- From: Dan Brickley <danbri@w3.org>
- Date: Tue, 16 Oct 2001 22:25:18 -0400 (EDT)
- To: Andrew Layman <andrewl@microsoft.com>
- cc: <Noah_Mendelsohn@lotus.com>, "Hutchison, Nigel" <Nigel.Hutchison@softwareag.com>, <jacek@idoox.com>, <xml-dist-app@w3.org>
What is a "DLG schema"? Dan On Tue, 16 Oct 2001, Andrew Layman wrote: > We are using in a limited way the ID mechanism in section 5. The SOAP > encoding rules allow us to convert from a DLG instance plus DLG schema > to XML syntax plus XML schema; they also allow the reverse translation. > The reference to ID indicates that in such a produced XML schema, the > "id" attribute should be of type ID. However, the conversion from an > XML instance to a DLG instance is determined by the DLG schema, not the > XML schema. Hence, it is true but not a problem that, as Asir notes, > the schema information, if any, that asserts the ID type is not used > during XML to DLG conversion. > > -----Original Message----- > From: Noah_Mendelsohn@lotus.com [mailto:Noah_Mendelsohn@lotus.com] > Sent: Tuesday, October 16, 2001 2:03 PM > To: Hutchison, Nigel > Cc: danbri@w3.org; jacek@idoox.com; xml-dist-app@w3.org > Subject: RE: Issue 29: Exist non-serialisable data models? > > There are limitations on the XML that can be within a SOAP envelope. No > > PI's, no user-defined entities (no internal subset DTD), and although > there have been some very useful points made by Asir that suggest we > aren't really using the XML ID mechanism, in practice (because XML only > knows about ID types when DTDs are processed, and we don't have 'em) > it's > probably a mistake to duplicate an ID values between the contents of > your > data and any ID's used in other header entries. > > ------------------------------------------------------------------------ > Noah Mendelsohn Voice: 1-617-693-4036 > Lotus Development Corp. Fax: 1-617-693-8676 > One Rogers Street > Cambridge, MA 02142 > ------------------------------------------------------------------------ > > > > > > > > "Hutchison, Nigel" <Nigel.Hutchison@softwareag.com> > Sent by: xml-dist-app-request@w3.org > 10/16/01 12:56 PM > > > To: "'Jacek Kopecky'" <jacek@idoox.com>, danbri@w3.org > cc: xml-dist-app@w3.org, (bcc: Noah Mendelsohn/CAM/Lotus) > Subject: RE: Issue 29: Exist non-serialisable data > models? > > Jacek, > > Supposing a Soap message carried a query(say X-Query) to an XML Database > > and > the database sent back a response > representing a node set as a serialized XML document. Would all possible > responses be encodeable as a SOAP data model? > I think not - unless it was a severely crippled XML Database. > > But it seems like a reasonable requirement. In fact users have asked for > > it. > > Does this support your case? > > Nigel W.O Hutchison > Chief Scientist > Software AG > Uhlandstr 12,D-64297 Darmstadt, Germany > +49 6151 92 1207 > > > > > -----Original Message----- > From: Jacek Kopecky [mailto:jacek@idoox.com] > Sent: Tuesday, October 16, 2001 6:02 PM > To: danbri@w3.org > Cc: xml-dist-app@w3.org > Subject: Re: Issue 29: Exist non-serialisable data models? > > > Dan, > > You seem to assume that data passed in SOAP messages must > follow the SOAP data model and be encoded using the SOAP encoding > rules. Neither is true, please read on. > > As SOAP (as specified in [3], without the Adjuncts) is a > messaging protocol, it can carry any data serialized into XML. > >From the point of view of the core SOAP, the serialization rules > are application-dependent. > > SOAP provides a mechanism for specifying the encoding rules used > for serialization of the data contained in a message - the > encodingStyle attribute information item (see [1]). A specified > encodingStyle implicitly specifes also the data model. > > Requirement R402 (and the issue #29 resulting from it) says that > SOAP must be able to serialize data in data models not directly > representable by XML Schema (which would be a tree data model). > It explicitly mentions the object graph data model. > > SOAP specifies a serialization of one data model, and that would > be sections 4 and 3 of Adjuncts [2], so that any data following > this data model, which is prevalent e.g. in RPC applications, can > be serialized in a common way. I agree the data model section is > yet to be written. > > In case an application's data follows the data model from > section 3, it may be serialized using the encoding rules from > section 4. > > In case an application's data (like RDF, for example) doesn't > map naturally onto our data model, the application can use its > own serialization rules, which can follow some already existing > specification. Applications wishing to communicate RDF data only > need to agree on a URI that would identify the RDF XML > representation, and use that as the encodingStyle attribute > information item's value. The serialized form would then follow > the already existing RDF XML representation. > > So I think the right resolution to issue #29 would be: > > "SOAP specifies how to encode data from the object-graph data > model. SOAP also allows the encoding of other data models > representable in XML using custom encoding rules identified in > the encodingStyla attribute information item in a message. > Therefore no data models exist that are serializable to XML but > not serializable to SOAP." > > Jacek Kopecky > > Idoox > http://www.idoox.com/ > > [1] http://www.w3.org/TR/2001/WD-soap12-part1-20011002/#soapencattr > [2] http://www.w3.org/TR/2001/WD-soap12-part2-20011002/ > [3] http://www.w3.org/TR/2001/WD-soap12-part1-20011002/ > > > > On Fri, 12 Oct 2001, Dan Brickley wrote: > > > > > Hi Paul, > > > > > > On Thu, 11 Oct 2001, Paul Cotton wrote: > > > > > Issue 29: "Exist non-serialisable data models?" from [1] implies > that > > > there _might_ be data models that cannot be encoded using the SOAP > 1.2 > > > data model. > > > > > > When this issue was created I suggested [2] that it was > > > only a true issue if someone could bring forward such a > non-serialisable > > > data model. I would like to propose we now close this issue (with > no > > > further action) based on the following resolution text: > > > > > > "The current SOAP/1.2 model is capable of representing directed > graphs > as > > > well as object graphs and enables a recipient to deserialize an XML > > > instance to recreate those graphs. It is not clear whether there > are > > > other data models that potentially are interesting to serialize but > > not > > > representable within the SOAP data model. Since no examples of > > > non-serialisable data models have been brought to the attention of > the > > > XML Protocol WG, it is proposed to resolve this issue with no > further > > > changes to SOAP 1.2." > > > > > > This is premature!. All the while the SOAP/1.2 spec sports a section > "The > > SOAP Data Model[3] that is yet to be written, you cannot reasonably > close > > this issue by saying "nobody failed to map to our model". Right now, > the > > latest SOAP Working Draft says, under Data Model: > > > > "This section is the placeholder for the description of > > the SOAP > data > > model". > > > > The XML Protocol WG charter[4] explicitly calls out (s1.4) two > particular > > information models, RDF and UML. I don't know much about the UML/SOAP > > relationship, but I've been looking out for opportunities to map RDF > into > > SOAP. > > > > You propose to move directly from the current Issue 29 text, > > > > "The current SOAP/1.1 model seems to be capable of > representing > > directed graphs as well as object graphs [...]" > > > > ...to closure of this issue w.r.t. SOAP 1.2. I suggest we > > wait until a version of 1.2 has been published that includes a > > specification of the SOAP Data Model. Currently, the SOAP Data Model > is > > not explicitly articulated, but is described rather indirectly > through > a > > rather narrative account of the serialized form given in section > > 4 of the specification. This makes it hard for other groups reviewing > SOAP 1.2 to > > assess the expressivity of the SOAP data model, or to say with any > > confidence that SOAP can, or cannot, adequately encode their data > model. > > > > I appreciate the need to finalise a SOAP 1.2 specification asap, and > that > > there may be other reasons to leave some aspects of the > encoding/serialization > > work to future efforts. Nevertheless, I really don't think the > current > > proposed closure is appropriate at this stage. My particular concern > here > > is the importance of keeping W3C's RDF work alligned with mainstream > > developments in the XML world, notably SOAP. RDF was, per [3], > brought > to > > the attention of the Protocols WG from the start, and makes a fine > test > > case for the closure of Issue 29. I have been looking forward to the > day > when I > > can point RDF implementors at a maturing SOAP spec > > and say "here's the SOAP data model; here's a suite of SOAP test > > cases; do these map to/from RDF?". I don't believe we're at that > stage > > yet, and that consequently it is too early to say that > > > > ..."no examples of non-serialisable data models have > been > > brought to the attention of the XML Protocol WG". > > > > > > The RDF community has been living with a W3C REC (the '99 RDF Model > > and Syntax spec) that did not adequately distinguish between an > abstract > > information model and its particular default XML encoding. For RDF, > this > caused > > significant problems for users of the spec, which we are now > addressing > > through a reformulation of the RDF syntax spec[5], through a more > formal > > and mathematical account of our underlying model[6], and through a > set > of > > test cases that guide our discussions[7]. My understanding is that > the > > SOAP 1.2 spec is taking a similar turn: a re-articulation of the SOAP > > Data Model, (also too the account of serialization rules?), and I > believe > > working towards a SOAP test suite? If so, these efforts have more in > > common with the RDF Work than some might have expected. > > > > > > I didn't mean to write such a long note, just really wanted to pop up > > and > > say "please don't close this issue before publishing a description of > > the > > SOAP data model". When that's done, I will take care (via the W3C XML > > and > > S.W. CGs) to make sure the spec gets a careful review from > > the RDF community, particularly regarding the ability to round-trip > RDF > > data graphs through a SOAP representation. > > > > best wishes, > > > > danbri > > > > > > > > [3] http://www.w3.org/TR/soap12-part2/#datamodel > > [4] http://www.w3.org/2000/09/XML-Protocol-Charter#scope > > [5] http://www.w3.org/TR/rdf-syntax-grammar/ > > [6] http://www.w3.org/TR/rdf-mt/ > > [7] http://www.w3.org/TR/rdf-testcases/ > > > > > >
Received on Tuesday, 16 October 2001 22:25:22 UTC