This is documentation on a preview feature.

绑定

创建一个绑定组件只需要几个基本步骤。

添加绑定命名空间

添加 using 语句来引用与绑定相关的命名空间。

using Dapr.PluggableComponents.Components;
using Dapr.PluggableComponents.Components.Bindings;

输入绑定: 实现IInputBinding

创建一个实现IInputBinding接口的类。

internal sealed class MyBinding : IInputBinding
{
    public Task InitAsync(MetadataRequest request, CancellationToken cancellationToken = default)
    {
        // Called to initialize the component with its configured metadata...
    }

    public async Task ReadAsync(MessageDeliveryHandler<InputBindingReadRequest, InputBindingReadResponse> deliveryHandler, CancellationToken cancellationToken = default)
    {
        // Until canceled, check the underlying store for messages and deliver them to the Dapr runtime...
    }
}

对 ReadAsync() 方法的调用是“长时间运行”的，即该方法不会在取消之前返回（例如，通过 cancellationToken）。 当消息从组件的底层存储中被读取时，它们通过deliveryHandler回调函数传递给Dapr运行时。 Delivery 允许组件在应用程序（由 Dapr 运行时提供服务）确认处理消息后，接收通知。

    public async Task ReadAsync(MessageDeliveryHandler<InputBindingReadRequest, InputBindingReadResponse> deliveryHandler, CancellationToken cancellationToken = default)
    {
        TimeSpan pollInterval = // Polling interval (e.g. from initalization metadata)...

        // Poll the underlying store until canceled...
        while (!cancellationToken.IsCancellationRequested)
        {
            var messages = // Poll underlying store for messages...

            foreach (var message in messages)
            {
                // Deliver the message to the Dapr runtime...
                await deliveryHandler(
                    new InputBindingReadResponse
                    {
                        // Set the message content...
                    },
                    // Callback invoked when application acknowledges the message...
                    async request =>
                    {
                        // Process response data or error message...
                    })
            }

            // Wait for the next poll (or cancellation)...
            await Task.Delay(pollInterval, cancellationToken);
        }
    }

输出绑定: 实现IOutputBinding

创建一个实现IOutputBinding接口的类。

internal sealed class MyBinding : IOutputBinding
{
    public Task InitAsync(MetadataRequest request, CancellationToken cancellationToken = default)
    {
        // Called to initialize the component with its configured metadata...
    }

    public Task<OutputBindingInvokeResponse> InvokeAsync(OutputBindingInvokeRequest request, CancellationToken cancellationToken = default)
    {
        // Called to invoke a specific operation...
    }

    public Task<string[]> ListOperationsAsync(CancellationToken cancellationToken = default)
    {
        // Called to list the operations that can be invoked.
    }
}

输入和输出绑定组件

一个组件可以通过实现两个接口，同时成为输入和输出绑定。

internal sealed class MyBinding : IInputBinding, IOutputBinding
{
    // IInputBinding Implementation...

    // IOutputBinding Implementation...
}

注册绑定组件

在主程序文件中（例如，Program.cs），在应用程序服务中注册绑定组件。

using Dapr.PluggableComponents;

var app = DaprPluggableComponentsApplication.Create();

app.RegisterService(
    "<socket name>",
    serviceBuilder =>
    {
        serviceBuilder.RegisterBinding<MyBinding>();
    });

app.Run();