Subject: RE: profiles in AS2

From: "Richard Bigelow" <[email-masked]>
Date: Mon, 19 Dec 2005 10:56:20 -0800

Concerning a 1.2 version interoperating with a 1.1 version:  The 1.1
version should accept the 1.2 messages.  The compression draft says that
a version of 1.1 or greater indicates compression.  

I have some concern about Kyle's comment that this WG may be closing
soon.  Is this in response to IETF's requirement to make progress on
AS3?  I hope that this WG will continue.  We have some proposals on the
table, including Reliability and CEM and perhaps Profiles in the future.

Richard Bigelow
Inovis
[email-masked]

________________________________

From: [email-masked]
[mailto:[email-masked]] On Behalf Of Dale Moberg
Sent: Saturday, December 17, 2005 7:49 AM
To: Kyle Meadors; [email-masked]
Subject: RE: profiles in AS2

The consensus seems to be that it should be possible to support some AS2
features independently, rather than cumulatively. Although I think the
combinations of features of Reliability, CEM, and Multipart could be
coded up by 8 numbers, if more end user requirements get specified, that
encoding would become inconvenient to support. So moving to an
EDIINT-Features header seems to be a reasonable way to advertise
capabilities.

Would AS1, AS2 and AS3 all use this header? I assume that CEM and
attachments are OK, but Reliability mainly pertains to AS2. Also, would
AS1 have to add an "X-" preface to the header? (So we would have
somemething like "X-EdiintFeatures" as the header value?)

I take it that there is some concern about the waste of sending this
header every time and that partially motivates inventing new behavior to
supply these values in a MDN (when requested). While that might be more
elegant, I guess the logic would be that you can only use that form of
request when the original has an AS2-Version of "1.2"? My preference
here is not to try to develop option 4 into a new capability query and
response pattern, but just accept that the Ediint-Features header may
waste a few bytes per message. 

How will existing applications respond to this? Presumably they would
(or should) ignore an included "EdiintFeatures" header and also never
send one. If they never sent one (and their ASx-version was either 1.0
or 1.1), then they must not be sent multiparts or CEM. In that case,
messages with the new features would not even be sent to older
applications and could not cause them to malfunction. So it should be
stated that you may not use these features unless the other side both
has a version value greater than 1.1 and also has included the feature
in its EdiintFeatures header.

What should be said about a 1.2 version interoperating with a 1.1
version? Since a 1.1 level app. would be entitled to ignore a message
with a higher version, should a 1.2 app be advised to be configurable to
advertise itself as a 1.1 version to promote interoperation?

What should be done about detecting a change (upgrade) of versions when
the other side begins sending the higher "1.2" value? Are
implementations expected to check the version or is this left to the
implementation? Richard B. says "A should update some state for every
message received from B" I think it would be sufficient to check the
state and update if a change is noticed. (Maybe that is what Richard
meant though.) I suppose an empty message could be sent to announce a
change in capabilities, but again only to ediint agents with a version
greater than 1.1.

So far the specifications have not really required that the version be
checked for every message. For example, the AS3 draft says 

    The AS3-Version header is a header which is required only if the
value

    of the header is not "1.0".  Its purpose is to allow systems to 

    determine which version of this specification, should the

    specification evolve over time, the sender of a document has used to

    package the document. A user agent MUST NOT reject a message if the 

    version header is missing.

    AS3-Version: 1*DIGIT . 1*DIGIT

    A version header value of "1.1" indicates an implementation can

    support EDIINT data compression [18]. A user agent MUST NOT send 

    compressed messages to trading partners who do not use a version 

    header of "1.1" or greater. 

It seems to me that versions greater than 1.1 will need to check the
version values for every message. If a version header is missing, it is
version 1.0.

________________________________

From: [email-masked]
[mailto:[email-masked]] On Behalf Of Kyle Meadors
Sent: Thursday, December 15, 2005 3:21 PM
To: [email-masked]
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:[email-masked]] 
Sent: Wednesday, December 07, 2005 9:14 AM
To: Kyle Meadors; [email-masked]
Subject: RE: profiles in AS2

Seems to me that a combination of features 2 and 4 would provide
everything we'd need.

________________________________

From: [email-masked]
[mailto:[email-masked]] On Behalf Of Richard Bigelow
Sent: Tuesday, December 06, 2005 5:07 PM
To: Kyle Meadors; [email-masked]
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
[email-masked]

________________________________

From: [email-masked]
[mailto:[email-masked]] On Behalf Of Kyle Meadors
Sent: Thursday, December 01, 2005 9:04 AM
To: [email-masked]
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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From: "Kyle Meadors" <[email-masked]>
Date: Tue, 20 Dec 2005 10:29:36 -0600

The closing of WG is decision to be made by Rik Drummond and Scott
Hollenbeck. Discussion on EDIINT–Features, CEM and the like are peripheral
to EDIINT but not part of the charter. When EDIINT charter is complete, and
only a decision on AS3 is remaining, the elist will be closed as well. 

However, it is open for the time being – let’s continue to use this space
for this discussion. We have only heard from a relative handful of
individuals – can others chime in? 

Kyle Meadors

DGI

   _____  

From: Richard Bigelow [mailto:[email-masked]] 
Sent: Monday, December 19, 2005 12:56 PM
To: Dale Moberg; Kyle Meadors; [email-masked]
Subject: RE: profiles in AS2

Concerning a 1.2 version interoperating with a 1.1 version:  The 1.1 version
should accept the 1.2 messages.  The compression draft says that a version
of 1.1 or greater indicates compression.  

I have some concern about Kyle's comment that this WG may be closing soon.
Is this in response to IETF's requirement to make progress on AS3?  I hope
that this WG will continue.  We have some proposals on the table, including
Reliability and CEM and perhaps Profiles in the future.

Richard Bigelow
Inovis
HYPERLINK "mailto:[email-masked]"[email-masked]

   _____  

From: [email-masked] [mailto:[email-masked]]
On Behalf Of Dale Moberg
Sent: Saturday, December 17, 2005 7:49 AM
To: Kyle Meadors; [email-masked]
Subject: RE: profiles in AS2

The consensus seems to be that it should be possible to support some AS2
features independently, rather than cumulatively. Although I think the
combinations of features of Reliability, CEM, and Multipart could be coded
up by 8 numbers, if more end user requirements get specified, that encoding
would become inconvenient to support. So moving to an EDIINT-Features header
seems to be a reasonable way to advertise capabilities.

Would AS1, AS2 and AS3 all use this header? I assume that CEM and
attachments are OK, but Reliability mainly pertains to AS2. Also, would AS1
have to add an “X-“ preface to the header? (So we would have somemething
like “X-EdiintFeatures” as the header value?)

I take it that there is some concern about the waste of sending this header
every time and that partially motivates inventing new behavior to supply
these values in a MDN (when requested). While that might be more elegant, I
guess the logic would be that you can only use that form of request when the
original has an AS2-Version of “1.2”? My preference here is not to try to
develop option 4 into a new capability query and response pattern, but just
accept that the Ediint-Features header may waste a few bytes per message. 

How will existing applications respond to this? Presumably they would (or
should) ignore an included “EdiintFeatures” header and also never send one.
If they never sent one (and their ASx-version was either 1.0 or 1.1), then
they must not be sent multiparts or CEM. In that case, messages with the new
features would not even be sent to older applications and could not cause
them to malfunction. So it should be stated that you may not use these
features unless the other side both has a version value greater than 1.1 and
also has included the feature in its EdiintFeatures header.

What should be said about a 1.2 version interoperating with a 1.1 version?
Since a 1.1 level app. would be entitled to ignore a message with a higher
version, should a 1.2 app be advised to be configurable to advertise itself
as a 1.1 version to promote interoperation?

What should be done about detecting a change (upgrade) of versions when the
other side begins sending the higher “1.2” value? Are implementations
expected to check the version or is this left to the implementation? Richard
B. says “A should update some state for every message received from B” I
think it would be sufficient to check the state and update if a change is
noticed. (Maybe that is what Richard meant though.) I suppose an empty
message could be sent to announce a change in capabilities, but again only
to ediint agents with a version greater than 1.1.

    The AS3-Version header is a header which is required only if the value

 

It seems to me that versions greater than 1.1 will need to check the version
values for every message. If a version header is missing, it is version 1.0.

   _____  

From: [email-masked] [mailto:[email-masked]]
On Behalf Of Kyle Meadors
Sent: Thursday, December 15, 2005 3:21 PM
To: [email-masked]
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 

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

   _____  

Seems to me that a combination of features 2 and 4 would provide everything
we’d need.

   _____  

From: [email-masked] [mailto:[email-masked]]
On Behalf Of Richard Bigelow
Sent: Tuesday, December 06, 2005 5:07 PM
To: Kyle Meadors; [email-masked]
Subject: RE: profiles 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
HYPERLINK "mailto:[email-masked]"[email-masked]

   _____  

From: [email-masked] [mailto:[email-masked]]
On Behalf Of Kyle Meadors
Sent: Thursday, December 01, 2005 9:04 AM
To: [email-masked]
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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