相关疑难解决方法(0)

我有以下WCF合同:

[ServiceContract(Namespace = "http://abc/Services/AdminService")]
public interface IAdminService
{
    [OperationContract]
    string GetServiceVersion();

    // More methods here
}

这GetServiceVersion是一个返回一些字符串的简单方法.它用作ping来检查服务是否可访问.

现在我想异步调用它,认为它比使用.NET线程在后台调用它更有效.

所以,我为此提出了以下接口:

[ServiceContract(Namespace = "http://abc/Services/AdminService")]
public interface IMiniAdminService
{
    [OperationContract(Action = "http://abc/Services/AdminService/IAdminService/GetServiceVersion", ReplyAction = "http://abc/Services/AdminService/IAdminService/GetServiceVersionResponse")]
    Task<string> GetServiceVersionAsync();
}

这使得可以GetServiceVersion异步调用API:

var tmp = new ChannelFactory<IAdminService>("AdminServiceClientEndpoint");
var channelFactory = new ChannelFactory<IMiniAdminService>(tmp.Endpoint.Binding, tmp.Endpoint.Address);
var miniAdminService = channelFactory.CreateChannel();
return miniAdminService.GetServiceVersionAsync().ContinueWith(t =>
{
    if (t.Exception != null)
    {
        // The Admin Service seems to be unavailable
    }
    else
    {
        // The Admin Service is …

对此问题予以评论引发的这一个:

如何在async/await没有的情况下将非线性代码反向移植到.NET 4.0 Microsoft.Bcl.Async？

在链接的问题中,我们有一个WebRequest操作,如果它一直失败,我们想要重试有限次数.该Async/await代码看起来是这样的:

async Task<HttpWebResponse> GetResponseWithRetryAsync(string url, int retries)
{
    if (retries < 0)
        throw new ArgumentOutOfRangeException();

    var request = WebRequest.Create(url);
    while (true)
    {
        WebResponse task = null;
        try
        {
            task = request.GetResponseAsync();
            return (HttpWebResponse)await task;
        }
        catch (Exception ex)
        {
            if (task.IsCanceled)
                throw;

            if (--retries == 0)
                throw; // rethrow last error

            // otherwise, log the error and retry
            Debug.Print("Retrying after error: " + ex.Message);
        }
    }
} …