--- old/src/share/jaxws_classes/com/sun/xml/internal/ws/encoding/MtomCodec.java	2013-08-13 18:18:00.211914745 +0200
+++ new/src/share/jaxws_classes/com/sun/xml/internal/ws/encoding/MtomCodec.java	2013-08-13 18:18:00.151912088 +0200
@@ -41,6 +41,7 @@
 import com.sun.xml.internal.ws.message.MimeAttachmentSet;
 import com.sun.xml.internal.ws.streaming.XMLStreamWriterUtil;
 import com.sun.xml.internal.ws.util.ByteArrayDataSource;
+import com.sun.xml.internal.ws.util.xml.NamespaceContextExAdaper;
 import com.sun.xml.internal.ws.util.xml.XMLStreamReaderFilter;
 import com.sun.xml.internal.ws.util.xml.XMLStreamWriterFilter;
 import com.sun.xml.internal.ws.streaming.MtomStreamWriter;
@@ -374,8 +375,11 @@
         private void writeBinary(ByteArrayBuffer bab) {
             try {
                 mtomAttachments.add(bab);
-                writer.setPrefix("xop", XOP_NAMESPACEURI);
-                writer.writeNamespace("xop", XOP_NAMESPACEURI);
+                String prefix = writer.getPrefix(XOP_NAMESPACEURI);
+                if (prefix == null || !prefix.equals("xop")) {
+                    writer.setPrefix("xop", XOP_NAMESPACEURI);
+                    writer.writeNamespace("xop", XOP_NAMESPACEURI);
+                }
                 writer.writeStartElement(XOP_NAMESPACEURI, XOP_LOCALNAME);
                 writer.writeAttribute("href", "cid:"+bab.contentId);
                 writer.writeEndElement();
@@ -513,8 +517,7 @@
 
         @Override
         public NamespaceContextEx getNamespaceContext() {
-            NamespaceContext nsContext = reader.getNamespaceContext();
-            return new MtomNamespaceContextEx(nsContext);
+            return new NamespaceContextExAdaper(reader.getNamespaceContext());
         }
 
         @Override
@@ -522,35 +525,6 @@
             throw new UnsupportedOperationException();
         }
 
-        private static class MtomNamespaceContextEx implements NamespaceContextEx {
-            private final NamespaceContext nsContext;
-
-            public MtomNamespaceContextEx(NamespaceContext nsContext) {
-                this.nsContext = nsContext;
-            }
-
-            @Override
-            public Iterator<Binding> iterator() {
-                throw new UnsupportedOperationException();
-            }
-
-            @Override
-            public String getNamespaceURI(String prefix) {
-                return nsContext.getNamespaceURI(prefix);
-            }
-
-            @Override
-            public String getPrefix(String namespaceURI) {
-                return nsContext.getPrefix(namespaceURI);
-            }
-
-            @Override
-            public Iterator getPrefixes(String namespaceURI) {
-                return nsContext.getPrefixes(namespaceURI);
-            }
-
-        }
-
         @Override
         public int getTextLength() {
             if (xopReferencePresent) {