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https://issues.apache.org/jira/browse/SIS-74?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13696714#comment-13696714
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Martin Desruisseaux commented on SIS-74:
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The approach taken in SIS 0.3 is to put an empty skeleton of 
{{NamespacePrefixMapper}} is the {{sis-utility}} module, and delete the 
compiled {{.class}} with an Ant task executed by the Maven Ant plugin.

Experience with JDK6 and JDK7 suggests that the {{@XmlNs}} annotation works as 
expected with JDK7, while it do not with JDK6. The the "prefix mapping" part 
could be removed on JDK7. However our mapper is also used for defining the 
default namespace. Whether this later feature can also be done with JDK7 still 
need to be verified.
                
> Remove reference to NamespacePrefixMapper from MarshallerPool
> -------------------------------------------------------------
>
>                 Key: SIS-74
>                 URL: https://issues.apache.org/jira/browse/SIS-74
>             Project: Spatial Information Systems
>          Issue Type: Task
>          Components: Utilities
>         Environment: JDK6 and JDK7 (both may need a different approach)
>            Reporter: Martin Desruisseaux
>            Assignee: Martin Desruisseaux
>             Fix For: 0.4
>
>
> h2. The problem
> The SIS {{MarshallerPool}} class uses the {{NamespacePrefixMapper}} class 
> from the {{com.sun.xml.internal.bind}} package. We are obviously not supposed 
> to use this internal class, but research on Internet 3 years ago suggested 
> that they were no way (at least at that time) to specify the root namespace 
> (the namespace that do not need prefix) and to customize the prefixes. Worst, 
> this internal feature was 
> [advertised|http://java.sun.com/webservices/docs/1.5/jaxb/vendorProperties.html]
>  as customizable by the following properties:
> * {{com.sun.xml.internal.bind.NamespacePrefixMapper}} (bundled JAXB)
> * {{com.sun.xml.bind.NamespacePrefixMapper}} (endorsed JAXB)
> Furthermore the {{NamespacePrefixMapper}} javadoc said: "_Implemented by the 
> user application to determine URI -> prefix mapping_".
> As an alternative, research on Internet suggests that the 
> {{javax.xml.bind.annotation.XmlSchema}} annotation works as expected in JDK7, 
> but JDK6 users have to use the endorsed JAXB version 2.2.4 or above. Bundled 
> versions are:
> * Java 1.6.0_37 is bundled with JAXB 2.1.10, so {{@XmlSchema}} doesn't seem 
> to work on that platform.
> * Java 1.7.0_15 is bundled with JAXB 2.2.4-2, so {{@XmlSchema}} would work on 
> that platform but we still have to check if it really works for us.
> Note that the {{NamespacePrefixMapper}} approach is still advertised even in 
> the [JAXB 2.2.6 
> documentation|http://jaxb.java.net/nonav/2.2.6/docs/ch03.html#marshalling-changing-prefixes].
> h2. Using {{NamespacePrefixMapper}}
> If the {{@XmlSchema}} annotations do not work, or if we want to be compatible 
> with the JAXB version bundled in JDK6, then we may have to keep the 
> {{NamespacePrefixMapper}} hack. Problem is that the {{javac}} compiler 
> normally blocks attempts to use this {{com.sun.xml.internal}} class. A 
> workaround found on Internet (not yet tested) is to use the following 
> compiler option:
> {noformat}
> -XDignore.symbol.file
> {noformat}
> If the above does not work, an alternative is to put {{rt.jar}} on the 
> classpath as a Maven dependency using {{<scope>system</scope>}}. But this 
> work only for Oracle JDK.
> An other alternative is to put a 
> {{com.sun.xml.internal.bind.NamespacePrefixMapper}} class with only the 
> method signature in the {{sis-utility}} module, and exclude that class from 
> the JAR file. The {{maven-jar-plugin}} [provides an exclusion 
> mechanism|http://maven.apache.org/plugins/maven-jar-plugin/usage.html] for 
> that kind of purpose, but I have been unable to make it work. We may have to 
> use (again) our {{sis-build-helper}} module for deleting the {{com/**}} files 
> before JAR packaging.

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