WCF无法解析SOAP信封，仅获取默认值问题排查

问题背景 #

我创建了一个用于回调服务的WCF服务器，预期远程机器会按照指定信封格式调用该服务以完成任务。但服务无法正确解析SOAP信封：Delivery方法的起始断点能触发，但参数均为默认值（例如GUID全为0，items数组为空）。

待解析的SOAP信封 #

<s:Envelope
  xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
  <s:Header>
    <ActivityId CorrelationId="e801930b-bf31-4509-b98a-96d106b5513f"
      xmlns="http://schemas.microsoft.com/2004/09/ServiceModel/Diagnostics">00000000-0000-0000-0000-000000000000
        
    </ActivityId>
  </s:Header>
  <s:Body>
    <Delivery
      xmlns="http://hsbdserver/calcula/v1">
      <info
        xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
        <Guid>5869a5c5-243e-11ed-4a4c-b14560d0fb70</Guid>
        <Name>Name</Name>
      </info>
      <items
        xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
        <Item>
          <Guid>43207e16-906e-d94a-86f6-753ae31092ef</Guid>
          <Name>c37fb62f-2729-244b-a082-4be80d952c1e.txt</Name>
          <ExtDocId i:nil="true"/>
          <NewUserId i:nil="true"
            xmlns:a="http://schemas.microsoft.com/2003/10/Serialization/Arrays"/>
          <NewUserName i:nil="true"
            xmlns:a="http://schemas.microsoft.com/2003/10/Serialization/Arrays"/>
            <NewWorkflow>Done</NewWorkflow>
            <PreviousUserId
              xmlns:a="http://schemas.microsoft.com/2003/10/Serialization/Arrays">
              <a:guid>0e67f61a-d1c6-c448-a11c-82ee8428028a</a:guid>
            </PreviousUserId>
            <PreviousUserName
              xmlns:a="http://schemas.microsoft.com/2003/10/Serialization/Arrays">
              <a:string>Nick</a:string>
            </PreviousUserName>
            <PreviousWorkflow>Progress</PreviousWorkflow>
            <Code>xkde</Code>
          </Item>
        </items>
      </Delivery>
    </s:Body>
  </s:Envelope>

现有C#实现 #

[ServiceContract(Namespace = "http://hsbdserver/calcula/v1")]
public interface IServerCallback
{
  [OperationContract]
  void Delivery(Info info, Item[] items);
}

[DataContract]
public class Info
{
  Guid guid;
  string name;

  [DataMember]
  public Guid Guid
  {
    get { return guid; }
    set { guid = value; }
  }

  [DataMember]
  public string Name
  {
    get { return name; }
    set { name = value; }
  }
}

[DataContract]
public class Item
{
  Guid guid;
  string name;
  string extDocId;
  Guid[] newAssignedUserId;
  string[] newUserId;
  Workflow newWorkflow;
  Guid[] previousUserId;
  string[] previousUserName;
  Workflow previousWorkflow;
  string code;

  [DataMember]
  public Guid Guid
  {
    get { return guid; }
    set { guid = value; }
  }

  [DataMember]
  public string Name
  {
    get { return name; }
    set { name = value; }
  }

  [DataMember]
  public string ExtDocId
  {
    get { return extDocId; }
    set { extDocId = value; }
  }

  [DataMember]
  public Guid[] NewAssignedUserId
  {
    get { return newAssignedUserId; }
    set { newAssignedUserId = value; }
  }

  [DataMember]
  public string[] NewUserId
  {
    get { return newUserId; }
    set { newUserId = value; }
  }

  [DataMember]
  public Workflow NewWorkflow
  {
    get { return newWorkflow; }
    set { newWorkflow = value; }
  }

  [DataMember]
  public Guid[] PreviousUserId
  {
    get { return previousUserId; }
    set { previousUserId = value; }
  }

  [DataMember]
  public string[] PreviousUserName
  {
    get { return previousUserName; }
    set { previousUserName = value; }
  }

  [DataMember]
  public Workflow PreviousWorkflow
  {
    get { return previousWorkflow; }
    set { previousWorkflow = value; }
  }

  [DataMember]
  public string Code
  {
    get { return code; }
    set { code = value; }
  }
}

public enum Workflow
{
  Progress,
  Done
}

问题原因与修复方案 #

1. 数据契约命名空间不匹配 #

SOAP中的Delivery、info、Item等元素都属于http://hsbdserver/calcula/v1命名空间，但你的Info、Item类未指定对应命名空间，WCF无法将XML元素与类正确映射。

修复： 给Info和Item类的DataContract属性添加命名空间：

[DataContract(Namespace = "http://hsbdserver/calcula/v1")]
public class Info { ... }

[DataContract(Namespace = "http://hsbdserver/calcula/v1")]
public class Item { ... }

2. 方法参数与XML元素大小写/名称不匹配 #

SOAP中的参数是<info>（小写开头）、<items>（小写开头），WCF默认对参数名称大小写敏感，需明确映射XML元素名。

修复： 给Delivery方法参数添加MessageParameter属性指定映射名称：

[OperationContract]
void Delivery([MessageParameter(Name = "info")] Info info, [MessageParameter(Name = "items")] Item[] items);

3. Item类属性与XML元素名称不匹配 #

• SOAP中是<NewUserId>，你的属性是NewAssignedUserId，名称完全不符；
• SOAP中是<NewUserName>，你的属性是NewUserId，名称错误。

修复： 修改属性名称，或用DataMember的Name属性指定映射：

[DataMember(Name = "NewUserId")]
public Guid[] NewUserId { get; set; }

[DataMember(Name = "NewUserName")]
public string[] NewUserName { get; set; }

4. 枚举类未标记数据契约 #

SOAP中的<NewWorkflow>、<PreviousWorkflow>是字符串值，枚举类需标记DataContract以确保WCF正确解析。

修复： 给Workflow枚举添加DataContract和EnumMember属性：

[DataContract(Namespace = "http://hsbdserver/calcula/v1")]
public enum Workflow
{
  [EnumMember]
  Progress,
  [EnumMember]
  Done
}

最终修改后的核心代码 #

[ServiceContract(Namespace = "http://hsbdserver/calcula/v1")]
public interface IServerCallback
{
  [OperationContract]
  void Delivery([MessageParameter(Name = "info")] Info info, [MessageParameter(Name = "items")] Item[] items);
}

[DataContract(Namespace = "http://hsbdserver/calcula/v1")]
public class Info
{
  [DataMember]
  public Guid Guid { get; set; }
  [DataMember]
  public string Name { get; set; }
}

[DataContract(Namespace = "http://hsbdserver/calcula/v1")]
public class Item
{
  [DataMember]
  public Guid Guid { get; set; }
  [DataMember]
  public string Name { get; set; }
  [DataMember]
  public string ExtDocId { get; set; }
  [DataMember(Name = "NewUserId")]
  public Guid[] NewUserId { get; set; }
  [DataMember(Name = "NewUserName")]
  public string[] NewUserName { get; set; }
  [DataMember]
  public Workflow NewWorkflow { get; set; }
  [DataMember]
  public Guid[] PreviousUserId { get; set; }
  [DataMember]
  public string[] PreviousUserName { get; set; }
  [DataMember]
  public Workflow PreviousWorkflow { get; set; }
  [DataMember]
  public string Code { get; set; }
}

[DataContract(Namespace = "http://hsbdserver/calcula/v1")]
public enum Workflow
{
  [EnumMember]
  Progress,
  [EnumMember]
  Done
}

内容的提问来源于stack exchange，提问作者Isham Mohamed