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 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 void addContext(String aContext) {
  75                 if (_context == null ) {
  76                         _context = aContext;
  77                 }
  78                 else {
  79                         _context = aContext + "." + _context;
  80                 }
  81         }
  82
  83         @Override
  84         public String getQualifiedName() {
  85                 if ( _context == null ) {
  86                         return getName();
  87                 }
  88                 return _context + "." + getName();
  89         }
  90
  91         @Override
  92         public final ProvidedInterface[] getProvidedInterfaces() {
  93                 return _provided.toArray(new ProvidedInterface[0]);
  94         }
  95
  96         @Override
  97         public final RequiredInterface[] getRequiredInterfaces() {
  98                 return _required.toArray(new RequiredInterface[0]);
  99         }
 100
 101         @Override
 102         public final void start() {
 103                 LOG.info("Initializing '" + getQualifiedName() + "'");
 104                 doStart();
 105                 _status = Status.RUNNING;
 106                 if ( _running.size() != _provided.size()) {
 107                         List<ProvidedInterface> remaining =
 108                                 new ArrayList<ProvidedInterface>(_provided);
 109                         remaining.removeAll(_running);
 110                         throw new SystemAssemblyException(getQualifiedName() + ": not all services were started, missing " + remaining);
 111                 }
 112         }
 113
 114         /**
 115          * Must be implemented for initializing the subsystem. The implementation
 116          * must call {@link #addService(Service)} for each service that is started.
 117          */
 118         protected abstract void doStart();
 119
 120         /**
 121          * Implementations must call this method to indicate that a new service has
 122          * been started.
 123          *
 124          * @param aService
 125          *            Service.
 126          */
 127         protected final void addService(
 128                         ProvidedInterface aDescriptor, Object aService) {
 129                 LOG.info("Interface '" + getQualifiedName() + "." + aDescriptor.getName() + "' started.");
 130                 _running.add(aDescriptor);
 131                 aDescriptor.publish(aService);
 132         }
 133
 134         @Override
 135         public ProvidedInterface[] getRunningServices() {
 136                 return _running.toArray(new ProvidedInterface[0]);
 137         }
 138
 139         @Override
 140         public void stop() {
 141                 doStop();
 142                 _status = Status.STOPPED;
 143         }
 144
 145         protected abstract void doStop();
 146
 147         @Override
 148         public String toString() {
 149                 return _name;
 150         }
 151
 152 }