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<Type> implements Component<Type> {
  31
  32         private static final Log LOG = LogFactory.getLog(AbstractComponent.class);
  33
  34         private ThreadLocal<List<ProvidedInterface>> _remaining;
  35
  36         private String _context;
  37         private String _name;
  38         private ReadWriteProvidedInterfaces _provided;
  39         private ReadWriteRequiredInterfaces _required;
  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                 _remaining = new ThreadLocal<List<ProvidedInterface>>();
  54                 _context = null;
  55                 _name = aName;
  56                 _provided = new ReadWriteProvidedInterfaces(aProvided);
  57                 _required = new ReadWriteRequiredInterfaces(aRequired);
  58         }
  59
  60         protected AbstractComponent(String aName) {
  61                 this(aName, new ProvidedInterface[0], new RequiredInterface[0]);
  62         }
  63
  64         public AbstractComponent addProvidedInterface(ProvidedInterface aProvided) {
  65                 _provided.add(aProvided);
  66                 return this;
  67         }
  68
  69         public AbstractComponent addRequiredInterface(RequiredInterface aRequired) {
  70                 _required.add(aRequired);
  71                 return this;
  72         }
  73
  74         @Override
  75         public final String getName() {
  76                 return _name;
  77         }
  78
  79         @Override
  80         public void addContext(String aContext) {
  81                 if (_context == null) {
  82                         _context = aContext;
  83                 } else {
  84                         _context = aContext + "." + _context;
  85                 }
  86         }
  87
  88         @Override
  89         public String getContext() {
  90                 return _context;
  91         }
  92
  93         @Override
  94         public String getQualifiedName() {
  95                 if (_context == null) {
  96                         return getName();
  97                 }
  98                 return _context + "." + getName();
  99         }
 100
 101         @Override
 102         public final ProvidedInterfaces getProvidedInterfaces() {
 103                 return _provided.readOnlyView();
 104         }
 105
 106         @Override
 107         public final RequiredInterfaces getRequiredInterfaces() {
 108                 return _required.readOnlyView();
 109         }
 110
 111         @Override
 112         public final Type start(Scope aScope) {
 113                 LOG.info("Initialization starting '" + getQualifiedName() + "'");
 114                 List<ProvidedInterface> oldRemaining = _remaining.get();
 115                 _remaining.set(new ArrayList<ProvidedInterface>(Arrays.asList(getProvidedInterfaces().toArray())));
 116                 try {
 117                         Type runtime = doStart(aScope);
 118                         checkNotStartedInterfaces();
 119                         LOG.info("Initialization finished '" + getQualifiedName() + "'");
 120                         return runtime;
 121                 } finally {
 122                         _remaining.set(oldRemaining);
 123                 }
 124         }
 125
 126         private void checkNotStartedInterfaces() {
 127                 if (_remaining.get().size() > 0) {
 128                         String notProvided = "";
 129                         for (ProvidedInterface provided : _remaining.get()) {
 130                                 notProvided += "\nComponent " + getQualifiedName()
 131                                                 + " did not start interface " + provided;
 132                         }
 133                         throw new SystemAssemblyException(notProvided);
 134                 }
 135         }
 136
 137         /**
 138          * Must be implemented for initializing the subsystem. The implementation
 139          * must call {@link #addService(Service)} for each service that is started.
 140          *
 141          * @return Returns the runtime of the component.
 142          */
 143         protected abstract Type doStart(Scope aScope);
 144
 145         /**
 146          * Implementations must call this method to indicate that a new service has
 147          * been started.
 148          *
 149          * @param aDescriptor
 150          *            Provided interface.
 151          * @param aService
 152          *            Implementation of the interface.
 153          * @param aScope
 154          *            scope in which to publish the implementation.
 155          */
 156         protected final void addInterface(ProvidedInterface aDescriptor,
 157                         Object aService, Scope aScope) {
 158                 LOG.info("Interface '" + getQualifiedName() + "."
 159                                 + aDescriptor.getName() + "' started.");
 160                 if ( !_remaining.get().remove(aDescriptor) ) {
 161                     throw new SystemAssemblyException("Component '" + getQualifiedName() + "' started an unexpected interface '" +
 162                             aDescriptor + "' that was not registerd as a provided interface before");
 163                 }
 164                 aScope.publishInterface(aDescriptor, aService);
 165         }
 166
 167         @Override
 168         public void stop(Type aRuntime) {
 169             LOG.info("Stopping initiated '" + getQualifiedName() + "'");
 170                 doStop(aRuntime);
 171                 LOG.info("Stopping completed '" + getQualifiedName() + "'");
 172         }
 173
 174         protected abstract void doStop(Type aRuntime);
 175
 176         @Override
 177         public String toString() {
 178                 return getQualifiedName();
 179         }
 180
 181         public ProvidedInterface findProvidedInterface(String aName) {
 182             for (ProvidedInterface provided: getProvidedInterfaces()) {
 183                 if ( provided.getName().equals(aName)) {
 184                     return provided;
 185                 }
 186             }
 187             return null;
 188         }
 189
 190         public RequiredInterface findRequiredInterface(String aName) {
 191             for (RequiredInterface required: getRequiredInterfaces()) {
 192                 if ( required.getName().equals(aName)) {
 193                     return required;
 194                 }
 195             }
 196             return null;
 197         }
 198
 199 }