Presented by
Syeda Umme Salma

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Introduction
 Jini is a “network infrastructure” running on top of Java to create a federation of virtual machines.
 A “federation” is a set of services that can work together, in a single distributed computing space, to perform a task.
 Network citizens (e.g. devices and applications) within this federation are “dynamically” connected to share information and perform tasks.
History of Jini Technology
• The idea of the Jini system sprang from Sun cofounder “Bill Joy” at Sun Aspen Smallworks R&D lab in 1994.
• On January 25, 1999, Jini was officially launched and the technology is available for download.
• Sun currently has agreement with a wide range of technology companies to develop Jini technology services, both hardware and software.
Features in Jini
• Distributed processing infrastructure –Dynamic configuration
• Ability to “automatically recognize" devices that are plugged – Plug and Play
• No manual configuration required
• Network includes hardware devices (consumer appliances) like telephones, fax, printer, cameras, television, mobile phones, PDA etc..
How to use Jini ?
• Jini takes up 400K which includes the class libraries, the server programs, and the virtual machine – Software
• Can be embedded at the device level within almost any hardware containing a JVM – Hardware
- The only external interfaces for Jini-enabled devices are a power cord and a telephone plug
An Example Scenario
• Printer driver must be installed.
• Location must be known to the clients.
• If the printer is moved to the new location, driver must be reinstalled.
• If the printer is replaced with a new enhanced capabilities again reinstallation of the driver is required.
Literature Survey
• Distributed system – consists of multiple autonomous computers that communicate through a computer network
Types - Client-server, 3-tier architecture, N-tier architecture, loose coupling, or tight coupling.
• Java Remote Method Invocation – clients use objects from different JVM
import java.rmi.*;
interface ComputeTask extends Remote { void acceptTask(Task task) throws
RemoteException, InvalidTask;
}

Literature Survey
• Broker Architecture – structures distributed objects with decoupled components that interact by remote service invocations. Example CORBA (Common Object Request Broker Architecture)- object oriented technology for distributed objects in heterogeneous systems. Supports multiple platforms.
Literature Survey
• Multicast - Multicast addressing is a network technology for the delivery of information to a group of destinations simultaneously.
Delivery the messages over each page link of the network only once.
Statement of Problem
 Many aspects of Distributed systems, say configuration or topology if the devices are mobile, may be subject to change as part of a dynamic networking system.
 Jini provides mechanisms to recognize, acknowledge, and build their systems to accommodate change.
 Enables true plug and play mechanism.
 Provides scalable, evolvable, and flexible system for dynamic runtime environments.
Approaches and Methods
Jini Architecture
• The Jini Client – needs service
• The Service Locator – finds services in distributed network
• The Jini Service – services used by client like printer, television etc..
Jini specifications
• A Programming Model – builds a distributed system.
 Leasing
 Distributed events
 Transactions
A Runtime Infrastructure –
• Discovery protocol: Used to find the “lookup” services on the network, which are used to register a new service or to find a service.
• Join protocol: Used for registering a new service.
• Lookup protocol: Used by client devices to find a needed service.
Discovery Protocol
• A pair of these protocols – discovery and join -- occurs when a device is plugged in.
• Discovery occurs when a service is looking for a lookup service with which to register.
• The service provider locates a lookup service by multicasting a request on the local network for any lookup services to identify themselves.
Join Protocol
• Join occurs when a service has located a lookup service and wishes to join it.
• A service object for the service is loaded into the lookup service.
• Service object contains the Java programming language interface for the service, including the methods.
Lookup Protocol
• A client locates an appropriate service by its type.
• The service object is loaded into the client.
• The final stage is to invoke the service.
The Discovery/Join/Lookup Process
Jini Services
• Service registration: Every new service must register itself to allow users to find and use it.
• Service discovery: Enables users to find the service.
• Service use: A Java object that specifies service capabilities and contains Java code that allows a client computer to use the service.
• Service removal: A service is removed by removing the associated service proxy object from the LUSs.

Jini Features for Distributed Computing
 Code Mobility
-relies heavily on RMI so both data and code can be moved.
- enables you to allocate and migrate code transparently.
 Leasing
- Jini is designed to be used in an unreliable environment.
-Uses leasing model, which imposes a time limit for the use of the service
- the client holder requests a lease from a grantor.
-Can effectively recover from disconnection and/or partial system failure.
-Has the equivalent of a garbage collection process for stale and unreferenced entries and resources.
Jini Features for Distributed Computing
 Distributed events
- Jini-based services can notify each other when a change in their state occurs.
- Event Notification Mechanism , this distributed event model allows services to register with each other and receive notification.
- The Event Generator generates remote events upon abstract state changes. The Event Listener registers interest.
- Objects that want to receive notification of a remote event, implement the RemoteEventListener interface.
- An UnknownEventException is thrown if the event is unrecognizable.
Jini Features for Distributed Computing
 Transactions
-A transaction is essentially multiple atomic operations that can be treated as a single unit.
-The transaction protocol provides two steps to coordinate the actions of a group of distributed objects.
Voting phase: each object “votes” whether it has completed its portion of the task and is ready to commit any changes it made.
Commit phase: a coordinator issues a “commit” request to each object.
Advantages of Jini Technology
• Location independent -a service requester need not be prewired with the lookup service location information.
• Protocol agnostic -a service requester can interact with any type of service provider using appropriate protocols.
• Loosely coupled-a service requester can discover the service provider's interface at run-time.
• Dynamic and self-managed-the entire community is self-formed and self-managed at run-time.
• More fault tolerant
• Plug and Play – spontaneous networking.
Results and Discussion
• Results in a system in which the network supports a fluid configuration of objects that can move from place to place as needed.
• Uses the the Java application environment to simplify the construction of a distributed system.
• Allows fluidity of all components in a distributed system, extending the easy movement of objects(data and code) to the entire networked system.
• Provides mechanisms for devices, services, and users to join and detach from a network(automatically).
• The system is Adaptive, Scalable, Evolvable, and Flexible.
Conclusions and Further Scope
• Jini is a network middleware for the new age of ubiquitous computing.
• It enables communication between applications and devices in a heterogeneous network environment.
• Jini Technology provides global high-performance distributed computing.
• Future work includes re-implementing the system in Jini.