(VBScript) MIME Body vs. Sub-Parts
Explains the difference between sub-parts and body.
MIME documents (i.e. messages) can have a nested structure. The simplest MIME message contains a header followed by content (possibly encoded). The header is delimited from the content by two consecutive CRLF's.
A MIME message may be multipart. If so, then the Content-Type header field indicates "multipart" and the content the follows the header is itself a MIME message, which may also be multipart, etc. You can see how MIME messages effectively have a tree structure. The non-leaf nodes have Content-Types that are "multipart/" and the leaf nodes have non-multipart Content-Types.
The Chilkat MIME component/library uses two terms that need to be understood in order to effectively use the API. These are "body" and "sub-part". A multipart node has 1 or more sub-parts, but its body is empty. A leaf node (i.e. non-multipart node) has no sub-parts, but the body is (usually) non-empty.
This example creates a multipart MIME message and shows the results of getting the sub-parts and body of each node.
Dim fso, outFile
Set fso = CreateObject("Scripting.FileSystemObject")
'Create a Unicode (utf-16) output text file.
Set outFile = fso.CreateTextFile("output.txt", True, True)
' This example assumes the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Mime")
set mime = CreateObject("Chilkat.Mime")
' Create a multipart/mixed MIME message with two sub-parts.
' We'll use the Base64 encoding for the 2nd sub-part.
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Mime")
set part1 = CreateObject("Chilkat.Mime")
success = part1.SetBodyFromPlainText("This is part 1")
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Mime")
set part2 = CreateObject("Chilkat.Mime")
success = part2.SetBodyFromPlainText("This is part 2")
part2.Encoding = "base64"
success = mime.NewMultipartMixed()
mime.UseMmDescription = 0
success = mime.AppendPart(part1)
success = mime.AppendPart(part2)
' Show the MIME message:
outFile.WriteLine(mime.GetMime())
' Here's the MIME:
' Content-Type: multipart/mixed;
' boundary="------------040605030407000302060008"
'
' --------------040605030407000302060008
' Content-Type: text/plain;
' charset="us-ascii"
' Content-Transfer-Encoding: 7bit
'
' This is part 1
' --------------040605030407000302060008
' Content-Type: text/plain;
' charset="us-ascii"
' Content-Transfer-Encoding: base64
'
' VGhpcyBpcyBwYXJ0IDI=
'
' --------------040605030407000302060008--
' If we examine the root node of the MIME message,
' we see that it has 2 sub-parts and the body is empty (as expected)
n = mime.NumParts
outFile.WriteLine("Num Parts = " & n)
outFile.WriteLine("Body = " & mime.GetBodyDecoded())
' The GetEntireBody retrieves the entire content after
' the header. (Perhaps GetEntireBody should've been named
' GetEntireContent to make it less confusing...)
outFile.WriteLine("---- EntireBody:")
outFile.WriteLine(mime.GetEntireBody())
outFile.WriteLine("********")
' Now examine the 2nd sub-part. It has a body encoded
' using base64. Get the contents of the body in both
' decoded and encoded forms:
' index 0 is the 1st part, index 1 is the 2nd part.
' part is a Chilkat.Mime
Set part = mime.GetPart(1)
outFile.WriteLine("Decoded Body:")
outFile.WriteLine(part.GetBodyDecoded())
outFile.WriteLine("Encoded Body:")
outFile.WriteLine(part.GetBodyEncoded())
outFile.Close
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