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 _context;
  36         private String _name;
  37         private List<ProvidedInterface> _provided;
  38         private List<RequiredInterface> _required;
  39         private Set<ProvidedInterface> _running;
  40
  41         /**
  42          * Constructs the subsystem.
  43          *
  44          * @param aName
  45          *            Name of the system.
  46          * @param aProvided
  47          *            Provided services.
  48          * @param aRequired
  49          *            Required services.
  50          */
  51         protected AbstractComponent(String aName, ProvidedInterface[] aProvided,
  52                         RequiredInterface[] aRequired) {
  53                 _status = Status.NOT_STARTED;
  54                 _context = null;
  55                 _name = aName;
  56                 _provided = new ArrayList<ProvidedInterface>();
  57                 _provided.addAll(Arrays.asList(aProvided));
  58                 _required = new ArrayList<RequiredInterface>();
  59                 _required.addAll(Arrays.asList(aRequired));
  60                 _running = new HashSet<ProvidedInterface>();
  61         }
  62
  63         @Override
  64         public Status getStatus() {
  65                 return _status;
  66         }
  67
  68         @Override
  69         public final String getName() {
  70                 return _name;
  71         }
  72
  73         @Override
  74         public String getQualifiedName() {
  75                 if ( _context == null ) {
  76                         return getName();
  77                 }
  78                 return _context + "." + getName();
  79         }
  80
  81         @Override
  82         public final ProvidedInterface[] getProvidedServices() {
  83                 return _provided.toArray(new ProvidedInterface[0]);
  84         }
  85
  86         @Override
  87         public final RequiredInterface[] getRequiredServices() {
  88                 return _required.toArray(new RequiredInterface[0]);
  89         }
  90
  91         @Override
  92         public final void start(String aContext) {
  93                 LOG.info("Initializing '" + aContext + "." + _name + "'");
  94                 _context = aContext;
  95                 doStart(aContext + "." + getName());
  96                 _status = Status.RUNNING;
  97                 if ( _running.size() != _provided.size()) {
  98                         List<ProvidedInterface> remaining =
  99                                 new ArrayList<ProvidedInterface>(_provided);
 100                         remaining.removeAll(_running);
 101                         throw new SystemAssemblyException(aContext + "." + getName() + ": not all services were started, missing " + remaining);
 102                 }
 103         }
 104
 105         /**
 106          * Must be implemented for initializing the subsystem. The implementation
 107          * must call {@link #addService(Service)} for each service that is started.
 108          */
 109         protected abstract void doStart(String aContext);
 110
 111         /**
 112          * Implementations must call this method to indicate that a new service has
 113          * been started.
 114          *
 115          * @param aService
 116          *            Service.
 117          */
 118         protected final void addService(String aContext,
 119                         ProvidedInterface aDescriptor, Object aService) {
 120                 LOG.info(aContext + ": service '" + aService + "' started.");
 121                 _running.add(aDescriptor);
 122                 aDescriptor.publish(aService);
 123         }
 124
 125         @Override
 126         public ProvidedInterface[] getRunningServices() {
 127                 return _running.toArray(new ProvidedInterface[0]);
 128         }
 129
 130         @Override
 131         public void stop() {
 132                 doStop();
 133                 _status = Status.STOPPED;
 134         }
 135
 136         protected abstract void doStop();
 137
 138         @Override
 139         public String toString() {
 140                 return _name;
 141         }
 142
 143 }