001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     * 
010     *      http://www.apache.org/licenses/LICENSE-2.0
011     * 
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    package org.apache.oozie.service;
019    
020    import org.apache.hadoop.conf.Configuration;
021    import org.apache.oozie.util.IOUtils;
022    import org.apache.oozie.ErrorCode;
023    import org.xml.sax.SAXException;
024    
025    import javax.xml.XMLConstants;
026    import javax.xml.transform.stream.StreamSource;
027    import javax.xml.validation.Schema;
028    import javax.xml.validation.SchemaFactory;
029    import java.io.IOException;
030    import java.util.ArrayList;
031    import java.util.List;
032    
033    /**
034     * Service that loads Oozie workflow definition schema and registered extension schemas.
035     */
036    public class WorkflowSchemaService implements Service {
037    
038        public static final String CONF_PREFIX = Service.CONF_PREFIX + "WorkflowSchemaService.";
039    
040        public static final String CONF_EXT_SCHEMAS = CONF_PREFIX + "ext.schemas";
041    
042        private Schema dagSchema;
043    
044        private static final String OOZIE_WORKFLOW_XSD = "oozie-workflow-0.1.xsd";
045    
046        private Schema loadSchema(Configuration conf) throws SAXException, IOException {
047            List<StreamSource> sources = new ArrayList<StreamSource>();
048            sources.add(new StreamSource(IOUtils.getResourceAsStream(OOZIE_WORKFLOW_XSD, -1)));
049            String[] schemas = conf.getStrings(CONF_EXT_SCHEMAS);
050            if (schemas != null) {
051                for (String schema : schemas) {
052                    sources.add(new StreamSource(IOUtils.getResourceAsStream(schema, -1)));
053                }
054            }
055            SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
056            return factory.newSchema(sources.toArray(new StreamSource[sources.size()]));
057        }
058    
059        /**
060         * Initialize the service.
061         *
062         * @param services services instance.
063         * @throws ServiceException thrown if the service could not be initialized.
064         */
065        public void init(Services services) throws ServiceException {
066            try {
067                dagSchema = loadSchema(services.getConf());
068            }
069            catch (SAXException ex) {
070                throw new ServiceException(ErrorCode.E0130, ex.getMessage(), ex);
071            }
072            catch (IOException ex) {
073                throw new ServiceException(ErrorCode.E0131, ex.getMessage(), ex);
074            }
075        }
076    
077        /**
078         * Return the public interface of the service.
079         *
080         * @return {@link WorkflowSchemaService}.
081         */
082        public Class<? extends Service> getInterface() {
083            return WorkflowSchemaService.class;
084        }
085    
086        /**
087         * Destroy the service.
088         */
089        public void destroy() {
090            dagSchema = null;
091        }
092    
093        /**
094         * Return the schema for XML validation of application definitions.
095         *
096         * @return the schema for XML validation of application definitions.
097         */
098        public Schema getSchema() {
099            return dagSchema;
100        }
101    
102    }