/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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.apache.tuscany.sca.implementation.osgi.runtime;

import java.util.Collection;
import java.util.Map;

import org.osgi.framework.ServiceReference;

/**
 * Every Distribution Provider registers exactly one Service in the
 * ServiceRegistry implementing this interface. The service is registered with
 * extra properties identified at the beginning of this interface to denote the
 * Distribution Provider product name, version, vendor and supported intents.
 */
public interface OSGiDistributionProvider {

    /**
     * Service Registration property for the name of the Distribution Provider
     * product.
     */
    static final String PROP_KEY_PRODUCT_NAME = "osgi.remote.distribution.product";

    /**
     * Service Registration property for the version of the Distribution
     * Provider product.
     */
    static final String PROP_KEY_PRODUCT_VERSION = "osgi.remote.distribution.product.version";

    /**
     * Service Registration property for the Distribution Provider product
     * vendor name.
     */
    static final String PROP_KEY_VENDOR_NAME = "osgi.remote.distribution.vendor";

    /**
     * Service Registration property that lists the intents supported by this
     * DistributionProvider. Value of this property is of type 
     * Collection (<? extends String>).
     */
    static final String PROP_KEY_SUPPORTED_INTENTS = "osgi.remote.distribition.supported_intents";

    /**
     * @return ServiceReferences of services registered in the local Service
     *         Registry that are proxies to remote services. If no proxies are
     *         registered, then an empty collection is returned.
     */
    Collection<ServiceReference> getRemoteServices();

    /**
     * @return ServiceReferences of local services that are exposed remotely 
     *         using this DisitributionProvider. Note that certain services may be
     *         exposed and without being published to a discovery service. This 
     *         API returns all the exposed services. If no services are exposed an 
     *         empty collection is returned.
     */
    Collection<ServiceReference> getExposedServices();

    /**
     * Provides access to extra properties set by the DistributionProvider on
     * endpoints, as they will appear on client side proxies given an exposed
     * ServiceReference. 
     * These properties are not always available on the server-side
     * ServiceReference of the exposed
     * service but will be on the remote client side proxy to this service.
     * This API provides access to these extra properties from the exposing
     * side.
     * E.g. a service is exposed remotely, the distribution software is configured
     * to add transactionality to the remote service. Because of this, on the 
     * client-side proxy the property service.intents=”transactionality” is set. 
     * However, these intents are *not* always set on the original
     * ServiceRegistration on the server-side since on the server side the service
     * object is a local pojo which doesn’t provide transactionality by itself.
     * This QoS is added by the distribution.
     * This API provides access to these extra properties from the server-side.
     * 
     * @param sr A ServiceReference of an exposed service.
     * @return The map of extra properties.
     */
    Map<String, String> getExposedProperties(ServiceReference sr);

}