Hi
David,
If the forwarding and
routing amount to distinct ebXML conversations, then the situation is really
two ebXML messages between two pairs of participants, call them A and B and B
and C. Then CPAs exist for each of the two
conversations.
If there are
additional requirements (such as A’s signature has to be transferred to C),
then WSS would allow a lot of new combinations in ebMS 3 that are not
mentioned in ebMS 2.0. But CPP/CPA are still between the source and
destination parties of an ebMS messaging
conversation.
So far ebMS 3.0 has
not specified exactly what to do with SOAP intermediaries. Nor is there
agreement as to whether there is a need for ebXML intermediaries with
distinctive behavior. You can always have SOAP intermediaries, but it is not
clear that there will be specific ebMS MEPs involving them. I think we have
some proposed requirements to consider in this area but we have deferred
consideration until we get some core ebMS 3.0 profiles
completed.
Jacques’s case can be
construed as a termination of the ebMS message and then followed by an
internal integration using SOAP. This functionality is add-on functionality of
a MSH (which is almost always found in real implementations of a
MSH).
Dale
From: David
RR Webber [mailto:david@drrw.info]
Sent: Tuesday, January 16, 2007 7:23
PM
To: 'Durand, Jacques R.';
ebxml-msg@lists.oasis-open.org
Cc:
ebxml-cppa@lists.oasis-open.org
Subject: [ebxml-cppa] RE: [ebxml-msg] HL7
ORG: Fw: Issues with Web services
transport
Jacques,
This most
helpful. I believe your answers goes a long way to addressing this for
IHE/XDS.
One further
question before I forward this to them.
At NIH we are
using multiple CPAs in situations where forwarding and routing is occurring –
therefore – the intermediary has a CPA in place between the originator and
themselves as well as the CPA between the recipient and NIH. Clearly
this allows for additional controls and aspects about the transport to be
contained in these additional CPA(s) and then accessed by CPAid in the
envelope.
Does this
potentially offer additional configuration options for the intermediary?
My sense is probably “Yes”?
Thanks,
DW
From:
Durand, Jacques R. [mailto:JDurand@us.fujitsu.com]
Sent: Tuesday, January 16, 2007 4:53
PM
To: David RR Webber (XML);
ebxml-msg@lists.oasis-open.org
Cc:
ebxml-cppa@lists.oasis-open.org
Subject: RE: [ebxml-msg] HL7 ORG: Fw:
Issues with Web services transport
The document is
interesting as it clearly raises the issue of application-level intermediation
(contrasting the "service application" with the "worker applications"), for
which the SOAP model is only a foundation - and a simplistic one w/r to
routing - yet one that should be leveraged.
It shows the need to
represent and process differently what we could call "application
meta-data" and application data, the former being intended for the
intermediary (more horizontal SOAP headers, e.g. WSA, are probably too
low-level here).
An analogy could
be the use of "topics" in the publish-subscribe
model.
> Does anything in ebMS V3.0
mitigate this?
So I'd say that ebMS3
does (much) better than ebMS2 on this. Both distinguish app meta-data in form
of business header elements - including payload manifest - distinct from
payload parts, helping an (unspecified) forwarding function. But when
the "worker application" is wrapped as a Web service deployed on the
back-end (as it typically would in an SOA model) the ebMS V3 model is much
friendlier to the needed conversion into a service invocation: in V3 the ebMS
header being just a SOAP header bloc like any, and leaving the SOAP body free
for business payload, can be stripped from the SOAP message by the MSH acting
as intermediary. What remains can just be a plain Web service invocation,
ready as is to forward (you would never guess it has been an ebMS message...).
We have prototyped this at Fujitsu. One issue with ebMS2 is the SOAP body used
by the ebMS header, forcing payloads in attachments, and hard to deal
with when using end-to-end security (with V3, you could even have
security headers that the MSH would not touch,if intended to ultimate
destination - V3 Part 2 will be more explicit on this).
The paper also makes
a very sound observation regarding cases where the application needs to know
authentication credentials as context to its processing ("is this request to
this service allowed for this type of client?"). You typically want to deal
with this before the request hits the application service or server
supporting it, yet this kind of application-level authorization (which is
closer to access control) is out of infrastructure scope in the
current Web service security model (WS-Security) - and current WSS
implementations do not seem to facilitate this. Clearly the application-level
intermediation pattern is key to supporting this. I believe a decent support
has been proposed in V3 in the "message authorization" section which still
leverages WS-Security as much as possible.
Jacques
From: David
RR Webber (XML) [mailto:david@drrw.info]
Sent: Thursday, January 11, 2007 7:51
AM
To: ebxml-cppa
Cc:
ebxml-msg@lists.oasis-open.org
Subject: [ebxml-msg] HL7 ORG: Fw: Issues
with Web services transport
Importance:
High
Does
ebXML CPA address some of these issues? I believe it
might.
Could
CPA's between participants provide the missing information - or enough for
common uses?
Does
anything in ebMS V3.0 mitigate this?
I also
think that the idea we've been working on in BCM/ebSOA/BP of a pan-ebxml
context mechanism - could also be a next peice - so a shared context could be
retained across participants - that summarizes the salient information needed
to deliver correctly.
Please
let me know so I can reply back the HL7 list with our
considerations?
I'm
seeing this notion of an Uber-WS infrastructure gaining ground - so you call
that Uber-API - and then delivery occurs in the dialect for a
partner.
Of
course I beleive ebXML provides a B2B superset here that plain WSDL clearly is
not able to match.
Thanks,
DW
"The way to be is to do" - Confucius (551-472
B.C.)
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