c# - 使用自定义 header : This OperationContextScope is being disposed out of order 的异步 WCF 客户端调用

Question

我正在从 WinRT 应用调用 WCF 服务。该服务要求为身份验证设置一些 header 。问题是，如果我同时对该服务进行多次调用，我会得到以下异常:

此 OperationContextScope 被乱序处置。

当前代码如下所示:

public async Task<Result> CallServerAsync()
{
    var address = new EndpointAddress(url);
    var client = new AdminServiceClient(endpointConfig, address);

    using (new OperationContextScope(client.InnerChannel))
    {
        OperationContext.Current.OutgoingMessageProperties[HttpRequestMessageProperty.Name] = GetHeader();

        var request = new MyRequest(...); 
        {
            context = context,
        };

        var result = await client.GetDataFromServerAsync(request);
    }
}

我找到了以下评论 from the docs :

Do not use the asynchronous “await” pattern within a OperationContextScope block. When the continuation occurs, it may run on a different thread and OperationContextScope is thread specific. If you need to call “await” for an async call, use it outside of the OperationContextScope block.

看来我显然错误地调用了该服务。但正确的方法是什么？

Answer 1

根据 Microsoft documentation :

Do not use the asynchronous "await" pattern within a OperationContextScope block. When the continuation occurs, it may run on a different thread and OperationContextScope is thread specific. If you need to call "await" for an async call, use it outside of the OperationContextScope block.

所以最简单的正确解决方案是:

Task<ResponseType> task;
using (new OperationContextScope(client.InnerChannel))
{
    OperationContext.Current.OutgoingMessageProperties[HttpRequestMessageProperty.Name] = GetHeader();

    var request = new MyRequest(...); 
    {
        context = context,
    };

    task = client.GetDataFromServerAsync(request);
}

var result = await task;