vb.net - WCF 服务 TcpNetBinding StreamRequest 未接收流

Question

我的第一个问题，所以要温柔=)

以下是VS2010中的所有.Net 4、VB.Net。最终目标是通过 Tcp 绑定(bind)从客户端接收(完整)流到 IIS 托管 WCF 服务。我面临的问题是该服务无法从提供的流中读取任何字节。现在有了细节......为了简洁起见，我已经删除了相当多的内容，但是如果我遗漏了一些重要的内容，请告诉我。

服务契约(Contract)如下:

<ServiceContract(Namespace:="ImageSystem")> _
Public Interface IUploadService
    <OperationContract()> _
    Function UploadFile(ByVal file As ImageUpload) As ImageUpload
End Interface

数据合约 ImageUpload 如下:

<MessageContract()> _
Public Class ImageUpload

#Region " Message Header "

    Private _ImageID As Nullable(Of Long)
    <MessageHeader()> _
    Public Property ImageID() As Nullable(Of Long)
        Get
            Return _ImageID
        End Get
        Set(ByVal value As Nullable(Of Long))
            _ImageID = value
        End Set
    End Property

    '... a few other value type properties

#End Region

#Region " Message Body"
    ' Do not add any more members to the message body or streaming support will be disabled!

    <MessageBodyMember()> _
    Public Data As System.IO.Stream

#End Region

End Class

相关的服务器配置/绑定(bind)如下(这些显然只是开发环境设置):

<system.serviceModel>
    <bindings>
      <netTcpBinding>
        <binding name="netTcpStreamBinding" transferMode="Streamed" maxBufferSize="20971520" maxReceivedMessageSize="20971520"/>
      </netTcpBinding>
    </bindings>
    <services>
      <service behaviorConfiguration="UploadServiceBehaviour"
        name="ImageSystem.SVC.UploadService">
        <endpoint address="" binding="netTcpBinding" bindingConfiguration="netTcpStreamBinding"
          contract="ImageSystem.SVC.IUploadService">
          <identity>
            <dns value="localhost" />
          </identity>
        </endpoint>
        <endpoint address="mex" binding="mexTcpBinding" contract="IMetadataExchange" />
        <host>
          <baseAddresses>
            <add baseAddress="net.tcp://localhost:809/UploadService" />
          </baseAddresses>
        </host>
      </service>
    </services>
    <behaviors>
      <serviceBehaviors>
        <behavior name="UploadServiceBehaviour">
          <serviceMetadata httpGetEnabled="false"/>
          <serviceDebug includeExceptionDetailInFaults="true"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
  </system.serviceModel>

WCF 服务是一个服务库，由 Web 应用程序托管。 Web 应用程序项目在我的本地 IIS 7.5 中运行。 IIS 已配置为启用 TCP 连接，并为应用程序池标识配置了合约实现的相关权限。 VS2010 以管理员身份运行以在 IIS 中启用调试。

为了测试契约(Contract)实现，我将 Windows 控制台应用程序设置为(测试)客户端。客户端代理类是通过在 IIS 主机 (http://localhost/ImageSystem/UploadService.svc) 中添加对服务的服务引用来生成的。服务引用被配置为生成异步方法。

相关的自动生成的客户端配置如下(注意，我尝试增加 maxBufferPoolSize、maxBufferSize 和 maxReceivedMessageSize 以匹配“20971520”的服务器配置，但无济于事):

[编辑:根据 Sixto Saez 的建议，reliableSessions 部分已注释掉，但无济于事]

<system.serviceModel>

    <bindings>
        <binding name="NetTcpBinding_IUploadService" closeTimeout="00:01:00"
          openTimeout="00:01:00" receiveTimeout="00:10:00" sendTimeout="00:01:00"
          transactionFlow="false" transferMode="Streamed" transactionProtocol="OleTransactions"
          hostNameComparisonMode="StrongWildcard" listenBacklog="10" maxBufferPoolSize="20971520"
          maxBufferSize="20971520" maxConnections="10" maxReceivedMessageSize="20971520">
          <readerQuotas maxDepth="32" maxStringContentLength="8192" maxArrayLength="16384"
            maxBytesPerRead="4096" maxNameTableCharCount="16384" />
          <!--<reliableSession ordered="true" inactivityTimeout="00:10:00"
            enabled="false" />-->
          <security mode="None">
            <transport clientCredentialType="Windows" protectionLevel="EncryptAndSign" />
            <message clientCredentialType="Windows" />
          </security>
        </binding>
      </netTcpBinding>
    </bindings>

    <client>
      <endpoint address="net.tcp://mycomputername.mydomain/ImageSystem/UploadService.svc"
        binding="netTcpBinding" bindingConfiguration="NetTcpBinding_IUploadService"
        contract="UploadService.Local.IUploadService" name="NetTcpBinding_IUploadService">
        <identity>
          <dns value="localhost" />
        </identity>
      </endpoint>
    </client>

  </system.serviceModel>

客户端使用情况如下:

Public Sub Test()
    Dim serviceClient As UploadService.Local.UploadServiceClient = New UploadService.Local.UploadServiceClient
    AddHandler serviceClient.UploadFileCompleted, AddressOf LocalTestCallback
    Dim ms As MemoryStream = New MemoryStream
    My.Resources.Penguins.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg)
    serviceClient.ClientCredentials.Windows.ClientCredential.Domain = "MYDOMAIN"
    serviceClient.ClientCredentials.Windows.ClientCredential.UserName = "User"
    serviceClient.ClientCredentials.Windows.ClientCredential.Domain = "Password123"
    serviceClient.UploadFileAsync(Nothing, ..., ms, ms) '"..." is obviously not actually here, other values omitted. "ms" is passed as UserState object in addition to fulfilling the 'Data' parameter
End Sub

如果您想知道(或很重要)，企鹅图像是 Windows 7 在示例图片目录中提供的图像。图像为 777,835 字节(应在相关请求/缓冲区最大大小范围内)。

我尝试了两种方法来读取服务器端的图像。

方法一:

Public Function UploadFile(ByVal file As ImageUpload) As ImageUpload Implements IUploadService.UploadFile

    Dim uploadBuffer(Helper.Settings.AppSettings(Of Integer)("UploadBufferSize", True) - 1) As Byte
    Dim ms As MemoryStream = New MemoryStream()
    Dim bytesRead As Integer
    Do
        bytesRead = file.Data.Read(uploadBuffer, 0, uploadBuffer.Length)
        ms.Write(uploadBuffer, 0, bytesRead)
    Loop Until bytesRead = 0

End Function

方法二:

Public Function UploadFile(ByVal file As ImageUpload) As ImageUpload Implements IUploadService.UploadFile

    Dim reader As StreamReader = New StreamReader(file.Data)
    Dim imageB64 As String = reader.ReadToEnd
    ms = New MemoryStream(Convert.FromBase64String(imageB64))

End Function

在这两种情况下，ms.Length = 0。更清楚的是，在第二种方法中，imageB64 = ""(空字符串)。

为什么我没有从流中收到任何东西？另外，作为一个偷偷摸摸的子问题，为什么生成的代理类不提供接受 ImageUpload 类型对象的重载？

先感谢您!!

Answer 1

你会遇到你提到的问题对我来说似乎很奇怪，所以我很好奇并使用你的服务契约(Contract)组合了一个实现。那一个实际上立即起作用了。我实际上不知道您的情况出了什么问题(这并不明显)，但是让我在这里发布一个可行的解决方案，希望这可以帮助您解决问题。

不幸的是，由于多年前我放弃了 VB，我只能提供 C# 代码。希望没关系。

服务器 Web.config(在 IIS 中测试，使用 net.tcp 绑定(bind)):

  <system.serviceModel>
    <bindings>
      <netTcpBinding>
        <binding transferMode="Streamed" maxReceivedMessageSize="1000000">
          <security mode="None"/>
        </binding>
      </netTcpBinding>
    </bindings>
    <services>
      <service name="ImageSystem.SVC.UploadService">
        <endpoint address="" binding="netTcpBinding" contract="ImageSystem.SVC.IUploadService">
        </endpoint>
        <endpoint address="mex" kind="mexEndpoint" binding="mexTcpBinding"/>
      </service>
    </services>
    <behaviors>
      <serviceBehaviors>
        <behavior>
          <serviceMetadata httpGetEnabled="false"/>
          <serviceDebug includeExceptionDetailInFaults="true"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
  </system.serviceModel>

客户端 app.config(控制台测试应用):

<system.serviceModel>
    <bindings>
        <netTcpBinding>
            <binding transferMode="Streamed" maxReceivedMessageSize="1000000">
                <security mode="None"/>
            </binding>
        </netTcpBinding>
    </bindings>
    <client>
        <endpoint 
            address="net.tcp://localhost/WcfService1/UploadService.svc" 
            binding="netTcpBinding" 
            contract="ImageServices.IUploadService" 
            name="NetTcpBinding_IUploadService">
        </endpoint>
    </client>
</system.serviceModel>

服务契约(Contract)及执行:

[ServiceContract(Namespace="urn:ImageSystem")]
public interface IUploadService
{
    [OperationContract]
    ImageUpload UploadFile(ImageUpload file);
}

[MessageContract]
public class ImageUpload
{
    [MessageHeader]
    public long? ImageID { get; set; }
    [MessageBodyMember]
    public Stream Data;
}

public class UploadService : IUploadService
{

    public ImageUpload UploadFile(ImageUpload file)
    {
        long length;

        using (var ms = new MemoryStream())
        {
            file.Data.CopyTo(ms);
            length = ms.Length;
        }

        return new ImageUpload { ImageID = length, Data = new MemoryStream() };
    }
}

测试应用:

private static readonly string imgPath = @"C:\Pictures\somepicture.jpg";
private static readonly EventWaitHandle waitHandle = new AutoResetEvent(false);

static void Main()
{
    long? result;

    using (var service = new ImageServices.UploadServiceClient("NetTcpBinding_IUploadService"))
    {
        var image = new ImageServices.ImageUpload();
        using (var imgStream = File.OpenRead(imgPath))
        {
            image.Data = imgStream;
            service.UploadFileCompleted += (sender, e) => 
            { 
                result = e.Result;
                if (e.Data != null) image.Data.Dispose();
                waitHandle.Set();
            };

            service.UploadFileAsync(null, imgStream);

            waitHandle.WaitOne();
        }
    }
}

首先，如您所见，配置文件可以简单得多。尤其是大 BufferSize值不是必需的。然后，关于服务契约(Contract)，我不清楚为什么 Upload操作将接收并返回 ImageUpload信息。在我的实现中，我在 ImageID 中返回上传的文件大小。当然，参数仅用于演示目的。我不知道您签订该契约(Contract)的原因是什么，以及您实际上想要返回什么。

实际上，当我知道您的代码可能失败的原因时，我正要单击“发送”。在您的测试客户端中，在您调用 serviceClient.UploadFileAsync() 之前，将此行添加到您的代码中: ms.Seek(0, SeekOrigin.Begin) .

这会将 MemoryStream 的位置重置回其开头。如果您不这样做，则 MemoryStream 将仅从其当前位置(即其末端)消耗 - 这解释了在服务端接收到的流的 Length = 0!