wamblee.org Git - utils/blob - system/general/src/main/java/org/wamblee/system/AbstractComponent.java

   1 /*
   2  * Copyright 2007 the original author or authors.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *      http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16 package org.wamblee.system;
  17
  18 import java.util.ArrayList;
  19 import java.util.Arrays;
  20 import java.util.HashSet;
  21 import java.util.List;
  22 import java.util.Set;
  23
  24 import org.apache.commons.logging.Log;
  25 import org.apache.commons.logging.LogFactory;
  26
  27 /**
  28  * Abstract subsystem class making it easy to implement new subsystems.
  29  */
  30 public abstract class AbstractComponent implements Component {
  31
  32         private static final Log LOG = LogFactory.getLog(AbstractComponent.class);
  33
  34         private Status _status;
  35         private String _name;
  36         private List<ProvidedInterface> _provided;
  37         private List<RequiredInterface> _required;
  38         private Set<ProvidedInterface> _running;
  39
  40         /**
  41          * Constructs the subsystem.
  42          *
  43          * @param aName
  44          *            Name of the system.
  45          * @param aProvided
  46          *            Provided services.
  47          * @param aRequired
  48          *            Required services.
  49          */
  50         protected AbstractComponent(String aName, ProvidedInterface[] aProvided,
  51                         RequiredInterface[] aRequired) {
  52                 _status = Status.NOT_STARTED;
  53                 _name = aName;
  54                 _provided = new ArrayList<ProvidedInterface>();
  55                 _provided.addAll(Arrays.asList(aProvided));
  56                 _required = new ArrayList<RequiredInterface>();
  57                 _required.addAll(Arrays.asList(aRequired));
  58                 _running = new HashSet<ProvidedInterface>();
  59         }
  60
  61         @Override
  62         public Status getStatus() {
  63                 return _status;
  64         }
  65
  66         @Override
  67         public final String getName() {
  68                 return _name;
  69         }
  70
  71         @Override
  72         public final ProvidedInterface[] getProvidedServices() {
  73                 return _provided.toArray(new ProvidedInterface[0]);
  74         }
  75
  76         @Override
  77         public final RequiredInterface[] getRequiredServices() {
  78                 return _required.toArray(new RequiredInterface[0]);
  79         }
  80
  81         @Override
  82         public final void start(String aContext) {
  83                 LOG.info("Initializing '" + aContext + "." + _name + "'");
  84                 doStart(aContext + "." + getName());
  85                 _status = Status.RUNNING;
  86                 if ( _running.size() != _provided.size()) {
  87                         List<ProvidedInterface> remaining =
  88                                 new ArrayList<ProvidedInterface>(_provided);
  89                         remaining.removeAll(_running);
  90                         throw new SystemAssemblyException(aContext + "." + getName() + ": not all services were started, missing " + remaining);
  91                 }
  92         }
  93
  94         /**
  95          * Must be implemented for initializing the subsystem. The implementation
  96          * must call {@link #addService(Service)} for each service that is started.
  97          */
  98         protected abstract void doStart(String aContext);
  99
 100         /**
 101          * Implementations must call this method to indicate that a new service has
 102          * been started.
 103          *
 104          * @param aService
 105          *            Service.
 106          */
 107         protected final void addService(String aContext,
 108                         ProvidedInterface aDescriptor, Object aService) {
 109                 LOG.info(aContext + ": service '" + aService + "' started.");
 110                 _running.add(aDescriptor);
 111                 aDescriptor.publish(aService);
 112         }
 113
 114         @Override
 115         public ProvidedInterface[] getRunningServices() {
 116                 return _running.toArray(new ProvidedInterface[0]);
 117         }
 118
 119         @Override
 120         public void stop() {
 121                 doStop();
 122                 _status = Status.STOPPED;
 123         }
 124
 125         protected abstract void doStop();
 126
 127         @Override
 128         public String toString() {
 129                 return _name;
 130         }
 131
 132 }