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

   1 package org.wamblee.system;
   2
   3 import java.util.ArrayList;
   4 import java.util.Arrays;
   5 import java.util.Collection;
   6 import java.util.HashMap;
   7 import java.util.List;
   8 import java.util.Map;
   9
  10 import org.apache.commons.logging.Log;
  11 import org.apache.commons.logging.LogFactory;
  12 import org.wamblee.system.Component.Status;
  13
  14 /**
  15  * Abstract subsystem class making it easy to implement new subsystems.
  16  */
  17 public abstract class AbstractComponent implements Component {
  18
  19         private static final Log LOG = LogFactory.getLog(AbstractComponent.class);
  20
  21         private Status _status;
  22         private String _name;
  23         private ServiceRegistry _registry;
  24         private List<InterfaceDescriptor> _provided;
  25         private List<InterfaceDescriptor> _required;
  26         private Map<InterfaceDescriptor, Service> _running;
  27
  28         /**
  29          * Constructs the subsystem.
  30          *
  31          * @param aRegistry
  32          *            Registry of services.
  33          * @param aName
  34          *            Name of the system.
  35          * @param aProvided
  36          *            Provided services.
  37          * @param aRequired
  38          *            Required services.
  39          */
  40         protected AbstractComponent(String aName, ServiceRegistry aRegistry, ProvidedInterfaceDescriptor[] aProvided,
  41                         RequiredInterfaceDescriptor[] aRequired) {
  42                 _status = Status.NOT_STARTED;
  43                 _name = aName;
  44                 _registry = aRegistry;
  45                 _provided = new ArrayList<InterfaceDescriptor>();
  46                 _provided.addAll(Arrays.asList(aProvided));
  47                 _required = new ArrayList<InterfaceDescriptor>();
  48                 _required.addAll(Arrays.asList(aRequired));
  49                 _running = new HashMap<InterfaceDescriptor, Service>();
  50         }
  51
  52         @Override
  53         public Status getStatus() {
  54                 return _status;
  55         }
  56
  57         @Override
  58         public final String getName() {
  59                 return _name;
  60         }
  61
  62         public ServiceRegistry getRegistry() {
  63                 return _registry;
  64         }
  65
  66         @Override
  67         public final ProvidedInterfaceDescriptor[] getProvidedServices() {
  68                 return _provided.toArray(new ProvidedInterfaceDescriptor[0]);
  69         }
  70
  71         @Override
  72         public final RequiredInterfaceDescriptor[] getRequiredServices() {
  73                 return _required.toArray(new RequiredInterfaceDescriptor[0]);
  74         }
  75
  76         @Override
  77         public final Service[] start(String aContext,
  78                         Service[] aRequiredServices) {
  79                 LOG.info("Initializing '" + aContext + "." + _name + "' with "
  80                                 + Arrays.asList(aRequiredServices));
  81                 doStart(aContext + "." + getName(), aRequiredServices);
  82                 _status = Status.RUNNING;
  83                 return _running.values().toArray(new Service[0]);
  84         }
  85
  86         /**
  87          * Must be implemented for initializing the subsystem. The implementation
  88          * must call {@link #addService(Service)} for each service that is started.
  89          *
  90          * @param aRequiredServices
  91          *            Services that are already running from other subsystems that
  92          *            may be used.
  93          */
  94         protected abstract void doStart(String aContext,
  95                         Service[] aRequiredServices);
  96
  97         /**
  98          * Implementations must call this method to indicate that a new service has
  99          * been started.
 100          *
 101          * @param aService
 102          *            Service.
 103          */
 104         protected final void addService(String aContext,
 105                         ProvidedInterfaceDescriptor aDescriptor, Object aService) {
 106                 LOG.info(aContext + ": service '" + aService + "' started.");
 107                 Service svc = getRegistry().register(aDescriptor, aService);
 108                 _running.put(svc.getDescriptor(), svc);
 109         }
 110
 111         @Override
 112         public Service[] getRunningServices() {
 113                 return _running.values().toArray(new Service[0]);
 114         }
 115
 116         @Override
 117         public void stop() {
 118                 doStop();
 119                 for (Service svc: _running.values()) {
 120                         getRegistry().remove(svc);
 121                 }
 122                 _status = Status.STOPPED;
 123         }
 124
 125         protected abstract void doStop();
 126
 127         @Override
 128         public String toString() {
 129                 return _name;
 130         }
 131
 132 }