CTK/Libs/PluginFramework/service/cm/ctkManagedServiceFactory.h

/*=============================================================================

  Library: CTK

  Copyright (c) German Cancer Research Center,
    Division of Medical and Biological Informatics

  Licensed 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.

=============================================================================*/


#ifndef CTKMANAGEDSERVICEFACTORY_H
#define CTKMANAGEDSERVICEFACTORY_H

#include <QString>
#include <ctkPluginFramework_global.h>

/**
 * Manage multiple service instances.
 *
 * Plugins registering this interface are giving the Configuration Admin service
 * the ability to create and configure a number of instances of a service that
 * the implementing plugin can provide. For example, a plugin implementing a
 * DHCP server could be instantiated multiple times for different interfaces
 * using a factory.
 *
 * <p>
 * Each of these <i>service instances </i> is represented, in the persistent
 * storage of the Configuration Admin service, by a factory
 * {@code ctkConfiguration} object that has a PID. When such a
 * {@code ctkConfiguration} is updated, the Configuration Admin service
 * calls the {@code ctkManagedServiceFactory} updated method with the new
 * properties. When {@code updated} is called with a new PID, the Managed
 * Service Factory should create a new factory instance based on these
 * configuration properties. When called with a PID that it has seen before, it
 * should update that existing service instance with the new configuration
 * information.
 *
 * <p>
 * In general it is expected that the implementation of this interface will
 * maintain a data structure that maps PIDs to the factory instances that it has
 * created. The semantics of a factory instance are defined by the Managed
 * Service Factory. However, if the factory instance is registered as a service
 * object with the service registry, its PID should match the PID of the
 * corresponding {@code ctkConfiguration} object (but it should <b>not</b>
 * be registered as a Managed Service!).
 *
 * <p>
 * An example that demonstrates the use of a factory. It will create serial
 * ports under command of the Configuration Admin service.
 *
 * \code
 *
 *   class SerialPortFactory : public QObject, public ctkManagedServiceFactory
 *   {
 *
 *     ctkServiceRegistration registration;
 *     QHash<QString, SerialPort*> ports;
 *
 *     void start(ctkPluginContext* context)
 *     {
 *       ctkDictionary properties;
 *       properties.insert(ctkPluginConstants::SERVICE_PID,
 *         "com.acme.serialportfactory");
 *       registration = context->registerService<ctkManagedServiceFactory>(
 *         this, properties);
 *     }
 *
 *   public:
 *
 *     void updated(const QString& pid, const ctkDictionary& properties)
 *     {
 *       QString portName = properties["port"].toString();
 *       SerialPort* port = ports[pid];
 *       if (port == 0)
 *       {
 *         port = new SerialPort();
 *         ports.insert(pid, port);
 *         port->open();
 *       }
 *       if (port->getPortName() == portName)
 *         return;
 *       port->setPortName(portName);
 *     }
 *
 *     void deleted(const QString& pid)
 *     {
 *       SerialPort* port = ports[pid];
 *       port->close();
 *       ports.remove(pid);
 *     }
 *     ...
 *   };
 *
 * \endcode
 */
struct ctkManagedServiceFactory
{
  virtual ~ctkManagedServiceFactory() {}

  /**
   * Return a descriptive name of this factory.
   *
   * @return the name for the factory, which might be localized
   */
  virtual QString getName() = 0;

  /**
   * Create a new instance, or update the configuration of an existing
   * instance.
   *
   * If the PID of the {@code ctkConfiguration} object is new for the
   * Managed Service Factory, then create a new factory instance, using the
   * configuration {@code properties} provided. Else, update the
   * service instance with the provided {@code properties}.
   *
   * <p>
   * If the factory instance is registered with the Framework, then the
   * configuration {@code properties} should be copied to its registry
   * properties. This is not mandatory and security sensitive properties
   * should obviously not be copied.
   *
   * <p>
   * If this method throws any {@code exception}, the Configuration
   * Admin service must catch it and should log it.
   *
   * <p>
   * When the implementation of updated detects any kind of error in the
   * configuration properties, it should create a new
   * {@link ctkConfigurationException} which describes the problem.
   *
   * <p>
   * The Configuration Admin service must call this method asynchronously.
   * This implies that implementors of the {@code ctkManagedServiceFactory}
   * class can be assured that the callback will not take place during
   * registration when they execute the registration in a synchronized method.
   *
   * @param pid The PID for this configuration.
   * @param properties A copy of the configuration properties. This argument
   *        must not contain the service.pluginLocation" property. The value
   *        of this property may be obtained from the
   *        {@code ctkConfiguration#getPluginLocation} method.
   * @throws ctkConfigurationException when the configuration properties are
   *         invalid.
   */
  virtual void updated(const QString& pid, const ctkDictionary& properties) = 0;

  /**
   * Remove a factory instance.
   *
   * Remove the factory instance associated with the PID. If the instance was
   * registered with the service registry, it should be unregistered.
   * <p>
   * If this method throws any {@code exception}, the Configuration
   * Admin service must catch it and should log it.
   * <p>
   * The Configuration Admin service must call this method asynchronously.
   *
   * @param pid the PID of the service to be removed
   */
  virtual void deleted(const QString& pid) = 0;
};

Q_DECLARE_INTERFACE(ctkManagedServiceFactory, "org.commontk.service.cm.ManagedServiceFactory")

#endif // CTKMANAGEDSERVICEFACTORY_H