TransformationBundleTrackerCustomizer.java

/**
 * Licensed to the Austrian Association for Software Tool Integration (AASTI)
 * under one or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information regarding copyright
 * ownership. The AASTI licenses this file to you under the Apache License,
 * Version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.openengsb.core.ekb.transformation.wonderland.internal;

import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;

import org.openengsb.core.common.transformations.TransformationUtils;
import org.openengsb.core.ekb.api.TransformationEngine;
import org.openengsb.core.ekb.api.transformation.TransformationDescription;
import org.osgi.framework.Bundle;
import org.osgi.framework.BundleEvent;
import org.osgi.util.tracker.BundleTrackerCustomizer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * {@link BundleTrackerCustomizer} that scans new bundles for .transformation-files and registers them to the
 * {@link TransformationEngine} and removes them again, when the bundle is removed.
 */
public class TransformationBundleTrackerCustomizer implements BundleTrackerCustomizer<List<TransformationDescription>> {

    private static final Logger LOGGER = LoggerFactory.getLogger(TransformationBundleTrackerCustomizer.class);

    private TransformationEngine transformationEngine;

    public TransformationBundleTrackerCustomizer(TransformationEngine transformationEngine) {
        this.transformationEngine = transformationEngine;
    }

    @Override
    public List<TransformationDescription> addingBundle(Bundle bundle, BundleEvent bundleEvent) {
        Enumeration<URL> entries = bundle.findEntries("/META-INF/transformations/", "*.transformation", true);
        List<TransformationDescription> result = new ArrayList<TransformationDescription>();
        if (entries == null) {
            return null;
        }
        while (entries.hasMoreElements()) {
            URL entry = entries.nextElement();
            List<TransformationDescription> descriptionList;
            try {
                descriptionList = TransformationUtils.getDescriptionsFromXMLInputStream(entry.openStream());
            } catch (IOException e) {
                LOGGER.error("error reading transformation descriptions from {}", entry, e);
                continue;
            }
            result.addAll(descriptionList);
            transformationEngine.saveDescriptions(descriptionList);
        }
        return result;
    }

    @Override
    public void modifiedBundle(Bundle bundle, BundleEvent bundleEvent,
            List<TransformationDescription> transformationDescriptions) {
        // do nothing
    }

    @Override
    public void removedBundle(Bundle bundle, BundleEvent bundleEvent,
            List<TransformationDescription> transformationDescriptions) {
        for (TransformationDescription desc : transformationDescriptions) {
            transformationEngine.deleteDescription(desc);
        }
    }

}