WCF+XmlSerializer, leading spaces on [XmlText] field are trimmed

Question

One of products uses XmlSerialier with WCF. Recently we found a deserialization issues that is related to field/property of string type that is decorated with XmlTextAttribute. The symptom is when a message is deserialized, the leading spaces of the field/property gets trimmed.

However when we did stand-alone XmlSerializer tests outside of WCF context, deserialization works without such issue.

I have complete test projects that demonstrate the problem, which I can sent at request.

        [System.Xml.Serialization.XmlTextAttribute()]
        public string Value
        {
            get
            {
                return this.valueField;
            }
            set
            {
                this.valueField = value;
            }
        }

Answer 1

I did a simple sample that it uses XmlSerialier with WCF and also apply XmlText attribute to the field/property on my computer, but I cannot reproduce your above described scenario. Could you post a simple sample that I can reproduce the above scenario?

Thanks

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Answer 2

Thanks for looking, here's the sample code:

    [System.ServiceModel.ServiceContractAttribute(Namespace = "http://webservices.csgsystems.com/slbos/ccs", Name = "CcsUpstreamManagementService")]
    public interface ICcsUpstreamManagement
    {
        [System.ServiceModel.OperationContractAttribute(Action = "http://webservices.csgsystems.com/slbos/ccs/GetCCSEquipmentOperationRequest", ReplyAction = "http://webservices.csgsystems.com/slbos/ccs/GetCCSEquipmentOperationResponse")]
        [System.ServiceModel.XmlSerializerFormatAttribute(SupportFaults = true)]
        GetCCSEquipmentOperationResponse GetCCSEquipmentOperation(GetCCSEquipmentOperationRequest request);
    }

    [System.SerializableAttribute()]
    [System.Xml.Serialization.XmlTypeAttribute(AnonymousType = true, Namespace = "http://webservices.csgsystems.com/slbos/ccs")]
    public class CONV_UNIT_ADDR
    {
        private string iDXField;
        private string valueField;
        
        [System.Xml.Serialization.XmlAttributeAttribute()]
        public string IDX
        {
            get
            {
                return this.iDXField;
            }
            set
            {
                this.iDXField = value;
            }
        }
        [System.Xml.Serialization.XmlTextAttribute()]
        public string Value
        {
            get
            {
                return this.valueField;
            }
            set
            {
                this.valueField = value;
            }
        }
    }
    
    [System.SerializableAttribute()]
    [System.Xml.Serialization.XmlTypeAttribute(AnonymousType = true, Namespace = "http://webservices.csgsystems.com/slbos/ccs")]
    public class EqptComponent_Data
    {
        private string cOMPONENT_STATUSField;
        private CONV_UNIT_ADDR cONV_UNIT_ADDRField;        
        [System.Xml.Serialization.XmlElementAttribute(Order = 1)]
        public string COMPONENT_STATUS
        {
            get
            {
                return this.cOMPONENT_STATUSField;
            }
            set
            {
                this.cOMPONENT_STATUSField = value;
            }
        }
        
        [System.Xml.Serialization.XmlElementAttribute(Order = 2)]
        public CONV_UNIT_ADDR CONV_UNIT_ADDR
        {
            get
            {
                return this.cONV_UNIT_ADDRField;
            }
            set
            {
                this.cONV_UNIT_ADDRField = value;
            }
        }
    }
    
    [System.SerializableAttribute()]
    [System.Xml.Serialization.XmlTypeAttribute(AnonymousType = true, Namespace = "http://webservices.csgsystems.com/slbos/ccs")]
    public class GetCCSEquipment_Info
    {
        private EqptComponent_Data[] eqptComponent_DataField;
        
        [System.Xml.Serialization.XmlElementAttribute("EqptComponent_Data", Order = 61)]
        public EqptComponent_Data[] EqptComponent_Data
        {
            get
            {
                return this.eqptComponent_DataField;
            }
            set
            {
                this.eqptComponent_DataField = value;
            }
        }
    }
    [System.ServiceModel.MessageContractAttribute(WrapperName = "GetCCSEquipment", WrapperNamespace = "http://webservices.csgsystems.com/slbos/ccs", IsWrapped = true)]
    [System.SerializableAttribute()]
    public class GetCCSEquipmentOperationRequest
    {
    }
    [System.ServiceModel.MessageContractAttribute(WrapperName = "GetCCSEquipment_Resp", WrapperNamespace = "http://webservices.csgsystems.com/slbos/ccs", IsWrapped = true)]
    [System.SerializableAttribute()]
    public partial class GetCCSEquipmentOperationResponse
    {
        [System.ServiceModel.MessageBodyMemberAttribute(Namespace = "http://webservices.csgsystems.com/slbos/ccs", Order = 2)]
        public GetCCSEquipment_Info GetCCSEquipment_Info;
    
        public GetCCSEquipmentOperationResponse()
        {
        }
        public GetCCSEquipmentOperationResponse(GetCCSEquipment_Info GetCCSEquipment_Info)
        {
            this.GetCCSEquipment_Info = GetCCSEquipment_Info;
        }
    }

    [ServiceBehavior(Namespace = "http://webservices.csgsystems.com/slbos", Name = "EquipmentManagementService")]
    public class CcsUpstreamManagement : ICcsUpstreamManagement
    {
        public GetCCSEquipmentOperationResponse GetCCSEquipmentOperation(GetCCSEquipmentOperationRequest request)
        {
            var equipmentComponents = new EqptComponent_Data[2]
                                         {
                                             new EqptComponent_Data
                                                 {
                                                     COMPONENT_STATUS = " First Status ",
                                                     CONV_UNIT_ADDR = new CONV_UNIT_ADDR
                                                                          {
                                                                              IDX = "2",
                                                                              Value = " 2525 N. 117th Ave.                      ",
                                                                          },
                                                 },
                                             new EqptComponent_Data
                                                 {
                                                     COMPONENT_STATUS = " Second Status ",
                                                     CONV_UNIT_ADDR = new CONV_UNIT_ADDR
                                                                          {
                                                                              IDX = "20",
                                                                              Value = "15113 Whitmore Cir.",
                                                                          },
                                                 },
                                         };
            var response = new GetCCSEquipmentOperationResponse
                               {
                                   GetCCSEquipment_Info = new GetCCSEquipment_Info
                                                              {
                                                                  EqptComponent_Data = equipmentComponents,
                                                              },
                               };
            return response;
        }
    }
}

    class Program
    {
        static void Main(string[] args)
        {
            const string url = "http://localhost:9999/CcsUpstreamManagement";
            var serviceHost = new ServiceHost(typeof(CcsUpstreamManagement), new Uri(url));
            serviceHost.AddServiceEndpoint(typeof(ICcsUpstreamManagement), new BasicHttpBinding(), url);
            serviceHost.Open();
            var factory = new ChannelFactory<ICcsUpstreamManagement>(new BasicHttpBinding());
            var channel = factory.CreateChannel(new EndpointAddress(url));
            var response = channel.GetCCSEquipmentOperation(new GetCCSEquipmentOperationRequest());
            serviceHost.Close();
        }
    }

Answer 3

I applied your above code in my project, In my solution, I added a web application and add service reference to this WCF service, and when I debug the client code and found the leading space of the field/property decorated with XmlTextAttribute gets trimmed. and the return type of this WCF method is array and does not has any parameter.

            using (ServiceReference3.CcsUpstreamManagementServiceClient client1 = new ServiceReference3.CcsUpstreamManagementServiceClient())
            {
                GetCCSEquipment_RespEqptComponent_Data[] data = client1.GetCCSEquipmentOperation();
            } 

and the following GetCCSEquipmentOperation method code in the Reference.cs.

        public GetCCSEquipment_RespEqptComponent_Data[] GetCCSEquipmentOperation() {
            WebApp.ServiceReference3.GetCCSEquipmentOperationRequest inValue = new WebApp.ServiceReference3.GetCCSEquipmentOperationRequest();
            WebApp.ServiceReference3.GetCCSEquipmentOperationResponse retVal = ((WebApp.ServiceReference3.CcsUpstreamManagementService)(this)).GetCCSEquipmentOperation(inValue);
            return retVal.GetCCSEquipment_Info;
        }

If you wrapped the EqptComponent_Data array in one class, as for your example, you have already wrapped the EqptComponent_Data[] in the GetCCSEquipment_Info class and GetCCSEquipment_Info wrapped in the GetCCSEquipmentOperationResponse, and you use GetCCSEquipmentOperationResponse as return type for your WCF method, then you will find the leading space of the field/property does not trim.

If you use Fiddler to see the request and response message (you need to change the URL of wcf http://ipv4.fiddler/UpstreamManagement/CcsUpstreamManagement.svc, since I hosted this WCF service in local IIS). then you also can found the text of CONV_UNIT_ADDR will contains a leading space.

---

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Answer 4

Peter, thank you for running the testing.

I agree the messages on the wire look good based on the Fiddler trace, that's why I believe there's  a bug on deserialization side. I don't believe array in the response message is causing the trimming. I took out the arrays and found that the spaces are still trimmed(see code below).

namespace Contract
{
    [System.ServiceModel.ServiceContractAttribute(Namespace = "http://webservices.csgsystems.com/slbos/ccs", Name = "CcsUpstreamManagementService")]
    public interface ICcsUpstreamManagement // : IServiceDiagnostics
    {
        [System.ServiceModel.OperationContractAttribute(Action = "http://webservices.csgsystems.com/slbos/ccs/GetCCSEquipmentOperationRequest", ReplyAction = "http://webservices.csgsystems.com/slbos/ccs/GetCCSEquipmentOperationResponse")]
        [System.ServiceModel.XmlSerializerFormatAttribute(SupportFaults = true)]
        GetCCSEquipmentOperationResponse GetCCSEquipmentOperation(GetCCSEquipmentOperationRequest request);
    }
}

namespace Contract
{
    [System.SerializableAttribute()]
    [System.Xml.Serialization.XmlTypeAttribute(AnonymousType = true, Namespace = "http://webservices.csgsystems.com/slbos/ccs")]
    public class CONV_UNIT_ADDR
    {
        private string iDXField;
        private string valueField;
        [System.Xml.Serialization.XmlAttributeAttribute()]
        public string IDX
        {
            get
            {
                return this.iDXField;
            }
            set
            {
                this.iDXField = value;
            }
        }
        
        [System.Xml.Serialization.XmlTextAttribute()]
        public string Value
        {
            get
            {
                return this.valueField;
            }
            set
            {
                this.valueField = value;
            }
        }
    }
    [System.ServiceModel.MessageContractAttribute(WrapperName = "GetCCSEquipment", WrapperNamespace = "http://webservices.csgsystems.com/slbos/ccs", IsWrapped = true)]
    [System.SerializableAttribute()]
    public class GetCCSEquipmentOperationRequest
    {
    }
    [System.ServiceModel.MessageContractAttribute(WrapperName = "GetCCSEquipment_Resp", WrapperNamespace = "http://webservices.csgsystems.com/slbos/ccs", IsWrapped = true)]
    [System.SerializableAttribute()]
    public class GetCCSEquipmentOperationResponse
    {
        [System.ServiceModel.MessageBodyMemberAttribute(Namespace = "http://webservices.csgsystems.com/slbos/ccs", Order = 2)]
        public CONV_UNIT_ADDR Address;
        public GetCCSEquipmentOperationResponse()
        {
        }
        public GetCCSEquipmentOperationResponse(CONV_UNIT_ADDR address)
        {
            Address = address;
        }
    }
}

namespace Service
{
    [ServiceBehavior(Namespace = "http://webservices.csgsystems.com/slbos", Name = "EquipmentManagementService")]
    public class CcsUpstreamManagement : ICcsUpstreamManagement
    {
        public GetCCSEquipmentOperationResponse GetCCSEquipmentOperation(GetCCSEquipmentOperationRequest request)
        {
            var address = new CONV_UNIT_ADDR
                                       {
                                           IDX = "2",
                                           Value = "                2525 N. 117th Ave.                      ",
                                       };
            var response = new GetCCSEquipmentOperationResponse(address);
            return response;
        }
    }
}

namespace TestDriver
{
    class Program
    {
        static void Main(string[] args)
        {
            const string url = "http://qiuw01-w764:9999/CcsUpstreamManagement";
            var serviceHost = new ServiceHost(typeof(CcsUpstreamManagement), new Uri(url));
            serviceHost.AddServiceEndpoint(typeof(ICcsUpstreamManagement), new BasicHttpBinding(), url);
            serviceHost.Open();
            var factory = new ChannelFactory<ICcsUpstreamManagement>(new BasicHttpBinding());
            var channel = factory.CreateChannel(new EndpointAddress(url));
            var response = channel.GetCCSEquipmentOperation(new GetCCSEquipmentOperationRequest());
            serviceHost.Close();
        }
    }
}

Answer 5

I apply your above sample code and also found the same scenario that the leading space will trim while deserialization. and I also did a simple sample apply XmlSerializer to the custom object and found deserialization will not trim the leading space and the value is the same as before serizlization.

---

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Answer 6

Exactly, the stand-alone XmlSerializer works just fine. The issues occurs when it is used in WCF context. It appears to me like a bug. 

Answer 7

I have some different result, when apply the XmlText attribute, the leading space are trimed in both local or remote.

static void Main(string[] args)
        {
            const string url = "http://localhost:9999/CcsUpstreamManagement";
            var serviceHost = new ServiceHost(typeof(CcsUpstreamManagement), new Uri(url));
            serviceHost.AddServiceEndpoint(typeof(ICcsUpstreamManagement), new BasicHttpBinding(), url);
            serviceHost.Open();
            var factory = new ChannelFactory<ICcsUpstreamManagement>(new BasicHttpBinding());
            var channel = factory.CreateChannel(new EndpointAddress(url));
            var response = channel.GetCCSEquipmentOperation(new GetCCSEquipmentOperationRequest());

            string content = null;
            using (MemoryStream stream = new MemoryStream())
            {
                XmlSerializer serializer = new XmlSerializer(response.GetType());
                serializer.Serialize(stream, response);
                stream.Seek(0, SeekOrigin.Begin);
                using (StreamReader reader = new StreamReader(stream, Encoding.UTF8))
                {
                    content = reader.ReadToEnd();
                }
            }
            byte[] byteArray = Encoding.UTF8.GetBytes(content);
            object obj = null;
            using (MemoryStream stream = new MemoryStream(byteArray))
            {
                XmlSerializer serializer = new XmlSerializer(typeof(GetCCSEquipmentOperationResponse));
                obj = serializer.Deserialize(stream);
            }

            serviceHost.Close();
        }

Answer 8

I am really suffering from this behavior. Has anybody out there a workaround to prevent the WCF client from killing the leading blanks?

Answer 9

It looks like this bug isn't fixed in 4.5 either.

So, if anybody uses MTOM with Security=None in your binding and you want to transfer string-properties without loosing the leading whitespaces this is my actual workaround:

public string StringProperty
{
      get
      {
        return this.StringPropertySerialized.Replace((char)0, ' ');
      }
      set
      {
        this.StringPropertySerialized = value.Replace(' ', (char)0);
      }
}

string mStringPropertySerialized = "";
[DataMember]
public string StringPropertySerialized
{
      get
      {
        return this.mStringPropertySerialized;
      }
      set
      {
        this.mStringPropertySerialized = value;
      }
}