@@ -, +, @@ 
   Register http://www.netbeans.org/ns/foo/1 as ProjectXMLCatalog/foo/1.xsd to be found.
   a. When loading a project, if project.xml is invalid then make the load fail.
      (Effectively preventing older IDEs from trying to load newer IDEs' projects, if schemas changed.)
   b. Validate before saving project.xml/private.xml, to guard against buggy module code.
   c. Validate before loading project.xml/private.xml, to guard against e.g. bad user edits or VCS conflict markers.
   Note that e.g. <configuration> uses lax subelement processing, so children with no matching schemas will be skipped.
   Users can anyway use A-S-F9 to use the regular Validate action before saving.
--- a/ant.freeform/nbproject/project.xml	
+++ a/ant.freeform/nbproject/project.xml	
@@ -123,27 +123,11 @@ 
                     </run-dependency>
                 </dependency>
                 <dependency>
-                    <code-name-base>org.openide.explorer</code-name-base>
-                    <build-prerequisite/>
-                    <compile-dependency/>
-                    <run-dependency>
-                        <specification-version>6.8</specification-version>
-                    </run-dependency>
-                </dependency>
-                <dependency>
                     <code-name-base>org.openide.filesystems</code-name-base>
                     <build-prerequisite/>
                     <compile-dependency/>
                     <run-dependency>
                         <specification-version>6.2</specification-version>
-                    </run-dependency>
-                </dependency>
-                <dependency>
-                    <code-name-base>org.openide.io</code-name-base>
-                    <build-prerequisite/>
-                    <compile-dependency/>
-                    <run-dependency>
-                        <specification-version>1.2</specification-version>
                     </run-dependency>
                 </dependency>
                 <dependency>
@@ -158,14 +142,6 @@ 
                     <compile-dependency/>
                     <run-dependency>
                         <specification-version>6.2</specification-version>
-                    </run-dependency>
-                </dependency>
-                <dependency>
-                    <code-name-base>org.openide.text</code-name-base>
-                    <build-prerequisite/>
-                    <compile-dependency/>
-                    <run-dependency>
-                        <specification-version>6.16</specification-version>
                     </run-dependency>
                 </dependency>
                 <dependency>
--- a/ant.freeform/src/org/netbeans/modules/ant/freeform/FreeformProject.java	
+++ a/ant.freeform/src/org/netbeans/modules/ant/freeform/FreeformProject.java	
@@ -86,7 +86,6 @@ 
         eval = new FreeformEvaluator(this);
         lookup = initLookup();
         Logger.getLogger(FreeformProject.class.getName()).log(Level.FINER, "Initializing project in {0} with {1}", new Object[] {helper, lookup});
-        new ProjectXmlValidator(helper.resolveFileObject(AntProjectHelper.PROJECT_XML_PATH));
     }
     
     public AntProjectHelper helper() {
--- a/ant.freeform/src/org/netbeans/modules/ant/freeform/ProjectXmlValidator.java	
+++ a/ant.freeform/src/org/netbeans/modules/ant/freeform/ProjectXmlValidator.java	
@@ -1,245 +0,0 @@ 
-/*
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
- *
- * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
- *
- * The contents of this file are subject to the terms of either the GNU
- * General Public License Version 2 only ("GPL") or the Common
- * Development and Distribution License("CDDL") (collectively, the
- * "License"). You may not use this file except in compliance with the
- * License. You can obtain a copy of the License at
- * http://www.netbeans.org/cddl-gplv2.html
- * or nbbuild/licenses/CDDL-GPL-2-CP. See the License for the
- * specific language governing permissions and limitations under the
- * License.  When distributing the software, include this License Header
- * Notice in each file and include the License file at
- * nbbuild/licenses/CDDL-GPL-2-CP.  Sun designates this
- * particular file as subject to the "Classpath" exception as provided
- * by Sun in the GPL Version 2 section of the License file that
- * accompanied this code. If applicable, add the following below the
- * License Header, with the fields enclosed by brackets [] replaced by
- * your own identifying information:
- * "Portions Copyrighted [year] [name of copyright owner]"
- *
- * Contributor(s):
- *
- * The Original Software is NetBeans. The Initial Developer of the Original
- * Software is Sun Microsystems, Inc. Portions Copyright 1997-2006 Sun
- * Microsystems, Inc. All Rights Reserved.
- *
- * If you wish your version of this file to be governed by only the CDDL
- * or only the GPL Version 2, indicate your decision by adding
- * "[Contributor] elects to include this software in this distribution
- * under the [CDDL or GPL Version 2] license." If you do not indicate a
- * single choice of license, a recipient has the option to distribute
- * your version of this file under either the CDDL, the GPL Version 2 or
- * to extend the choice of license to its licensees as provided above.
- * However, if you add GPL Version 2 code and therefore, elected the GPL
- * Version 2 license, then the option applies only if the new code is
- * made subject to such option by the copyright holder.
- */
-
-package org.netbeans.modules.ant.freeform;
-
-import java.io.IOException;
-import java.net.MalformedURLException;
-import java.net.URL;
-import java.util.Iterator;
-import java.util.Set;
-import java.util.TreeSet;
-import javax.xml.parsers.SAXParser;
-import javax.xml.parsers.SAXParserFactory;
-import org.netbeans.modules.ant.freeform.spi.ProjectNature;
-import org.openide.ErrorManager;
-import org.openide.cookies.EditorCookie;
-import org.openide.filesystems.FileAttributeEvent;
-import org.openide.filesystems.FileChangeListener;
-import org.openide.filesystems.FileEvent;
-import org.openide.filesystems.FileObject;
-import org.openide.filesystems.FileRenameEvent;
-import org.openide.filesystems.FileUtil;
-import org.openide.filesystems.URLMapper;
-import org.openide.loaders.DataObject;
-import org.openide.loaders.DataObjectNotFoundException;
-import org.openide.text.Line;
-import org.openide.util.Lookup;
-import org.openide.util.NbBundle;
-import org.openide.windows.IOProvider;
-import org.openide.windows.InputOutput;
-import org.openide.windows.OutputEvent;
-import org.openide.windows.OutputListener;
-import org.xml.sax.SAXException;
-import org.xml.sax.SAXNotRecognizedException;
-import org.xml.sax.SAXParseException;
-import org.xml.sax.helpers.DefaultHandler;
-
-/**
- * Checks validity of freeform project.xml files.
- * @see "#47288"
- * @author Jesse Glick
- */
-final class ProjectXmlValidator extends DefaultHandler implements FileChangeListener {
-    
-    private final FileObject projectXml;
-    private InputOutput io;
-    
-    public ProjectXmlValidator(FileObject projectXml) {
-        this.projectXml = projectXml;
-        projectXml.addFileChangeListener(this);
-        validateProjectXml();
-    }
-    
-    private void validateProjectXml() {
-        if (System.getProperty("netbeans.user") == null) { // NOI18N
-            // Probably in a unit test; skip it.
-            return;
-        }
-        open();
-        try {
-            // XXX may want to preinitialize the desired SAXParserFactory and keep it statically, for speed
-            SAXParserFactory f = SAXParserFactory.newInstance();
-            f.setNamespaceAware(true);
-            f.setValidating(true);
-            SAXParser p = f.newSAXParser();
-            p.setProperty("http://java.sun.com/xml/jaxp/properties/schemaLanguage", // NOI18N
-                          "http://www.w3.org/2001/XMLSchema"); // NOI18N
-            p.setProperty("http://java.sun.com/xml/jaxp/properties/schemaSource", getSchemas()); // NOI18N
-            p.parse(projectXml.getURL().toString(), this);
-        } catch (SAXParseException e) {
-            log(e);
-        } catch (Exception e) {
-            ErrorManager.getDefault().notify(ErrorManager.INFORMATIONAL, e);
-        } finally {
-            close();
-        }
-    }
-
-    /**
-     * Compute a list of XML schema locations to be used for validating project.xml files.
-     */
-    private static String[] getSchemas() {
-        Set<String> schemas = new TreeSet<String>();
-        // XXX should not refer to schema in another module; wait for #42686 to solve properly
-        schemas.add("nbres:/org/netbeans/modules/project/ant/project.xsd"); // NOI18N
-        schemas.add("nbres:/org/netbeans/modules/ant/freeform/resources/freeform-project-general.xsd"); // NOI18N
-        schemas.add("nbres:/org/netbeans/modules/ant/freeform/resources/freeform-project-general-2.xsd"); // NOI18N
-        for (ProjectNature nature : FreeformProject.PROJECT_NATURES.allInstances()) {
-            schemas.addAll(nature.getSchemas());
-        }
-        return schemas.toArray(new String[schemas.size()]);
-    }
-    
-    public void fileChanged(FileEvent fe) {
-        validateProjectXml();
-    }
-
-    public void fileRenamed(FileRenameEvent fe) {}
-
-    public void fileAttributeChanged(FileAttributeEvent fe) {}
-
-    public void fileFolderCreated(FileEvent fe) {}
-
-    public void fileDeleted(FileEvent fe) {}
-
-    public void fileDataCreated(FileEvent fe) {}
-
-    public void warning(SAXParseException e) throws SAXException {
-        log(e);
-    }
-
-    public void error(SAXParseException e) throws SAXException {
-        log(e);
-    }
-
-    public void fatalError(SAXParseException e) throws SAXException {
-        throw e;
-    }
-    
-    /** Close any old error tab. */
-    private void open() {
-        if (io != null) {
-            io.closeInputOutput();
-            io = null;
-        }
-    }
-
-    /** Log a parse error, opening error tab as needed. */
-    private void log(SAXParseException e) {
-        if (io == null) {
-            String title = NbBundle.getMessage(ProjectXmlValidator.class, "LBL_project.xml_errors", FileUtil.getFileDisplayName(projectXml));
-            io = IOProvider.getDefault().getIO(title, true);
-            io.select();
-        }
-        try {
-            io.getErr().println(e.getLocalizedMessage(), new Hyperlink(e.getSystemId(), e.getLineNumber(), e.getColumnNumber()));
-        } catch (IOException x) {
-            ErrorManager.getDefault().notify(ErrorManager.INFORMATIONAL, x);
-        }
-    }
-
-    /** Close the stream for the error tab, if one is open, but leave it visible. */
-    private void close() {
-        if (io != null) {
-            io.getErr().close();
-            io.getOut().close(); // XXX why is this necessary?
-        }
-    }
-
-    private static final class Hyperlink implements OutputListener {
-        
-        private final String uri;
-        private final int line, column;
-        
-        public Hyperlink(String uri, int line, int column) {
-            this.uri = uri;
-            this.line = line;
-            this.column = column;
-        }
-        
-        public void outputLineAction(OutputEvent ev) {
-            FileObject fo;
-            try {
-                fo = URLMapper.findFileObject(new URL(uri));
-            } catch (MalformedURLException e) {
-                assert false : e;
-                return;
-            }
-            if (fo == null) {
-                return;
-            }
-            DataObject d;
-            try {
-                d = DataObject.find(fo);
-            } catch (DataObjectNotFoundException e) {
-                assert false : e;
-                return;
-            }
-            EditorCookie ec = d.getCookie(EditorCookie.class);
-            if (ec == null) {
-                return;
-            }
-            if (line != -1) {
-                try {
-                    // XXX do we need to call ec.openDocument as in org.apache.tools.ant.module.run.Hyperlink?
-                    Line l = ec.getLineSet().getOriginal(line - 1);
-                    if (column != -1) {
-                        l.show(Line.SHOW_GOTO, column - 1);
-                    } else {
-                        l.show(Line.SHOW_GOTO);
-                    }
-                } catch (IndexOutOfBoundsException e) {
-                    // forget it
-                    ec.open();
-                }
-            } else {
-                ec.open();
-            }
-        }
-        
-        public void outputLineSelected(OutputEvent ev) {}
-        
-        public void outputLineCleared(OutputEvent ev) {}
-        
-    }
-    
-}
--- a/ant.freeform/src/org/netbeans/modules/ant/freeform/resources/layer.xml	
+++ a/ant.freeform/src/org/netbeans/modules/ant/freeform/resources/layer.xml	
@@ -59,5 +59,10 @@ 
             </folder>    
          </folder>
     </folder>
-    
+    <folder name="ProjectXMLCatalog">
+        <folder name="freeform-project">
+            <file name="1.xsd" url="freeform-project-general.xsd"/>
+            <file name="2.xsd" url="freeform-project-general-2.xsd"/>
+        </folder>
+    </folder>
 </filesystem>
--- a/ant.freeform/src/org/netbeans/modules/ant/freeform/spi/ProjectNature.java	
+++ a/ant.freeform/src/org/netbeans/modules/ant/freeform/spi/ProjectNature.java	
@@ -49,7 +49,6 @@ 
 import org.netbeans.spi.project.support.ant.PropertyEvaluator;
 import org.openide.filesystems.FileObject;
 import org.openide.nodes.Node;
-import org.openide.util.Lookup;
 
 /**
  * Description of base freeform project extension. Instances should be
@@ -69,12 +68,6 @@ 
      * @return a list of {@link TargetDescriptor}s (can be empty but not null)
      */
     List<TargetDescriptor> getExtraTargets(Project project, AntProjectHelper projectHelper, PropertyEvaluator projectEvaluator, AuxiliaryConfiguration aux);
-    
-    /**
-     * Returns set of XML schemas describing syntax of <code>project.xml</code> defined by this project extension.
-     * @return set of <code>String</code>s whose value is URL of XML schema file
-     */
-    Set<String> getSchemas();
     
     /**
      * Get a set of view styles supported by the nature for displaying source folders in the logical view.
--- a/ant.freeform/src/org/netbeans/modules/ant/freeform/spi/support/Util.java	
+++ a/ant.freeform/src/org/netbeans/modules/ant/freeform/spi/support/Util.java	
@@ -45,15 +45,11 @@ 
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
-import java.util.Map;
 import javax.xml.XMLConstants;
-import javax.xml.transform.dom.DOMSource;
 import javax.xml.validation.Schema;
 import javax.xml.validation.SchemaFactory;
-import javax.xml.validation.Validator;
 import org.netbeans.api.project.Project;
 import org.netbeans.api.project.ProjectManager;
 import org.netbeans.api.queries.CollocationQuery;
@@ -70,7 +66,7 @@ 
 import org.openide.filesystems.FileObject;
 import org.openide.filesystems.FileUtil;
 import org.openide.util.Mutex;
-import org.w3c.dom.Attr;
+import org.openide.xml.XMLUtil;
 import org.w3c.dom.DOMException;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
@@ -80,9 +76,7 @@ 
 import org.w3c.dom.Text;
 import org.w3c.dom.ls.DOMImplementationLS;
 import org.w3c.dom.ls.LSSerializer;
-import org.xml.sax.ErrorHandler;
 import org.xml.sax.SAXException;
-import org.xml.sax.SAXParseException;
 
 /**
  * Miscellaneous helper methods.
@@ -360,11 +354,11 @@ 
             public Void run() {
                 Element dataAs1 = translateXML(data, FreeformProjectType.NS_GENERAL_1);
                 try {
-                    validate(dataAs1, SCHEMA_1);
+                    XMLUtil.validate(dataAs1, SCHEMA_1);
                     putPrimaryConfigurationDataAs1(helper, dataAs1);
                 } catch (SAXException x1) {
                     try {
-                        validate(data, SCHEMA_2);
+                        XMLUtil.validate(data, SCHEMA_2);
                         putPrimaryConfigurationDataAs2(helper, data);
                     } catch (SAXException x2) {
                         assert false : x2.getMessage() + "; rejected content: " + format(data);
@@ -398,51 +392,6 @@ 
             throw new ExceptionInInitializerError(e);
         }
     }
-    private static void validate(Element data, Schema schema) throws SAXException {
-        Validator v = schema.newValidator();
-        final SAXException[] error = {null};
-        v.setErrorHandler(new ErrorHandler() {
-            public void warning(SAXParseException x) throws SAXException {}
-            public void error(SAXParseException x) throws SAXException {
-                // Just rethrowing it is bad because it will also print it to stderr.
-                error[0] = x;
-            }
-            public void fatalError(SAXParseException x) throws SAXException {
-                error[0] = x;
-            }
-        });
-        try {
-            v.validate(new DOMSource(fixupNoNamespaceAttrs(data)));
-        } catch (IOException x) {
-            assert false : x;
-        }
-        if (error[0] != null) {
-            throw error[0];
-        }
-    }
-    private static Element fixupNoNamespaceAttrs(Element root) {
-        // XXX #6529766: some versions of JAXP reject attributes set using setAttribute
-        // (rather than setAttributeNS) even though the schema calls for no-NS attrs!
-        // JDK 5 is fine; JDK 6 broken; JDK 6u2 supposedly will be fixed; current JDK 7 broken
-        Element copy = (Element) root.cloneNode(true);
-        NodeList nl = copy.getElementsByTagName("*");
-        for (int i = 0; i < nl.getLength(); i++) {
-            Element e = (Element) nl.item(i);
-            Map<String,String> replace = new HashMap<String,String>();
-            NamedNodeMap attrs = e.getAttributes();
-            for (int j = 0; j < attrs.getLength(); j++) {
-                Attr attr = (Attr) attrs.item(j);
-                if (attr.getNamespaceURI() == null) {
-                    replace.put(attr.getName(), attr.getValue());
-                }
-            }
-            for (Map.Entry<String,String> entry : replace.entrySet()) {
-                e.removeAttribute(entry.getKey());
-                e.setAttributeNS(null, entry.getKey(), entry.getValue());
-            }
-        }
-        return copy;
-    }
     private static String format(Element data) {
         LSSerializer ser = ((DOMImplementationLS) data.getOwnerDocument().getImplementation().getFeature("LS", "3.0")).createLSSerializer();
         try {
--- a/java.freeform/src/org/netbeans/modules/java/freeform/JavaProjectNature.java	
+++ a/java.freeform/src/org/netbeans/modules/java/freeform/JavaProjectNature.java	
@@ -43,9 +43,7 @@ 
 
 import java.beans.PropertyChangeListener;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collections;
-import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
 import javax.swing.Icon;
@@ -70,8 +68,6 @@ 
     public static final String NS_JAVA_1 = "http://www.netbeans.org/ns/freeform-project-java/1"; // NOI18N
     public static final String NS_JAVA_2 = "http://www.netbeans.org/ns/freeform-project-java/2"; // NOI18N
     public static final String EL_JAVA = "java-data"; // NOI18N
-    private static final String SCHEMA_1 = "nbres:/org/netbeans/modules/java/freeform/resources/freeform-project-java.xsd"; // NOI18N
-    private static final String SCHEMA_2 = "nbres:/org/netbeans/modules/java/freeform/resources/freeform-project-java-2.xsd"; // NOI18N
     public static final String STYLE_PACKAGES = "packages"; // NOI18N
     
     
@@ -79,10 +75,6 @@ 
     
     public List<TargetDescriptor> getExtraTargets(Project project, AntProjectHelper projectHelper, PropertyEvaluator projectEvaluator, AuxiliaryConfiguration aux) {
         return new ArrayList<TargetDescriptor>();
-    }
-
-    public Set<String> getSchemas() {
-        return new HashSet<String>(Arrays.asList(SCHEMA_1, SCHEMA_2));
     }
 
     public Set<String> getSourceFolderViewStyles() {
--- a/java.freeform/src/org/netbeans/modules/java/freeform/resources/layer.xml	
+++ a/java.freeform/src/org/netbeans/modules/java/freeform/resources/layer.xml	
@@ -77,5 +77,10 @@ 
             </folder>
         </folder>
     </folder>
-    
+    <folder name="ProjectXMLCatalog">
+        <folder name="freeform-project-java">
+            <file name="1.xsd" url="freeform-project-java.xsd"/>
+            <file name="2.xsd" url="freeform-project-java-2.xsd"/>
+        </folder>
+    </folder>
 </filesystem>
--- a/java.j2seproject/src/org/netbeans/modules/java/j2seproject/ui/resources/layer.xml	
+++ a/java.j2seproject/src/org/netbeans/modules/java/j2seproject/ui/resources/layer.xml	
@@ -144,4 +144,14 @@ 
             
         </folder>
     </folder>
+    <folder name="ProjectXMLCatalog">
+        <folder name="j2se-project">
+            <file name="1.xsd" url="../../resources/j2se-project.xsd"/>
+            <file name="2.xsd" url="../../resources/j2se-project2.xsd"/>
+            <file name="3.xsd" url="../../resources/j2se-project3.xsd"/>
+        </folder>
+        <folder name="j2se-project-private">
+            <file name="1.xsd" url="../../resources/j2se-project-private.xsd"/>
+        </folder>
+    </folder>
 </filesystem>
--- a/openide.util/src/org/openide/xml/XMLUtil.java	
+++ a/openide.util/src/org/openide/xml/XMLUtil.java	
@@ -49,6 +49,7 @@ 
 import java.util.Set;
 import javax.xml.parsers.DocumentBuilder;
 import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.parsers.FactoryConfigurationError;
 import javax.xml.parsers.ParserConfigurationException;
 import javax.xml.parsers.SAXParserFactory;
 import javax.xml.transform.OutputKeys;
@@ -59,6 +60,8 @@ 
 import javax.xml.transform.dom.DOMSource;
 import javax.xml.transform.stream.StreamResult;
 import javax.xml.transform.stream.StreamSource;
+import javax.xml.validation.Schema;
+import javax.xml.validation.Validator;
 import org.openide.util.Lookup;
 import org.w3c.dom.CDATASection;
 import org.w3c.dom.DOMException;
@@ -73,6 +76,7 @@ 
 import org.xml.sax.ErrorHandler;
 import org.xml.sax.InputSource;
 import org.xml.sax.SAXException;
+import org.xml.sax.SAXParseException;
 import org.xml.sax.XMLReader;
 
 /**
@@ -455,7 +459,49 @@ 
             collectCDATASections(children.item(i), cdataQNames);
         }
     }
-    
+
+    /**
+     * Check whether a DOM tree is valid according to a schema.
+     * Example of usage:
+     * <pre>
+     * Element fragment = ...;
+     * SchemaFactory f = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
+     * Schema s = f.newSchema(This.class.getResource("something.xsd"));
+     * try {
+     *     XMLUtil.validate(fragment, s);
+     *     // valid
+     * } catch (SAXException x) {
+     *     // invalid
+     * }
+     * </pre>
+     * @param data a DOM tree
+     * @param schema a parsed schema
+     * @throws SAXException if validation failed
+     * @since XXX
+     */
+    public static void validate(Element data, Schema schema) throws SAXException {
+        Validator v = schema.newValidator();
+        final SAXException[] error = {null};
+        v.setErrorHandler(new ErrorHandler() {
+            public void warning(SAXParseException x) throws SAXException {}
+            public void error(SAXParseException x) throws SAXException {
+                // Just rethrowing it is bad because it will also print it to stderr.
+                error[0] = x;
+            }
+            public void fatalError(SAXParseException x) throws SAXException {
+                error[0] = x;
+            }
+        });
+        try {
+            v.validate(new DOMSource(data));
+        } catch (IOException x) {
+            assert false : x;
+        }
+        if (error[0] != null) {
+            throw error[0];
+        }
+    }
+
     /**
      * Escape passed string as XML attibute value
      * (<code>&lt;</code>, <code>&amp;</code>, <code>'</code> and <code>"</code>
--- a/openide.util/test/unit/src/org/openide/xml/XMLUtilTest.java	
+++ a/openide.util/test/unit/src/org/openide/xml/XMLUtilTest.java	
@@ -47,7 +47,13 @@ 
 import java.io.IOException;
 import java.io.StringReader;
 import java.lang.ref.WeakReference;
+import javax.xml.XMLConstants;
 import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.transform.dom.DOMSource;
+import javax.xml.transform.stream.StreamSource;
+import javax.xml.validation.Schema;
+import javax.xml.validation.SchemaFactory;
+import javax.xml.validation.Validator;
 import org.netbeans.junit.NbTestCase;
 import org.w3c.dom.CDATASection;
 import org.w3c.dom.Document;
@@ -153,6 +159,37 @@ 
             String data = "<!ELEMENT foo (x+)><!ELEMENT x EMPTY>";
             return new InputSource(new StringReader(data));
         }
+    }
+
+    public void testValidate() throws Exception {
+        Element r = XMLUtil.createDocument("root", "some://where", null, null).getDocumentElement();
+        r.setAttribute("hello", "there");
+        SchemaFactory f = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
+        String xsd =
+                "<xsd:schema xmlns:xsd='http://www.w3.org/2001/XMLSchema' targetNamespace='some://where' xmlns='some://where' elementFormDefault='qualified'>\n" +
+                " <xsd:element name='root'>\n" +
+                "  <xsd:complexType>\n" +
+                "   <xsd:attribute name='hello' type='xsd:NMTOKEN' use='required'/>\n" +
+                "  </xsd:complexType>\n" +
+                " </xsd:element>\n" +
+                "</xsd:schema>\n";
+        Schema s = f.newSchema(new StreamSource(new StringReader(xsd)));
+        XMLUtil.validate(r, s);
+        r.setAttribute("goodbye", "now");
+        try {
+            XMLUtil.validate(r, s);
+            fail();
+        } catch (SAXException x) {/*OK*/}
+        // Make sure Java #6529766 is fixed (no longer any need for fixupNoNamespaceAttrs):
+        String xml = "<root xmlns='some://where'/>";
+        r = XMLUtil.parse(new InputSource(new StringReader(xml)), false, true, null, null).getDocumentElement();
+        r.setAttribute("hello", "there");
+        XMLUtil.validate(r, s);
+        r.setAttribute("goodbye", "now");
+        try {
+            XMLUtil.validate(r, s);
+            fail();
+        } catch (SAXException x) {/*OK*/}
     }
     
     public void testToAttributeValue() throws IOException {
--- a/project.ant/nbproject/project.xml	
+++ a/project.ant/nbproject/project.xml	
@@ -96,6 +96,15 @@ 
                     <compile-dependency/>
                     <run-dependency>
                         <release-version>1</release-version>
+                    </run-dependency>
+                </dependency>
+                <dependency>
+                    <code-name-base>org.netbeans.modules.xml.catalog</code-name-base>
+                    <build-prerequisite/>
+                    <compile-dependency/>
+                    <run-dependency>
+                        <release-version>2</release-version>
+                        <specification-version>1.14</specification-version>
                     </run-dependency>
                 </dependency>
                 <dependency>
--- a/project.ant/src/org/netbeans/modules/project/ant/AntBasedProjectFactorySingleton.java	
+++ a/project.ant/src/org/netbeans/modules/project/ant/AntBasedProjectFactorySingleton.java	
@@ -163,18 +163,20 @@ 
             return null;
         }
         Document projectXml;
+        Element projectEl;
         try {
             projectXml = XMLUtil.parse(new InputSource(projectDiskFile.toURI().toString()), false, true, Util.defaultErrorHandler(), null);
+            projectEl = projectXml.getDocumentElement();
+            if (!"project".equals(projectEl.getLocalName()) || !PROJECT_NS.equals(projectEl.getNamespaceURI())) { // NOI18N
+                return null;
+            }
+            ProjectXMLCatalogReader.validate(projectEl);
         } catch (SAXException e) {
             IOException ioe = (IOException) new IOException(projectDiskFile + ": " + e.toString()).initCause(e);
             Exceptions.attachLocalizedMessage(ioe, NbBundle.getMessage(AntBasedProjectFactorySingleton.class,
                                                                         "AntBasedProjectFactorySingleton.parseError",
                                                                         projectDiskFile.getAbsolutePath(), e.getMessage()));
             throw ioe;
-        }
-        Element projectEl = projectXml.getDocumentElement();
-        if (!"project".equals(projectEl.getLocalName()) || !PROJECT_NS.equals(projectEl.getNamespaceURI())) { // NOI18N
-            return null;
         }
         Element typeEl = Util.findElement(projectEl, "type", PROJECT_NS); // NOI18N
         if (typeEl == null) {
--- a/project.ant/src/org/netbeans/modules/project/ant/Bundle.properties	
+++ a/project.ant/src/org/netbeans/modules/project/ant/Bundle.properties	
@@ -84,3 +84,7 @@ 
 MSG_Invalid_Location=Valid location must be set
 MSG_Variable_Already_Exists=Variable with this name already exists
 MSG_Invalid_Name=Valid name must be set
+
+# ProjectXMLCatalogReader
+LBL_project_xml_schemas=Project XML Schemas
+HINT_project_xml_schemas=Permits validation of project.xml and private.xml files from the IDE.
--- a/projectui/src/org/netbeans/modules/project/ui/ProjectXMLCatalogReader.java	
+++ a/projectui/src/org/netbeans/modules/project/ui/ProjectXMLCatalogReader.java	
@@ -39,17 +39,31 @@ 
  * made subject to such option by the copyright holder.
  */
 
-package org.netbeans.modules.project.ui;
+package org.netbeans.modules.project.ant;
 
 import java.awt.Image;
 import java.beans.PropertyChangeListener;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Iterator;
+import java.util.List;
+import javax.xml.XMLConstants;
+import javax.xml.transform.Source;
+import javax.xml.transform.stream.StreamSource;
+import javax.xml.validation.SchemaFactory;
 import org.netbeans.modules.xml.catalog.spi.CatalogDescriptor;
 import org.netbeans.modules.xml.catalog.spi.CatalogListener;
 import org.netbeans.modules.xml.catalog.spi.CatalogReader;
+import org.openide.filesystems.FileObject;
+import org.openide.filesystems.FileStateInvalidException;
+import org.openide.filesystems.Repository;
+import org.openide.util.Exceptions;
 import org.openide.util.NbBundle;
+import org.openide.util.NbCollections;
 import org.openide.util.Utilities;
+import org.openide.xml.XMLUtil;
+import org.w3c.dom.Element;
+import org.xml.sax.SAXException;
 
 /**
  * Supplies a catalog which lets users validate against project-related XML schemas.
@@ -59,17 +73,24 @@ 
 public class ProjectXMLCatalogReader implements CatalogReader, CatalogDescriptor {
     
     private static final String PREFIX = "http://www.netbeans.org/ns/"; // NOI18N
-    private static final String SUFFIX = ".xsd"; // NOI18N
+    private static final String EXTENSION = "xsd"; // NOI18N
+    private static final String CATALOG = "ProjectXMLCatalog"; // NOI18N
     
     /** Default constructor for use from layer. */
     public ProjectXMLCatalogReader() {}
 
     public String resolveURI(String name) {
         if (name.startsWith(PREFIX)) {
-            return name + SUFFIX;
-        } else {
-            return null;
+            FileObject rsrc = Repository.getDefault().getDefaultFileSystem().findResource(CATALOG + "/" + name.substring(PREFIX.length()) + "." + EXTENSION);
+            if (rsrc != null) {
+                try {
+                    return rsrc.getURL().toString();
+                } catch (FileStateInvalidException x) {
+                    Exceptions.printStackTrace(x);
+                }
+            }
         }
+        return null;
     }
 
     public String resolvePublic(String publicId) {
@@ -105,5 +126,28 @@ 
     public String getDisplayName() {
         return NbBundle.getMessage(ProjectXMLCatalogReader.class, "LBL_project_xml_schemas");
     }
+
+    /**
+     * Validate according to all *.xsd found in catalog.
+     * @param dom DOM fragment to validate
+     * @throws SAXException if schemas were malformed or the document was invalid
+     */
+    public static void validate(Element dom) throws SAXException {
+        // XXX should cache schemas (but then needs to listen to changes in SFS in a tree)
+        List<Source> sources = new ArrayList<Source>();
+        FileObject root = Repository.getDefault().getDefaultFileSystem().findResource(CATALOG);
+        if (root != null) {
+            for (FileObject f : NbCollections.iterable(root.getChildren(true))) {
+                if (f.isData() && f.hasExt(EXTENSION)) {
+                    try {
+                        sources.add(new StreamSource(f.getURL().toString()));
+                    } catch (FileStateInvalidException x) {
+                        Exceptions.printStackTrace(x);
+                    }
+                }
+            }
+        }
+        XMLUtil.validate(dom, SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI).newSchema(sources.toArray(new Source[sources.size()])));
+    }
     
 }
--- a/projectui/src/org/netbeans/modules/project/ui/ProjectXMLCatalogReaderBeanInfo.java	
+++ a/projectui/src/org/netbeans/modules/project/ui/ProjectXMLCatalogReaderBeanInfo.java	
@@ -39,7 +39,7 @@ 
  * made subject to such option by the copyright holder.
  */
 
-package org.netbeans.modules.project.ui;
+package org.netbeans.modules.project.ant;
 
 import java.beans.PropertyDescriptor;
 import java.beans.SimpleBeanInfo;
--- a/project.ant/src/org/netbeans/modules/project/ant/resources/mf-layer.xml	
+++ a/project.ant/src/org/netbeans/modules/project/ant/resources/mf-layer.xml	
@@ -42,7 +42,6 @@ 
 -->
 <!DOCTYPE filesystem PUBLIC "-//NetBeans//DTD Filesystem 1.1//EN" "http://www.netbeans.org/dtds/filesystem-1_1.dtd">
 <filesystem>
-
     <folder name="Menu">
         <folder name="Tools">
             <file name="VariablesCustomizerAction.instance">
@@ -51,5 +50,28 @@ 
             </file>
         </folder>
     </folder>
-
+    <folder name="Plugins">
+        <folder name="XML">
+            <folder name="UserCatalogs">
+                <file name="org-netbeans-modules-project-ant-ProjectXMLCatalogReader.instance">
+                    <attr name="instanceOf" stringvalue="org.netbeans.modules.xml.catalog.spi.CatalogReader"/>
+                </file>
+            </folder>
+        </folder>
+    </folder>
+    <folder name="ProjectXMLCatalog">
+        <folder name="ant-project-libraries">
+            <file name="1.xsd" url="../ant-project-libraries-1.xsd"/>
+        </folder>
+        <folder name="ant-project-references">
+            <file name="1.xsd" url="../ant-project-references.xsd"/>
+            <file name="2.xsd" url="../ant-project-references2.xsd"/>
+        </folder>
+        <folder name="project">
+            <file name="1.xsd" url="../project.xsd"/>
+        </folder>
+        <folder name="project-private">
+            <file name="1.xsd" url="../project-private.xsd"/>
+        </folder>
+    </folder>
 </filesystem>
--- a/project.ant/src/org/netbeans/spi/project/support/ant/AntProjectHelper.java	
+++ a/project.ant/src/org/netbeans/spi/project/support/ant/AntProjectHelper.java	
@@ -61,6 +61,7 @@ 
 import org.netbeans.modules.project.ant.FileChangeSupportEvent;
 import org.netbeans.modules.project.ant.FileChangeSupportListener;
 import org.netbeans.modules.project.ant.ProjectLibraryProvider;
+import org.netbeans.modules.project.ant.ProjectXMLCatalogReader;
 import org.netbeans.modules.project.ant.UserQuestionHandler;
 import org.netbeans.modules.project.ant.Util;
 import org.netbeans.spi.project.AuxiliaryConfiguration;
@@ -277,7 +278,9 @@ 
         File f = FileUtil.toFile(xml);
         assert f != null;
         try {
-            return XMLUtil.parse(new InputSource(f.toURI().toString()), false, true, Util.defaultErrorHandler(), null);
+            Document doc = XMLUtil.parse(new InputSource(f.toURI().toString()), false, true, Util.defaultErrorHandler(), null);
+            ProjectXMLCatalogReader.validate(doc.getDocumentElement());
+            return doc;
         } catch (IOException e) {
             if (!QUIETLY_SWALLOW_XML_LOAD_ERRORS) {
                 ErrorManager.getDefault().notify(ErrorManager.INFORMATIONAL, e);
@@ -298,6 +301,11 @@ 
         assert ProjectManager.mutex().isWriteAccess();
         assert !writingXML;
         assert Thread.holdsLock(modifiedMetadataPaths);
+        try {
+            ProjectXMLCatalogReader.validate(doc.getDocumentElement());
+        } catch (SAXException x) {
+            throw (IOException) new IOException(x.getMessage()).initCause(x);
+        }
         final FileLock[] _lock = new FileLock[1];
         writingXML = true;
         try {
@@ -778,6 +786,7 @@ 
                         return ;
                     }
                     path = PROJECT_XML_PATH;
+                    // XXX should rather set a separate flag but keep the (valid) content loaded
                     projectXml = null;
                 } else if (f.equals(resolveFile(PRIVATE_XML_PATH))) {
                     if (modifiedMetadataPaths.contains(PRIVATE_XML_PATH)) {
--- a/project.ant/test/unit/src/org/netbeans/modules/project/ant/AntBasedProjectFactorySingletonTest.java	
+++ a/project.ant/test/unit/src/org/netbeans/modules/project/ant/AntBasedProjectFactorySingletonTest.java	
@@ -116,5 +116,9 @@ 
         
         assertTrue(getAntBasedProjectTypeMethod.invoke(helper) == type2);
     }
+
+    public void testDoNotLoadInvalidProject() throws Exception {
+        // XXX create malformed project.xml and check that loadProject dies
+    }
     
 }
--- a/project.ant/test/unit/src/org/netbeans/spi/project/support/ant/AntProjectHelperTest.java	
+++ a/project.ant/test/unit/src/org/netbeans/spi/project/support/ant/AntProjectHelperTest.java	
@@ -190,6 +190,7 @@ 
         assertNotNull("have <data>", data);
         Element details = Util.findElement(data, "details", "urn:test:shared");
         assertNotNull("have <details>", details);
+        // XXX test well-formed but invalid content
     }
     
     /**
@@ -535,6 +536,7 @@ 
         // XXX try modifying both XML files, or different parts of the same, and saving in a batch
         // XXX try storing unmodified XML fragments and see what happens
         // XXX try storing a fresh Element not returned from getPrimaryConfigurationData
+        // XXX test storing invalid content
     }
     
     /**
--- a/projectapi/manifest.mf	
+++ a/projectapi/manifest.mf	
@@ -3,4 +3,5 @@ 
 OpenIDE-Module-Install: org/netbeans/modules/projectapi/Installer.class
 OpenIDE-Module-Specification-Version: 1.18
 OpenIDE-Module-Localizing-Bundle: org/netbeans/modules/projectapi/Bundle.properties
+OpenIDE-Module-Layer: org/netbeans/modules/projectapi/layer.xml
 
--- a/projectapi/src/org/netbeans/modules/projectapi/layer.xml	
+++ a/projectapi/src/org/netbeans/modules/projectapi/layer.xml	
@@ -0,0 +1,12 @@ 
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE filesystem PUBLIC "-//NetBeans//DTD Filesystem 1.1//EN" "http://www.netbeans.org/dtds/filesystem-1_1.dtd">
+<filesystem>
+    <folder name="ProjectXMLCatalog">
+        <folder name="auxiliary-configuration">
+            <file name="1.xsd" url="auxiliary-configuration.xsd"/>
+        </folder>
+        <folder name="auxiliary-configuration-preferences">
+            <file name="1.xsd" url="resources/auxiliary-configuration-preferences.xsd"/>
+        </folder>
+    </folder>
+</filesystem>
--- a/projectui/nbproject/project.xml	
+++ a/projectui/nbproject/project.xml	
@@ -115,15 +115,6 @@ 
                     <compile-dependency/>
                     <run-dependency>
                         <release-version>1</release-version>
-                    </run-dependency>
-                </dependency>
-                <dependency>
-                    <code-name-base>org.netbeans.modules.xml.catalog</code-name-base>
-                    <build-prerequisite/>
-                    <compile-dependency/>
-                    <run-dependency>
-                        <release-version>2</release-version>
-                        <specification-version>1.8</specification-version>
                     </run-dependency>
                 </dependency>
                 <dependency>
--- a/projectui/src/org/netbeans/modules/project/ui/Bundle.properties	
+++ a/projectui/src/org/netbeans/modules/project/ui/Bundle.properties	
@@ -44,10 +44,6 @@ 
 OpenIDE-Module-Long-Description=\
     GUI infrastructure for working with projects in the IDE: the Projects and Files tabs, \
     the project chooser dialog, the project-sensitive New File wizard, etc.
-
-# ProjectXMLCatalogReader
-LBL_project_xml_schemas=Project XML Schemas
-HINT_project_xml_schemas=Permits validation of project.xml and private.xml files from the IDE.
 
 #BrowseFolders
 BTN_BrowseFolders_Select_Option=&Select Folder
--- a/projectui/src/org/netbeans/modules/project/ui/resources/layer.xml	
+++ a/projectui/src/org/netbeans/modules/project/ui/resources/layer.xml	
@@ -622,16 +622,6 @@ 
         </folder>
     </folder>
     
-    <folder name="Plugins">
-        <folder name="XML">
-            <folder name="UserCatalogs">
-                <file name="org-netbeans-modules-project-ui-ProjectXMLCatalogReader.instance">
-                    <attr name="instanceOf" stringvalue="org.netbeans.modules.xml.catalog.spi.CatalogReader"/>
-                </file>
-            </folder>
-        </folder>
-    </folder>
-    
     <folder name="ProjectsTabActions"> <!-- #57068; cf. ProjectsRootNode.ACTIONS_FOLDER -->
         <file name="org-netbeans-modules-project-ui-NewProject.shadow">
             <attr name="originalFile" stringvalue="Actions/Project/org-netbeans-modules-project-ui-NewProject.instance"/>
@@ -690,5 +680,9 @@ 
             <attr name="position" intvalue="1500"/>
         </file>
     </folder>
-        
+    <folder name="ProjectXMLCatalog">
+        <folder name="projectui-open-files">
+            <file name="1.xsd" url="projectui-open-files.xsd"/>
+        </folder>
+    </folder>
 </filesystem>
--- a/web.freeform/src/org/netbeans/modules/web/freeform/WebProjectNature.java	
+++ a/web.freeform/src/org/netbeans/modules/web/freeform/WebProjectNature.java	
@@ -43,7 +43,6 @@ 
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
-import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
 import org.netbeans.api.project.Project;
@@ -63,10 +62,8 @@ 
 public class WebProjectNature implements ProjectNature {
 
     public static final String NS_WEB_1 = "http://www.netbeans.org/ns/freeform-project-web/1"; // NOI18N
-    private static final String SCHEMA_1 = "nbres:/org/netbeans/modules/web/freeform/resources/freeform-project-web.xsd"; // NOI18N
     public static final String EL_WEB = "web-data";
     public static final String NS_WEB_2 = "http://www.netbeans.org/ns/freeform-project-web/2"; // NOI18N
-    private static final String SCHEMA_2 = "nbres:/org/netbeans/modules/web/freeform/resources/freeform-project-web-2.xsd"; // NOI18N
     
   
     public WebProjectNature() {}
@@ -80,10 +77,6 @@ 
         return l;
     }
     
-    public Set<String> getSchemas() {
-        return new HashSet<String>(Arrays.asList(SCHEMA_1, SCHEMA_2));
-    }
-
     public Set<String> getSourceFolderViewStyles() {
         return Collections.<String>emptySet();
     }
--- a/web.freeform/src/org/netbeans/modules/web/freeform/resources/layer.xml	
+++ a/web.freeform/src/org/netbeans/modules/web/freeform/resources/layer.xml	
@@ -79,5 +79,10 @@ 
                 </folder>
         </folder>
     </folder>
-    
+    <folder name="ProjectXMLCatalog">
+        <folder name="freeform-project-web">
+            <file name="1.xsd" url="freeform-project-web.xsd"/>
+            <file name="2.xsd" url="freeform-project-web-2.xsd"/>
+        </folder>
+    </folder>
 </filesystem>