> mapping)
    {
        this.mapping = mapping;
    }
    /**
     * Set the properties that contain the mapping from document metadata to system metadata.
     * This is an alternative to the {@link #setMapping(Map)} method.  Any mappings already
     * present will be cleared out.
     * 
     * The property mapping is of the form:
     * 
     * # Namespaces prefixes
     * namespace.prefix.cm=http://www.alfresco.org/model/content/1.0
     * namespace.prefix.my=http://www....com/alfresco/1.0
     * 
     * # Mapping
     * editor=cm:author, my:editor
     * title=cm:title
     * user1=cm:summary
     * user2=cm:description
     * 
     * The mapping can therefore be from a single document property onto several system properties.
     * 
     * @param mappingProperties     the properties that map document properties to system properties
     */
    public void setMappingProperties(Properties mappingProperties)
    {
        mapping = readMappingProperties(mappingProperties);
    }
    
    /**
     * Helper method for derived classes to obtain the mappings that will be applied to raw
     * values.  This should be called after initialization in order to guarantee the complete
     * map is given.
     * 
     * Normally, the list of properties that can be extracted from a document is fixed and
     * well-known - in that case, just extract everything.  But Some implementations may have
     * an extra, indeterminate set of values available for extraction.  If the extraction of
     * these runtime parameters is expensive, then the keys provided by the return value can
     * be used to extract values from the documents.  The metadata extraction becomes fully
     * configuration-driven, i.e. declaring further mappings will result in more values being
     * extracted from the documents.
     * 
     * Most extractors will not be using this method.  For an example of its use, see the
     * {@linkplain OpenDocumentMetadataExtracter OpenDocument extractor}, which uses the mapping
     * to select specific user properties from a document.
     */
    protected final Map> getMapping()
    {
        if (!initialized)
        {
            throw new UnsupportedOperationException("The complete mapping is only available after initialization.");
        }
        return Collections.unmodifiableMap(mapping);
    }
    
    /**
     * A utility method to read mapping properties from a resource file and convert to the map form.
     * 
     * @param propertiesUrl     A standard Properties file URL location
     * 
     * @see #setMappingProperties(Properties)
     */
    protected Map> readMappingProperties(String propertiesUrl)
    {
        InputStream is = null;
        try
        {
            is = getClass().getClassLoader().getResourceAsStream(propertiesUrl);
            if(is == null)
            {
                throw new AlfrescoRuntimeException(
                        "Metadata Extracter mapping properties not found: \n" +
                        "   Extracter:  " + this + "\n" +
                        "   Bundle:     " + propertiesUrl);
            }
            Properties props = new Properties();
            props.load(is);
            // Process it
            Map> map = readMappingProperties(props);
            // Done
            if (logger.isDebugEnabled())
            {
                logger.debug("Loaded mapping properties from resource: " + propertiesUrl);
            }
            return map;
        }
        catch (Throwable e)
        {
            throw new AlfrescoRuntimeException(
                    "Unable to load properties file to read extracter mapping properties: \n" +
                    "   Extracter:  " + this + "\n" +
                    "   Bundle:     " + propertiesUrl,
                    e);
        }
        finally
        {
            if (is != null)
            {
                try { is.close(); } catch (Throwable e) {}
            }
        }
    }
    
    /**
     * A utility method to convert mapping properties to the Map form.
     * 
     * @see #setMappingProperties(Properties)
     */
    @SuppressWarnings("unchecked")
    protected Map> readMappingProperties(Properties mappingProperties)
    {
        Map namespacesByPrefix = new HashMap(5);
        // Get the namespaces
        for (Map.Entry entry : mappingProperties.entrySet())
        {
            String propertyName = (String) entry.getKey();
            if (propertyName.startsWith(NAMESPACE_PROPERTY_PREFIX))
            {
                String prefix = propertyName.substring(17);
                String namespace = (String) entry.getValue();
                namespacesByPrefix.put(prefix, namespace);
            }
        }
        // Create the mapping
        Map> convertedMapping = new HashMap>(17);
        for (Map.Entry entry : mappingProperties.entrySet())
        {
            String documentProperty = (String) entry.getKey();
            String qnamesStr = (String) entry.getValue();
            if (documentProperty.startsWith(NAMESPACE_PROPERTY_PREFIX))
            {
                // Ignore these now
                continue;
            }
            // Create the entry
            Set qnames = new HashSet(3);
            convertedMapping.put(documentProperty, qnames);
            // The to value can be a list of QNames
            StringTokenizer tokenizer = new StringTokenizer(qnamesStr, ",");
            while (tokenizer.hasMoreTokens())
            {
                String qnameStr = tokenizer.nextToken().trim();
                // Check if we need to resolve a namespace reference
                int index = qnameStr.indexOf(QName.NAMESPACE_PREFIX);
                if (index > -1 && qnameStr.charAt(0) != QName.NAMESPACE_BEGIN)
                {
                    String prefix = qnameStr.substring(0, index);
                    String suffix = qnameStr.substring(index + 1);
                    // It is prefixed
                    String uri = namespacesByPrefix.get(prefix);
                    if (uri == null)
                    {
                        throw new AlfrescoRuntimeException(
                                "No prefix mapping for extracter property mapping: \n" +
                                "   Extracter: " + this + "\n" +
                                "   Mapping: " + entry);
                    }
                    qnameStr = QName.NAMESPACE_BEGIN + uri + QName.NAMESPACE_END + suffix;
                }
                try
                {
                    QName qname = QName.createQName(qnameStr);
                    // Add it to the mapping
                    qnames.add(qname);
                }
                catch (InvalidQNameException e)
                {
                    throw new AlfrescoRuntimeException(
                            "Can't create metadata extracter property mapping: \n" +
                            "   Extracter: " + this + "\n" +
                            "   Mapping: " + entry);
                }
            }
            if (logger.isDebugEnabled())
            {
                logger.debug("Added mapping from " + documentProperty + " to " + qnames);
            }
        }
        // Done
        return convertedMapping;
    }
    
    /**
     * Registers this instance of the extracter with the registry.  This will call the
     * {@link #init()} method and then register if the registry is available.
     * 
     * @see #setRegistry(MetadataExtracterRegistry)
     * @see #init()
     */
    public final void register()
    {
        init();
        
        // Register the extracter, if necessary
        if (registry != null)
        {
            registry.register(this);
        }
    }
    
    /**
     * Provides a hook point for implementations to perform initialization.  The base
     * implementation must be invoked or the extracter will fail during extraction.
     * The {@link #getDefaultMapping() default mappings} will be requested during
     * initialization.
     */
    protected void init()
    {
        Map> defaultMapping = getDefaultMapping();
        if (defaultMapping == null)
        {
            throw new AlfrescoRuntimeException("The metadata extracter must provide a default mapping: " + this);
        }
        
        // Was a mapping explicitly provided
        if (mapping == null)
        {
            // No mapping, so use the default
            mapping = defaultMapping;
        }
        else if (inheritDefaultMapping)
        {
            // Merge the default mapping into the configured mapping
            for (String documentKey : defaultMapping.keySet())
            {
                Set systemQNames = mapping.get(documentKey);
                if (systemQNames == null)
                {
                    systemQNames = new HashSet(3);
                    mapping.put(documentKey, systemQNames);
                }
                Set defaultQNames = defaultMapping.get(documentKey);
                systemQNames.addAll(defaultQNames);
            }
        }
        
        // The configured mappings are empty, but there were default mappings
        if (mapping.size() == 0 && defaultMapping.size() > 0)
        {
            logger.warn(
                    "There are no property mappings for the metadata extracter.\n" +
                    "  Nothing will be extracted by: " + this);
        }
        // Done
        initialized = true;
    }
    /** {@inheritDoc} */
    public long getExtractionTime()
    {
        return 1000L;
    }
    /**
     * Checks if the mimetype is supported.
     * 
     * @param reader the reader to check
     * @throws AlfrescoRuntimeException if the mimetype is not supported
     */
    protected void checkIsSupported(ContentReader reader)
    {
        String mimetype = reader.getMimetype();
        if (!isSupported(mimetype))
        {
            throw new AlfrescoRuntimeException(
                    "Metadata extracter does not support mimetype: \n" +
                    "   reader: " + reader + "\n" +
                    "   supported: " + supportedMimetypes + "\n" +
                    "   extracter: " + this);
        }
    }
    /**
     * {@inheritDoc}
     */
    public final Map extract(ContentReader reader, Map destination)
    {
        return extract(reader, this.overwritePolicy, destination, this.mapping);
    }
    /**
     * {@inheritDoc}
     */
    public final Map extract(
            ContentReader reader,
            OverwritePolicy overwritePolicy,
            Map destination)
    {
        return extract(reader, overwritePolicy, destination, this.mapping);
    }
    /**
     * {@inheritDoc}
     */
    public Map extract(
            ContentReader reader,
            OverwritePolicy overwritePolicy,
            Map destination,
            Map> mapping)
    {
        // Done
        if (logger.isDebugEnabled())
        {
            logger.debug("Starting metadata extraction: \n" +
                    "   reader: " + reader + "\n" +
                    "   extracter: " + this);
        }
        if (!initialized)
        {
            throw new AlfrescoRuntimeException(
                    "Metadata extracter not initialized.\n" +
                    "  Call the 'register' method on: " + this + "\n" +
                    "  Implementations of the 'init' method must call the base implementation.");
        }
        // check the reliability
        checkIsSupported(reader);
        
        Map changedProperties = null;
        try
        {
            Map rawMetadata = null;
            // Check that the content has some meat
            if (reader.getSize() > 0 && reader.exists())
            {
                rawMetadata = extractRaw(reader);
            }
            else
            {
                rawMetadata = new HashMap(1);
            }
            // Convert to system properties (standalone)
            Map systemProperties = mapRawToSystem(rawMetadata);
            // Convert the properties according to the dictionary types
            systemProperties = convertSystemPropertyValues(systemProperties);
            // Now use the proper overwrite policy
            changedProperties = overwritePolicy.applyProperties(systemProperties, destination);
        }
        catch (Throwable e)
        {
            if (logger.isDebugEnabled())
            {
                logger.debug(
                        "Metadata extraction failed: \n" +
                        "   Extracter: " + this + "\n" +
                        "   Content:   " + reader,
                        e);
            }
            else
            {
                logger.warn(
                        "Metadata extraction failed (turn on DEBUG for full error): \n" +
                        "   Extracter: " + this + "\n" +
                        "   Content:   " + reader + "\n" +
                        "   Failure:   " + e.getMessage());
            }
        }
        finally
        {
            // check that the reader was closed (if used)
            if (reader.isChannelOpen())
            {
                logger.error("Content reader not closed by metadata extracter: \n" +
                        "   reader: " + reader + "\n" +
                        "   extracter: " + this);
            }
            // Make sure that we have something to return
            if (changedProperties == null)
            {
                changedProperties = new HashMap(0);
            }
        }
        
        // Done
        if (logger.isDebugEnabled())
        {
            logger.debug("Completed metadata extraction: \n" +
                    "   reader:    " + reader + "\n" +
                    "   extracter: " + this + "\n" +
                    "   changed:   " + changedProperties);
        }
        return changedProperties;
    }
    
    /**
     * 
     * @param rawMetadata   Metadata keyed by document properties
     * @return              Returns the metadata keyed by the system properties
     */
    private Map mapRawToSystem(Map rawMetadata)
    {
        Map systemProperties = new HashMap(rawMetadata.size() * 2 + 1);
        for (Map.Entry entry : rawMetadata.entrySet())
        {
            String documentKey = entry.getKey();
            // Check if there is a mapping for this
            if (!mapping.containsKey(documentKey))
            {
                // No mapping - ignore
                continue;
            }
            Serializable documentValue = entry.getValue();
            Set systemQNames = mapping.get(documentKey);
            for (QName systemQName : systemQNames)
            {
                systemProperties.put(systemQName, documentValue);
            }
        }
        // Done
        if (logger.isDebugEnabled())
        {
            logger.debug(
                    "Converted extracted raw values to system values: \n" +
                    "   Raw Properties:    " + rawMetadata + "\n" +
                    "   System Properties: " + systemProperties);
        }
        return systemProperties;
    }
    
    /**
     * Converts all values according to their dictionary-defined type.  This uses the
     * {@link #setFailOnTypeConversion(boolean) failOnTypeConversion flag} to determine how failures
     * are handled i.e. if values fail to convert, the process may discard the property.
     * 
     * @param systemProperties  the values keyed to system property names
     * @return                  Returns a modified map of properties that have been converted.
     */
    @SuppressWarnings("unchecked")
    private Map convertSystemPropertyValues(Map systemProperties)
    {
        Map convertedProperties = new HashMap(systemProperties.size() + 7);
        for (Map.Entry entry : systemProperties.entrySet())
        {
            QName propertyQName = entry.getKey();
            Serializable propertyValue = entry.getValue();
            // Get the property definition
            PropertyDefinition propertyDef = (dictionaryService == null) ? null : dictionaryService.getProperty(propertyQName);
            if (propertyDef == null)
            {
                // There is nothing in the DD about this so just transfer it
                convertedProperties.put(propertyQName, propertyValue);
                continue;
            }
            // It is in the DD, so attempt the conversion
            DataTypeDefinition propertyTypeDef = propertyDef.getDataType();
            Serializable convertedPropertyValue = null;
            
            try
            {
                // Attempt to make any date conversions
                if (propertyTypeDef.getName().equals(DataTypeDefinition.DATE) || propertyTypeDef.getName().equals(DataTypeDefinition.DATETIME))
                {
                    if (propertyValue instanceof Date)
                    {
                        convertedPropertyValue = propertyValue;
                    }
                    else if (propertyValue instanceof Collection)
                    {
                        convertedPropertyValue = (Serializable) makeDates((Collection) propertyValue);
                    }
                    else if (propertyValue instanceof String)
                    {
                        convertedPropertyValue = makeDate((String) propertyValue);
                    }
                    else
                    {
                        if (logger.isWarnEnabled())
                        {
                            StringBuilder mesg = new StringBuilder();
                            mesg.append("Unable to convert Date property: ").append(propertyQName)
                                .append(", value: ").append(propertyValue).append(", type: ").append(propertyTypeDef.getName());
                            logger.warn(mesg.toString());
                        }
                    }
                }
                else
                {
                    if (propertyValue instanceof Collection)
                    {
                        convertedPropertyValue = (Serializable) DefaultTypeConverter.INSTANCE.convert(
                                propertyTypeDef,
                                (Collection) propertyValue);
                    }
                    else if (propertyValue instanceof Object[])
                    {
                       convertedPropertyValue = (Serializable) DefaultTypeConverter.INSTANCE.convert(
                             propertyTypeDef,
                             (Object[]) propertyValue);
                    }
                    else
                    {
                        convertedPropertyValue = (Serializable) DefaultTypeConverter.INSTANCE.convert(
                                propertyTypeDef,
                                propertyValue);
                    }
                }
                convertedProperties.put(propertyQName, convertedPropertyValue);
            }
            catch (TypeConversionException e)
            {
                // Do we just absorb this or is it a problem?
                if (failOnTypeConversion)
                {
                    throw AlfrescoRuntimeException.create(
                            e,
                            ERR_TYPE_CONVERSION,
                            this,
                            propertyQName,
                            propertyTypeDef.getName(),
                            propertyValue);
                }
            }
        }
        // Done
        return convertedProperties;
    }
    /**
     * Convert a collection of date String to Date objects
     */
    private Collection makeDates(Collection dateStrs)
    {
        List dates = new ArrayList(dateStrs.size());
        for (String dateStr : dateStrs)
        {
            Date date = makeDate(dateStr);
            dates.add(date);
        }
        return dates;
    }
    
    /**
     * Convert a date String to a Date object
     */
    private Date makeDate(String dateStr)
    {
        Date date = null;
        try
        {
            date = DefaultTypeConverter.INSTANCE.convert(Date.class, dateStr);
        }
        catch (TypeConversionException e)
        {
            // Try one of the other formats
            for (DateFormat df : this.supportedDateFormats)
            {
                try
                {
                    date = df.parse(dateStr);
                }
                catch (ParseException ee)
                {
                    // Didn't work
                }
            }
            if (date == null)
            {
                // Still no luck
                throw new TypeConversionException("Unable to convert string to date: " + dateStr);
            }
        }
        return date;
    }
    
    /**
     * Adds a value to the map if it is non-trivial.  A value is trivial if
     * 
     *   - it is null*
- it is an empty string value after trimming*
- it is an empty collection*
- it is an empty array*
* String values are trimmed before being put into the map.
     * Otherwise, it is up to the extracter to ensure that the value is a Serializable.
     * It is not appropriate to implicitly convert values in order to make them Serializable
     * - the best conversion method will depend on the value's specific meaning.
     * 
     * @param key           the destination key
     * @param value         the serializable value
     * @param destination   the map to put values into
     * @return              Returns true if set, otherwise false
     */
    @SuppressWarnings("unchecked")
    protected boolean putRawValue(String key, Serializable value, Map destination)
    {
        if (value == null)
        {
            return false;
        }
        if (value instanceof String)
        {
            String valueStr = ((String) value).trim();
            if (valueStr.length() == 0)
            {
                return false;
            }
            else
            {
                // Keep the trimmed value
                value = valueStr;
            }
        }
        else if (value instanceof Collection)
        {
            Collection valueCollection = (Collection) value;
            if (valueCollection.isEmpty())
            {
                return false;
            }
        }
        else if (value.getClass().isArray())
        {
            if (Array.getLength(value) == 0)
            {
                return false;
            }
        }
        // It passed all the tests
        destination.put(key, value);
        return true;
    }
    /**
     * Helper method to fetch a clean map into which raw values can be dumped.
     * 
     * @return          Returns an empty map
     */
    protected final Map newRawMap()
    {
        return new HashMap(17);
    }
    /**
     * This method provides a best guess of where to store the values extracted
     * from the documents.  The list of properties mapped by default need not
     * include all properties extracted from the document; just the obvious set of mappings
     * need be supplied.
     * Implementations must either provide the default mapping properties in the expected
     * location or override the method to provide the default mapping.
     *
     * The default implementation looks for the default mapping file in the location
     * given by the class name and .properties.  If the extracter's class is
     * x.y.z.MyExtracter then the default properties will be picked up at
     * classpath:/x/y/z/MyExtracter.properties.
     * Inner classes are supported, but the '$' in the class name is replaced with '-', so
     * default properties for x.y.z.MyStuff$MyExtracter will be located using
     * x.y.z.MyStuff-MyExtracter.properties.
     * 
     * The default mapping implementation should include thorough Javadocs so that the
     * system administrators can accurately determine how to best enhance or override the
     * default mapping.
     * 
     * If the default mapping is declared in a properties file other than the one named after
     * the class, then the {@link #readMappingProperties(String)} method can be used to quickly
     * generate the return value:
     * 
     *      protected Map<> getDefaultMapping()
     *      {
     *          return readMappingProperties(DEFAULT_MAPPING);
     *      }
     * 
     * The map can also be created in code either statically or during the call.
     * 
     * @return              Returns the default, static mapping.  It may not be null.
     * 
     * @see #setInheritDefaultMapping(boolean inherit)
     */
    protected Map> getDefaultMapping()
    {
        String className = this.getClass().getName();
        // Replace $
        className = className.replace('$', '-');
        // Replace .
        className = className.replace('.', '/');
        // Append .properties
        String propertiesUrl = className + ".properties";
        // Attempt to load the properties
        return readMappingProperties(propertiesUrl);
    }
    
    /**
     * Override to provide the raw extracted metadata values.  An extracter should extract
     * as many of the available properties as is realistically possible.  Even if the
     * {@link #getDefaultMapping() default mapping} doesn't handle all properties, it is
     * possible for each instance of the extracter to be configured differently and more or
     * less of the properties may be used in different installations.
     * 
     * Raw values must not be trimmed or removed for any reason.  Null values and empty
     * strings are 
     * 
     *    - Null:              Removed*
- Empty String:      Passed to the {@link OverwritePolicy}*
- Non Serializable:  Converted to String or fails if that is not possible*
*
     * Properties extracted and their meanings and types should be thoroughly described in
     * the class-level javadocs of the extracter implementation, for example:
     * 
     * editor: - the document editor        -->  cm:author
     * title:  - the document title         -->  cm:title
     * user1:  - the document summary
     * user2:  - the document description   -->  cm:description
     * user3:  -
     * user4:  -
     * 
     * 
     * @param reader        the document to extract the values from.  This stream provided by
     *                      the reader must be closed if accessed directly.
     * @return              Returns a map of document property values keyed by property name.
     * @throws              All exception conditions can be handled.
     * 
     * @see #getDefaultMapping()
     */
    protected abstract Map extractRaw(ContentReader reader) throws Throwable;
}