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Subject: Re: [wsbpel] Issue 88 - Proposal to vote - updated
Hi, Paco. I have a couple of comments/questions about this. In reading the last paragraph about non-transitive imports, it wasn't clear to me whether this also applies to XML Schema include elements. If a BPEL process has this import: <import importType="http://www.w3.org/2001/XMLSchema" location="foo.xsd" namespace="urn:foo"/> and foo.xsd contains <xsd:include schemaLocation="bar.xsd"/> should the XML Schema imported into the BPEL process include bar.xsd? I would think that it should, because the import has brought in the "urn:foo" namespace. If so, perhaps a note could be added, such as: Note that the non-transitivity of import elements does not apply to XML Schema include elements. My other comment is about the paragraph about the<import> element being interpreted as an informational hint. The current text reads that the whole import element is treated as a hint. It seems to me it would be better to only treat the location attribute as a hint. Then the import element is treated as importing elements from a namespace (or from no namespace, in which case the namespace attribute can be omitted), and the location attribute merely provides a hint as to where to find a document describing that namespace. Jim Clune Parasoft Corporation email: jim.clune@parasoft.com 101 E. Huntington Ave. voice: (626) 256-3680 Monrovia, CA. 91016 fax : (626) 256-6884 ----- Original Message ----- From: "Francisco Curbera" <curbera@us.ibm.com> To: <wsbpel@lists.oasis-open.org> Sent: Wednesday, September 14, 2005 6:04 AM Subject: [wsbpel] Issue 88 - Proposal to vote - updated I made some changes following Monica's and Yaron's suggestions. The updated text is below. There are comments by Alex, Chris and Prasad which we can discuss later today if possible. =========================================================================================== The <import> element is used within a WS-BPEL process to explicitly indicate a dependency on external XML Schema or WSDL definitions. Any number of <import> elements may appear as initial children of the <process> element, before any other child element. Each <import> element contains a mandatory and two optional attributes. - namespace. The namespace attribute specifies an absolute URI that identifies the imported definitions. This attribute is optional. An import element without a namespace attribute indicates that external definitions are in use which are not namespace qualified. - location. The location attribute contains a URI indicating the location of a document that contains relevant definitions in the namespace specified. The location URI may be a relative URI, following the usual rules for resolution of the URI base (XML Base and RFC 2396). The location attribute is optional. An import element without a location attribute indicates that external definitions are used by the process but makes no statement about where those definitions may be found. The document located at the location URI MUST identify the definitions it contains with a URI matching the URI indicated by the namespace attribute. - importType. The importType attribute identifies the type of document being imported by providing an absolute URI that identifies the encoding language used in the document. The value of the importType attribute MUST be set to "http://www.w3.org/2001/XMLSchema" when importing XML Schema 1.0 documents, and to "http://schemas.xmlsoap.org/wsdl/" when importing WSDL 1.1 documents. Observe that according to these rules, it is permissible to have an import element without namespace and location attributes, and only containing an importType attribute. Such an import element indicates that external definitions of the indicated type are in use which are not namespace qualified, and makes no statement about where those definitions may be found. The presence of an <import> element should be interpreted as an informational hint to the WS-BPEL processor. In particular, processors are not required to retrieve the imported document from the location specified on the <import> element. Import elements are conceptually unordered. It is an error if the imported documents contain conflicting definitions of a component used by the importing process definition (as could be caused, for example, when the XSD redefinition mechanism is used). A BPEL process definition MUST import all XML Schema and WSDL definitions it uses. This includes all XML Schema type and element definitions, all WSLD port types and message types as well as property and property alias definitions used by the process. Schema definitions defined in the types section of a WSDL document which is imported by a BPEL process definition are considered to be effectively imported themselves and are available to the process for the purpose of defining XML Schema variables. However, documents (or namespaces) imported by an imported document (or namespace) MUST NOT be transitively imported by the BPEL processor. In particular, this means that if an external item is used by a BPEL process, then a document (or namespace) that defines that item MUST be directly imported by the process; observe however that this requirement does not limit the ability of the imported document itself to import other documents or namespaces. The following example clarifies some of the issues related to the the lack of transitivity of imports. Assume a document D1 define a type called a:Type. But a:Type's definition could depend on another type called b:Type which is defined in document D2. D1 could include an import for D2 thus making b:Type's definition available for use within the definition of a:Type. If a BPEL process refers to a:Type it must import document D1. By importing D1 the BPEL process can legally refer to a:Type. But the BPEL process could not refer to b:Type even though D1 imports D2. This is because transitivity of import is not supported by BPEL. Note, however, that D1 can still import D2 and a:Type can still use b:Type in its definition. In order to allow the BPEL process to refer to b:Type it would be necessary for the BPEL process to directly import document D2. --------------------------------------------------------------------- To unsubscribe from this mail list, you must leave the OASIS TC that generates this mail. 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