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https://issues.apache.org/jira/browse/AXIS2-4071?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Antonio Andrade updated AXIS2-4071:
-----------------------------------
Attachment: AXIS2-4071.patch
Submitting patch. Ready for review:
It's very important to note that the duplication of global element declarations
doesn't come from the WSDLs themselves -i.e. the WSDL is perfectly valid- but
from the fact that Axis2 converts other supported encoding styles into the
Document/Literal encoding style using the WRAPPED convention. This provides
significant advantages, like data abstraction and consistent processing of type
definitions for different binding types but has some side effects (i.e. this
bug). The "fix" for this bug is not trivial; I think it's a trade-off so is
important to keep in mind what we gain/loose with the different approaches that
can be taken.
I think that throwing an exception whenever a collision is detected have two
important implications: one technical and one conceptual, and may not be the
best thing to do. Technically, it would not be that simple -I think- since the
collisions may occur at any level inside imported XML schema documents (which
may add more complexity to the code and harm performance); Conceptually, there
may not be a justification for failing to parse the WSDL model since the
non-validity of the XML schema documents comes from Axis2, not from the WSDL
definition.
The attached patch is driven by the premise that 'internal data handling should
not have any side effect on any external data structure'.
a) It's ok to create new elements but not within the original XML schema
documents which may be used/reused outside of the WSDL11ToAxisServiceBuilder
class and that's why that part of the code was removed in favor of always
creating a separate XML schema document that can isolate all 'internally'
created elements. Creating the new elements in different documents (each for
targetnamespace involved) doesn't solve the duplication problem but clearly
separates the original documents from the created ones.
b) As described in the bug's description, a namespace binding declaration
(XMLNS_AXIS2WRAPPED) was used to 'mark' these new schema documents. This is
important because it can be used to consistently identify the presence of new
elements, which can be used to later determine if an actual duplication problem
exists or not. Previously, new elements could end up being inserted into
existing documents, which 1) is not ideal because of described above and 2)
would add additional complexity while finding duplicated elements declarations
c) Since the duplication problem still exists, the
'AxisService.getSchemaElement' method was updated to start looking the element
in the last-inserted schema document. This may be more intuitive since elements
declarations in the last schema document added would seem to ""overwrite""
previous ones.
d) Because in these type of global element element collisions nobody but the
the client knows which element is the "right" one to be used, clients
interested in resolving the collisions would need to remove/detach the
conflicted schema document from the list of schema documents saved into an
AxisService object (i.e. getting the schema document list through the
'AxisService .getSchema' method and detaching the conflicting schema. Note:
original schema documents may not be able to be removed due to possible
dependencies between other imported documents and the original document).
Again, I don't think any 'fix' for this bug would be trivial. I strongly feel
that the patch being submitted is the cleanest way to handle this but there may
be things that I'm overlooking so hopefully this will be reviewed and
eventually committed into trunk.
> WSDL11ToAxisServiceBuilder + RPC/Literal OR HTTP binding =~ Inconsistent
> XMLSchema object: duplicated global element declarations
> ---------------------------------------------------------------------------------------------------------------------------------
>
> Key: AXIS2-4071
> URL: https://issues.apache.org/jira/browse/AXIS2-4071
> Project: Axis 2.0 (Axis2)
> Issue Type: Bug
> Components: kernel
> Affects Versions: 1.4, nightly
> Environment: Windows XP. 4GB RAM Intel Xeon dual-core @2.75Ghz
> Reporter: Antonio Andrade
> Attachments: AXIS2-4071.patch
>
> Original Estimate: 72h
> Remaining Estimate: 72h
>
> In WSDL11ToAxisServiceBuilder:
> 1) Within the 'setup()' method, a map ('schemaMap') indexed by
> targetNamespace and values equal root (W3C) Elements is populated
> 2) When either a RPC/Literal binding or an HTTP binding with message parts
> referencing type definitions is found, new global element declarations based
> on the WSDL operation name are created. These new elements can either be
> added to an existing (W3C) Document (in case the 'schemMap' contains a
> document with the same target namespace as the one that the newly created
> element has) or added to a newly created Document.:
> a) If a new document is created, an additional namespace mapping
> declaration is added to that document (see 'XMLNS_AXIS2WRAPPED' ). This helps
> distinguishing this document among the other original ones.
> b) If an additional document is NOT created, the new global element
> declarations are added to an existing document. No additional namespace
> mapping declaration is added.
> 3) After all wrapped elements have been created, XmlSchema objects are
> created from the original, modified and newly created W3C Documents
> Note that all this leads to duplicate global element declarations any time
> there's already an element named after an operation name. This is very common
> and happens every time operation names across multiple bindings are the same.
> In general, all this is caused by the creation of XML schema elements while
> transforming operations using the RPC/Literal encoding style into the
> Document/Literal encoding style using the wrapped convention.
> There is more than one problem associated with the creation of new XML global
> element declarations:
> 1) First of all, the XML schema documents end up with duplicated global
> element declarations which makes the Schema invalid. But why nobody seems to
> have noticed it? I think it's just a coincidence, let me explain: A XmlSchema
> object maintains a MAP, indexed by element name (QName) and XmlSchemaElement
> objects as values. This map is used for a faster object retrieval. At the
> same time, the XmlSchema object also maintains a LIST of all nodes
> (XmlSchemaObject objects I think). So whenever duplicate elements are added
> to the schema, the last-inserted elements overwrite the previous elements on
> the MAP of elements but they are inserted with no problems in the LIST of
> nodes and because the latter elements are usually what people is looking for
> (i.e. in case of databinding libraries that create the client stub for a
> single port), the 'correct' element is returned
> 2) If the Definition object (from WSDL4J) is used to populate multiple
> AxisServices from different WSDL ports, for example, within the
> 'WSDL11ToAllAxisServicesBuilder' (which, by the way doesn't seem to work at
> all), the W3C Schema Document may end up with multiple duplicated global
> element declarations and the 'AxisService.getSchemaElement(QName)' method
> will fail to return the appropriate reference.
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