RestServiceTracker.java

/*
 * Licensed to The Apereo Foundation under one or more contributor license
 * agreements. See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.
 *
 *
 * The Apereo Foundation licenses this file to you under the Educational
 * Community 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://opensource.org/licenses/ecl2.txt
 *
 * 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.opencastproject.serviceregistry.internal;

import org.opencastproject.rest.RestConstants;
import org.opencastproject.serviceregistry.api.ServiceRegistry;
import org.opencastproject.serviceregistry.api.ServiceRegistryException;

import org.osgi.framework.BundleContext;
import org.osgi.framework.InvalidSyntaxException;
import org.osgi.framework.ServiceReference;
import org.osgi.service.component.annotations.Activate;
import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.annotations.Deactivate;
import org.osgi.service.component.annotations.Reference;
import org.osgi.service.jaxrs.whiteboard.JaxrsWhiteboardConstants;
import org.osgi.util.tracker.ServiceTracker;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Objects;

/**
 * A custom ServiceTracker that registers all locally published servlets so clients can find the most appropriate
 * service on the network to handle new jobs.
 */
@Component(
    immediate = true,
    property = {
        "service.description=Service registry"
    }
)
public class RestServiceTracker extends ServiceTracker<Object, Object> {

    private static final Logger logger = LoggerFactory.getLogger(RestServiceTracker.class);

    protected static final String FILTER = "(" +  JaxrsWhiteboardConstants.JAX_RS_RESOURCE + "=true)";

    protected BundleContext bundleContext;

    private final ServiceRegistry serviceRegistry;

    @Activate
    public RestServiceTracker(@Reference ServiceRegistry serviceRegistry, BundleContext bundleContext) throws InvalidSyntaxException {
        super(bundleContext, bundleContext.createFilter(FILTER), null);
        this.bundleContext = bundleContext;
        this.serviceRegistry = serviceRegistry;
        this.open(true);
    }

    @Deactivate
    void deactivate() {
        this.close();
    }

    @Override
    public Object addingService(ServiceReference reference) {
        String serviceType = (String) reference.getProperty(RestConstants.SERVICE_TYPE_PROPERTY);
        String servicePath = (String) reference.getProperty(RestConstants.SERVICE_PATH_PROPERTY);

        boolean publishFlag = Boolean.parseBoolean(
            Objects.requireNonNullElse(
                reference.getProperty(RestConstants.SERVICE_PUBLISH_PROPERTY), "true").toString()
        );
        boolean jobProducer = Boolean.parseBoolean(
            Objects.requireNonNullElse(
                reference.getProperty(RestConstants.SERVICE_JOBPRODUCER_PROPERTY), "false").toString()
        );

        // Only register services that have the "publish" flag set to "true"
        if (publishFlag) {
            try {
                serviceRegistry.registerService(serviceType, serviceRegistry.getRegistryHostname(), servicePath, jobProducer);
            } catch (ServiceRegistryException e) {
                logger.warn("Unable to register job producer of type " + serviceType + " on host " + serviceRegistry.getRegistryHostname());
            }
        } else {
            logger.debug("Not registering service " + serviceType + " in service registry by configuration");
        }

        return super.addingService(reference);
    }

    @Override
    public void removedService(ServiceReference reference, Object service) {
        String serviceType = (String) reference.getProperty(RestConstants.SERVICE_TYPE_PROPERTY);
        boolean publishFlag = Boolean.parseBoolean(Objects.toString(
            reference.getProperty(RestConstants.SERVICE_PUBLISH_PROPERTY),
            "true"));

        // Services that have the "publish" flag set to "true" have been registered before.
        if (publishFlag) {
            try {
                serviceRegistry.unRegisterService(serviceType, serviceRegistry.getRegistryHostname());
            } catch (ServiceRegistryException e) {
                logger.warn("Unable to unregister job producer of type {} on host {}",
                    serviceType, serviceRegistry.getRegistryHostname());
            }
        } else {
            logger.trace("Service {} was never registered", reference);
        }

        super.removedService(reference, service);
    }

}