OASIS Mailing List ArchivesView the OASIS mailing list archive below
or browse/search using MarkMail.


Help: OASIS Mailing Lists Help | MarkMail Help

ebxml-msg message

[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]

Subject: RE: [ebxml-msg] MOU on intermediate support by conformance profile and other auxiliary documents for ebMS 3.0

Here are some reasons why I would prefer to use ebMS headers for routing rather than WS-Addressing Reference Parameters:


Conformance to v3.0 Core

The ebMS 3.0 Part 1 Core does not specify the use of WS-Addressing.


Avoid yet another standard to support

Requiring support for WS-Addressing in a multihop context adds a burden to implement ebMS 3.0 in general and the multihop profile in particular.It is also true that the counterproposal requires adding ebMS headers in some situations where v3.0 Core does not require them, but any ebMS 3.0 implementation needs to know how to construct or handle ebMS 3.0 headers anyway, so this is just a reuse of that general functionality.



If we start using WS-Addressing reference parameters in the multihop context, the question comes up why we did not use them in ebMS 3.0 Core. There are already elements in the ebMS header that are also in WS-Addressing, such as MessageId. Nevertheless, v3.0 Core does not use WS-Addressing even for these header fields, let alone use reference parameters for the information types that are in an ebMS 3.0 header but are not regular WS-Addressing field. I think the ebMS 3.0 header is richer than WS-Addressing header, so that this decision was right at the time. But even if it were not, I think a multihop profile should stick to the approach taken in v3.0 Core.  


Limited reuse

It might look as if using WS-Addressing is an instance of reusing a more general specification instead of defining ebMS specific mechanisms. But unlike the reuse of WS-Security or WS-Reliability/WS-ReliableMessaging, this reuse is only a syntactic issue. We would just be adding information to some defined extension points in the schema. Any processing of that information would require ebMS-specific processing, rather than using generic WS-Addressing functionality. Any intermediary that provides WS-Addressing functionality and wants to conform to this profile would still need to have ebMS-specific functionality.


Duplication in message structure

Having to store or retrieve the same type of information in two different locations usually smells of missed generalizations, and I think that is true here too. We looked at putting the equivalent of an ebMS header in a URL (the earlier HTTP URL query parameters), I don’t find putting it in WS-Addressing parameters a lot more elegant. It also raises issue like how to handle any inconsistencies in situations where there is both a WS-Addressing structure and an ebMS header. Also, the WS-Addressing specification says that using reference parameters to store information that would otherwise be in other SOAP headers could cause “unintended or erroneous semantics in the resultant SOAP message".


Generalized routing

This is related to duplication. When using just ebMS headers,  assuming routing is done on destination PartyId, any message (user, signal, WS-* helper, bundles, piggy backs) can be routed based on the single following XPath expression:



From: Moberg Dale [mailto:dmoberg@axway.com]
Sent: 07 May 2008 23:14
To: Pim van der Eijk; ebxml-msg@lists.oasis-open.org
Subject: RE: [ebxml-msg] MOU on intermediate support by conformance profile and other auxiliary documents for ebMS 3.0

Yes, I agee that adding metadata  to ebMS signals or to other messages used in WS protocols is what is agreed upon as a MOU item.


The way or ways to do this is apparently TBD J


I think that since we have several ways to attach the metadata, we probably want to prune these down into a simple convention to do it in a standard way.


(Incidentally, would we then provide CPPA support for these messages? Would they be treated as msh level messages from the default packaging and delivery channel standpoint?)


From: Pim van der Eijk [mailto:pvde@sonnenglanz.net]
Sent: Wednesday, May 07, 2008 1:04 PM
To: Moberg Dale; ebxml-msg@lists.oasis-open.org
Subject: RE: [ebxml-msg] MOU on intermediate support by conformance profile and other auxiliary documents for ebMS 3.0



We agreed to add ebMS metadata also to signals and helper messages. And we also looked in some detail at one option for adding this metadata, by adding it to a WSA header.  Imo we did not fully compare this option to using a an eb:Messaging header (containing an eb:UserMessage but one that has no eb:PayloadInfo) to convey the ebMS metadata. I want to fully understand both options and compare their pros and cons.  Unfortunately, due to travel I will not be able to attend next week's meeting.





From: Moberg Dale [mailto:dmoberg@axway.com]
Sent: 07 May 2008 19:42
To: ebxml-msg@lists.oasis-open.org
Subject: [ebxml-msg] MOU on intermediate support by conformance profile and other auxiliary documents for ebMS 3.0



Transparency where feasible


Signature intact where feasible (important aspect of transparency)


WSI Conformance where feasible (especially with respect to WSI RSP policy that WS-RX Reliable Messaging headers be signed, including WS-Addressing elements where used within ReliableMessaging)


Spoke configuration to services within an I-Cloud should have simplicity of configuration change management.

Specifically, rerouting to services (within the I-Cloud ) can be accomplished without spoke configuration changes”)


Hub service destinations and spoke clients have “vanilla” ebMS 3 conformance where feasible. (Some specializations of general functionality and of extension points is allowed.)


Additional Implicit Constraints


The internal addresses within an I-Cloud can have private IP addresses and DNS names that are not publicly reachable or resolvable in the Internet.




Rerouting by intermediaries can be based on ebMS “metadata” both in forward and return paths.

This functionality is referred to as a “table” mapping ebMS metadata to next hop URLs so that the HTTP POST (or other?) command can be rewritten.

   TBD: This map may be augmented for return paths by keeping a map involving Message-Id and Relates-To values.


For ebMS user messages, no special treatment is needed (so far anyway).


For ebMS signal messages and for WS clerical messages (such as CreateSequence, CreateSequenceResponse, etc.) several approaches are under consideration

  1. Define a ebMS Reference Parameter that allows the wsa attribute “isReferenceParameter” applied and that contains the metadata needed for routing.

  2. Allow use of WS-Addressing headers such as From or ReplyTo or FaultTo that have an EndpointReference model (and include ReferenceParameter within the EPR).

  3. For return path, if WS-Addressing Messaging-Id was present in incoming message, require use of RelatesTo in response message.

  4. For using the request connection for a response, some read-only access to ReplyTo is needed to check for the “anonymous” URL value.

     In this case, all intermediaries would be expected to hold the connection open (?) to allow the final service to use the HTTP backchannel for its response.


For Pull MEP-binding, allow first intermediary to handle MPC requests and let internal I-Cloud arrangements for this option be implementation specific.







[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]