public  void addSource(DOMImplementationSource s) 
{
        if (s == null) {
            throw new NullPointerException();
        }
        if (!sources.contains(s)) {
            sources.addElement(s);
        }
}

Register an implementation.

 public DOMImplementation getDOMImplementation(String features) 
{
        int size = sources.size();
        String name = null;
        for (int i = 0; i <  size; i++) {
            DOMImplementationSource source =
                (DOMImplementationSource) sources.elementAt(i);
            DOMImplementation impl = source.getDOMImplementation(features);
            if (impl != null) {
                return impl;
            }
        }
        return null;
}

Return the first implementation that has the desired features, or null if none is found.

 public DOMImplementationList getDOMImplementationList(String features) 
{
        final Vector implementations = new Vector();
        int size = sources.size();
        for (int i = 0; i <  size; i++) {
            DOMImplementationSource source =
                (DOMImplementationSource) sources.elementAt(i);
            DOMImplementationList impls =
                source.getDOMImplementationList(features);
            for (int j = 0; j <  impls.getLength(); j++) {
                DOMImplementation impl = impls.item(j);
                implementations.addElement(impl);
            }
        }
        return new DOMImplementationList() {
                public DOMImplementation item(final int index) {
                    if (index  >= 0 && index <  implementations.size()) {
                        try {
                            return (DOMImplementation)
                                implementations.elementAt(index);
                        } catch (ArrayIndexOutOfBoundsException e) {
                            return null;
                        }
                    }
                    return null;
                }
                public int getLength() {
                    return implementations.size();
                }
            };
}

Return a list of implementations that support the desired features.

 public static DOMImplementationRegistry newInstance() throws ClassNotFoundException, ClassCastException, IllegalAccessException, InstantiationException 
{
        Vector sources = new Vector();
        ClassLoader classLoader = getClassLoader();
        // fetch system property:
        String p = getSystemProperty(PROPERTY);
        //
        // if property is not specified then use contents of
        // META_INF/org.w3c.dom.DOMImplementationSourceList from classpath
        if (p == null) {
            p = getServiceValue(classLoader);
        }
        if (p == null) {
            //
            // DOM Implementations can modify here to add *additional* fallback
            // mechanisms to access a list of default DOMImplementationSources.
            //fall back to JAXP implementation class com.sun.org.apache.xerces.internal.dom.DOMXSImplementationSourceImpl
            p = FALLBACK_CLASS;
        }
        if (p != null) {
            StringTokenizer st = new StringTokenizer(p);
            while (st.hasMoreTokens()) {
                String sourceName = st.nextToken();
                // Use context class loader, falling back to Class.forName
                // if and only if this fails...
                Class sourceClass = null;
                if (classLoader != null) {
                    sourceClass = classLoader.loadClass(sourceName);
                } else {
                    sourceClass = Class.forName(sourceName);
                }
                DOMImplementationSource source =
                    (DOMImplementationSource) sourceClass.newInstance();
                sources.addElement(source);
            }
        }
        return new DOMImplementationRegistry(sources);
}

Obtain a new instance of a DOMImplementationRegistry. The DOMImplementationRegistry is initialized by the application or the implementation, depending on the context, by first checking the value of the Java system property org.w3c.dom.DOMImplementationSourceList and the the service provider whose contents are at "META_INF/services/org.w3c.dom.DOMImplementationSourceList" The value of this property is a white-space separated list of names of availables classes implementing the DOMImplementationSource interface. Each class listed in the class name list is instantiated and any exceptions encountered are thrown to the application.