What's wrong with xlangMessage.GetPropertyValue (BT2009)

Question

I have a specific function to get the value of a context property.
It works for ALL context properties except for 'BTS.MessageType'

if i do

xlangMessage.GetPropertyValue(typeof(BTS.MessageType))

I  get the following exception.

Exception type: System.Xml.XmlException
Message: Data at the root level is invalid. Line 1, position 1.
Source: System.Xml
StackTrace:
   at System.Xml.XmlTextReaderImpl.Throw(Exception e)
   at System.Xml.XmlTextReaderImpl.Throw(String res, String arg)
   at System.Xml.XmlTextReaderImpl.ParseRootLevelWhitespace()
   at System.Xml.XmlTextReaderImpl.ParseDocumentContent()
   at System.Xml.XmlTextReaderImpl.Read()
   at System.Xml.XmlTextReader.Read()
   at Microsoft.XLANGs.Core.Value.GetActualMessageTypeName()
   at Microsoft.XLANGs.Core.Part.GetActualMessageTypeName()
   at Microsoft.BizTalk.XLANGs.BTXEngine.BTXMessage._getBTSMessageType(XMessage msg, XmlQName propQName)
   at Microsoft.XLANGs.Core.PropertyHanlderCollection.Get(XMessage msg, XmlQName propQName, Object& res)
   at Microsoft.XLANGs.Core.XMessage.GetGenericProperty(XmlQName propQName, Object& val)
   at Microsoft.XLANGs.Core.XMessage.InternalGetContextProperty(XmlQName propQName)
   at Microsoft.XLANGs.Core.XMessage.GetPropertyValue(Type propType)
   at Microsoft.BizTalk.XLANGs.BTXEngine.BTXMessage.GetPropertyValue(Type propType)
   at Microsoft.XLANGs.Core.MessageWrapperForUserCode.GetPropertyValue(Type propType)
  

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Well0549

This happens ONLY when i am using UNTYPED messaging !, for typed messages everything works as expected

Answer 1

You have to promote the BTS.MessageType property your self in the Custom Receive Pipeline component(Disassemble). If you are using untyped messages (System.Xml.XmlDocument) this property will not be promoted by the pipeline. Also you can make sure by opening the HAT tool and extracting the message context property and you can confirm that it is not being promoted.

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Abdul Rafay http://abdulrafaysbiztalk.wordpress.com/ Please mark this answer if it helps

Answer 2

I think you are makin an error here.

I said it worked for ALL context properties, promoted and not promoted.

In the documentation it states :

XLANGMessage.GetPropertyValue Method

Returns the value of a content or context property.

[Visual Basic]

Public MustOverride Function GetPropertyValue( _
   ByVal propType As Type _
) As Object
[C#]
public abstract object GetPropertyValue(
   Type propType
);
[C++]
public: virtual Object* GetPropertyValue(
   Type* propType
) = 0;
[JScript]
public abstract function GetPropertyValue(
   propType : Type
) : Object;

Parameters

propType

Message context or message context property type. These types are defined using a property schema. 

Exceptions

Exception Type	Condition
InvalidCastException	The value of the property that appears in the data or context of the message cannot be converted into the property’s field type.
InvalidPropertyTypeException	A data property that is not defined on the message is being accessed.
AmbiguousXPathException	XPath associated with the property did not resolve to a single value.

Remarks

Returns null if the property does not exist on the message.

Message context and message context property types are defined using a property schema. For more information, see MessageContextPropertyBase and MessageDataPropertyBase.

Even the exception i get is not documented............

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Well0549

Answer 3

And after digging around in Reflector I found the following code.....

public override object GetPropertyValue(Type propType)
{
    if (this._opContext != null)
    {
        PropertyMetadata metadata = PropertyMetadata.For(propType);
        if (metadata == null)
        {
            throw new ArgumentNullException("PropertyMetadata pm = PropertyMetadata.For( propType )");
        }
        XmlQName qName = metadata.QName;
        object obj2 = this._opContext[qName];
        if (obj2 != null)
        {
            return obj2;
        }
    }
    if (!(propType.FullName == "BTS.MessageType"))
    {
        return this._msg.GetPropertyValue(propType);
    }
    string messageTypeName = MessageMetadata.For(this._msg).MessageTypeName;
    if (messageTypeName == "http://schemas.microsoft.com/BizTalk/2003/Any#Root")
    {
        string nonGenericContextProperty = (string) this._msg.InternalGetNonGenericContextProperty(propType);
        if (nonGenericContextProperty != null)
        {
            return nonGenericContextProperty;
        }
    }
    return messageTypeName;
}

 

 

So there is definitely something stinky going on with BTS.MessageType.
I found this piecece of code in :

public override object GetPropertyValue(Type propType);
Declaring Type: Microsoft.XLANGs.Core.MessageWrapperForTracking
Assembly: Microsoft.XLANGs.Engine, Version=3.0.1.0

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Well0549

Answer 4

If the message is untyped then message type property won't be there so I'm not surprised it throws an exception (althought it should be a nicer looking exception instead of an xml exception)

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Thiago Almeida - http://connectedthoughts.wordpress.com

Answer 5

Exceptions defined according to the documentation :

Exception Type	Condition
InvalidCastException	The value of the property that appears in the data or context of the message cannot be converted into the property’s field type.
InvalidPropertyTypeException	A data property that is not defined on the message is being accessed.
AmbiguousXPathException	XPath associated with the property did not resolve to a single value.

So i am really surprised to see an xml exception

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Well0549

Answer 6

Message type is stored and retrieved as xml if you look through the path in the exception stack trace.

public string GetActualMessageTypeName()
{
    if (this._xdw != null)
    {
        XmlElement documentElement = this._xdw.GetXmlDocument().DocumentElement;
        if (documentElement == null)
        {
            return null;
        }
        return PartTypeMetadata.ComposeMessageType(documentElement.NamespaceURI, documentElement.LocalName);
    }
    XmlReader xmlReader = this.GetXmlReader();
    if (xmlReader != null)
    {
        while (xmlReader.Read())
        {
            if (XmlNodeType.Element == xmlReader.NodeType)
            {
                return PartTypeMetadata.ComposeMessageType(xmlReader.NamespaceURI, xmlReader.LocalName);
            }
        }
        return null;
    }
    return null;
}

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Thiago Almeida - http://connectedthoughts.wordpress.com

Answer 7

I agree, but the docuemntation states only three exceptions.....
And i get an undocumented one.....
( that was my point )

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Well0549

Answer 8

I was just saying you shouldn't be surprised to see an xml exception since it's stored as XML. But also agree with you that the xml exception should have been handled more graceously and thrown a proper exception.

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Thiago Almeida - http://connectedthoughts.wordpress.com