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Subject: RE: [ebxml-msg] Groups - AS4-profile-v1.0-wd20.odt uploaded
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Jacques,
In my email to the list of December 13, there are a number of
examples using MessagePartIdentifier. There is also an XSLT that computes
an AS4 receipt, with documentation, for the range of diverse situations to
support.
The ebBP signal assumes a receipt for a message includes
information about constituent parts of a message using either XML Signature
references or using a MessagePartIdentifier. The structure seems oriented
towards MIME-structured messages that have MIME part identifiers.
If we are re-using this signal structure, we should stick to its
structure and semantics, beyond making sure the receipts pass XML
validation. So if a message has part identifiers (Payload
references), it seems to me that a receipt should use those part
identifiers and not (just) the ebMS MessageId.
If we find the ebBP structure to be limiting, we could
also ask ebCore (which maintains the schema) to update the ebBP signal schema,
e.g. via the Errata process. The XSLT would be much simpler if the schema
would support an empty list of message parts (User Messages with no
Payloads), or part identifiers that have the empty string value (for messages
that have no "href" attribute, using the implicit assumption that this refers to
a payload in the SOAP Body).
Pim From: ebxml-msg@lists.oasis-open.org [mailto:ebxml-msg@lists.oasis-open.org] On Behalf Of Jacques Durand Sent: 24 December 2011 02:53 To: ebxml-msg@lists.oasis-open.org Subject: RE: [ebxml-msg] Groups - AS4-profile-v1.0-wd20.odt uploaded I
have uploaded AS4-profile-v1.0-wd21.odt. Diffs show compounded changes with
wd20, from wd19. Note: -
5.1.8
left untouched. It strikes me we have no example of using
ebbp:MessagePartIdentifier .
We should have one at least, as this is a foreign element to ebms. Also,
it does not sound right to state “The ebbp:MessagePartIdentifier element
SHOULD contain the
eb:MessageId of the received message.” As
Pim mentioned, this is a SHOULD which does not help much. But why shouldn’t we
refer to each message part, if we have to use
ebbp:MessagePartIdentifier?
I
would expect to see in a Receipt the content of href string from the original
message ( <eb:PartInfo
href="">) for
each part referred in the receipt. -
I
added in the AS4 additional features section, a couple of Receipt-related error
codes recommended by Pim. -jacques From:
ebxml-msg@lists.oasis-open.org [mailto:ebxml-msg@lists.oasis-open.org] On
Behalf Of Jacques Durand Pim
and all: Inline
, a few more comments <JD>. I
am not sure I can attend tomorrow’s meeting – will try, but am in another F2F
meeting out of office. -jacques From: Pim van der Eijk
[mailto:pvde@sonnenglanz.net] Unfortunately
not all changes to previous versions were tracked.
Comments
inline. Pim From:
ebxml-msg@lists.oasis-open.org [mailto:ebxml-msg@lists.oasis-open.org] On
Behalf Of Jacques Durand I
have uploaded a candidate AS4 spec (AS4-profile-v1.0-wd20.odt) from wd19, that
implements most of Pim’s recommendations, remaining from Sander’s (in
wd19). 1- Compression property with
value "true" instead of empty string for XML schema
compliance. Did
the update that requires the “Compressed” property to have a value (I
believe the Example in 3.1 was the main culprit?). Also it seems we never
introduced the “Compressed” property used in the example (so I
did). Section
3.1 now requires two properties "Compressed" (fixed value "true") and
"CompressionType" (fixed value "application/gzip"), but the example in that
section still only has "Compressed". Having a separate property for the type of
Compression seems useful if more than one type is allowed (other compression
algorithms have emerged after GZIP that have advantages in some cases, though
it's fine if AS4 does not want to use them for interoperability), but if we have
just one allowed value, what does it add? Isn't the "Compressed" property
redundant if we specify the "CompressionType" ? <JD>
I see. So the example alone was wrong. And if we have to choose between
Compressed=”true”
/ “false” and
CompressionType=”application/gzip”
(no
other altearnative – so far) then I’d choose to keep CompressionType=”application/gzip”
because
in a future version of AS4 there might be another compression option, and we
don’t want to change the schema to support that. So I would not give it “true”
as value, or did I misunderstand this issue? 2- MIME type value in property
for a compressed attachment required instead of
recommended. Done
by Sander. 3- Add note that a compressed
payload must be in a separate MIME part and not in the SOAP
Body Added
a simple note in 3.1. 4- In AS4
5.1.8.(a) and 5.1.8.(b), clarify use of receipts with simple SOAP messages,
where the SOAP envelope is not in a part with a content identifier, and has no
MIME content ID, so here there can be no part identifier.
Done
by Sander. 5.1.8
(b) references message parts using ds:References, but 5.1.8 (a) now should
references the ebMS message ID in a PartInfo ? The MessageId is already
referenced in the eb3:RefToMessageId in the MessageInfo of the SignalMessage in
both cases, having it as value for MessagePartIdentifier in one case is
redundant, is inconsistent with the other non-repudiation use and does not
match the semantics of the ebbp:NonRepudiationInformation structure.
<JD>
I noticed this redundancy. Should we remove that requirement? I don’t recall why
we made it. BTW what
would "should" mean, are other values allowed, if yes, which
ones? The
earlier proposal was to use the MIME part identifiers for reception awareness.
This works for all SOAP with attachment messages. The
issue was about plain SOAP messages with any payload in the SOAP
body. Another solution is to require SOAP with attachments for AS4
messages (or at least for the ones that require receipts), after all that
worked in ebMS 2.0. Unfortunately
the value of a MessagePartIdentifier is a non-empty string, so it cannot be left
unspecified. 5- In AS4 5.1.8.(a) and
5.1.8.(b), note that it is impossible to generate a valid ebBP reception
awareness We
have to decide what note to be added in 5.1.8 for this. 6- In AS4 5.1.8.(a) and
5.1.8.(b), decide on ebbp:MessagePartIdentifier format for a payload part in
SOAP body that is implicitly identified by absence of an "href" attribute as
described in ebMS3Core. Should
we just require something like a string “soap:body”, for readability?
(not done
yet) Unfortunately
the value of a MessagePartIdentifier is a non-empty string, so it cannot be left
unspecified. We could profile AS4 to make the href attribute mandatory, always
or for messages that request receipts. 7- Clarify that an identifier
of a payload in the SOAP Body is a stored as an attribute value on the SOAP Body
element, not on the contained document root (AS4 interop).
Not
sure I understand this: the soap Body could have several payload parts actually,
and the @id attribute is at the root of each one of these (not on the Body
element). See example in Appendix C2 of Core V3. There is
a problem with that example in the core spec: the business document is
submitted by the Sending application, and it may not have an "id"
attribute. We shouldn't let the sending MSH add an id, as the
receiving MSH may not know if it was added by the sending application or by the
sending MSH, so it can't remove it. The XML schema of that document may not even
allow an "id" attribute, so unless it were removed, the receiving application
would consider it an invalid XML document. When
using WS-Security, the identifying attribute is on the SOAP:Body, not on the
enclosed XML document. We don't require WS-Security, but the place to put
the attribute should be the same whether we use it or
not. <JD>
I see. Should we – as part of AS4 profile – recommend that in case several
payloads are added in the Body, there should be a wrapper that will have this
@id (like <payloadpart id=…>. That’s not pretty but I don’t see how
to do better… 8- Discuss the format of the
identifier (xml:id or wsu:Id). It
seems to be @id (not @Id) see examples in core V3. 9- Bad references to SOAP 1.1
instead of 1.2. Done
by Sander. 10-Guidelines on values for
mpc (message partition channel) attributes. Pullrequests do not have ebMS
metadata, so a partner that sends documents to multiple partners using Pull mode
must assign them to different channels, unless we want to require support for
the "selective pulling" feature of Part 2 in ebMS. Here
I think it would be better to add as an optional extra feature (for a
Sender), support for sub-channels. We have defined this feature in Part 2 for
intermediaries only. We can refer to it as an (optional) extra feature, as it
was initially defined for a multi-hop context but can easily be considered in a
single hop case here.. See new proposed section 3.5. We need
a way to specify, as a new PMode parameter the "receiver sub-MPC". This is
the MPC that the receiver pulls from. It may be different from the MPC the
sender submits it to, but not completely different, it is required to be a
sub-channel. <JD>
AS4
can add a new PMode parameter
PMode[1].BusinessInfo.subMPCext
that
must contain the extension only to be appended to
the
PMode[1].BusinessInfo.MPC. E.g. if
MPC = “http://sender.example.com/mpc123” and
subMPCext =
“subc42”, then
the subchannel to pull from is: http://sender.example.com/mpc123/subc42 The
Sending MSH needs to know how to partition the set of messages submitted to an
MPC across various sub-MPCs. What rules control this
partitioning? <JD>
the assignment of messages to sub-channels is done similarly to the way its
described in Part 2: there is a different PMode for each subchannel receiver, so
this is just like regular message-to-PMode
matching. We might
associate a sub-channel with an XPath _expression_ over the UserMessage
header. Here the partitioning is done at submission time and authorization
can be done at a fine-grained sub-channel level. Another
option is the selective pulling feature in Part 2. Basically, a
receiver could pull from a generic MPC and select it using the
to:PartyId=<<their ID>>. Here the selection is done more
dynamically, the receiving MSH has more control. But the receiver must be
authorized for the MPC, so this is more a feature to give better control to the
receiver. <JD>
the issue with this is that there is no guarantee that your messages will NOT be
pulled by unauthorized parties (as everyone is authorized the same way for
selective pulling) 11- Support for Two
Way MEPs. This is not needed for EDIINT, but in essence
allowing an MSH to set the value for RefToMessageId adds minimal complexity to
an implementation. It allows AS4 to be used also for SOA-style,
request/response interactions. I
think Sander addressed this (just as an option) with a simple
note. If we
want this, we need to allow them in 2.1.1 and 2.2.1. I'm in favour of allowing
Two Way MEPs. All it means is that an MSH must be able to set an
eb3:RefToMessageId in an outgoing message, which is trivial. (We require
them to set ConversationId already, after all). I can't think of any
interop reasons to leave this out. The main benefit is that AS4 can be used for
SOA-style, request/response interactions and not just for batch EDI. AS4
could replace ebMS 2.0 for all of my customers' applications if it supported
this. The
OASIS Energy Interop TC is currently profiling ebMS 3.0 for smart grid, and this
issue came up there are well. IncludingRefToMessageId
in responses supports a style of asynchronous programming where the sender
registers a callback based on MessageId. It is possible to do this by
correlating message payloads, but it is much more practical and consistent
to be able to use a UserMessage element. When the response comes it, the
appropriate handler can be called before any payloads are processed.
IMPORTANT:
regarding support for compression: -
The
question whether light AS4 clients – in particular “minimal” client - should
support compression (meaning also attachments, and msg properties) is still
controversial in my view: if we want to “certify” very light clients and
devices, I’d be in favor of keeping the “minimal client” conformance level low,
i.e. not requiring these features. There
was a questionabout this in the OASIS Energy Interop TC as well.
They asked if GZIP support is widespread or practical in low-end devices
that are in their scope. A strong advantage of GZIP is
that it has a very small memory footprint and is fast (compared to other
algorithms that have a better compression ratio). They
also asked if we had considered http://www.w3.org/TR/2011/REC-exi-20110310/as
an alternative. -
So
my uploaded draft reflects this option (low bar for “minimal client” conformance
level). See the conformance Clause: to be discussed. NOTE:
a small issue not fixed yet: the ref to V3 Part 2 is using a different acronym
in the ref section ([ebMS3ADV]) than
in the body of the spec (ebMSP2) Thanks Jacques From:
ebxml-msg@lists.oasis-open.org [mailto:ebxml-msg@lists.oasis-open.org] On
Behalf Of Pim van der Eijk Submitter's message
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