Title: Re: [ebxml-msg] Section 2.4.5 Compliance with the SOAP Intermediary Model: initial questions and reservations
An ebms role would be the most compliant solution,
agree.
But this role needs be assigned to eb:Messaging header
which is also indended to the ultimate receiver.
So end-point MSHs - not just intermediaries - need also act
in this role.
(which is good as I think message content - at least for
User message - should not depend on whether it goes through the I-Cloud or
not.)
-jacques
From: Sander Fieten
[mailto:]
Sent: Monday, June 15, 2009 2:46
PM
To:
Subject: Re:
[ebxml-msg] Section 2.4.5 Compliance with the SOAP Intermediary Model: initial
questions and reservations
Surely we don’t want to block “plain” SOAP
Intermediaries, i.e. SOAP nodes that don’t understand ebMS meta data, from
processing SOAP messages part of an ebMS message exchange.
The most easy
way would of course be to define a new target role specific to ebMS nodes /
intermediaries. This way these headers are automatically ignored and
forwarded by plain SOAP intermediaries (see Table-3 in part 1 of the SOAP
spec). This would impose a requirement on the endpoint to supply these target in
the messages.
Another option is not to require processing of the ebMS
related SOAP headers by setting “false” as the value for the mustUnderstand
attribute. This allows “plain” SOAP nodes to ignore the ebMS SOAP headers. Again
according to Table-3 of the SOAP spec this would however remove these headers
from the message unless the relay attribute exists with value “true”. So the
requirement on the endpoint would be to supply these attributes.
The option not to supply a role attribute
with a SOAP header would set the header targeted at the ultimateReceiver (see
section 5.2.2 SOAP spec) and therefore prevent it from being processed at all by
any intermediary SOAP node including the ebMS intermediary. This follows from
the SOAP processing model defined in section 2.6 of the SOAP spec and specific
from rule #4 that states that “A SOAP node MAY also choose to process
non-mandatory SOAP header blocks targeted at it”. So headers not
targeted at the node SHALL NOT be processed.
Therefore in my opinion the
headers that need processing by the ebMS intermediaries should have a role
attribute value which targets it at the intermediary.
Regards
Sander
On 12/06/2009 21:03, "Jacques
R. Durand" <>
wrote:
>For the ebMS header, we do not want a mere SOAP
intermediary to throw a SOAP fault
>because it does not grok ebMS. And
we should architecturally allow mere SOAP intermediaries.
>But by
targeting “next” and requiring ebMS header processing, we block things.
Good point.
I think the SOAP model has not
given much thoughts to intermediaries that are mere "routers", and therefore
we should not be too eager to make the ebms multi-hop use case "fit in" this
model.
Clearly the concept of processing SOAP headers has been defined
assuming that whoever is targeted to do this processing, is the final consumer
of this header, and "re-insertion" appears to be mostly a kludge, a way out
some annoying corner case.
If we have a rationale for NOT adding @role - and it looks like we
might, given that the notion of "header processing" falls short of
supporting our case - I am all for it.
By not having this addition we also ensure that any message good
for a point-to-point exchange, can also be sent to the I-Cloud, given the
right routing function.
(we should make this one of our basic
principles)
If not that introduces some embarrassing dependency to the
topology.
Jacques
From: Moberg Dale
[mailto:]
Sent: Friday, June 12, 2009 8:42 AM
To:
Subject:
[ebxml-msg] Section 2.4.5 Compliance with the SOAP Intermediary Model: initial
questions and reservations
1. Versions: Is this
section intended to apply to SOAP 1.2 only?
If so, is the first or
second edition of 1.2 relevant?
2.There is a SOAP
processing model mentioned in http://www.w3.org/TR/soap12-part1/
but nothing explicitly referred to by “SOAP intermediary
model”
But consider Section 2.7
in the second edition, entitled, “Relaying SOAP
Messages”:
As mentioned earlier in
this section, it is assumed that a SOAP message originates at an initial SOAP
sender and is sent to an ultimate SOAP receiver via zero or more SOAP
intermediaries. While SOAP does not itself define any routing or forwarding
semantics, it is anticipated that such functionality can be described as one
or more SOAP features (see 3. SOAP Extensibility Model <http://www.w3.org/TR/soap12-part1/#extensibility>
). The purpose of this section is to describe how message forwarding interacts
with the SOAP distributed processing model.
ebMS does not make use of
the SOAP Extensibility Model to define forwarding. Therefore, what we are
doing is not what “is anticipated” So, should we really be discussing
compliance? What exactly is it that we are complying with? WS-I has not
released any conformance Rxxxx requirements targeted at intermediaries that I
recall. We are not using the extensibility model. I think the title of our
section 2.4.5 is misleading.
3. “It is assumed that
ebMS Intermediaries are also SOAP intermediaries. By default all
nodes in the multi-hop path act in the “next” role (http://www.w3.org/2003/05/soap-envelope/role/next).
Replace “by default” with
“Therefore”
4. In the SOAP processing
model for intermediaries, any header that is understood and
processed must be removed from the SOAP message.
Remove “for
intermediaries”
5. “If one wants the
headers to be available to further SOAP processors on the message path the
headers have to be “reinserted” in the SOAP message. When a SOAP intermediary
does not process a header it may relay this header to the next SOAP node, i.e.
not remove the header from the message.”
“As the routing function
of the ebMS Intermediary requires processing of SOAP headers these headers are
not subject to “relay” but to “reinsertion” [SOAP12]. As relaying does not
apply to the ebMS headers, the @relay=”true” attribute should not be set. The
ebMS routing function is then a “header reinsertion” case.
”NOTE: When the
intermediary would reinsert header attributes by removing them first and then
add them again this might break signatures. It is therefore strongly
RECOMMENDED that intermediaries do not alter in any way the SOAP header of
routed messages, i.e. implementations must consider the “reinsert” operation
as a virtual extraction and reinsertion of header blocs. An intermediary
implementation SHOULD NOT rebuild the SOAP header of routed messages by
actually extracting then reinserting header
blocks.”
Please reduce this to a
statement of the required functionality and do not describe how implementation
should occur (IMO!) Put something like “Header processing by an intermediary
MUST not break digital signatures.”
7. NOTE: set the @role of
all headers to “next”, as that does not seem to be a default in SOAP1.2
?
The “@role” is a 1.2
attribute. What happens for SOAP 1.1? Why do we want all headers to have that
role? Why is the wss header set that way? We at most only want to set the role
value to “next” for the header containing metadata consulted by the
intermediary. What about mustUnderstand? For the ebMS header, we do not want a
mere SOAP intermediary to throw a SOAP fault because it does not grok ebMS.
And we should architecturally allow mere SOAP intermediaries. But by targeting
“next” and requiring ebMS header processing, we block things. We really need
to understand which header needs to be targeted and what the target value
should be? We might well be better off making up our own role value
here.
