c# - 返回数据时出现 WCF CommunicationException

Question

在工作中，我们开发了一个可以从外部访问的 SOAP WCF API。由于对 API 的要求之一发生了变化，我想向该 API 添加一个新类，以便为某些函数调用生成正确的路径。

我们的 API 分为 3 个独立的库:

• 一个对象
• 一个用于接口(interface)
• 一个用于实现。

客户端当然可以在脚本中使用前两个，服务器拥有所有三个。

我希望添加到 API 的类如下所示:

namespace TenForce.Execution.API.Objects.Helpers
{
/// <summary>
/// <para>This interface defines the functionality available in the PathHelper for the API.</para>
/// </summary>
public interface IPathHelper
{
    string ApplicationFolder { get; }   // The HomeDataFolder for the application
    string CompanyHomeFolder { get; }   // The HomeDataFolder for the company.
    string CustomFolder { get; }        // The custom folder for professional services.
    string WikiFolder { get; }          // The WIKI folder to store pages.
    string AddinsFolder { get; }        // The AddinFolder to access the addins.
}
}

实际的类实现看起来像这样:

using System.IO;
using System.Runtime.Serialization;
using TenForce.Execution.BUL;
using TenForce.Execution.Framework;

namespace TenForce.Execution.API.Implementation.Helpers
{
/// <summary>
/// <para>This class provides a direct implementation of the IPathHelper for the API implementation
/// and manages all the paths inside the DataHomeFolder structure for the TenForce application.</para>
/// </summary>
[DataContract]
public class PathHelper : Objects.Helpers.IPathHelper
{
    #region Private Fields

    private readonly ParameterBUL _mParameterBul;
    private const Parameter.ParameterId DataHomeFolderId = Parameter.ParameterId.DataHomeFolder;
    private const Parameter.ParameterId CompanyNameId = Parameter.ParameterId.CompanyName;

    #endregion

    #region Constructor

    /// <summary>
    /// <para>Creates a new instance of the PathHelper class</para>
    /// </summary>
    public PathHelper()
    {
        _mParameterBul = new ParameterBUL();
    }

    #endregion

    #region IPathHelper Members

    /// <summary>
    /// <para>Returns the absolute path to the DataHomeFolder of the TenForce Application.</para>
    /// </summary>
    [DataMember]
    public string ApplicationFolder
    {
        get
        {
            return CreatePath(_mParameterBul.GetParameterValue(DataHomeFolderId));
        }
    }

    /// <summary>
    /// <para>Returns the absolute path to the Company DataHomeFolder.</para>
    /// </summary>
    [DataMember]
    public string CompanyHomeFolder
    {
        get
        {
            return CreatePath(Path.Combine(ApplicationFolder, _mParameterBul.GetParameterValue(CompanyNameId)));
        }
    }

    /// <summary>
    /// <para>Returns the absolute path to the Company custom folder.</para>
    /// </summary>
    [DataMember]
    public string CustomFolder
    {
        get
        {
            return CreatePath(Path.Combine(CompanyHomeFolder, @"custom"));
        }
    }

    /// <summary>
    /// <para>Returns the absolute path to the Company wiki folder.</para>
    /// </summary>
    [DataMember]
    public string WikiFolder
    {
        get
        {
            return CreatePath(Path.Combine(CompanyHomeFolder, @"wiki"));
        }
    }

    /// <summary>
    /// <para>Returns the absolute path to the Company addins folder.</para>
    /// </summary>
    [DataMember]
    public string AddinsFolder
    {
        get
        {
            return CreatePath(Path.Combine(CompanyHomeFolder, @"addins"));
        }
    }

    #endregion

    #region Private Members

    /// <summary>
    /// <para>Checks if the specified path exists, and creates the path 
    /// if the system cannot find it.</para>
    /// </summary>
    /// <param name="path">The path to verify.</param>
    private static string CreatePath(string path)
    {
        if (!Directory.Exists(path))
            Directory.CreateDirectory(path);
        return path;
    }

    #endregion
}
}

总的来说，这是非常基本的东西。 WCF 服务由我们使用可通过 .NET 获得的工厂和类动态创建。 WCF 服务可以完美地处理服务中已存在的所有代码。

所以我决定在我们的服务类中添加以下行:

    /// <summary>
    /// <para>Returns the PathHelper to construct the various paths for API Scripts.</para>
    /// </summary>
    /// <returns>An instance of the PathHelper.</returns>
    public Objects.Helpers.IPathHelper GetPathHelper()
    {
        return new Helpers.PathHelper();
    }

    #endregion

当我运行单元测试时，除了那些检查 PathHelper 功能的测试之外，所有测试都在工作，它们都以相同的错误消息/异常结束:

Error 1 TestCase 'TenForce.Execution.API.ImplementationTest/HelperTests/CheckApplicationFolderPath' failed: Execute System.ServiceModel.CommunicationException: The remote endpoint no longer recognizes this sequence. This is most likely due to an abort on the remote endpoint. The value of wsrm:Identifier is not a known Sequence identifier. The reliable session was faulted.

Server stack trace: at System.ServiceModel.Channels.ReliableRequestSessionChannel.SyncRequest.WaitForReply(TimeSpan timeout) at System.ServiceModel.Channels.RequestChannel.Request(Message message, TimeSpan timeout) at System.ServiceModel.Dispatcher.RequestChannelBinder.Request(Message message, TimeSpan timeout) at System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs, TimeSpan timeout) at System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs) at System.ServiceModel.Channels.ServiceChannelProxy.InvokeService(IMethodCallMessage methodCall, ProxyOperationRuntime operation) at System.ServiceModel.Channels.ServiceChannelProxy.Invoke(IMessage message)

Exception rethrown at [0]: at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg) at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type) at TenForce.Execution.API.Contracts.IAPI.GetPathHelper() at TenForce.Execution.API.ServiceClient.ServiceAPI.GetPathHelper() in c:\Users\arne.de.herdt\Documents\Trunk\Robinson\TenForce.Execution.API.ServiceClient\ServiceAPI.cs:line 163 at TenForce.Execution.API.ImplementationTest.HelperTests.CheckApplicationFolderPath() in C:\Users\arne.de.herdt\Documents\Trunk\Robinson\TenForce.Execution.API.ImplementationTest\HelperTests.cs:line 56 c:\Users\arne.de.herdt\Documents\Trunk\Robinson\TenForce.Execution.API.ServiceClient\ServiceAPI.cs 163

我不知道哪里出了问题，或者我错过了什么。该代码适用于已经存在的内容，但是当我添加我的作品时，它变得乱七八糟，但现有功能仍然有效。是我造成了问题。

Answer 1

这个错误对我来说似乎很奇怪，可能与您动态生成服务的方式有关。

但是，该类不可序列化，该类的属性是只读的(没有设置访问器)。为了将属性标记为 DataMember，属性需要有一个 set 访问器，即使它被标记为私有(private)。来自 MSDN:

Note Properties to which the DataMemberAttribute attribute has been applied must have both get and set fields; they cannot be get-only or set-only.

DataMember Documentation

您可能希望在该类中序列化的唯一对象是 m_ParameterBul 变量，因此将其标记为 DataMember 并从只读属性中删除所有其他 DataMember 属性即可。

您应该注意，如果 m_ParameterBul 不依赖于服务器，则无需在服务器端创建此类，因为一切都与客户端相关。在这种情况下，您应该直接在客户端上创建它。

希望对您有所帮助!

/// <summary>
/// <para>This class provides a direct implementation of the IPathHelper for the API implementation
/// and manages all the paths inside the DataHomeFolder structure for the TenForce application.</para>
/// </summary>
[DataContract]
public class PathHelper : Objects.Helpers.IPathHelper
{
    #region Private Fields
    [DataMember]
    private readonly ParameterBUL _mParameterBul;
    private const Parameter.ParameterId DataHomeFolderId = Parameter.ParameterId.DataHomeFolder;
    private const Parameter.ParameterId CompanyNameId = Parameter.ParameterId.CompanyName;

    #endregion

    #region Constructor

    /// <summary>
    /// <para>Creates a new instance of the PathHelper class</para>
    /// </summary>
    public PathHelper()
    {
        _mParameterBul = new ParameterBUL();
    }

    #endregion

    #region IPathHelper Members

    /// <summary>
    /// <para>Returns the absolute path to the DataHomeFolder of the TenForce Application.</para>
    /// </summary>   
    public string ApplicationFolder
    {
        get
        {
            return CreatePath(_mParameterBul.GetParameterValue(DataHomeFolderId));
        }
    }

    /// <summary>
    /// <para>Returns the absolute path to the Company DataHomeFolder.</para>
    /// </summary>   
    public string CompanyHomeFolder
    {
        get
        {
            return CreatePath(Path.Combine(ApplicationFolder, _mParameterBul.GetParameterValue(CompanyNameId)));
        }
    }

    /// <summary>
    /// <para>Returns the absolute path to the Company custom folder.</para>
    /// </summary>
    public string CustomFolder
    {
        get
        {
            return CreatePath(Path.Combine(CompanyHomeFolder, @"custom"));
        }
    }

    /// <summary>
    /// <para>Returns the absolute path to the Company wiki folder.</para>
    /// </summary>
    public string WikiFolder
    {
        get
        {
            return CreatePath(Path.Combine(CompanyHomeFolder, @"wiki"));
        }
    }

    /// <summary>
    /// <para>Returns the absolute path to the Company addins folder.</para>
    /// </summary>    
    public string AddinsFolder
    {
        get
        {
            return CreatePath(Path.Combine(CompanyHomeFolder, @"addins"));
        }
    }

    #endregion

    #region Private Members

    /// <summary>
    /// <para>Checks if the specified path exists, and creates the path 
    /// if the system cannot find it.</para>
    /// </summary>
    /// <param name="path">The path to verify.</param>
    private static string CreatePath(string path)
    {
        if (!Directory.Exists(path))
            Directory.CreateDirectory(path);
        return path;
    }

    #endregion
}