- From: Doug Davis <dug@us.ibm.com>
- Date: Sun, 8 Feb 2009 16:28:47 -0500
- To: Geoff Bullen <Geoff.Bullen@microsoft.com>
- Cc: Gilbert Pilz <gilbert.pilz@oracle.com>, "public-ws-resource-access@w3.org" <public-ws-resource-access@w3.org>
- Message-ID: <OF739CA209.4A7859CB-ON85257557.006BF729-85257557.00760587@us.ibm.com>
Geoff,
this raises some interesting questions, points and possibilities.
1 - can you show me where this alignment of HTTP and Transfer is viewed by
the W3C Team/Tag as good thing? As I've stated before, the team comments
[1] talk about a "parallel" between the two but that is not the same thing
as a statement of love. In fact, the rest of the team comments, and Tim's
comments [2] could be interpreted as the exact opposite. The sharing of
similar verbs is not enough to "align" the two. IMO, the key quote is
(bolding is mine):
...which means that WS-Transfer resources are potentially identified by
more than just a URI, making them unsuitable for referencing and use in
other Web technologies
I'm having a hard time thinking of another WS spec that has caused more
tension between the Web/HTTP and SOAP worlds - aside from perhaps
WS-Addressing - and Transfer seems to have all of those same criticisms
plus more.
2 - you seem to be really straining hard to avoid using meaningful XML
elements in the Body. Can you please explain why? Most WS specs have
element names in the Body that are not meaningless and in fact you
yourself opened an issue for MEX to follow this same pattern [3]. Why
should WS-Transfer be different from the other WS specs? I feel like
there's something deeper here and you're not letting us in on the secret.
Especially when in the note below you now seem to be ok with a wrapper -
but you want it to have an HTTP-based meaning.
3 - you assert that "More than other specifications, Transfer should
continue to be aligned with HTTP", I actually very strongly disagree with
this. Web Services are transport agnostic and any attempt to make it
favor one transport over another should not be allowed.
4 - WS-Transfer is, first and foremost, a SOAP specification. Given a
choice between aligning with HTTP and the rest of the SOAP
specifications/stacks, I'd choose the latter.
5 - having said that, your insistence that WS-Transfer be aligned with
HTTP is an interesting perspective and one that I think we need to
consider further - especially given the W3C's concerns about its lack of
alignment with the Web itself. I think in the interest of trying to
address the W3C concerns (and this alignment you seem to see), I would
suggest that we consider having WS-Transfer profile its use of
WS-Addressing so that it bans the use of reference-parameters for
identification purposes - in all transports. (We may even want to
consider banning their use entirely just to really force the issue). And
we then make a formal requirement that a "naked HTTP GET" to the
wsa:Address of a WS-Transfer resource's EPR be the semantic equivalent of
a WS-Transfer.Get to that same resource. This requirement will ensure two
things: 1) people aren't ignoring the "no ref-params for identification
purposes" rule, and 2) address the W3C's concern about whether WS-Transfer
resources will play nicely with the rest of the Web technologies. IMO,
this will go a lot further to align HTTP and WS-Transfer than worrying
about the name of an XML wrapper.
[1] http://www.w3.org/Submission/2006/04/Comment
[2] http://lists.w3.org/Archives/Public/www-tag/2006Oct/0061.html
[3] http://www.w3.org/Bugs/Public/show_bug.cgi?id=6500
thanks
-Doug
______________________________________________________
STSM | Standards Architect | IBM Software Group
(919) 254-6905 | IBM 444-6905 | dug@us.ibm.com
Geoff Bullen <Geoff.Bullen@microsoft.com>
02/08/2009 01:03 PM
To
Gilbert Pilz <gilbert.pilz@oracle.com>
cc
Doug Davis/Raleigh/IBM@IBMUS, "public-ws-resource-access@w3.org"
<public-ws-resource-access@w3.org>
Subject
RE: issue 6398: updated proposal - HTTP Linkage
Gil,
More than other specifications, Transfer should continue to be aligned
with HTTP. Wrappers represent one area we can look at in order to achieve
that goal. looking at RFC 2616, we note that it uses some specific terms
to refer to what Doug might be calling a wrapper.
Some possibilities we found we:
body
entity-body
message-body
Ashok, do you think that the TAG would find the use of any of these terms
as the wrapper for all 8 Transfer messages as further indication of the
alignment between Transfer and HTTP? Is there another wrapper name that
would be more aligned?
--Geoff
From: Gilbert Pilz [mailto:gilbert.pilz@oracle.com]
Sent: Thursday, February 05, 2009 10:38 PM
To: Geoff Bullen
Cc: Doug Davis; public-ws-resource-access@w3.org
Subject: Re: issue 6398: updated proposal - HTTP Linkage
Geoff,
Let me see if I understand your objections. You are saying (and correct me
if I am wrong) that, because Doug chose to name his wrapper elements
things like "wst:Get" and "wst:Put", this implies that these wrappers will
or should be regarded as verbs. Would it make any difference if we called
them "wst:Foo", "wst:FooResponse", "wst:Baz", "wst:BazResponse", etc.?
- gp
Geoff Bullen wrote:
Doug,
Transfer and HTTP are already linked to some extent, I think we agree on
that, and from the number of emails going around concerning this linkage,
I suspect it is certainly one we need to look at more closely.
One of the ways in which Transfer and HTTP are currently linked, is that
they share a common model.
As stated in an earlier email, the HTTP message body carries the content
(or message body) and not the verb (action). In the same way, the
Transfer SOAP body carries the content and not the action. In both cases,
the action is handled separated from the message body.
Now let?s look at your current wrapper proposal.
While you call it a ?wrapper? proposal, the names you use for those
wrapper elements are the same as the names of the associated actions
(verbs). For example:
The action: ?http://.../transfer/GetResponse? directly maps to a
corresponding outer element in the body:
wst:GetResponse ...>
xs:any +
</wst:GetResponse>
This is the pattern that is used throughout your wrapper proposal.
Stating the obvious, there appears to be a direct correlation between the
action name and the name of the outer element of the soap body (in this
case ?GetResponse?). Whether implied or intentional, this correlation
breaks the basic model of separation (of verb and content) described
earlier. Note that it also violates the basic premise of addressing, that
wsa:action is what is used to differentiate messages.
--Geoff
From: public-ws-resource-access-request@w3.org [
mailto:public-ws-resource-access-request@w3.org] On Behalf Of Doug Davis
Sent: Wednesday, February 04, 2009 3:01 PM
To: public-ws-resource-access@w3.org
Subject: RE: issue 6398: updated proposal
To follow-up on the conf call yesterday....
Geoff mentioned the Team Comments on WS-Transfer [1] as an implicit
endorsement of the supposed alignment between HTTP and WS-Transfer.
However, I think this is not the case:
- the team comments do not actually say that the "parallel" between HTTP
and WS-Transfer is a good thing it just points out that both have similar
verbs/operations.
- in fact, after this similarity is pointed out the comments go on to say
how misaligned WS-Transfer is with the Web due to the use of EPRs instead
of URIs. It says things like WS-Transfer resources could be
"...unsuitable for referencing and use in other Web technologies".
- add to this Tim's comments [2], as Bob pointed out on the call, that
there is a concern over WS-Transfer's lack of alignment with HTTP around
such things as its use (or lack of use) of HTTP GET. Its worth noting
that Tim reiterates the concern about the misalignment of WS-Transfer with
the Web itself because of its use of EPRs.
- also, no where in the team comments do they make any reference to the
notion that because the Body is 'unwrapped' its more aligned with HTTP. It
doesn't even touch on this subject at all. And, as I pointed out on the
call, this would be a mistake for them to even head down this path because
there are lots of cases where the HTTP Body is wrapped (like
mime-encoding) and those are clearly not misaligned with HTTP.
I do agree with Geoff that the alignment of WS-Transfer with HTTP, and the
Web itself, should be more closely examined - especially given the
Team/Tag/Tim comments - but this is a separate issue that has nothing to
do with whether the Transfer operations include a wrapper in the Body or
not.
[1] http://www.w3.org/Submission/2006/04/Comment
[2] http://lists.w3.org/Archives/Public/www-tag/2006Oct/0061.html
thanks
-Doug
______________________________________________________
STSM | Standards Architect | IBM Software Group
(919) 254-6905 | IBM 444-6905 | dug@us.ibm.com
Geoff Bullen <Geoff.Bullen@microsoft.com>
Sent by: public-ws-resource-access-request@w3.org
02/03/2009 12:35 PM
To
Doug Davis/Raleigh/IBM@IBMUS
cc
"public-ws-resource-access@w3.org" <public-ws-resource-access@w3.org>
Subject
RE: issue 6398: updated proposal
Hi Doug,
Having re-read our previous email a couple of times, it is still kind of
unclear exactly what you think we are in agreement on here. J While it is
hopeful we will find common ground at some point, we are not there yet.
Regarding Transfer Create Operation ?
T.Create and RT.Create currently have different cardinalities and one of
them therefore must change in order for them to remain ?in sync?.
The current version of T.Create() states that the first child element MUST
NOT be omitted. But the draft proposal allows senders to emit empty Create
requests. This means, current Transfer Resource Factories cannot process
the proposed Create request messages without changing the underlying
processing logic.
Cheers,
Geoff
From: Doug Davis [mailto:dug@us.ibm.com]
Sent: Monday, February 02, 2009 5:27 PM
To: Geoff Bullen
Cc: public-ws-resource-access@w3.org
Subject: RE: issue 6398: updated proposal
Geoff,
thanks for the comments. I'm glad that we're in agreement that there is
no functional difference between what the current version of Transfer and
my proposal because I tried to ensure that it was just a syntax change. As
to the change of cardinality of Create, I was very clear as to why I
changed it - please reread my proposal. Also, it does not break backwards
compatibility - aside from the addition of a wrapper, existing impls will
still be sending valid WS-T messages.
thanks
-Doug
______________________________________________________
STSM | Standards Architect | IBM Software Group
(919) 254-6905 | IBM 444-6905 | dug@us.ibm.com
Geoff Bullen <Geoff.Bullen@microsoft.com>
02/02/2009 07:32 PM
To
Doug Davis/Raleigh/IBM@IBMUS
cc
"public-ws-resource-access@w3.org" <public-ws-resource-access@w3.org>
Subject
RE: issue 6398: updated proposal
Doug,
We have been looking more closely at the wrapper issue (Issue 6398) and
your current proposal and there are a number of concerns that we have.
Summary
We believe that the proposed changes will affect the current alignment of
Transfer with HTTP, and that it breaks the current implementation of
Transfer by changing the cardinality of message formats. More specific
details can be seen below:
1) Wrappers and the Alignment of Transfer with HTTP
We believe that the proposed wrapper changes disrupt the current alignment
between Transfer and HTTP. Since the TAG articulated in Nov, 2008 that
they were interested in a closer alignment between Transfer and HTTP, it
is unclear to us if this is the right direction for the WG to be heading.
There are a set of principles that guide us as we move through this issue:
a) Transfer continues to have alignment with HTTP as much as possible.
b) Transfer is built on WS-A and honors the WS-A action based dispatch
model.
c) Transfer should be aligned with Basic Profile as much as possible.
With regards to goal a) above, the HTTP message body carries the content
(or message body) and not the verb (action). In the same way, the
Transfer SOAP body carries the content and not the action. We believe
using specific wrapper element names, such as <get> and <getresponse>,
implies there is semantic meaning in those names, which affects the
separation described above and thus disrupts the existing alignment
between Transfer and HTTP. Any semantic meaning also goes against goal
b).
Also with regards to goal a), the WG has not yet received any technical
comments from the TAG nor has the TAG articulated its wishes clearly to
us. Shouldn't we engage the TAG ASAP?
2) Wrappers, Cardinality and the Create verb
While you expressed a desire to treat cardinality as separate from the
wrapper issue, your proposal does in fact change the cardinality of the
Transfer messages, Delete and Create. While changing the cardinality of
T.delete does not break backwards compatibility, changing the cardinality
of T.create certainly does. It is unclear to us why your proposal has
chosen to break backwards compatibility with T implementations. It is our
understanding that there are many current interoperable implementations of
the T spec, so would not it be more prudent to align more closely with the
current version of T?
--Geoff
From: public-ws-resource-access-request@w3.org [
mailto:public-ws-resource-access-request@w3.org] On Behalf Of Doug Davis
Sent: Sunday, January 18, 2009 10:34 AM
To: public-ws-resource-access@w3.org
Subject: RE: issue 6398: updated proposal
Hey Geoff,
thanks for the heads up on the cardinality - I'll double check those - but
what's correct depends on whether you're looking at the schema or the text
of the spec. For example, GetResponse, per the pseudo schema should be as
you noted (+), but per the schema it should be a singleton. Either way -
this is our chance to make sure things are aligned. As for the MEX change,
despite some possible ribbing from Jeff :-), I like consistency - so if
you open an issue I wouldn't object.
All,
below is a modified version of the proposal, showing the pseudo schema
changes to T and RT (some of the cardinalities will vary slightly from
previous proposal and from the specs in an effort to ensure things are
consistent and allow for RT to do its job) - I tried to make a note of
each one as I detected it (hopefully the following shows up ok for
everyone - if not let me know and I'll put it into a separate file):
T-GetRequest: RT-GetRequest:
<wst:Get ... > <wst:Get Dialect="xs:anyURI" ...>
xs:any * <wsrt:Expression ...> xs:any
</wsrt:Expression> *
</wst:Get> </wst:Get>
Note: to allow for more than one Expression, I had to change the 'xs:any
?' to a "xs:any *" on the xs:any of the T.Get(), and for full
extensibility (an attribute on Get could make the need for children
unnecessary).
T-GetResponse: RT-GetResponse:
<wst:GetResponse ...> <wst:GetResponse ...>
xs:any + <wsrt:Result...>xs:any</wsrt:Result> +
</wst:GetResponse> </wst:GetResponce>
Note: We should consider changing the "xs:any +" to "xs:any *" since the
resource representation could technically be empty and we should allow for
that (<wsrt:Result>+ too), and for full extensibility (an attribute on
GetResponse could make the need for children unnecessary).
T-PutRequest: RT-PutRequest:
<wst:Put ...> <wst:Put Dialect="xs:anyURI" ...>
xs:any + <wsrt:Fragment ...> +
</wst:Put> <wst:Put>
Note: We should change "xs:any +" to "xs:any *" to allow for an empty
represenation to be 'put', and for full extensibility (an attribute on Put
could make the need for children unnecessary).
T-PutResponse: RT-PutResponse:
<wst:PutResponse ...> <wst:PutResponse ...>
xs:any ? xs:any ?
</wst:PutResponse> </wst:PutResponse>
Note: We should change the "xs:any ?" to "xs:any *" to allow for full
extensbility.
T-DeleteRequest: RT-DeleteRequest:
<wst:Delete ...> <wst:Delete ...>
xs:any * xs:any *
</wst:Delete> </wst:Delete>
Note: I added the "xs:any *" extensibility point in here.
T-DeleteResponse: RT-DeleteResponse:
<wst:DeleteResponse ...> <wst:DeleteResponse>
xs:any ? xs:any ?
</wst:DeleteResponse> </wst:DeleteResponse>
Note: We should change the "xs:any ?" to "xs:any *" to allow for full
extensbility.
T-CreateRequest: RT-CreateRequest:
<wst:Create ...> <wst:Create Dialect="xs:anyURI" ...>
xs:any * <wsmex:Metadata ...> ?
<wsrt:Fragment ...> *
</wst:CreateRequest> </wst:CreateRequest>
Note: I changed the "xs:any +" to "xs:any *" for three reasons: 1) it
seems like it should be possible to allow the entire resource to have
default values, 2) per the RT spec the mex and fragment elements are
optional, 3) to allow for full extensibility (an attribute on the Create
could make up for the absence of child elements).
T-CreateResponse: RT-CreateResponse:
<wst:CreateResponse ...> <wst:CreateResponse ...>
<wst:ResourceCreated> <wst:ResourceCreated>
xs:any ? xs:any ?
</wst:CreateResponse> </wst:CreateResponse>
Note: We should change the "xs:any ?" to "xs:any *" to allow for full
extensbility.
We should discuss the "xs:any ?" -> "xs:any *" notes I made - if there
isn't any objection we can include it as part of this.
thanks
-Doug
______________________________________________________
STSM | Web Services Architect | IBM Software Group
(919) 254-6905 | IBM T/L 444-6905 | dug@us.ibm.com
Geoff Bullen <Geoff.Bullen@microsoft.com>
Sent by: public-ws-resource-access-request@w3.org
01/16/2009 12:09 PM
To
Doug Davis/Raleigh/IBM@IBMUS
cc
"public-ws-resource-access@w3.org" <public-ws-resource-access@w3.org>
Subject
RE: issue 6398: updated proposal
Doug,
A couple of things:
1) I believe the "xs:any" defined in GetResponse, PutRequest,
CreateRequest should actually be "xs:any +" defining one or more.
2) I am wondering if, for the sake of consistency and extensibility,
we should also be looking at the GetMetadata Request and Response messages
in MEX and adding a similar outer wrappers and extensibility concepts?
Thoughts?
--Geoff
From: public-ws-resource-access-request@w3.org [
mailto:public-ws-resource-access-request@w3.org] On Behalf Of Doug Davis
Sent: Thursday, January 15, 2009 6:36 AM
To: public-ws-resource-access@w3.org
Subject: issue 6398: updated proposal
per my AI from yesterday, the updated pseudo schema for the wrapped
WS-Transfer operations would be:
GetRequest:
<wst:Get ... >
xs:any ?
</wst:Get>
GetResponse:
<wst:GetResponse ...>
xs:any
</wst:GetResponse>
PutRequest:
<wst:PutRequest ...>
xs:any
</wst:PutRequest>
PutResponse:
<wst:PutResponse ...>
xs:any ?
</wst:PutResponse>
DeleteResponse:
<wst:DeleteResponse ...>
xs:any ?
</wst:DeleteResponse>
CreateRequest:
<wst:CreateRequest ...>
xs:any
</wst:CreateRequest>
CreateResponse:
<wst:CreateResponse ...>
<wxf:ResourceCreated>endpoint-reference</wxf:ResourceCreated>
xs:any ?
</wst:CreateResponse>
In looking at how this impacts RT... it shouldn't. RT overrides T's Body
(in some cases already using a wrapper similar to the above) so that can
continue as is. The only thing missing from the previous proposal was the
extensibilty points on the wrapper elements so that attributes could be
added - but that was a typo :-) . Existing RT can continue to override
the the above messages with a well defined element - this, along with the
RT header allows the receiver to know this isn't a normal/vanilla Transfer
operation.
There is no impact on MEX. I couldn't find any reference to the transfer
operations that needed to be changed - no samples using it either.
thanks
-Doug
______________________________________________________
STSM | Web Services Architect | IBM Software Group
(919) 254-6905 | IBM T/L 444-6905 | dug@us.ibm.com
Received on Sunday, 8 February 2009 21:29:32 UTC