4.1.1 SDK Problems with missing xpacket tags in sidecar XMP files

Question

The current 4.1.1 SDK has problems with sidecar XMP files that don't have the xpacket headers and trailers, i.e:
<?xpacket begin='' id='W5M0MpCehiHzreSzNTczkc9d'?>
<?xpacket end='w'?>
is missing. Now, unfortunately Adobe Bridge CS2/CS3 does not export these xpackets in sidecar XMP files.
The standard, http://www.aiim.org/documents/standards/xmpspecification.pdf, is also very vague about it all:
● Write external metadata as though it were embedded and then had the XMP Packets
extracted and catenated by a postprocessor.
The grammar is strange(past tense had) and the spec implies that the xpacket should be extracted and again catenated... Someone should review this document and clearly state if xpacket statements should be in sidecar files or not. I suspect myself that they should be there, but the standard is very vague.
Anyway, there are two places in the SDK code where changes might be needed:
XMPFiles::Initialize has XMP_Asserts in case the xpacket header/trailer is missing, but the underlying assert is only active in debug builds.
XMPScanner::PacketMachine::FindNextPacket () also has in its truth table the assumption that the xpackets exist.
There could be even other places in the code that assumes that the xpacket tags are present in all files, which includes text XMP sidecar files.
Anyway.
a) Shouldn't bridge export the xpacket tags? Same with any other application?
b) If the spec is vague, then the SDK should not assume that the xpacket tags are present.
Any comments? Has someone already fixed this issue as I suspect a lot of apps using the the XMP SDK would break concerning reading XMP sidecar files? Thx, Kent

Answer 1

I was able to work around the problem by creating a mapped view of the .xmp file (this creates an array in memory backed by the file on disk, so there's no need to read the file into a separate internal buffer), and constructing the SXMPMeta object directly from the buffer. (The ctor for that class calls ParseFromBuffer, so this is the same thing as was suggested by other messages in this thread.)
It seems that Adobe needs to do one of these things:
(1) say that Bridge CS3 has a bug, and agree that Bridge CS3 should include a proper xpacket header when writing xmp sidecar files
(2) say that the XMP Toolkit has a bug, and that the SDK should be able to parse sidecar files without an xpacket header, and agree to fix the toolkit
(3) say that Bridge CS3 and the XMP Toolkit behave as expected, but then provide a sequence of steps by which users of the XMP Toolkit are expected to read xmp sidecar files written by Bridge CS3
Does Bridge CS4 write an xpacket header to the xmp sidecar files?
Maybe what I could do is create a custom file handler for .xmp sidecar files, so I could use the SXMPFiles for everything, instead of having to special-case .xmp files.
My needs are pretty modest though, and it might be just as simple to use the MS DOM-based XML parser for load the xmp sidecar file. I bet I could get the data I need (only the "Rating" for now) using a simple XPath expression.
-Matt