castor

Namespace problem when using multiple namespaces

Details

  • Type: Bug Bug
  • Status: Open Open
  • Priority: Major Major
  • Resolution: Unresolved
  • Affects Version/s: 1.1
  • Fix Version/s: None
  • Component/s: XML
  • Labels:
    None
  • Environment:
    Java 1.4, Windows 2000
  • Number of attachments :
    0

Description

Hi all,

I am not 100% sure if this is a bug or if there is a workaround but I have created this as a bug. I am trying to use Castor 1.0M4 as my binding framework inside of XFire 1.2.6 but I am running into a namespace problem. I can reproduce the problem using Castor 1.1 which is what I will describe now. I have a Castor mapping file that defines the mapping for a class "order.Order" in the "http://order" namespace. This order has an orderNumber and 2 names. The names are of type "common.Name" which is in the "http://common" namespace. The mapping file looks as follows:

<?xml version="1.0" encoding="UTF-8"?>
<mapping>
<class name="order.Order">
<map-to xml="order" ns-uri="http://order" ns-prefix="order"/>
<field name="orderNumber" type="integer">
<bind-xml name="order-number" node="element"/>
</field>
<field name="sellerName" type="common.Name">
<bind-xml name="seller-name" node="element"/>
</field>
<field name="buyerName" type="common.Name">
<bind-xml name="buyer-name" node="element"/>
</field>
</class>
<class name="common.Name">
<map-to xml="name" ns-uri="http://common" ns-prefix="common"/>
<field name="firstName" type="java.lang.String">
<bind-xml name="first-name" node="element"/>
</field>
<field name="lastName" type="java.lang.String">
<bind-xml name="last-name" node="element"/>
</field>
</class>
</mapping>

When I create an instance of Order and pass in an orderNumber and 2 names, Castor generates the following XML:

<?xml version="1.0" encoding="UTF-8"?>
<order:order xmlns:order="http://order">
<order:order-number>1234</order:order-number>
<common:seller-name xmlns:common="http://common">
<common:first-name>Bob</common:first-name>
<common:last-name>Smith</common:last-name>
</common:seller-name>
<common:buyer-name xmlns:common="http://common">
<common:first-name>Fred</common:first-name>
<common:last-name>Peterson</common:last-name>
</common:buyer-name>
</order:order>

The important thing to note in the XML generated above is that the "seller-name" and "buyer-name" namespaces are "common" and not "order". The problem is that I cannot generate an XML schema for this (I want a schema for my common types and another for the order). If my seller-name and buyer-name complex types use the "type" attribute to specify my common Name type, then the namespace of seller-name and buyer-name should be "order" and not "common". If my complex types use the "ref" attribute to point to a Name element in my common schema, then I cannot change the name of the element from "name" to "buyer-name" and "seller-name". Please let me know if I am missing something and there is a way to have Castor generate XML in such a way that I can break out the schemas.

Here are the different schemas I have tried:

Attempt 1:

This is how I originally wanted to have my schemas. I have a common schema that defines my "name" type and my order schema uses that type using the "type" attribute:

The common.xsd:

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://www.w3.org/2001/XMLSchema" xmlns:common="http://common" targetNamespace="http://common" elementFormDefault="qualified">
<xsd:complexType name="name">
<xsd:sequence>
<xsd:element name="first-name" type="string"/>
<xsd:element name="last-name" type="string"/>
</xsd:sequence>
</xsd:complexType>
</xsd:schema>

The order.xsd:

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://order" xmlns:order="http://order" xmlns:common="http://common" elementFormDefault="qualified">
<xsd:import namespace="http://common" schemaLocation="common.xsd"/>
<xsd:element name="order">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="order-number" type="xsd:integer"/>
<xsd:element name="buyer-name" type="common:name"/>
<xsd:element name="seller-name" type="common:name"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
</xsd:schema>

The problem with these schemas is that namespace expected for the "seller-name" and "buyer-name" is "order" and not "common". So either I need to be able to configure Castor to return the different namespace (remember, Castor is returning the "common" namespace for the name elements) or I can't use these schemas. Here is an XML that is validated by these schemas:

<?xml version="1.0" encoding="UTF-8"?>
<order:order xmlns:order="http://order" xmlns:common="http://common">
<order:order-number>1234</order:order-number>
<order:seller-name>
<common:first-name>Bob</common:first-name>
<common:last-name>Smith</common:last-name>
</order:seller-name>
<order:buyer-name>
<common:first-name>Fred</common:first-name>
<common:last-name>Peterson</common:last-name>
</order:buyer-name>
</order:order>

Attempt 2:

In order to get the correct namespace for the name elements in the schema, I could define an element in my common schema and refer to this element in the order schema using the "ref" attribute as follows:

The common.xsd (note: I am defining an element instead of a type now):

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://www.w3.org/2001/XMLSchema" xmlns:common="http://common" targetNamespace="http://common" elementFormDefault="qualified">
<xsd:element name="name">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="first-name" type="string"/>
<xsd:element name="last-name" type="string"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
</xsd:schema>

The order.xsd (note: I am using the "ref" attribute in the element instead of specifying a name):

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://order" xmlns:order="http://order" xmlns:common="http://common" elementFormDefault="qualified">
<xsd:import namespace="http://common" schemaLocation="common.xsd"/>
<xsd:element name="order">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="order-number" type="xsd:integer"/>
<xsd:element ref="common:name"/>
<xsd:element ref="common:name"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
</xsd:schema>

With these schemas the namespace for the "name" elements are "common" but now both of the "name" elements need to be called "name". I cannot use the "seller-name" or "buyer-name" names. Here is an XML that is validated by these schemas:

<order:order xmlns:order="http://order" xmlns:common="http://common">
<order:order-number>1234</order:order-number>
<common:name>
<common:first-name>Bob</common:first-name>
<common:last-name>Smith</common:last-name>
</common:name>
<common:name>
<common:first-name>Fred</common:first-name>
<common:last-name>Peterson</common:last-name>
</common:name>
</order:order>

Attempt 3:

The only way I was able to create a schema that would validate the output generated by Castor was to nest my common elements inside a dummy element using the "location" attribute in the Castor mapping file as follows. I replaced my "buyerName" and "sellerName" mapping as follows:

<field name="sellerName" type="common.Name">
<bind-xml name="name" node="element" location="seller-name"/>
</field>
<field name="buyerName" type="common.Name">
<bind-xml name="name" node="element" location="buyer-name"/>
</field>

This generates the following XML where I have the "seller-name" and "buyer-name" in the "order" schema that has a nested "name" element in the "common" schema:

<?xml version="1.0" encoding="UTF-8"?>
<order:order xmlns:order="http://order">
<order:order-number>1234</order:order-number>
<order:seller-name>
<common:name xmlns:common="http://common">
<common:first-name>Bob</common:first-name>
<common:last-name>Smith</common:last-name>
</common:name>
</order:seller-name>
<order:buyer-name>
<common:name xmlns:common="http://common">
<common:first-name>Fred</common:first-name>
<common:last-name>Peterson</common:last-name>
</common:name>
</order:buyer-name>
</order:order>

Here is the common.xsd:

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://www.w3.org/2001/XMLSchema" xmlns:common="http://common" targetNamespace="http://common" elementFormDefault="qualified">
<xsd:element name="name">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="first-name" type="string"/>
<xsd:element name="last-name" type="string"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
</xsd:schema>

And this is the order.xsd:

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://order" xmlns:order="http://order" xmlns:common="http://common" elementFormDefault="qualified">
<xsd:import namespace="http://common" schemaLocation="common.xsd"/>
<xsd:element name="order">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="order-number" type="xsd:integer"/>
<xsd:element name="seller-name">
<complexType >
<xsd:sequence>
<xsd:element ref="common:name"/>
</xsd:sequence>
</complexType>
</xsd:element>
<xsd:element name="buyer-name">
<complexType >
<xsd:sequence>
<xsd:element ref="common:name"/>
</xsd:sequence>
</complexType>
</xsd:element>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
</xsd:schema>

As you can see this makes the schema a lot more complicated and I don't like the fact that I need to have both a "seller-name" and a "name" element nested. But that's the only way I found it to work.

Thanks for your help,
Josh

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Werner Guttmann added a comment -

Before looking into this in detail, can you please let me know why you are using a mapping file even though you are starting with XML schemas ? When you generate the Java sources from your schemas, you don't have to provide a mapping file, as Castor will generate descriptor classes that provide all the information as specified in the XML schema (at (un)marshalling time).

Show
Werner Guttmann added a comment - Before looking into this in detail, can you please let me know why you are using a mapping file even though you are starting with XML schemas ? When you generate the Java sources from your schemas, you don't have to provide a mapping file, as Castor will generate descriptor classes that provide all the information as specified in the XML schema (at (un)marshalling time).
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Artur Karazniewicz added a comment -

I agree with Josh. We've exactly the same problem. Basically, as Josh showed it, there is problem with element, whose type is defined in other namespace.

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Artur Karazniewicz added a comment - I agree with Josh. We've exactly the same problem. Basically, as Josh showed it, there is problem with element, whose type is defined in other namespace.
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Werner Guttmann added a comment -

Fine by me. But I'd still like to see my previous question addressed before starting to analyze things.

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Werner Guttmann added a comment - Fine by me. But I'd still like to see my previous question addressed before starting to analyze things.
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Artur Karazniewicz added a comment -

Werner, in my case I do not wanna generate files from schema. I wanna just map my POJO to XML, without any additional stuff. Found Castor as state of the art solution in this regard. It works really well, except this very problem . Also believe this is probably easy to fix.

Show
Artur Karazniewicz added a comment - Werner, in my case I do not wanna generate files from schema. I wanna just map my POJO to XML, without any additional stuff. Found Castor as state of the art solution in this regard. It works really well, except this very problem . Also believe this is probably easy to fix.
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Werner Guttmann added a comment -

Well, well .. . First off, Josh, I'd like you to try something. Can you please take your preferred solution in terms of XML schemas, and run them through the Castor code generator ? I'd like to get an idea of whether this is related to using mapping files only, of whether the same issue exists with code generation. Would that be an option ?

Show
Werner Guttmann added a comment - Well, well .. . First off, Josh, I'd like you to try something. Can you please take your preferred solution in terms of XML schemas, and run them through the Castor code generator ? I'd like to get an idea of whether this is related to using mapping files only, of whether the same issue exists with code generation. Would that be an option ?
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Werner Guttmann added a comment -

Next, in order to be bale to e.g. debug things, I'd need the Java classes attached to this Jira issue. Thanks in advance,

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Werner Guttmann added a comment - Next, in order to be bale to e.g. debug things, I'd need the Java classes attached to this Jira issue. Thanks in advance,
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David Geary added a comment -

We have exactly the same problem also, and will probably have to use the same work around as above for now (which makes the schemas more complicated than they need to be) - any chance of this being fixed in the next release?

Show
David Geary added a comment - We have exactly the same problem also, and will probably have to use the same work around as above for now (which makes the schemas more complicated than they need to be) - any chance of this being fixed in the next release?
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Werner Guttmann added a comment -

Okay, trying to address your questions/issues one by one.

a) In the original output XML 

<?xml version="1.0" encoding="UTF-8"?>
<order:order xmlns:order="http://order">
   <order:order-number>1234</order:order-number>
   <common:seller-name xmlns:common="http://common">
      <common:first-name>Bob</common:first-name>
      <common:last-name>Smith</common:last-name>
   </common:seller-name>
   <common:buyer-name xmlns:common="http://common">
      <common:first-name>Fred</common:first-name>
      <common:last-name>Peterson</common:last-name>
   </common:buyer-name>
</order:order>

why would you expect that the selelr-name and buyer-name elements carry the order namespace ? In your mapping file, you have specified that the class Name carries a namespace of

{http://common}

common. As such, the output generated by Castor during marshalling meets your definition.

Show
Werner Guttmann added a comment - Okay, trying to address your questions/issues one by one. a) In the original output XML <?xml version= "1.0" encoding= "UTF-8" ?> <order:order xmlns:order= "http: //order" > <order:order-number>1234</order:order-number> <common:seller-name xmlns:common= "http: //common" > <common:first-name>Bob</common:first-name> <common:last-name>Smith</common:last-name> </common:seller-name> <common:buyer-name xmlns:common= "http: //common" > <common:first-name>Fred</common:first-name> <common:last-name>Peterson</common:last-name> </common:buyer-name> </order:order> why would you expect that the selelr-name and buyer-name elements carry the order namespace ? In your mapping file, you have specified that the class Name carries a namespace of {http://common} common. As such, the output generated by Castor during marshalling meets your definition.
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Werner Guttmann added a comment -

The important thing to note in the XML generated above is that the "seller-name" and "buyer-name" namespaces are "common" and not "order". The problem is that I cannot generate an XML schema for this (I want a schema for my common types and another for the order).

Well, here's some observations. If you define a complexType definition in an XML schema, the complexType will be associated with the target namespace of the XML schema where the complexType is defined. You will not be able to change this. When you want to (re-)use this complexType in another XML schema, you've got two options there.

a) import
b) include

Option b) is ppossible if and only if both schema (importing and imported) carry the same namespace. Option a) is always possible, but the namespaces are always relative to the XML schemas where they are defined.

Show
Werner Guttmann added a comment - The important thing to note in the XML generated above is that the "seller-name" and "buyer-name" namespaces are "common" and not "order". The problem is that I cannot generate an XML schema for this (I want a schema for my common types and another for the order). Well, here's some observations. If you define a complexType definition in an XML schema, the complexType will be associated with the target namespace of the XML schema where the complexType is defined. You will not be able to change this. When you want to (re-)use this complexType in another XML schema, you've got two options there. a) import b) include Option b) is ppossible if and only if both schema (importing and imported) carry the same namespace. Option a) is always possible, but the namespaces are always relative to the XML schemas where they are defined.
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Werner Guttmann added a comment - - edited

Somehow I think that you are trying to do something that is in contrast to what XML is at all. I was just looking at the XML schemas given by you in attempt 1 and 2). They are all correct ways of structuring your type definitions and make them re-usable.

For both schema sets given, I used the source generator and generated Java domain classes and descriptor classes, which I then used as input for the Marshaller during marshalling. Nothing wrong about any of those approaches. This is how namespaces and XML schemas can be used to structure your domain model.

Please note that I am not using a mapping file at all, just the classes as generated by the source generator.

Show
Werner Guttmann added a comment - - edited Somehow I think that you are trying to do something that is in contrast to what XML is at all. I was just looking at the XML schemas given by you in attempt 1 and 2). They are all correct ways of structuring your type definitions and make them re-usable. For both schema sets given, I used the source generator and generated Java domain classes and descriptor classes, which I then used as input for the Marshaller during marshalling. Nothing wrong about any of those approaches. This is how namespaces and XML schemas can be used to structure your domain model. Please note that I am not using a mapping file at all, just the classes as generated by the source generator.
Hide
Permalink
Werner Guttmann added a comment -

We have exactly the same problem also, and will probably have to use the same work around as above for now (which makes the schemas more complicated than they need to be) - any chance of this being fixed in the next release?

David, for completeness sake, what exactly is the problem you are having ?

Show
Werner Guttmann added a comment - We have exactly the same problem also, and will probably have to use the same work around as above for now (which makes the schemas more complicated than they need to be) - any chance of this being fixed in the next release? David, for completeness sake, what exactly is the problem you are having ?
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David Geary added a comment -

I want to use option a) above, so I want to import the complex type 'name' from the 'common' namespace.

I'm defining the elements sellername and buyername in the order schema (and hence the order namespace) as the imported complex type. Surely the namespace of those elements should be in the order namespace since they are defined in that schema? and their sub elements in the common namespace since that type is imported?

XML in that format gets validated , but when i use castor to generate the xml the sellername and buyername are in the common namespace and the validation fails.

Show
David Geary added a comment - I want to use option a) above, so I want to import the complex type 'name' from the 'common' namespace. I'm defining the elements sellername and buyername in the order schema (and hence the order namespace) as the imported complex type. Surely the namespace of those elements should be in the order namespace since they are defined in that schema? and their sub elements in the common namespace since that type is imported? XML in that format gets validated , but when i use castor to generate the xml the sellername and buyername are in the common namespace and the validation fails.
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Chien-Hsing Wu added a comment -

Hi. I am encountering the same issue. However, I found that if you don't put ns-prefix in your map-to element and specify your prefix-namespace mappings in your marshaller then the generated xml conforms to what you want; seller-name will be prefixed with order, and elements under common:Name type are prefixed with common.

I believe all this is related to the code in Marshaller class that determines namespace and prefix for a field by looking at the field and class descriptor of that field class. The field descritpor does not have the prefix but it has the namespace from the containg class. The class descrptor has both if you put both ns-prefix and ns-uri in your map-to element. So the class's ns-prefix will be used based on the mapping file. If you dont put ns-prefix the code will get the prefix in the namespace mapping based on the field's ns-uri.

Now coming back to the question about defining 'buyer-name' element in namespace http://order and that element's type 'name' defined in namespace http://common, I believe that the correct xml should have the 'buyer-name' element prefixed with 'order' and the containing elements in

{http://common}

name prefixed with 'common'.

I think it makes sense that this applies to the top-level elements in order.xsd. Meaning that if I define a top-level element called middleman-name like:

<xsd:element name="middleman-name" type="common:name"/>

An correct xml, in my opinion, would be

<order:middleman-name xmlns:order="http://order" xmlns:common="http://common">
<common:first-name>Fred</common:first-name>
<common:last-name>Peterson</common:last-name>
</order:middleman-name>

I understand that the marshaller can be set with a different root element's localPart name. However, there is no way to specify the namespace. if you agree with what I said above, I propose that org.exolab.castor.xml.Marshaller property rootElement be made to accept namespace in addition to the local name. Something thing like

{http://order}

middleman-name. And then change the implementation to support it by setting the field descriptor with the name space properly for the case when it's processing a root element in the method in org.exolab.castor.xml.Marshaller

private void marshal
(Object object,
XMLFieldDescriptor descriptor,
ContentHandler handler,
final MarshalState mstate)
throws MarshalException, ValidationException

Please let me know what you think.

Thanks.

Show
Chien-Hsing Wu added a comment - Hi. I am encountering the same issue. However, I found that if you don't put ns-prefix in your map-to element and specify your prefix-namespace mappings in your marshaller then the generated xml conforms to what you want; seller-name will be prefixed with order, and elements under common:Name type are prefixed with common. I believe all this is related to the code in Marshaller class that determines namespace and prefix for a field by looking at the field and class descriptor of that field class. The field descritpor does not have the prefix but it has the namespace from the containg class. The class descrptor has both if you put both ns-prefix and ns-uri in your map-to element. So the class's ns-prefix will be used based on the mapping file. If you dont put ns-prefix the code will get the prefix in the namespace mapping based on the field's ns-uri. Now coming back to the question about defining 'buyer-name' element in namespace http://order and that element's type 'name' defined in namespace http://common , I believe that the correct xml should have the 'buyer-name' element prefixed with 'order' and the containing elements in {http://common} name prefixed with 'common'. I think it makes sense that this applies to the top-level elements in order.xsd. Meaning that if I define a top-level element called middleman-name like: <xsd:element name="middleman-name" type="common:name"/> An correct xml, in my opinion, would be <order:middleman-name xmlns:order="http://order" xmlns:common="http://common"> <common:first-name>Fred</common:first-name> <common:last-name>Peterson</common:last-name> </order:middleman-name> I understand that the marshaller can be set with a different root element's localPart name. However, there is no way to specify the namespace. if you agree with what I said above, I propose that org.exolab.castor.xml.Marshaller property rootElement be made to accept namespace in addition to the local name. Something thing like {http://order} middleman-name. And then change the implementation to support it by setting the field descriptor with the name space properly for the case when it's processing a root element in the method in org.exolab.castor.xml.Marshaller private void marshal (Object object, XMLFieldDescriptor descriptor, ContentHandler handler, final MarshalState mstate) throws MarshalException, ValidationException Please let me know what you think. Thanks.
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David Geary added a comment -

Chien - thanks for the info. We have got this working as you suggest. The one tricky part was the format of bind-xml for the buyer and seller names. To help anyone else the solution is

1) Remove the ns-prefix in the map-to element - <map-to xml="order" ns-uri="http://order"/>

2) Add the namespace explicitly again in the buyer and seller elements fields -

<field name="sellerName" type="common.Name">
<bind-xml name="order:seller-name" xmlns:order="http://order" node="element"/>
</field>
<field name="buyerName" type="common.Name">
<bind-xml name="order:buyer-name" xmlns:order="http://order" node="element"/>
</field>

(Note the prefixes here are just used to set up the namespace there are not used in the generated xml)

3) Add the prefix-namespace mappings to the marshallers. We are using Spring OXM so this can be done in the spring config there. Actually this is quite nice as is keeps the prefixes in a separate place.

I agree there is still an issue in the code as you describe and it should work the original way as well but at least this works around the problem.

Show
David Geary added a comment - Chien - thanks for the info. We have got this working as you suggest. The one tricky part was the format of bind-xml for the buyer and seller names. To help anyone else the solution is 1) Remove the ns-prefix in the map-to element - <map-to xml="order" ns-uri="http://order"/> 2) Add the namespace explicitly again in the buyer and seller elements fields - <field name="sellerName" type="common.Name"> <bind-xml name="order:seller-name" xmlns:order="http://order" node="element"/> </field> <field name="buyerName" type="common.Name"> <bind-xml name="order:buyer-name" xmlns:order="http://order" node="element"/> </field> (Note the prefixes here are just used to set up the namespace there are not used in the generated xml) 3) Add the prefix-namespace mappings to the marshallers. We are using Spring OXM so this can be done in the spring config there. Actually this is quite nice as is keeps the prefixes in a separate place. I agree there is still an issue in the code as you describe and it should work the original way as well but at least this works around the problem.

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  • Assignee:
    Werner Guttmann
    Reporter:
    Josh
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    Updated: