wamblee.org Git - utils/blob - system/general/src/main/java/org/wamblee/system/core/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.core;
  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 String _context;
  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                 _context = null;
  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 final String getName() {
  63                 return _name;
  64         }
  65
  66         @Override
  67         public void addContext(String aContext) {
  68                 if (_context == null ) {
  69                         _context = aContext;
  70                 }
  71                 else {
  72                         _context = aContext + "." + _context;
  73                 }
  74         }
  75
  76         @Override
  77         public String getQualifiedName() {
  78                 if ( _context == null ) {
  79                         return getName();
  80                 }
  81                 return _context + "." + getName();
  82         }
  83
  84         @Override
  85         public final ProvidedInterface[] getProvidedInterfaces() {
  86                 return _provided.toArray(new ProvidedInterface[0]);
  87         }
  88
  89         @Override
  90         public final RequiredInterface[] getRequiredInterfaces() {
  91                 return _required.toArray(new RequiredInterface[0]);
  92         }
  93
  94         @Override
  95         public final void start() {
  96                 LOG.info("Initializing '" + getQualifiedName() + "'");
  97                 doStart();
  98                 if ( _running.size() != _provided.size()) {
  99                         List<ProvidedInterface> remaining =
 100                                 new ArrayList<ProvidedInterface>(_provided);
 101                         remaining.removeAll(_running);
 102                         throw new SystemAssemblyException(getQualifiedName() + ": not all services were started, missing " + remaining);
 103                 }
 104         }
 105
 106         /**
 107          * Must be implemented for initializing the subsystem. The implementation
 108          * must call {@link #addService(Service)} for each service that is started.
 109          */
 110         protected abstract void doStart();
 111
 112         /**
 113          * Implementations must call this method to indicate that a new service has
 114          * been started.
 115          *
 116          * @param aService
 117          *            Service.
 118          */
 119         protected final void addInterface(
 120                         ProvidedInterface aDescriptor, Object aService) {
 121                 LOG.info("Interface '" + getQualifiedName() + "." + aDescriptor.getName() + "' started.");
 122                 _running.add(aDescriptor);
 123                 aDescriptor.publish(aService);
 124         }
 125
 126         @Override
 127         public ProvidedInterface[] getRunningInterfaces() {
 128                 return _running.toArray(new ProvidedInterface[0]);
 129         }
 130
 131         @Override
 132         public void stop() {
 133                 doStop();
 134                 if ( _running.size() > 0 ) {
 135                         // programming error.
 136                         throw new RuntimeException(getQualifiedName() + ": still services running after the stop call.");
 137                 }
 138         }
 139
 140         protected abstract void doStop();
 141
 142         /**
 143          * Implementations must call this method to indicate that a running service has
 144          * been stopped.
 145          *
 146          * @param aService
 147          *            Service.
 148          */
 149         protected final void removeInterface(
 150                         ProvidedInterface aDescriptor) {
 151                 LOG.info("Interface '" + getQualifiedName() + "." + aDescriptor.getName() + "' stopped.");
 152                 _running.remove(aDescriptor);
 153                 aDescriptor.publish(null);
 154         }
 155
 156         @Override
 157         public String toString() {
 158                 return getQualifiedName();
 159         }
 160
 161 }