17-03-2011, 12:51 PM
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Jini Technology
Introduction and Architecture Overview
What is Jini
A breakthrough initiative based on Java™ technology
Enables all types of devices to simply connect into impromptu networks, making access to and delivery of new network services as simple as plugging in a telephone.
Enables all types of digital devices to work together in a community put together without extensive planning, installation, or human intervention.
Each device provides services that other devices in the community may use.
What is Jini
A distributed system based on the idea of federating groups of users and the resources required by those users
The overall goal is to turn the network into a flexible, easily administered tool
The focus of the system is to make the network a more dynamic entity
Where Jini Technology be Used
Almost anything that passes digital information in and out
Traditional computer hardware and software
Consumer appliances such as personal digital assistants (PDAs), digital cameras, VCRs, TVs, DVD players, cell phones, and CD players.
An Example Scenario
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.
Under the leadership of Bill Joy and Jim Waldo
Ann Wollrath, the inventor and designer for Java Remote Method Invocation (Java RMI)
Ken Arnold, the designer of JavaSpaces™ technology
Bob Scheifler, a principal of the X Consortium and designer of Lookup/Discovery.
Based on the potential to create a ubiquitous network by leveraging the unique distributed computing characteristics of Java technology
History of Jini Technology
On January 25, 1999, Jini was officially launched and the technology is available for download
By September 1999, 18,000 click-thru agreement /downloads of Jini release from Sun’s web site
Sun currently has agreement with a wide range of technology companies to develop Jini technology services, both hardware and software.
includes Axis, Canon, Datek, Epson, FedEx, Mitsubishi, Norwest Mortgage, Novell, ODI, Quantum, Seagate, Toshiba, Computer Associates, Oki, Salomon Brothers
History of Jini Technology
It is expected that by using Jini technology, we can enable infinitely connected network of services into which anyone will be able to plug-and-participate anytime, from anywhere, using the simplest possible technology.
Why Jini Technology
Network plug and work
Enables a services based architecture
Spontaneous networking
Erase the distinction between hardware and software
A distributed computing infrastructure to make writing distributed programs easier
Jini Technology Builds on Java Technology
Nomenclature
Key terms used in talking about Jini
Federation -- A federation consists of a group of devices (like printers, hard disks and so on) and software programs (any program that is compiled down to Java bytecode) that form a single, dynamic, distributed system.
Resource -- The devices and programs within a federation are called resources
Service -- A resource offers a service. A service can be storage, communication, computation or anything that a resource can do.
Structure of Jini Technology
Jini Infrastructure
Infrastructure is the set of components that enables building a federated Jini system:
The lookup service, which serves as a repository of services. It reflects the current members of the federation and acts as the central marketplace for offering and finding services by members of the federation
The discovery/join protocol, a service protocol that allows services (both hardware and software) to discover, become part of, and advertise supplied services to the other members of the federation
A distributed security system, integrated into RMI, defines how entities are identified and how they get the rights to perform actions on their own behalf and on the behalf of others
Jini Infrastructure -
Lookup Service
The central organizing mechanism for Jini-based systems
The lookup service reflects the current members of the federation
When new services become available on the network, they register themselves with a lookup service
When clients wish to locate a service to assist with some task, they consult a lookup service
Jini Infrastructure -
Discovery / Join / Lookup protocol
Discovery enables clients and services to locate lookup services.
Join enables a service to register itself in a lookup service.
Lookup enables a client to query a lookup service for services that can help the client accomplish its goals.
Jini Infrastructure -
Registering a Service
Jini Infrastructure -
Finding a Service
Jini Infrastructure -
Using a Service
Programming Model
A set of interfaces that enables the construction of reliable services, including those that are part of the infrastructure and those that join into the federation
Leasing interface: defines a way of allocating and freeing resources using a renewable, duration-based model
Event and notification interface: a notification mechanism between services and resources that stretches beyond machine boundaries
Transaction interface: wrapping of multiple operations on multiple services into a single unit of work that either completely succeeds or is rolled back
Programming Model -
Leasing interface
A lease in Jini is a finite duration agreement between two Jini entities. A lease is negotiated between the entity requesting and the entity granting the lease.
With this design, resources claimed in a lease can be automatically released after a period of time. A long-running Jini system
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
Programming Model -
Transaction interface
The transaction interfaces introduce a light-weight, object-oriented protocol enabling Jini applications to coordinate state changes.
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.
Various levels of Atomicity, Consistency, Isolation, and Durability (ACID) can be implemented and guaranteed
Programming Model -
Event and notification interface
Distributed event notification is handled via registration to event generating entities and providing objects that implement the appropriate listener interface
These interfaces are specially designed to cater for the less predictable event propagation characteristic over a distributed system. Specifically, it caters for having agents or middlemen that will manage and handle event registration and notification on behalf of client objects.
Services
Hand-coded using the programming model. Can be programmed to do any task suitable of the resource
Services appear programmatically as objects written in the Java programming language, perhaps made up of other objects.
A service has an interface which defines the operations that can be requested of that service.
The type of the service determines the interfaces that make up that service and also define the set of methods that can be used to access the service.
A single service may be implemented by using other services.
Separation of interface and implementation
Service object can be:
completely local proxy
RMI stub as a proxy
smart proxy
Client does not care about network protocol
Service implementation can evolve over time
A Jini System in Action - Remote PDA Printing
Jini Technology
Introduction and Architecture Overview
What is Jini
A breakthrough initiative based on Java™ technology
Enables all types of devices to simply connect into impromptu networks, making access to and delivery of new network services as simple as plugging in a telephone.
Enables all types of digital devices to work together in a community put together without extensive planning, installation, or human intervention.
Each device provides services that other devices in the community may use.
What is Jini
A distributed system based on the idea of federating groups of users and the resources required by those users
The overall goal is to turn the network into a flexible, easily administered tool
The focus of the system is to make the network a more dynamic entity
Where Jini Technology be Used
Almost anything that passes digital information in and out
Traditional computer hardware and software
Consumer appliances such as personal digital assistants (PDAs), digital cameras, VCRs, TVs, DVD players, cell phones, and CD players.
An Example Scenario
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.
Under the leadership of Bill Joy and Jim Waldo
Ann Wollrath, the inventor and designer for Java Remote Method Invocation (Java RMI)
Ken Arnold, the designer of JavaSpaces™ technology
Bob Scheifler, a principal of the X Consortium and designer of Lookup/Discovery.
Based on the potential to create a ubiquitous network by leveraging the unique distributed computing characteristics of Java technology
History of Jini Technology
On January 25, 1999, Jini was officially launched and the technology is available for download
By September 1999, 18,000 click-thru agreement /downloads of Jini release from Sun’s web site
Sun currently has agreement with a wide range of technology companies to develop Jini technology services, both hardware and software.
includes Axis, Canon, Datek, Epson, FedEx, Mitsubishi, Norwest Mortgage, Novell, ODI, Quantum, Seagate, Toshiba, Computer Associates, Oki, Salomon Brothers
History of Jini Technology
It is expected that by using Jini technology, we can enable infinitely connected network of services into which anyone will be able to plug-and-participate anytime, from anywhere, using the simplest possible technology.
Why Jini Technology
Network plug and work
Enables a services based architecture
Spontaneous networking
Erase the distinction between hardware and software
A distributed computing infrastructure to make writing distributed programs easier
Jini Technology Builds on Java Technology
Nomenclature
Key terms used in talking about Jini
Federation -- A federation consists of a group of devices (like printers, hard disks and so on) and software programs (any program that is compiled down to Java bytecode) that form a single, dynamic, distributed system.
Resource -- The devices and programs within a federation are called resources
Service -- A resource offers a service. A service can be storage, communication, computation or anything that a resource can do.
Structure of Jini Technology
Jini Infrastructure
Infrastructure is the set of components that enables building a federated Jini system:
The lookup service, which serves as a repository of services. It reflects the current members of the federation and acts as the central marketplace for offering and finding services by members of the federation
The discovery/join protocol, a service protocol that allows services (both hardware and software) to discover, become part of, and advertise supplied services to the other members of the federation
A distributed security system, integrated into RMI, defines how entities are identified and how they get the rights to perform actions on their own behalf and on the behalf of others
Jini Infrastructure -
Lookup Service
The central organizing mechanism for Jini-based systems
The lookup service reflects the current members of the federation
When new services become available on the network, they register themselves with a lookup service
When clients wish to locate a service to assist with some task, they consult a lookup service
Jini Infrastructure -
Discovery / Join / Lookup protocol
Discovery enables clients and services to locate lookup services.
Join enables a service to register itself in a lookup service.
Lookup enables a client to query a lookup service for services that can help the client accomplish its goals.
Jini Infrastructure -
Registering a Service
Jini Infrastructure -
Finding a Service
Jini Infrastructure -
Using a Service
Programming Model
A set of interfaces that enables the construction of reliable services, including those that are part of the infrastructure and those that join into the federation
Leasing interface: defines a way of allocating and freeing resources using a renewable, duration-based model
Event and notification interface: a notification mechanism between services and resources that stretches beyond machine boundaries
Transaction interface: wrapping of multiple operations on multiple services into a single unit of work that either completely succeeds or is rolled back
Programming Model -
Leasing interface
A lease in Jini is a finite duration agreement between two Jini entities. A lease is negotiated between the entity requesting and the entity granting the lease.
With this design, resources claimed in a lease can be automatically released after a period of time. A long-running Jini system
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
Programming Model -
Transaction interface
The transaction interfaces introduce a light-weight, object-oriented protocol enabling Jini applications to coordinate state changes.
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.
Various levels of Atomicity, Consistency, Isolation, and Durability (ACID) can be implemented and guaranteed
Programming Model -
Event and notification interface
Distributed event notification is handled via registration to event generating entities and providing objects that implement the appropriate listener interface
These interfaces are specially designed to cater for the less predictable event propagation characteristic over a distributed system. Specifically, it caters for having agents or middlemen that will manage and handle event registration and notification on behalf of client objects.
Services
Hand-coded using the programming model. Can be programmed to do any task suitable of the resource
Services appear programmatically as objects written in the Java programming language, perhaps made up of other objects.
A service has an interface which defines the operations that can be requested of that service.
The type of the service determines the interfaces that make up that service and also define the set of methods that can be used to access the service.
A single service may be implemented by using other services.
Separation of interface and implementation
Service object can be:
completely local proxy
RMI stub as a proxy
smart proxy
Client does not care about network protocol
Service implementation can evolve over time
A Jini System in Action - Remote PDA Printing
