Schema Namespace Scope

Question

Is there a way to set the scope that JAXB uses when marshalling? I found that the marshaller inserts a xmlns attribute on each element that needs that particular namespace. Instead, I want my instance documrnents to have the xmlns namespace prefix attribute in the root element declaration. This way, the remote namespace location and prefix is only declared once instead of repeatedly defining it for each complex element inherited from the remote namespace. My schema includes the identification of the remote namespace and prefix and also has an import line to identify the namespace and a specific schema to import from the namespace.
Here is the schema:
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema targetNamespace="urn:xmlns:UGS.MDB" xmlns:cmnLib="urn:xmlns:UGS.CMN" xmlns="urn:xmlns:UGS.MDB" xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified">
     <xs:import namespace="urn:xmlns:UGS.CMN" schemaLocation="Common.xsd"/>
     <xs:include schemaLocation="MdbCommon.xsd"/>
     <xs:element name="MdbClientIDQueryResponse">
          <xs:complexType>
               <xs:sequence>
                    <xs:element ref="CmnQueryDialog"/>
               </xs:sequence>
          </xs:complexType>
     </xs:element>
</xs:schema>
Here is the resulting XML instance document from the Marshaller:
<?xml version="1.0" encoding="UTF-8"?>
<MdbClientIDQueryResponse xmlns="urn:xmlns:UGS.MDB" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="urn:xmlns:UGS.MDB MdbClientIDQueryResponse.xsd">
     <CmnQueryDialog>
          <cmnLib:Security xmlns:cmnLib="urn:xmlns:UGS.CMN">
               <cmnLib:Classification>UNCLASSIFIED</cmnLib:Classification>
               <cmnLib:Handling>String</cmnLib:Handling>
          </cmnLib:Security>
          <cmnLib:Power xmlns:cmnLib="urn:xmlns:UGS.CMN">
               <cmnLib:Current>Low</cmnLib:Current>
               <cmnLib:Remaining>4 hours</cmnLib:Remaining>
          </cmnLib:Power>
          <ClientID>alphatango25</ClientID>
     </CmnQueryDialog>
</MdbClientIDQueryResponse>
Here is what I want the XML instance document to look like:
<?xml version="1.0" encoding="UTF-8"?>
<MdbClientIDQueryResponse xmlns="urn:xmlns:UGS.MDB" xmlns:cmnLib="urn:xmlns:UGS.CMN" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="urn:xmlns:UGS.MDB MdbClientIDQueryResponse.xsd">
     <CmnQueryDialog>
          <cmnLib:Security>
               <cmnLib:Classification>UNCLASSIFIED</cmnLib:Classification>
               <cmnLib:Handling>String</cmnLib:Handling>
          </cmnLib:Security>
          <cmnLib:Power>
               <cmnLib:Current>Low</cmnLib:Current>
<cmnLib:Remaining>4 hours</cmnLib:Remaining>
          </cmnLib:Power>
          <ClientID>alphatango25</ClientID>
     </CmnQueryDialog>
</MdbClientIDQueryResponse>

Answer 1

I also faced the same problems and have the solution. If you unmarshal the object to an outputstream using JAXB, then JAXB has no idea what the current scope is. So, create your xml file using either a SAX XMLEventWriter or a StAX XMLSreamWriter. JAXB 2 allows you to marshal your object to either of these writers. These writers know not to bother rebinding the default namespace and this removes the problem.
Other answers on this thread are very unhelpful. There's nothing wrong with wanting to keep xml readable. Why should my xml be littered with unnecessary namespace declarations. Removing these has cut down my file sizes by several Mb.