项目中一个小模块需要向服务器上传文件的功能，考虑性能问题，使用了基于流的传输，同时因要兼顾到仍有 IIS 6 上的部署的可能，传输协议只能选择“basicHttpBinding”。
基于 WCF，此功能实现起来非常简单，起初为了方便，服务端使用了控制台方式的托管宿主，没有遇到任何问题，测试传输小到几个字节，大到几百M的文件稳定通过，但在将服务端托管到 IIS 后就不行了，无论文件大小，使用“Streamed”传输模式就是出错，只有改为“Buffered”才能成功，查阅 MSDN 并未发现有此限制，所以我有了疑虑，IIS 托管的 WCF 服务中“basicHttpBinding”协议究竟能否以“流”方式进行大文件传输？如果可以，正确的做法是什么呢？肯请大家指点迷津!
测试环境：
服务器端：Windows Server 2008 R2 + IIS 7.5 + .Net 4.0
客户端： Windows 7 U (管理员权限) + .Net 4.0
为便于说明问题，精简代码如下：
服务器端：
==========
消息契约：
[MessageContract]
public class FileMessage : IDisposable
{
[MessageHeader(MustUnderstand = true)]
public string FileName { get; set; }
[MessageHeader(MustUnderstand = true)]
public long Length { get; set; }
[MessageBodyMember(Order = 1)]
public System.IO.Stream FileContents { get; set; }
public void Dispose()
{
if (FileContents != null)
{
FileContents.Close();
FileContents = null;
}
}
}
服务契约及实现：
[ServiceContract]
public interface IFileTransferService
{
[OperationContract]
void UplodaFile(FileMessage fileMessage);
}
public class FileTransferService : IFileTransferService
{
private string StoragePath{ get { return "R:\\UploadFiles\\";} }
public void UplodaFile(FileMessage fileMessage)
{
string fileFullName = this.StoragePath + fileMessage.FileName;
const int chunkSize = 2048;
byte[] buffer = new byte[chunkSize];
using (System.IO.FileStream writeStream = new System.IO.FileStream(fileFullName, System.IO.FileMode.CreateNew, System.IO.FileAccess.Write))
{
do
{
int bytesRead = fileMessage.FileContents.Read(buffer, 0, chunkSize);
if (bytesRead == 0) break;
writeStream.Write(buffer, 0, bytesRead);
} while (true);
}
}
}
web.config：
<?xml version="1.0"?>
<configuration>
<system.web>
<compilation debug="true" targetFramework="4.0"/>
<httpRuntime maxRequestLength="2147483647"/>
</system.web>
<system.serviceModel>
<bindings>
<basicHttpBinding>
<binding name="MyBasicHttpBinding" messageEncoding="Mtom" transferMode="Streamed"
maxBufferSize="2147483647" maxBufferPoolSize="2147483647" maxReceivedMessageSize="2147483647">
<readerQuotas maxDepth="2147483647" maxStringContentLength="2147483647" maxArrayLength="2147483647"
maxBytesPerRead="2147483647" maxNameTableCharCount="2147483647"/>
</binding>
</basicHttpBinding>
</bindings>
<services>
<service name="Org.AnnexService.FileTransferService">
<endpoint address="" binding="basicHttpBinding" bindingConfiguration="MyBasicHttpBinding"
contract="Org.AnnexService.IFileTransferService" />
<endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />
</service>
</services>
<behaviors>
<serviceBehaviors>
<behavior name="">
<serviceMetadata httpGetEnabled="true" />
<serviceDebug includeExceptionDetailInFaults="true" />
<dataContractSerializer maxItemsInObjectGraph="2147483647"/>
</behavior>
</serviceBehaviors>
</behaviors>
<!--<serviceHostingEnvironment aspNetCompatibilityEnabled="true" />-->
</system.serviceModel>
</configuration>
客户端：
==========
public class ServiceClient : IDisposable
{
private AnnexServiceReference.FileTransferServiceClient _client;
public ServiceClient(string serviceAddress)
{
// 客户端没有使用配置文件，因为服务地址不是固定的，所以直接用代码创建
EndpointAddress address = new EndpointAddress(serviceAddress);
BasicHttpBinding binding = new BasicHttpBinding()
{
TransferMode = System.ServiceModel.TransferMode.Streamed, // 如果这里设置为 Buffered 则一切正常
MessageEncoding = WSMessageEncoding.Mtom,
SendTimeout = TimeSpan.FromMinutes(10),
MaxBufferSize = 2147483647,
MaxBufferPoolSize = 2147483647,
MaxReceivedMessageSize = 2147483647
};
_client = new AnnexServiceReference.FileTransferServiceClient(binding, address);
}
public void UploadFile(string fileName, string storagePath)
{
try
{
using (System.IO.FileStream stream = new System.IO.FileStream(fileName, System.IO.FileMode.Open, System.IO.FileAccess.Read))
{
FileMessage fileMsg = new FileMessage()
{
FileName = System.IO.Path.GetFileName(fileName),
FileContents = stream,
Length = stream.Length
};
_client.UplodaFile(fileMsg.FileName, fileMsg.Length, fileMsg.FileContents);
}
}
catch
{
// ...
}
}
}
以上客户端代码调用 “_client.UplodaFile 方法时即会抛出如下异常：
捕捉到 System.ServiceModel.ProtocolException
Message=远程服务器返回了意外响应: (400) Bad Request。
Source=mscorlib
...
InnerException: System.Net.WebException
Message=远程服务器返回错误: (400) 错误的请求。
Source=System
StackTrace:
在 System.Net.HttpWebRequest.GetResponse()
在 System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelRequest.WaitForReply(TimeSpan timeout)
InnerException:
