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Summary
Receive information about extracted message.
Description
The OnRecvHeader event occurs after calling the ExtractMessageEnd method. This event
will occur during the extract message process to deliver information about the message and
any attachments the message may have.
The MIME ActiveX control will first extract the message header and body. The Mime
ActiveX control will fire the OnRecvHeader event, to notify the application that it has
set the message properties, and to deliver the entire message header. The body will be
saved to the Destination directory (set in the call to the ExtractMessageStart method) and
the OnRecvBody event will be fired to deliver the file name. If the Destination was set to
NULL the MIME ActiveX control will deliver the message by firing the OnRecvBody event one
or more times, after each OnRecvHeader event, to deliver the contents of the message body.
Extracted attachments will be delivered to the application in the same way.
The OnRecvHeader notifies the application that the MIME ActiveX control has set the
FileName, Encoding, ContentType, Subtype, MultipartStart, MultipartType, ContentId,
ContentBase, ContentLocation, FileSize, Charset, BinHexType, BinHexCreator and BinHexFlag
properties. The FileName property will contain the name of the file containing the
extracted information, or if no Destination was given it will contain either the name of
the attachment file if present in the header or else it will be empty. The other
properties will contain the appropriate information or will be empty if they are not
relevant to the message. The value of these properties will change with each occurrence of
the OnRecvHeader event.
The OnRecvHeader event also delivers the entire header information to the application
in the Buffer parameter. The length of the Buffer is specified in the Length
parameter. This allows the application to parse the header for any additional information
the application may have included when creating the message (By setting the Info
parameter in the OnSetHeader event).
For a partial message, the OnRecvHeader event will only be fired when all the parts
have been extracted and reassembled to form the original file. Otherwise an OnError event
will occur to indicate that only a partial message was extracted.
Note: In all cases the OnRecvBodyB event will occur instead of the OnRecvBody event if
the UseVariant property is set to True.
Technical Note
If the message to be extracted is of type multipart or
"message/external-body" the sequence of the OnRecvHeader and OnRecvBody events
may differ. In case of multipart messages an OnRecvHeader event can be followed by another
OnRecvHeader event instead of an OnRecvBody event. After MIME ActiveX control fires the
OnRecvHeader event with the initial header , the sequence will be OnRecvHeader event
followed by an OnRecvBody event unless there is a part with no body or if there is a
nested multipart in which case an OnRecvHeader event may be followed by another
OnRecvHeader event. The first body part is usually treated as the message body. The
extraction of the rest of the body parts will follow same sequence. The MIME ActiveX
control will automatically decode any encoded body part.
Similarly if the message is of type message/external-body then the initial OnRecvHeader
event will be followed by an OnRecvHeader event instead of an OnRecvBody event.
Note that the general sequence of upcalls will be OnRecvHeader event followed by an
OnRecvBody event unless there is a part with no header or an empty body, in those special
cases a OnRecvHeader event may be followed by another OnRecvHeader event or a OnRecvBody
event may be followed by another OnRecvBody event. It is the application's responsibility
to keep track of, and decide how to treat the data received in each OnRecvBody event. The
application can so this by checking the ContentType and Subtype properties after each
OnRecvHeader event.
If the message is a non-MIME message then only the Encoding and the Filename properties
will be set by the OnRecvHeader event.
Example
Sub Mime_OnRecvHeader (Buffer As String, Length As
Integer)
' display
Message = "Extracted...." + Chr(10) + Chr(10)
' filename
Message = Message & "FileName: " & Mime.FileName & Chr(10)
' encoding type
Message = Message & "Encoding: " & Mime.Encoding & Chr(10)
' content type
Message = Message & "ContentType: " & Mime.ContentType & Chr(10)
' subtype
Message = Message & "SubType: " & Mime.Subtype & Chr(10)
' display message
MsgBox Message, 64, "Sample Program"
End Sub
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