CS 696 Emerging Technologies: Java Distributed Computing Spring Semester, 1999 Starting Jini Services
	Previous    Lecture Notes Index    Next     © 1999, All Rights Reserved, SDSU & Roger Whitney San Diego State University -- This page last updated 16-Mar-99

References
Basics of Jini Services
Starting Jini Services

Starting an HTTP Server
rmid
Jini Lookup Service (reggie)

Lookup Service related Properties

Jini Transaction Manager (mahalo)

Mahalo's System Properties

JavaSpaces

What is a JavaSpace
JavaSpace Implementations (outrigger)
JavaSpaces Properties

References

Local Web Location: http://www-rohan.sdsu.edu/doc/jini/doc/release-notes/jstk.html

Local Web Location: http://www-rohan.sdsu.edu/doc/jini/doc/release-notes/jxp.html

Local Web Location: http://www-rohan.sdsu.edu/doc/jini/doc/example/StartingService.html

Local Web Location: http://www-rohan.sdsu.edu/doc/jini/doc/example/StartingServiceGUI.html

Doc 17, Starting Jini Services Slide # 2

Basics of Jini Services

Doc 17, Starting Jini Services Slide # 3

Starting Jini Services

Starting an HTTP Server

java  -jar  /opt/jini1_0/lib/tools.jar  -port 8888  -dir  /opt/jini1_0/lib/

Cause the HTTP server to search all the jar files in its document root and download the class it finds

log downloading

Doc 17, Starting Jini Services Slide # 4

rmid

Doc 17, Starting Jini Services Slide # 5

Jini Lookup Service (reggie)

• unicast request

• multicast request

The multicast request protocol is used by objects that need to find nearby Jini Lookup services in a LAN environment.

• multicast announcement protocols

The multicast announcement protocol is used by Jini Lookup services to periodically announce their presence to nearby listeners.

java -jar <lookup-server-jarfile> <lookup-client-codebase> 
   <lookup-policy-file>  <output-log-dir>  <lookup-service-group> 

java   -jar  /opt/jini1_0/lib/reggie.jar 
   http://fargo.sdsu.edu:8888/reggie-dl.jar 
   /opt/jini1_0/example/lookup/policy 
   /tmp/reggie_log 
   public 
Doc 17, Starting Jini Services Slide # 6

Lookup Service related Properties

A Jini Lookup service will send out multicast packets announcing its existence every N milliseconds, where N is defined by this property. Currently, the default value of this property is 120,000 milliseconds (2 minutes).

When an instance of the current implementation of the Jini Lookup service uses the unicast request protocol to communicate with a client or service attempting to discover that lookup service, the socket connection used by the protocol will time out after N milliseconds, where N is defined by this property. Currently, the default value of this property is 60,000 milliseconds (1 minute).

If set to any value, this property indicates that debugging information related to the execution of the lookup service's proxy should be printed to System.err. Set this property on clients if calls to the lookup service are unexpectedly returning null values for service objects, service types, attribute set classes, attribute sets, or attribute values.

If set to any value, this property indicates that debugging information related to the execution of the Jini Discovery and Join protocols should be printed to System.err.

If set, this property must be an integer between 512 and the maximum MTU allowed by your system. The value of this property specifies the maximum permissible size of multicast request and announcement packets. The default value is 512.

If set, this property must be an integer between 1 and 255. This property specifies the time-to-live parameter used by both the multicast announcement and multicast request protocol implementations. The default value is 15.

When a client or service uses the unicast request protocol to communicate with a particular lookup service, the socket connection used by the protocol will time out after N milliseconds, where N is defined by this property. The default value is 60,000 milliseconds (1 minute).

Doc 17, Starting Jini Services Slide # 7

Jini Transaction Manager (mahalo)

• does not actually run until clients use references to it
• uses a thread-pool model, so transactions are handled efficiently
• transactions are leased resources
• begins settling transactions aggressively and backs off after successive failed attempts

java -jar <policy-property> 
   <use-rmi-registry-property> [rmi-registry-port-property] 
   <txn-manager-name-property> <txn-manager-server-jarfile> 
   <txn-manager-client-codebase> <security-policy-file> 
   <absolute-path-to-txn-log-dir>  [lookup-service-group] 

java   -jar   -Djava.security.policy=/opt/jini1_0/example/txn/policy.all
   -Dcom.sun.jini.mahalo.managerName=TransactionManager 
   /opt/jini1_0/lib/mahalo.jar
   http://'hostname':8080/mahalo-dl.jar 
   /opt/jini1_0/example/txn/policy.all
   /tmp/txn_log 
   public 
Doc 17, Starting Jini Services Slide # 8

Mahalo's System Properties

If the com.sun.jini.use.registry property is set to a non-null value, the service will bind itself into the RMI registry. This property must be set on the VM that is creating the service. It is only used when creating a service from the command line. This property has no effect on how the service binds itself into Jini Lookup servers.

If the RMI registry is being used, this property can be used to set the port on which the service will look for the registry. This property must be set on the VM that is creating the Mahalo service. It is only used when creating a service from the command line.

The com.sun.jini.mahalo.managerName property defines the name associated with the transaction manager. If the transaction manager is bound to the RMI registry, then the value of the managerName property is the name to which it is bound. If the transaction manager is bound to the Jini Lookup service, this name is used to create an attribute of type net.jini.lookup.entry.Name which is associated with the transaction manager's ServiceItem. This property must be set on the VM that is creating the service. It is only used when creating a Mahalo service from the command line.

When using Mahalo, the java.security.policy property defines the path to the security policy file for the program that sets up the transaction manager. The security policy for transaction manager's VM should be specified by the second command-line argument to Mahalo.

When using Mahalo, the java.rmi.server.codebase property determines the URL that clients will use to load the classes of objects they get from the transaction manager. This URL is set by the first required command-line argument.

Doc 17, Starting Jini Services Slide # 9

JavaSpaces

What is a JavaSpace

• Write

Write an entry into a JavaSpace

• Read

Read an entry from a JavaSpace that matches a template

• Take

Read an entry from a JavaSpace that matches a template

Removing the entry from the space.

• Notify

Notify a specified object when entries that match a template are written into the JavaSpace

Doc 17, Starting Jini Services Slide # 10

public interface JavaSpace {
   public final long NO_WAIT = 0; // don’t wait at all
   Lease write(Entry e, Transaction txn, long lease)
      throws RemoteException, TransactionException;
   Entry read(Entry tmpl, Transaction txn, long timeout)
      throws TransactionException, UnusableEntryException, 
         RemoteException, InterruptedException;
   Entry readIfExists(Entry tmpl, Transaction txn, long timeout)
   throws TransactionException, UnusableEntryException,
      RemoteException, InterruptedException;
   Entry take(Entry tmpl, Transaction txn, long timeout)
      throws TransactionException, UnusableEntryException,
         RemoteException, InterruptedException;
   Entry takeIfExists(Entry tmpl, Transaction txn, long timeout)
      throws TransactionException, UnusableEntryException,
         RemoteException, InterruptedException;
   EventRegistration notify(Entry tmpl, Transaction txn,
      RemoteEventListener listener, long lease,
      MarshalledObject handback)
      throws RemoteException, TransactionException;
   Entry snapshot(Entry e) throws RemoteException;
}
Doc 17, Starting Jini Services Slide # 11

JavaSpace Implementations (outrigger)

• com.sun.jini.outrigger.TransientSpace

Data does not persist after TransientSpace ends

Slightly faster than FrontEndSpace

• com.sun.jini.outrigger.FrontEndSpace

Data persists after FrontEndSpace ends

java -jar <security-policy-property> <use-rmi-registry-property>
    [rmi-registry-port-property] <javaspace-client-codebase-property>
   <javaspace-name-property> <javaspace-server-jarfile> 
   [lookup-service-group] 

java   -jar   -Djava.security.policy=/opt/jini1_0/example/books/policy.all
   -Djava.rmi.server.codebase=http://fargo.sdsu.edu:8888/outrigger-dl.jar 
   -Dcom.sun.jini.outrigger.spaceName=JavaSpaces
   /opt/jini1_0/lib/transient-outrigger.jar
   public 
Doc 17, Starting Jini Services Slide # 12

java -jar <security-policy-property> <use-rmi-registry-property> 
   [rmi-registry-port-property] <javaspace-name-property> 
   <javaspace-server-jarfile> <javaspace-client-codebase> 
   <security-policy-file> <persistent-log-dir> [lookup-service-group] 
java  -jar  -Djava.security.policy=/opt/jini1_0/example/books/policy.all 
   -Dcom.sun.jini.outrigger.spaceName=JavaSpaces    /opt/jini1_0/lib/outrigger.jar
   http://fargo.sdsu.edu:8888/outrigger-dl.jar
   /opt/jini1_0/example/books/policy.all
   /tmp/persistentlogdir
   public 
Doc 17, Starting Jini Services Slide # 13

JavaSpaces Properties

When using a TransientSpace, the java.security.policy property defines the path to the security policy file for the server. When using FrontEndSpace, the java.security.policy property defines the path to the security policy file for the program that sets up the server. In the case of FrontEndSpace, the security policy file for the VM in which the service is actually running is specified by the second required command-line argument.

When using TransientSpace, the java.rmi.server.codebase property determines the URL that clients will use to load the classes of objects they get from the space. When using FrontEndSpace, the codebase of the VM in which the service is running is set by the first required command-line argument.

If the com.sun.jini.use.registry property is set to a non-null value, the service will bind itself to RMI registry. This property must be set on the VM that is creating the service. It is used only when creating a service from the command line, as opposed to creating the service programmatically. This property has no effect on how the service binds itself to Jini Lookup services.

If the RMI registry is being used, this property can assign the port on which the service will look for the registry (1099 is used if this property is not set). It is used only when creating a service from the command line, as opposed to creating the service programmatically.

The com.sun.jini.outrigger.spaceName property defines the name associated with the space. If the space is bound to the RMI registry, then the value of the spaceName property is the name to which it is bound. If the space is bound to the Jini Lookup service, this name is used to create an attribute of type net.jini.lookup.entry.Name that is associated with the space's ServiceItem. It is used only when creating a service from the command line, as opposed to creating the service programmatically.

This property allows extra VM command line arguments to be passed to the back-end process associated with a FrontEndSpace. It must be set on the VM in which the FrontEndSpace is running. The value of this property should be a string that can be passed as an argument to the VM in which the back-end is running.

This property specifies which java executable is used to spawn the VM in which the back-end process runs. The value of this property must be the name of a java executable, including its full path. The named program must be able to accept multiple -Dpropname=value options and the -Xbootclasspath: option. If this property is not set, a default value of "java" is used.

This property controls how aggressive the FrontEndSpace will be when garbage collecting the persistent store. The FrontEndSpace writes directives into logs that are consumed by a back end. This property is set to an integer which represents how many logs must be consumed before the persistent store is garbage collected. Once set to an integer, N, the persistent store is garbage collected by the back end every N logs. If not specified, a default value of 5 is used. This property must be set on the VM in which the back-end process is running

Previous    visitors since 16-Mar-99    Next