Spring Semester, 1999
An Activatable Jini Service
© 1999, All Rights Reserved, SDSU & Roger Whitney
San Diego State University -- This page last updated 25-Apr-99
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CS 696 Emerging Technologies: Java Distributed Computing Spring Semester, 1999 An Activatable Jini Service |
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© 1999, All Rights Reserved, SDSU & Roger Whitney San Diego State University -- This page last updated 25-Apr-99 |
import java.rmi.Remote;
import java.rmi.RemoteException;
public interface HelloInterface extends Remote
{
public String sayHello() throws RemoteException;
}
import net.jini.core.entry.Entry;
import net.jini.core.lookup.ServiceTemplate;
import net.jini.core.lookup.ServiceRegistrar;
import net.jini.core.discovery.LookupLocator;
import net.jini.lookup.entry.Name;
import java.rmi.RMISecurityManager;
public class HelloClient
{
private static final REGGIE_URL = "jini://eli.sdsu.edu";
private static final SERVER_LABEL = "HelloServer";
public static void main (String[] args) throws Exception
{
System.setSecurityManager (new RMISecurityManager ());
LookupLocator lookup = new LookupLocator(REGGIE_URL);
ServiceRegistrar registrar = lookup.getRegistrar ();
Entry[] serverAttributes = new Entry[1];
serverAttributes[0] = new Name( SERVER_LABEL );
ServiceTemplate template =
new ServiceTemplate (null, null, serverAttributes);
HelloInterface myServerInterface =
(HelloInterface) registrar.lookup (template);
System.out.println ( myServerInterface.sayHello () );
}
}
Click here for the source code.
public class HelloServer extends Activatable
implements HelloInterface, ServiceIDListener
{
//MarshalledObject hash keys
// In passing data to the HelloServer in the constructor
public static final String GROUP_KEY = "reggieGroups";
public static final String DATA_DIR_KEY = "dataStore";
public static final String SERVICE_LABEL_KEY = "name";
// File used to store the service id.
private static final String SERVICE_ID_FILE = "serviceID";
// Logging keys and default values
private static final String LOG_SETTING_FILE = "log.properties";
private static final String LOG_FILE = "ServerLog";
private static final String LOG_FILE_KEY = "file";
private static final String LOG_TYPE_KEY = "type";
private static final String LOG_TYPE_FILE = "file";
private static final String LOG_TYPE_SCREEN = "screen";
private static final String DEBUG_KEY = "debug";
private static final String DEBUG_ON = "on";
// Directory containing log file, log configuration file and
// service ID file, value comes from marshalledObject
private File storageLocation;
// the server is registered under this name with lookup service
// value is obtained from marshalledObject passed to server
private String serviceName;
public HelloServer( ActivationID id, MarshalledObject data)
throws RemoteException
{
super(id, 0);
try
{
// Get the data from the MarshalledObject
HashMap initialData = (HashMap) data.get();
String[] groups = (String[]) initialData.get( GROUP_KEY );
String dataLocation =
(String )initialData.get( DATA_DIR_KEY );
serviceName =
(String )initialData.get( SERVICE_LABEL_KEY );
storageLocation = new File( dataLocation );
initializeLogging();
Logger.log( "HelloServer Started" );
joinReggie( groups);
}
catch (Exception startupError)
{
Logger.error( "Start up error" );
Logger.error( startupError );
}
}
public void serviceIDNotify (ServiceID uniqueID)
{
Logger.log( "Obtained serviceID " + uniqueID );
saveServiceID( uniqueID );
}
public String sayHello () throws RemoteException
{
try
{
Logger.log( "Connection from " + getClientHost() );
}
catch (java.rmi.server.ServerNotActiveException error)
{
Logger.log( "Connection, client data not available" );
}
return ("Hello World from Jini Hello server!");
}
private void joinReggie( String[] groups ) throws IOException
{
Logger.debug( "Join" );
ServiceID helloID = getServiceID();
Entry[] labels = getServiceLabels();
// Avoid all Jini services registering at same time when
// machine is brought up - use random delay
randomPause( 1000 * 15 );
if (helloID == null )
{
Logger.debug( "Join, no ID" );
new JoinManager(this, labels, groups, null, this,
new LeaseRenewalManager () );
}
else
{
Logger.debug( "Join with ID" );
new JoinManager( helloID, this,labels, groups, null,
new LeaseRenewalManager () );
}
}
private Entry[] getServiceLabels()
{
Entry[] labels = new Entry[1];
labels[0] = new Name(serviceName);
return labels;
}
/**
* Delay execution for random time between 0 and maxDelay
* milliseconds
*/
private void randomPause(int maxDelay)
{
try
{
Random delayGenerator = new Random();
long delay = delayGenerator.nextInt( maxDelay );
Logger.debug( "Pause for " + delay + " milliseconds" );
Thread.sleep( delay );
}
catch (InterruptedException interuptedError )
{//just proceed, as this is just a pause method
}
}
/**
* Save the service id in a file. If save does not succeed, no file
* will be created.
*/
private void saveServiceID( ServiceID uniqueID )
{
File serviceIDFile =
new File( storageLocation, SERVICE_ID_FILE );
try
{
FileOutputStream out = new FileOutputStream( serviceIDFile );
BufferedOutputStream buffered =
new BufferedOutputStream( out);
DataOutputStream cout = new DataOutputStream( buffered);
uniqueID.writeBytes( cout );
cout.close();
}
catch (IOException writeProblem)
{
Logger.error( "Error in writing service id file" );
Logger.error( writeProblem );
serviceIDFile.delete();
}
}
/**
* Recover ServiceID from file. Return null if ServiceID
* does not exist or can not be recovered
*/
private ServiceID getServiceID()
{
File serviceIDFile =
new File( storageLocation, SERVICE_ID_FILE );
if ( !serviceIDFile.exists() )
return null;
try
{
FileInputStream in = new FileInputStream( serviceIDFile );
BufferedInputStream buffered = new BufferedInputStream( in);
DataInputStream cin = new DataInputStream( buffered);
ServiceID id = new ServiceID( cin );
cin.close();
return id;
}
catch (IOException readProblem)
{
Logger.error( "Error in reading service id file" );
Logger.error( readProblem );
return null;
}
}
private void initializeLogging( )
{
Properties logSettings = getLogProperties( );
String logType =
logSettings.getProperty(LOG_TYPE_KEY,LOG_TYPE_FILE );
String debug =
logSettings.getProperty( DEBUG_KEY, DEBUG_ON );
String logFileName =
logSettings.getProperty( LOG_FILE_KEY, LOG_FILE );
SelectiveLogger serverLogger;
try
{
if ( logType.equals( LOG_TYPE_SCREEN ) )
serverLogger = (SelectiveLogger) ScreenLogger.register( );
else
{
File logFile = new File( storageLocation, logFileName );
serverLogger = (SelectiveLogger) FileLogger.register( logFile.getPath() );
}
if (debug.equals(DEBUG_ON) )
serverLogger.debugOn();
else
serverLogger.debugOff();
}
catch (LoggerCreationException logFileProblem )
{
// Can't create Filelogger so use screenlogger.
ScreenLogger.register( );
}
}
private Properties getLogProperties()
{
Properties logSettings = new Properties();
File logSettingFile =
new File( storageLocation, LOG_SETTING_FILE);
try
{
if ( logSettingFile.exists() )
{
FileInputStream in = new FileInputStream( logSettingFile );
BufferedInputStream buffered = new BufferedInputStream( in);
logSettings.load( buffered );
}
return logSettings;
}
catch (Exception readLoadError)
{
return new Properties();
}
}
public class RegisterHelloServer
{
// Place important constants in one place
static String serviceLabel = "HelloServer";
static String serverClass = "HelloServer";
static String serverClassLocation =
"file:/export/home/whitney/java/whitney/jini/examples/activatable/";
static String serverDataDir =
"/export/home/whitney/java/whitney/jini/examples/activatable/ServerData";
static String policyFileLocation = "/export/home/whitney/jini_data";
static String[] reggieGroups = { "whitney" };
public static void main( String[] args ) throws Exception
{
System.setSecurityManager(new RMISecurityManager());
System.out.println("Start main");
Properties policyFileLocation = new Properties();
policyFileLocation.put("policy", policyFileLocation);
ActivationGroupDesc.CommandEnvironment ace = null;
ActivationGroupDesc exampleGroup =
new ActivationGroupDesc(policyFileLocation, ace);
ActivationGroupID agi =
ActivationGroup.getSystem().registerGroup(exampleGroup);
ActivationGroup.createGroup(agi, exampleGroup, 0);
HashMap initializationData = new HashMap();
initializationData.put( HelloServer.GROUP_KEY, reggieGroups );
initializationData.put( HelloServer.DATA_DIR_KEY, serverDataDir );
initializationData.put( HelloServer.SERVICE_LABEL_KEY, serviceLabel );
MarshalledObject data = new MarshalledObject( initializationData );
ActivationDesc desc =
new ActivationDesc(serverClass, serverClassLocation, data, true);
System.out.println("Register with rmid");
HelloInterface server = (HelloInterface) Activatable.register(desc);
System.out.println("Class registered with rmid");
//Force object to be activated by accessing it.
System.out.println( server.sayHello() );
System.out.println("Class activated");
}
}