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April 18, 2023
Introduction to Jini & JavaSpaces
Source references: JGrid project
Agenda
Jini SOA Jini intro Jini detailed view Summary
Introduction to Jini
What Is Jini
Java Based SOA Platform Designed as a native extension of the
J2SDK Project in Sun First announced in 1998 Positioned for dynamic networking
Web Services - SOA
Web ServiceWeb Service
UDDI RegistryUDDI
Registry
ClientClient
Publish Find
Bind/Invoke
WSDLWSDL
Web Services
Jini SOA
Jini ServiceJini Service
LookupServiceLookupService
ClientClient
Publish
Bind/Invoke
Java InterfaceJava Interface
Find
Jini
Jini Components
How does it work
Service Registry
Lookup Service Jini Service
ServiceProxy
Publish
Bind/Invoke
Jini ClientFind
Jini – A Detailed view
Discovery Registration Lookup Events Leasing Proxies
Unicast discovery
LookupLocator lookup = null;
ServiceRegistrar registrar = null;
lookup = new LookupLocator(“jini://hostname”);
registrar = lookup.getRegistrar();
Service AService A
Lookup ServiceLookup Service
download
registrarregistrar
LUS proxy
Discovery request
Multicast discovery Discovery is initiated by class LookupDiscovery
LookupDiscovery discover = new LookupDiscovery(LookupDiscovery.ALL_GROUPS);
Asynchronous responses are handled by a listener object (implementing the DiscoveryListener interface)discover.addDiscoveryListener(listener);
Registrationpublic void discovered(DiscoveryEvent e){
//Lookup service discovered – register}
Lookup Service NLookup Service N
Discovering entityDiscovering entityLookup Service …Lookup Service …
Lookup Service 2Lookup Service 2
Lookup Service 1Lookup Service 1
multicast request
Main steps
Discovery Registration Lookup Events Leasing Proxies
try{// register for 100 seconds registration registrar.register(
serviceItem, 100000L); } catch (java.rmi.RemoteException e){}
Service registration
Once we have a proxy to the lookup service, can register the service ServiceRegistration registration = null;//create serviceItem (no ID, no attributes)
ServiceItem serviceItem = new ServiceItem(null, new
GreetingServiceProxy(), null); Service AService A
Lookup ServiceLookup Service
registrarregistrar
download
LUS proxy
register( )
registration
Service Proxy
Main steps
Discovery Registration Lookup Events Leasing Proxies
The client side
// create template for service search
...
GreetingServiceInterface returnedService = null;
try{
returnedService = (GreetingServiceInterface)
registrar.lookup(template);
}catch (java.rmi.RemoteException e){
...
}
returnedService.hello();
}
Lookup ServiceLookup Service
Client 1Client 1
Found proxy
lookup( )
Interface
Template
Template
registrarregistrar
Main steps
Discovery Registration Lookup Events Leasing Proxies
Remote Events
Jini provides remote events to make a Jini system dynamic Services coming and going State changes
The event mechanism is based on Event registration Event handling through an event listener’s
notify() method
Main steps
Discovery Registration Lookup Events Leasing Proxies
Obtaining a Lease
The lease grantor is usually the lookup service and the leaseholder usually is the service.
ServiceRegistration reg = registrar.register();
Lease lease = reg.getLease(); Visually this can be represented as
Service AService ALookup ServiceLookup Service
registrarregistrar
registrationregistrationgetLease(
)
leaselease
Main steps
Discovery Registration Lookup Events Leasing Proxies
Jini service proxy models
There are several ways (patterns) of creating service proxies.
A proxy can: Run entirely in the client JVM Be an RMI stub Be a proxy with local logic using RMI to the back end
service Be a proxy with local logic using its own communication
protocol (e.g. socket) to the back end service Be a wrapper to legacy code (e.g. CORBA)
Introduction to JavaSpaces
What is JavaSpaces?
A JINI service that provides distributed shared memory capabilities
A simple yet powerful service that can be used for solving distributed programming issues such as: Collaboration WorkFlow Synchronization Distributed Computing
JavaSpaces model
Write
Read, Take,Notify
Wri
te
Rea
d, T
ake,
Not
ify
•Write –writes a data object.•Read – reads a copy of a data object.•Take – reads a data object and deletes it.•Notify – generates an event on data updates.
Clustered JavaSpaces
JavaSpaces Methods (Space Operations) JavaSpaces provides a basic API for storing
and reading data objects in a shared resource (a space).
The methods are: Write –writes a data object. Read – reads a copy of a data object. Take – reads a data object and deletes it. Notify – generates an event on data updates.
Example Entry
This shows a minimal entry:
package hello;
import net.jini.core.entry.Entry;
public class Message implements Entry
{
public String content;
public Message()
{
}
}
Must include a constructor
Entry Filed need to be public
Must Implements Entry interface
Write/Read Operations
Instantiate an Entry Set its fields as necessary Write the entry to the space
Read an Entry
Message msg = new Message();
msg.content = "Hello World";
JavaSpace space = (JavaSpace)SpaceFinder.find( “jini://*/*/JavaSpaces” );
Lease l=space.write(msg, null, Lease.FOREVER);
Message template = new Message();
Template.content = “data to match”;
Message result = (Message)space.read(template, null, Long.MAX_VALUE);
Notify Operation
Registering for notifications
// Register a notification
template = space.snapshot(new Message());
EventRegistration reg = space.notify( template,
null, //TX
SpaceEventListener() , // The listener
60000 , // Lease
null); // handbag
System.out.println( "Notification registered. Registration id: " + reg.getID() + “Sequence number: " + reg.getSequenceNumber());
Grid engine for parallel processing
Parallel Batch Processing
Monte Carlo Simulation Details
18,000 Securities, 20 Scenarios, 2,000 Paths/Scenario
1 run = 18K x 20 x 2K (720M) theoretically separate tasks
1 run = 18K x 20 (360k) tasks in reality due to granularity
These larger tasks are separable Computation time per task ranges from 20-2000
ms Total computation time in sequence ~100 H Setup for run takes 1-5 minutes First pass attempts with threading on 8-way box
used 56 H of elapsed time Using the space with 50 units ~2 H
(Source-Invesco)
0
500
1000
Tim
e (s
ec)
1 2 4 8 16 32
CPUs
Optimum Time Elapsed Time
Source: Dr. Alexander Gebhart - Development ArchitectSAP – JavaOne presentation 2003
Scalability & Performance
Parallel Parsing Grid
Provisioning & Monitoring Using the RIO project
RIO Project - SLA based deployment
Monitoring
