Custom Disassembler

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Date: Tue, 4 Jan 2005 07:30:51 +1030

Hi. I'm trying unsuccessfully to implement a custom disassembler. The
inbound message, and desired message formats are as follows:

Inbound:
FieldName:Value
FieldName:Value
FieldName:Value

Required Disassembled Format:
<message>
  <fieldName>Value</fieldName>
  <fieldName>Value</fieldName>
  <fieldName>Value</fieldName>
</message>

When the inbound message is placed in the receive location it is picked up
and then can be seen in HAT as suspended. When saving the message from HAT
it can be seen in the original format, so I suspect the disassembler is
either not functioning correctly, or not fired at all. Looking in the event
viewer the following error can be seen:

"The data at the root level is invalid. Line 1, position 1."

I have read that this may be due to seekable streams and have tried various
suggestions that I've read on various posts but with no success, so I've
decided to post the original code to my disassembler below. Any help is
greatly appreciated. The code I am using in my disassembler is as follows
(apologies for the large post, please cut code below from replies to reduce
bloated messages in thread):

<code>

Imports Microsoft.Biztalk.Component.Interop
Imports Microsoft.Biztalk.Message.Interop
Imports System
Imports System.Collections
Imports System.Diagnostics
Imports System.IO
Imports System.Text
Imports System.Xml

<ComponentCategory(CategoryTypes.CATID_PipelineComponent), _
ComponentCategory(CategoryTypes.CATID_DisassemblingParser), _
System.Runtime.InteropServices.Guid("B60F6801-C07E-45f7-A9C7-E8797671D710")>
_
Public Class MyDisassembler
  Implements IBaseComponent, _
              IComponent, _
              IComponentUI, _
              IPersistPropertyBag, _
              IDisassemblerComponent

  ' Constant pipeline component values:
  Private Const ComponentName As String = "MyDisassembler"
  Private Const ComponentDescription As String = "My Custom Receive Pipeline
Disassembler."
  Private Const ComponentVersion As String = "1.0.0.0"

  ' Private Constant Declarations
  Private Const NameValueSeparator As String = ":"
  Private Const RootMessageElementName As String = "message"

  ' Private Variable Declarations
  Private _nameValues As Hashtable
  Private _originalMsgContext As IBaseMessageContext ' Original's message
context.

  Private _outputFile As FileStream

  Public Sub New()

    ' Create a trace listener for the event log.
    Dim myTraceListener As New EventLogTraceListener("MyDisassemblerTrace")

    ' Add the event log trace listener to the collection.
    Trace.Listeners.Add(myTraceListener)

  End Sub

#Region "Microsoft.Biztalk.Component.Interop.IBaseComponent Implementation"

  Public ReadOnly Property Description() As String _
  Implements Microsoft.Biztalk.Component.Interop.IBaseComponent.Description
    Get
      Return ComponentDescription
    End Get
  End Property

  Public ReadOnly Property Name() As String _
  Implements Microsoft.Biztalk.Component.Interop.IBaseComponent.Name
    Get
      Return ComponentName
    End Get
  End Property

  Public ReadOnly Property Version() As String _
  Implements Microsoft.Biztalk.Component.Interop.IBaseComponent.Version
    Get
      Return ComponentVersion
    End Get
  End Property

#End Region

#Region "Microsoft.Biztalk.Component.Interop.IComponent Implementation"

  Public Function Execute( _
              ByVal pContext As
Microsoft.Biztalk.Component.Interop.IPipelineContext, _
              ByVal pInMsg As
Microsoft.Biztalk.Message.Interop.IBaseMessage) As
Microsoft.Biztalk.Message.Interop.IBaseMessage _
  Implements Microsoft.Biztalk.Component.Interop.IComponent.Execute
    '
  End Function

#End Region

#Region "Microsoft.Biztalk.Component.Interop.IComponentUI Implementation"

  Public ReadOnly Property Icon() As System.IntPtr _
  Implements Microsoft.Biztalk.Component.Interop.IComponentUI.Icon
    Get
      ' No icon associated with this pipeline component:
      Return IntPtr.Zero
    End Get
  End Property

  Public Function Validate(ByVal projectSystem As Object) As
System.Collections.IEnumerator _
  Implements Microsoft.Biztalk.Component.Interop.IComponentUI.Validate

    Dim validationResult As System.Collections.Specialized.StringCollection
= New System.Collections.Specialized.StringCollection
    Return DirectCast(validationResult.GetEnumerator(), IEnumerator)

  End Function

#End Region

#Region "Microsoft.Biztalk.Component.Interop.IPersistPropertyBag
Implementation"

  Public Sub GetClassID(ByRef classID As System.Guid) _
  Implements
Microsoft.Biztalk.Component.Interop.IPersistPropertyBag.GetClassID
    classID = Me.GetType().GUID
  End Sub

  Public Sub InitNew() _
  Implements Microsoft.Biztalk.Component.Interop.IPersistPropertyBag.InitNew
    '
  End Sub

  Public Sub Load(ByVal propertyBag As
Microsoft.Biztalk.Component.Interop.IPropertyBag, ByVal errorLog As Integer)
_
  Implements Microsoft.Biztalk.Component.Interop.IPersistPropertyBag.Load
    '
  End Sub

  Public Sub Save(ByVal propertyBag As
Microsoft.Biztalk.Component.Interop.IPropertyBag, ByVal clearDirty As
Boolean, ByVal saveAllProperties As Boolean) _
  Implements Microsoft.Biztalk.Component.Interop.IPersistPropertyBag.Save
    '
  End Sub

#End Region

#Region "Microsoft.Biztalk.Component.Interop.IDisassemblerComponent
Implementation"

  Public Sub Disassemble(ByVal pContext As
Microsoft.Biztalk.Component.Interop.IPipelineContext, ByVal pInMsg As
Microsoft.Biztalk.Message.Interop.IBaseMessage) _
  Implements
Microsoft.Biztalk.Component.Interop.IDisassemblerComponent.Disassemble

    Trace.WriteLine(String.Format("{0} : Entering Disassemble",
DateTime.Now().ToLongTimeString()))

    Dim outputMessage As XmlDocument = Nothing

    ' Initialise the field name value collection
    _nameValues = New Hashtable

    Trace.WriteLine(String.Format("{0} : pInMsg.PartCount = {1}",
DateTime.Now().ToLongTimeString(), pInMsg.PartCount))

    ' Consider this document only if it has parts
    If (pInMsg.PartCount >= 1) Then

      Dim bodyPart As IBaseMessagePart = pInMsg.BodyPart

      Trace.WriteLine(String.Format("{0} : bodyPart Is Nothing? {1}",
DateTime.Now().ToLongTimeString(), (bodyPart Is Nothing).ToString()))

      ' Clone the message context so we can associate it with the new
message later
      _originalMsgContext = PipelineUtil.CloneMessageContext(pInMsg.Context)

      ' Consider this only if this is not null
      If (Not bodyPart Is Nothing) Then

        Trace.WriteLine(String.Format("{0} : About to reference bodyPart
Stream ...", DateTime.Now().ToLongTimeString()))

        Dim docStream As Stream = bodyPart.GetOriginalDataStream()
        Dim lineRead As String = Nothing
        Dim lineNum As Integer = 1

        ' We got the original data stream (not a copy) so rewind the stream
        docStream.Seek(0, SeekOrigin.Begin)

        Trace.WriteLine(String.Format("{0} : Creating StreamReader from
bodyPart stream to read each line in input data",
DateTime.Now().ToLongTimeString()))

        ' Use a stream reader to facilitate reading line by line
        Dim streamReader As New streamReader(docStream)

        ' Parse all tables and all values in betwen them
        lineRead = streamReader.ReadLine()
        While (Not lineRead Is Nothing)

          Trace.WriteLine(String.Format("{0} : lineRead = '{1}'",
DateTime.Now().ToLongTimeString(), lineRead))

          ' TODO - Do we need to associate schema here?
          ' If so then we can determine which schema by HMT:150, HMV:001

          ' Make sure we don't process an empty line
          If lineRead.Trim().Length > 0 Then
            ' Process the field definition and value

            ' Make sure the name/value separator exists in line
            If (lineRead.IndexOf(NameValueSeparator) > 0) Then
              Try
                ' Read name & value details from line
                Dim nameValue() As String =
lineRead.Split(NameValueSeparator.ToCharArray())
                Dim fieldName As String = nameValue(0).Trim().ToLower()
                Dim value As String = nameValue(1).Trim()

                Trace.WriteLine(String.Format("{0} : Adding data to
collection with :: fieldName='{1}' and value='{2}'",
DateTime.Now().ToLongTimeString(), fieldName, value))

                ' Add the field to our collection
                _nameValues.Add(fieldName, value)

              Catch ex As Exception
                ' Invalid line - ignore
                ' (Invalid messages will be picked up in the validate
                ' stage of the receive pipeline)
              End Try
            End If
          End If

          ' Get the next line
          lineRead = streamReader.ReadLine()
          lineNum += 1
        End While
      End If
    End If

    Trace.WriteLine(String.Format("{0} : Exiting Disassemble",
DateTime.Now().ToLongTimeString()))

  End Sub

  Public Function GetNext(ByVal pContext As
Microsoft.Biztalk.Component.Interop.IPipelineContext) As
Microsoft.Biztalk.Message.Interop.IBaseMessage _
  Implements
Microsoft.Biztalk.Component.Interop.IDisassemblerComponent.GetNext

    Trace.WriteLine(String.Format("{0} : Entering GetNext",
DateTime.Now().ToLongTimeString()))

    Dim newMsg As IBaseMessage = Nothing

    ' We have something to return
    If ((Not _nameValues Is Nothing) AndAlso (_nameValues.Count > 0)) Then
      ' Creates a new message
      newMsg = pContext.GetMessageFactory().CreateMessage()

      ' Prepare the message: We combine all tables into one XML document
      ' like the following:
      ' <message>
      ' <name>value</name>
      ' [...]
      ' </message>

      ' Get a new stream so we can prepare the XML and connect it to an
XMLTextWriter
      Dim outputStream As New MemoryStream
      Dim xmlWriter As New XmlTextWriter(outputStream, Encoding.UTF8)

      ' Apply the appropriate formatting and start the XML document
      xmlWriter.Formatting = Formatting.Indented
      xmlWriter.WriteStartDocument(True)

      ' Write the root element
      xmlWriter.WriteStartElement(String.Empty, RootMessageElementName,
String.Empty)

      ' Emit all name/value pairs
      For Each key As Object In _nameValues.Keys
        xmlWriter.WriteElementString(key.ToString(),
_nameValues(key).ToString())
      Next

      ' Close the document
      xmlWriter.WriteEndElement()
      xmlWriter.WriteEndDocument()
      xmlWriter.Flush()

      ' Rewind the stream so it is ready for use by the messaging engine
      outputStream.Seek(0, SeekOrigin.Begin)

      ' Add one part to it. This part will be the "body"
      Dim newMsgPart As IBaseMessagePart =
pContext.GetMessageFactory().CreateMessagePart()
      newMsgPart.Charset = "UTF-8"
      newMsgPart.ContentType = "text/xml"
      newMsgPart.Data = outputStream

      newMsg.AddPart("body", newMsgPart, True)

      ' Copy the original message context to the newly created message
      For iProp As Integer = 0 To
(Convert.ToInt32(_originalMsgContext.CountProperties) - 1)
        Dim strName As String
        Dim strNSpace As String

        Dim val As Object = _originalMsgContext.ReadAt(iProp, strName,
strNSpace)

        ' If the property has been promoted, respect the settings
        If (_originalMsgContext.IsPromoted(strName, strNSpace)) Then
          newMsg.Context.Promote(strName, strNSpace, val)
        Else
          newMsg.Context.Write(strName, strNSpace, val)
        End If
      Next

      ' There is a new stream so let's make it visible to the
resourceTracker
      pContext.ResourceTracker.AddResource(outputStream)

      ' We returned this message so drop our internal table representation
      _nameValues = Nothing
    End If

    Trace.WriteLine(String.Format("{0} : newMsg Is Nothing? {1}",
DateTime.Now().ToLongTimeString(), (newMsg Is Nothing).ToString()))
    Trace.WriteLine(String.Format("{0} : Exiting GetNext",
DateTime.Now().ToLongTimeString()))

    Return newMsg

  End Function

#End Region

End Class

</code>

• Previous message: Jon Flanders: "Re: Visual Studio 2003 Biztalk projects"
• Next in thread: WenJun Zhang[msft]: "RE: Custom Disassembler"
• Reply: WenJun Zhang[msft]: "RE: Custom Disassembler"
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