WCF Datacontractserializer not being used. Guid is string - wcf

Question

I Have the following basicHttpBinding in my service config. When I consume this service any guids are serialised as strings. On closer inspection of the reference file i see that my classes and objects are being serialised with the system.xml.serialization not the datacontractserializer.
I have another service in the same project which shares the endpoint behaviours & configs and this service treats the guids as expected.
Any pointers greatly appreciated!
<service behaviorConfiguration="DefaultServiceBehaviour" name="ExtranetService.Repositories.Client.Submission.PSPSubmission.GoalRepository.GoalRepositoryService">
<endpoint address="basic"
behaviorConfiguration="basicBehaviorConfig"
binding="basicHttpBinding"
bindingConfiguration="basicBindingConfig"
name="basicEndpoint"
bindingName="basicBinding"
contract="ExtranetService.Repositories.Client.Submission.PSPSubmission.GoalRepository.GoalRepositoryService"
listenUriMode="Explicit" />
<host>
<baseAddresses>
<add baseAddress="https://blah.com/Repositories/client/submission/pspsubmission/GoalRepositoryService.svc"/>
</baseAddresses>
</host>
</service>
<basicHttpBinding>
<binding name="basicBindingConfig"
closeTimeout="00:05:00"
maxBufferPoolSize="2147483646" maxBufferSize="2147483646"
maxReceivedMessageSize="2147483646">
<readerQuotas maxDepth="32"
maxStringContentLength="2147483646"
maxArrayLength="2147483646" />
<security mode="Transport">
<message clientCredentialType="Certificate" />
</security>
</binding>
</basicHttpBinding>
<serviceBehaviors>
<behavior name="DefaultServiceBehaviour">
<serviceMetadata />
<serviceDebug />
<dataContractSerializer />
</behavior>
</serviceBehaviors>
<endpointBehaviors>
<behavior name="basicBehaviorConfig">
<dataContractSerializer />
</behavior>
</endpointBehaviors>
<System.CodeDom.Compiler.GeneratedCodeAttribute("System.Xml", "4.0.30319.34234"), _
System.SerializableAttribute(), _
System.Diagnostics.DebuggerStepThroughAttribute(), _
System.ComponentModel.DesignerCategoryAttribute("code"), _
System.Xml.Serialization.XmlTypeAttribute([Namespace]:="http://schemas.datacontract.org/2004/07/ExtranetService.Repositories.Client.Submission.PSPSubmission.GoalRepository")> _
Partial Public Class GetGoalByIdRequestObject
Inherits Object
Implements System.ComponentModel.INotifyPropertyChanged
Private idField As String
<System.Xml.Serialization.XmlElementAttribute(Order:=0)> _
Public Property Id() As String
Get
Return Me.idField
End Get
Set
Me.idField = value
Me.RaisePropertyChanged("Id")
End Set
End Property
Public Event PropertyChanged As System.ComponentModel.PropertyChangedEventHandler Implements System.ComponentModel.INotifyPropertyChanged.PropertyChanged
Protected Sub RaisePropertyChanged(ByVal propertyName As String)
Dim propertyChanged As System.ComponentModel.PropertyChangedEventHandler = Me.PropertyChangedEvent
If (Not (propertyChanged) Is Nothing) Then
propertyChanged(Me, New System.ComponentModel.PropertyChangedEventArgs(propertyName))
End If
End Sub
End Class
Edit
This is code from another service in the same project showing the guids as expected
<System.Diagnostics.DebuggerStepThroughAttribute(), _
System.CodeDom.Compiler.GeneratedCodeAttribute("System.Runtime.Serialization", "4.0.0.0"), _
System.Runtime.Serialization.DataContractAttribute(Name:="GetClientRecommendationListRequestObject", [Namespace]:="http://schemas.datacontract.org/2004/07/ExtranetService.Repositories.Client.Submi"& _
"ssion.PSPSubmission"), _
System.SerializableAttribute()> _
Partial Public Class GetClientRecommendationListRequestObject
Inherits Object
Implements System.Runtime.Serialization.IExtensibleDataObject, System.ComponentModel.INotifyPropertyChanged
<System.NonSerializedAttribute()> _
Private extensionDataField As System.Runtime.Serialization.ExtensionDataObject
<System.Runtime.Serialization.OptionalFieldAttribute()> _
Private CLNT_CLIENT_IDField As System.Guid
<Global.System.ComponentModel.BrowsableAttribute(false)> _
Public Property ExtensionData() As System.Runtime.Serialization.ExtensionDataObject Implements System.Runtime.Serialization.IExtensibleDataObject.ExtensionData
Get
Return Me.extensionDataField
End Get
Set
Me.extensionDataField = value
End Set
End Property
<System.Runtime.Serialization.DataMemberAttribute()> _
Public Property CLNT_CLIENT_ID() As System.Guid
Get
Return Me.CLNT_CLIENT_IDField
End Get
Set
If (Me.CLNT_CLIENT_IDField.Equals(value) <> true) Then
Me.CLNT_CLIENT_IDField = value
Me.RaisePropertyChanged("CLNT_CLIENT_ID")
End If
End Set
End Property
Public Event PropertyChanged As System.ComponentModel.PropertyChangedEventHandler Implements System.ComponentModel.INotifyPropertyChanged.PropertyChanged
Protected Sub RaisePropertyChanged(ByVal propertyName As String)
Dim propertyChanged As System.ComponentModel.PropertyChangedEventHandler = Me.PropertyChangedEvent
If (Not (propertyChanged) Is Nothing) Then
propertyChanged(Me, New System.ComponentModel.PropertyChangedEventArgs(propertyName))
End If
End Sub
End Class

Answer 1

GUIDs aren't a valid XML data type so they can't be used as a member type in the XSD schema. No matter which serializer you use, if you want to use one of the Http bindings, GUIDs will be serialized as strings and defined as strings in the schema.
Any proxy generated from this schema will create a string-typed property because that's what the XSD defines.
The duplicate question shows how to pass the GUID as a byte array, although this will hurt interoperability.
Another option is to put all data contract classes in a separate library that is shared by both client and server code. The classes in the DTO assembly will be used when generating the proxy instead of creating new ones.
Another alternative is to add another property to the proxy DTO class eg IdAsGuid() that parses the string value and returns a GUID. All proxy classes are partial so you can add new properties without modifying the generated files