Status: New
Owner: [email protected]
Labels: Type-Defect Priority-Medium
New issue 219 by zoran.rajic: MTOM with Protocol Buffers
http://code.google.com/p/protobuf/issues/detail?id=219
I was wondering if you guys plan to implement the SOAP/MTOM and XML+XOP
-like extension on top of PB's.
I came to realize that the Protocol Buffers can very efficiently replace
the XML part of the SOAP message, but PB's can't handle large binary
attachments coming with the same payload (or, the XOP equivalent -- see
http://www.w3.org/TR/xop10/).
The Developer's Guide and
http://code.google.com/apis/protocolbuffers/docs/techniques.html#large-data
article suggests that the PB should be used only to replace the XML, and
not deal with the binary attachments. Based on this, one could potentially
combine the MIME and protobuf to handle the binary attachments (similar to
what XML+XOP does), ie:
| MIME-Version: 1.0
| Content-Type: Multipart/Related; boundary=MIME_boundary
|
| --MIME_boundary
| Content-Type: x-protobuf
| Content-Transfer-Encoding: binary
|
| // binary encoded equivalent of
| person {
| name: "John Doe"
| email: "[email protected]"
| photo: "cid:http://example.org/me.png";
| }
|
| --MIME_boundary
| Content-Type: image/png
| Content-Transfer-Encoding: binary
| Content-ID: <http://example.org/me.png>
|
| // binary octets for png
| --MIME_boundary--
Unfortunately, even when this seems technically feasible, I find it that it
would be contradictory to the Protocol Buffers design principles - the
reason why one would consider moving away from XML and into PB's is likely
because of the efficiency, and here we'd use inefficient MIME to handle
multiple parts of the message.
The PB's "mutipart/multimessage issue" has been brought up on a number of
articles, and I understand that the general recommendation is to prefix the
segments with a size, and use size/offset -constrained CodedInputStream(),
or alternatively something like this:
http://efreedom.com/Question/1-1681263/Using-GPB-Make-Wrapper-Classes-Stop-Accepting-Binary-Messages-Meant
Looking at the ideal solution to implement MTOM, we could consider
introducing the "iostream" data-type into the PBs to accept and handle the
data streams for the binary attachments. I believe that there was already
some discussion about reusing the ByteString() for the similar purpose (see
http://groups.google.com/group/protobuf/browse_thread/thread/abd65bfadb8b3439)
So, back to the original question - would anyone care to comment if the
Protocol Buffers should have the MTOM-equivalent feature?
Thanks,
Zoran
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![http://example.org/me.png"](http://example.org/me.png"){kind=link}
