I prefer Richard Bigelow's suggestion of an addition (or variant) to Option 2 vs. negotiating during a session setup (which could be a significant change to existing AS2 processes). An originator could send a message to all its trading partners when its capabilities change. This message would have headers only, no content, and would be sent only to partners who are using AS2-Version 1.2 or greater (indicating they support the Feature Header). This would ensure that partners would be notified of new capabilities prior to the originator using the new capability.
As a fail-safe, all partners should send the Feature Header to partners who are using AS2-Version 1.2 or greater with every message, in case the Header-only message is lost or not processed.
This would require software implementations to keep state information (probably in a partner profile) recording the AS2-Version, and indication of which Features each partner supports.
Do other AS2 software vendors object to Option 2 (with AS2-Version 1.2)?
Can anyone see any backward compatibility problems with Option 2 (using the AS2-Version 1.2 indicator) in communicating with version 1.0 or 1.1 products?
Would existing AS2 products (or products already supporting Option 2 in test) handle a Header-only message?
best regards,
John Duker
Procter & Gamble
|
| "Gijsbert in 't Veld" <Gijsbert.intVeld@xxxxxxxxxx>
Sent by: owner-ietf-ediint@xxxxxxxxxxxx
12/16/2005 03:43 AM
|
To: "Kyle Meadors" <kyle@xxxxxxxxxxxxxxxxx>, <ietf-ediint@xxxxxxx>
cc:
Subject: RE: profiles in AS2 |
I'm in favor of the features header in combination with the version indicator, but the features (capabilities) should always be negotiated during session setup. For each capability, the lowest "level" wins. So if A sets up a connection with B and requests "Multiple attachments=Yes" then B could say "Multiple attachments=No". The result will then be "Multiple attachments=No".
Also, the mininum AS2 protocol version supported should be 1.0. All the AS2 implementions should be backwards compatible. Detecting an older version then the one that will support feature negotiation always means that there are no features to be negotiated.
That way it's very flexible. This is how it's done in other major protocols as well (for example OFTP).
Best,
Gijsbert in 't Veld
Covast CTO
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From: owner-ietf-ediint@xxxxxxxxxxxx [mailto:owner-ietf-ediint@xxxxxxxxxxxx] On Behalf Of Kyle Meadors
Sent: Thursday, December 15, 2005 11:21 PM
To: ietf-ediint@xxxxxxx
Subject: RE: profiles in AS2
Not a lot of comments on this thread. But to summarize…
3 in favor of Option 2 (Features header) and use of AS2–Version 1.2
1 in favor Option 3 where filtering is done on a message
Still does not fully address the initial start–up conditions as Richard pointed out, but perhaps that just can not be done without some manual setup.
Since this EDIINT WG will likely be closing relatively soon, I hope we can get some more to weigh in on this. Do others object to Option 2 (with AS2–Version 1.2)?
For those AS2 vendors supporting Option 2, would this impact your product, including those deployed in existing supply chains? Are their significant backward compatibility problems with this choice?
Kyle Meadors
DGI
From: Tim McCarthy [mailto:TMcCarthy@xxxxxxxxxxxxx]
Sent: Wednesday, December 07, 2005 9:14 AM
To: Kyle Meadors; ietf-ediint@xxxxxxx
Subject: RE: profiles in AS2
Seems to me that a combination of features 2 and 4 would provide everything we'd need.
From: owner-ietf-ediint@xxxxxxxxxxxx [mailto:owner-ietf-ediint@xxxxxxxxxxxx] On Behalf Of Richard Bigelow
Sent: Tuesday, December 06, 2005 5:07 PM
To: Kyle Meadors; ietf-ediint@xxxxxxx
Subject: RE: profiles in AS2
These are my comments. Option 2 is preferred. This memo essentially supports John Duker's memo of Dec. 5, Features Profile in AS2.
1. This option requires that implementers of feature 1.n also implement all earlier features. Is that reasonable? What if 1.5 is difficult and many vendors don't want to do it, but many want to support 1.6? Not recommended.
2. The features header allows the partner A receiving the message to know the other partner's (B's) capabilities. So when A sends to B, A knows what is allowed. A can also check B's AS2-version; 1.1 does not allow any of the controlled features, but does allow compression. A should update some state for every message received from B. B might stop supporting some feature. Recommended.
A possible variant of (2) is that a partner could send some message to all its trading partners when its capabilities change. This message would have headers only, no content. It might be useful to send this capabilities message to partners that would rarely receive normal messages.
3. This option allows receivers to ignore messages they don't understand, and to detect those messages without looking for unknown headers. But it does not provide a mechanism for the sender to know whether a receiver can receive the message. Suppose we had done compression this way. A could send a compressed file to B, and B could ignore it based on the feature header, but then the file is lost. B could return a new MDN code indicating unsupported-feature, and A could then send the uncompressed file, in this example. In other cases, A would have to use some other mechanism. A could remember that B rejected the file and not try that feature again, but how would A know if B upgraded and can now support the feature? The original intent of the features header was that the sender could know in advance if the receiver supports the feature. 3 is not recommended.
4. Before sending a message to B, A should ask B for B's capabilities, and check if B supports the feature. Since B might stop supporting a feature, A should ask each time. This is ok for rare messages, like CEM, but not for common ones, like Multiple Attachments. Not recommended.
None of these protocols fully addresses the initial case. Before any messages are exchanged, how do the partners know each other's capabilities? Each partner must assume that the other supports only the basic 1.0 AS2 protocol. Hopefully, they will be able to exchange normal messages, which will contain at least the 1.2 version header. They can then use option 2 to discover each other capabilities. This probably works for most features. For CEM, either they must first exchange test messages that are unencrypted and unsigned to establish CEM capability, or exchange initial certificates manually.
Alternatively, the partners would configure each other manually the first time. Thereafter, they would be automatically updated on each other's capabilities.
Richard Bigelow
Inovis
richard.bigelow@xxxxxxxxxx
From: owner-ietf-ediint@xxxxxxxxxxxx [mailto:owner-ietf-ediint@xxxxxxxxxxxx] On Behalf Of Kyle Meadors
Sent: Thursday, December 01, 2005 9:04 AM
To: ietf-ediint@xxxxxxx
Subject: profiles in AS2
I am needing the opinion of the AS2 community on the use of a feature profiles within AS2. Back in 2002, compression was added as an extra feature. Using "AS2–Version: 1.1" in a message indicated the UA could support compression even if the actual message did not contain the compressed envelope. This assisted implementers in knowing if their trading partners could support compression.
Moving to the present, users are requesting new features. These include I–Ds for Reliability (from GS1), Multiple–Attachments (oil & gas users) and Certificate Exchange Messaging (Wal–mart, P&G and others GS1 companies). Given AS2's adoption, I am sure there will be others in the future.
My question to those on this elist is how to do move forward with new features. What do we do to insure only those who support a feature receive it (e.g., only sending CEM message to trading partners who support that profile)? Also, can anything be done to insure backward compatibility to keep new Feature Header messages from being sent to & breaking older, existing implementations (e.g. older implementation errors gracefully when getting an unrecognized MA message).
Here are some options. I would like to hear your thoughts on what is best or other ideas.
1. Use AS2–Version header to indicate UA support of profiles (e.g. 1.2 indicates CEM, 1.3 indicates CEM, Reliability). Works like compression (e.g. "1.2" indicates capability of CEM but not an actual CEM message).
2. Use a new header, e.g. EDIINT–Features. The features header shows all features supported by UA (e.g. EDIINT–Features: CEM, multiple–attachment) but like AS2–Version does not indicate every message contains profile.
3. Use a new header for each feature which is present ONLY in the message using that feature. For example, "CEM–Profile" for CEM messages. This could allow receiving UA to filter in only profiles it recognizes.
4. Create a "Capability Query" AS2 Message which returns a Capability MDN. MDN indicates what features receiving UA can support.
Kyle Meadors
Principal, Test Process
Drummond Group Inc.
615.212.0826
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