Notes from the OASIS
WSRF TC Teleconference
July 12th 2004
Roll call
The roll call is kept on the TC web site under the meeting record.
See http://www.oasis-open.org/apps/org/workgroup/wsrf/event.php?event_id=5432
Phone: TomF, SimonLaws, Mario (epcc), DavidLevine.
Irc: SueM
Ian, Alan Weissberger, Steveg, TomM, Alan Regnier, Latha, Lily,SamMeder, Abdeslem, Willliam, Jem, BryanMurray,William, Martin, Anish, Hide, Tim, Igor, Roger Mendez, Dave Snelling,
Approval of minutes from previous meeting (12th July)
See: http://www.oasis-open.org/apps/org/workgroup/wsrf/download.php/7732/
There were no comments and no objections to approving the minutes.
Other Action Review
There were no comments on the minutes and no objections to approving them.
(Bryan) Move issue 16 to ‘resolved’, issues 23 & 34 to ‘closed’ & issue 48 to ‘open’ Done
(Bryan) Open new issue as a result of the requirement from WSDM: Ability to register for notification when any of the properties changes. Done (issue 55)
(SteveG) Draft detailed proposal for new ops to resolve Issue 21: Factoring of SetResourceProperties. Publish to mailing list. Done
(SamM) Propose resolution text for issue 48 (Nillable properties). Publish to mailing list. Outstanding (but See below)
(IanR) Cancel phone call on July 26th Done
(SamM) Publish a list of the errata on the published drafts to the mailing list. Done
Agenda bash and Call for AOB
(MatinC): Is the document management sorted out.
(DaveS). Document review is described in the issues document
(MartinC) Please can we discuss because tracking continuous small changes is hard. We need a plan for a document release cycle.
(DaveS) Agreed.
Issue review
Issue 48: Nillable properties
(SamM): The document is fine if the – just needs some explanatory information. Is thi
(TimB): We can produce a document containing this kind of non-normative information. Please publish material to
( ): What’s the difference. Whitepapaer explains concepts and puts stakes in the ground, tuseful for explaining what the WSRF TC is about. It is not a deliverable of the TC.
A primer could be deliverable of the TC, nad
(?1) In other OASIS TCs, this has been called an implementers guide. How are return codes interpreted etc.
(DaveS) we are gathering information for such a document.
Action: (Bryan) Re-categorise the issue as an application note and (Alan Wiessberger) create an issue to discuss the creation of a ‘Usage Notes’ document.
Issue 4: GetResourceProperty on property document with xsd:any
(SteveG) Properties can be made dynamically visible – for example a stack trace is useful, but not obviously part of the resource property. The question is how to respond to a request for a property which does not exist. One proposal is to return a fault, or return an empty element (since the property is potentially there).
(William) It is useful to diagnose typos in requests.
(Anish) Getting an any is the same as a property that is optional, but not present.
(TomM) It should be up to the implementer to decide the meaning of any.
(SteveG) Need to distinguish the use cases between dynamic properties and extensibility. An extensibility use should reject unknown requests.
(DaveS) extensibility is guaranteed by the ‘cut and paste’ rule.
(SteveS) a) for minoccurs=0 a nil response is right (Agreed)
b) For an instance document with a dynamic ‘stacktrace’ a request for ‘stooktrace’ should return an error.
c) What if there is a request for a property that sometimes is present
(TomM) The server may behave as if its there, or if its not. It may even depend on the timing of the request vs the creation of the property by the service we can only describe what the service could do.
Action: Steve to propose text. (Hopefully, for review later in the meeting)
Issue 9: Need an API to list all properties
(DaveS) Reads proposed recommendations from Steve here:
http://www.oasis-open.org/archives/wsrf/200406/msg00070.html
(TimB) What is the use case – what are the ‘metrics’ that can exploit these dynamic properties?
(WilliamV) An example is a printer in front of which is placed a proxy which counts pages. A printer might have paper size, speed and ‘any’ published on a dmtf site. The any can be used to hold a newly-invented page count.
(SteveG) this seems the same as issue 4 – asking the service if a qname is valid as a property name.
(Anish) Perhaps we need a different extensibility mechanism (rather than xsd:any).
(SteveG) We chose xsd:any because the document can still be validated when xsd:any is included as a child element - xsd: any fits the bill.
(Anish) But we’re not valdating the document that comes back to the client.
(DaveS) but the client can validate the property values.
(SteveG) If the printer designers want to introduce a new property they can cut and paste (WSDL1.1) document and extend it, or they can introduce it via the any, and always call it dynamic.
(MartinC)We sould have more restrictive ‘any’s in application-specific domains (such as WSDM or a manufacturer-extension).
(DavaS) Yes, but we are defining a general mechanism.
We need to decide: Do we need a scheme for obtaining the info
Is it Via resource property or via operation
Do we need qnames known by the service, present at the service, and do we need to set the schema.
(TomM) It’s not clear what the schema would add over the qname + schemalocation – the clients mostly can’t use the schema dynamically to discover the meaning of the property.
(IanR) We need to distinguish the need to know which properties are defined, and issue 27 which is about the properties currently ‘present’ (non-empty).
(William) there are three issues. Get ‘known’ properties, get ‘present’ properties, and get all the values.
(TomM)we need to rationalize the term ‘present’ vs ‘known’ which is interesting in the case of minoccurs=0. This would produce an empty response.
(SteveG) Is there a distinction between ‘present’ and ‘known’ if we include ‘empty’ as a valid response.
(Anish) ‘Known’ would return all qnames – even those created dynamically.
(IanR) Seem agreed that issue 9 is a requirement. We need to discuss the details.
(long…) discussion produced this picture:
Where
§ R1 is <GetRPResponse/> (A response to a request for a property which has minoccurs=0 and for which there are no property values.)
§
R2 is a reponse to a request for a non-nill value
element.
<getRPResponse>
<tns:something/>
</getRPResponse>
§
R3 is a in response to a request for a value which
is nill:
<getRPResponse>
<tns:something xsi:nil=true/>
</getRPResponse>
§ R4 is a ‘Qnames not recognised’ fault.
(SteveG)
Proposed we need two resource properties:
- WSRP: AllowedRPQnames
- WSRP: PresentRPQNames
Neither is required, and either can be present without the other.
Both properties would be lists of structures of two values, a url indicating a qname and a url indicating schemalocation.
We also need to address the need for minoccurs/maxoccurs of the property.
Action: (Martin Chapman) Need a new issue to address Schema discovery on a dynamic property., including the cardinality within the RP document – need more information in the Allowed/Present RPQNames variables.
(Igor) Do we need this minoccurs/maxoccurs/nillable info? – it could be simply read from an offline specification (description) of the service written in English.
(Anish) Then why do we bother in the case of the statically declared RPs?
(steveG) A solution to the new issue is to define an operation GetRPDecl(QName) which returns an xsd:element with the additional information on it.
(DaveS) We are going to add this stuff:
Proposed a) A new resource property – allowedRPQNames, ie those which will not throw ‘unknown resource’ fault.
This properties will return the relevant RP QNames and the schemalocation.
(No objections)
Proposed b) A new resource property – presentRPQNnames, which indicates a property of the relevant name in the instance document.
This property will return the relevant RP QNames and the schemalocation.
(No Objections)
Proposed c) A capability - GetRPDecl (QName) - to return the current RP document declaration ( minoccurs/maxoccurs/nillable etc) for each QName requested.
(No Objections)
Issue 10: Mechanism to express metadata on properties such as ‘Read Only’
(IanR)Where can we put this information
(SteveG) In OGSi, putting it into the schema broke xml tooling because it exploited open content – it needs to go into a different document. We need to agree what the properties are and where to put them are, for example: 1) ‘Appinfo’ in the xsd schema (which is a child of annotation) 2) Use the ‘any’ attribute, but tools really don’t like the latter. 3) A separate metadata document.
(William) are these things needed at design time, run time or both.
(SteveG) Both.
(Igor) So we could use the annotation at design time and pull out the attributes into a separate document at runtime, if needed?
(SteveG) Yes, that could be done.
(DaveS) Can the metadata be out into the new GetRPDecl(QName) operation.
(SteveG) Yes. But that leave the design time question. Having one document (all in the Schema) is neat, but so is the ability to deploy a service independently from the design stage which suggests a separate deployment document.
(DaveS) There may be some properties which are invariant wrt implementation – eg current time is read only – it can’t be made settable.
(SteveG) Yes, but there’s a lot that is independent.
(Lily) Will the attreibutes be extensible
(SteveG) Yes, They need to be.
(DaveS) Proposed: To add metadata to the RP declaration.
(No objections)
Action: (TomMaguire) Write a description of a new metadata document to hold the info, and an operation for runtime access.
(DaveS) So the properties in OGSi were: Modifyable (Boolean), Mutability (static, constant, extendable, mutable)
(Igor) Insertable, deletable, updateable?
(SteveG) xsd:default only works for simple types, but many properties will be complex types, so we need another mechanism.
(TomM) Schema defaults are for the use of the schema processor, it is not present in an instance document, but is inferred in the PSVI (post-schema validation infoset) at the client.
Action: This meaning of ‘default’ use of needs to be elucidated. Need a new issue on the list (MartinC)
(DaveS) Do we need a facility for data in the WSDL?
(Igor) No – the client only needs one round trip to get the value - it should be the same as a constant (unchanging) value set at service initialisation.
(DaveS) But it may be useful to be able to specify this at design time. The list seems to be:
§ Insertable:bool
§ Updateable: bool
§ Deleteable: bool
§ Readable: bool
§ Initial Value(s): <any>
§ Constant: bool
§ ValidValue: <any> (??)
Action: TomMaguire – write a proposal. – including how to get these values which was not discussed.
Issue 21 Splitting SetResourceProperties
(IanR) A proposal was published by Steve to introduce set/update/delete methods:
http://www.oasis-open.org/archives/wsrf/200407/msg00065.html
Proposed: to accept this as the text:
(except for a few small typos to be noted to SteveG) No objections
Recessed at 17:03 to reconvene at 9:00 am.
Review New issues since last telecom
Any Other Business
Meeting closed
Summary of actions