content: /*
   *  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.
   *
   *  See the NOTICE file distributed with this work for additional
   *  information regarding copyright ownership.
   */
  
  package org.seaborne.delta.server.system;
  
  import java.util.List ;
  
  /**
   * A {@code SubsystemRegistry} is a set of objects implementing {@code T}.
   */
  public interface SubsystemRegistry<T> {
      
      /** Load - peform some kinds of search for {@link SubsystemLifecycle} implementations.
       * This is called once in the initialization process.
       */
      public void load();
      
      /** Add to the collection. */
      public void add(T module);
  
      /** check whether registered */
      public boolean isRegistered(T module);
  
      /** Remove from the collection. */
      public void remove(T module);
  
      public int size();
  
      public boolean isEmpty();
  
      /**
       * Return the registered items in a copied list.
       * The list is detached from the
       * registry and the caller can mutate it.
       * There is no specific ordering requirement. 
       */
      public List<T> snapshot();
  }
  