web PubSub service events. After user register the event handler in service side, these events will be forwarded from service to server. And WebPubSubHub provides 4 methods mapping to the service events to enable users deal with these events, for example, client management, validations or working with Azure.Messaging.WebPubSub to broadcast the messages. See samples below for details.

NOTE

Among the 4 methods, OnConnectAsync() and OnMessageReceivedAsync() are blocking events that service will respect server returns. Besides the mapped correct response, server can throw exceptions whenever the request is against the server side logic. And UnauthorizedAccessException will be converted to 401Unauthorized and rest will be converted to 500InternalServerError along with exception message to return service. Then service will drop current client connection.

Examples

Add Web PubSub service with options

public void ConfigureServices(IServiceCollection services)
{
    services.AddWebPubSub(o =>
    {
        o.ValidationOptions.Add("<connection-string>");
    });
}

Map WebPubSubHub to endpoint routing.

The path should match the value configured in the Azure Web PubSub service EventHandler. For example, if placeholder is using like /api/{event}, then the path set in code should be /api/{event} as well.

public void Configure(IApplicationBuilder app)
{
    app.UseEndpoints(endpoint =>
    {
        endpoint.MapWebPubSubHub<SampleHub>("/eventhander");
    });
}

Handle Upstream event

public override ValueTask<ConnectEventResponse> OnConnectAsync(ConnectEventRequest request, CancellationToken cancellationToken)
{
    var response = new ConnectEventResponse
    {
        UserId = request.ConnectionContext.UserId
    };
    return new ValueTask<ConnectEventResponse>(response);
}

Troubleshooting

Setting up console logging

You can also easily enable console logging if you want to dig deeper into the requests you're making against the service.

Next steps

Please take a look at the [samples][samples_ref] directory for detailed examples on how to use this library.

Contributing

This project welcomes contributions and suggestions. Most contributions require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us the rights to use your contribution. For details, visit https://cla.microsoft.com.

When you submit a pull request, a CLA-bot will automatically determine whether you need to provide a CLA and decorate the PR appropriately (e.g., label, comment). Simply follow the instructions provided by the bot. You will only need to do this once across all repos using our CLA.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact [email protected] with any additional questions or comments.