A Guide for Online Information
About:
Jini Technology
by Naveen PN
Jini
is a technology developed by Sun Microsystems
that uses and expands the power of the Java
platform to establish impromptu networks of devices. In other words,
the devices form a community in which each device can use the services
provided by other devices in the community. The devices provide their
own interfaces, ensuring reliability and compatibility. Any device which
processes digital data can be connected to the network using Jini technology,
offering a new level of services to the businesses and consumers alike.
Illustration by NaveenIt's
not possible to set up such networks using traditional network topologies
because the traditional networks used today are complex to setup, manage,
and expand. They are also brittle and inflexible. A slight change can
cause havoc which cannot be fixed. What is needed is a simple technology
that allows plug-and-play interfacing of any device. This is where Jini
steps in.Related
links:
The Jini Vision
•
The device should work just by plugging in the power and network cords.
•
Devices and software automatically learn about each other (the concept
of community).
•
No driver installations
•
Recover from network and machine failures
•
Virtually administration free
Click
here for a "Glimpse into the vision behind Jini technology."
How Jini WorksAny
service, whether hardware or software, registers itself with a lookup
service (an application software on one or more hosts in the network).
The services use the "discover" protocol to find the lookup
services and the "join" protocol to register and become available
to service consumers. The
lookup services keep track of the services available in the Jini community
by continuously listening for discovery request datagram packets. The
client (service consumers) requests for services by sending a generic
description of the service to the lookup service. The lookup service then
sends a list of matching services to the client, which selects one or
more of them. The lookup service will then send the Java byte code, which
implements the communication between the client and the service.
Thus, the Jini
technology serves as the link between the client and any service available
on the network and the Java platform frees Jini from dealing with a specific
operating system or hardware. Related
links:
A Popular Jini
ExampleThis
example shows how easy it is to add a CD-ROM drive to a Jini network.
The CD-ROM can
have any one of the several common interfaces and each interface has its
own unique driver for a particular operating system. In a Jini network,
the Administrator just plugs the Jini-enabled drive into the network.
The drive broadcasts discovery requests to the lookup services in the
network. One of the lookup services responds and receives the Java byte
code, which will then implement the interface to the device.
When a computer requests the services of the CD-ROM drive, the lookup
service, which listens to the request, responds with the Java code corresponding
to the drive. The lookup service may even lease the drive to the computer
for some specified time if there is more demand for services from the
drive. The Java byte code establishes the communication between the drive
and the computer. Related
links:
Additional AdvantagesEven
though we cannot build bullet proof software, hardware, and networks using
Jini, we can build them with smart recovery properties. The client doesn't
get access to the service for an infinite period of time, but it is leased
to the client for a specific period of time. This prevents resource hogging
by any specific client and also time sharing of the services between various
clients. (It is easy to find a service only if its lookup service is known.
The ability of Jini to scale up to thousands of network devices and maintain
high security under great stress needs to be tested and refined.)Other
Applications:
-
software
services can easily be provided on a network using Jini
-
Jini
adds value to existing software because other Jini services can
also use the software
-
non-Jini
enabled services can also be used with a Jini wrapper
-
Jini
model easily supports JVM (Java Virtual Machine) enabled devices
and also host-connected devices
-
also
supports mobile devices like cell phones and PDAs
Final CommentsJini
is a young technology, but is promising for a wide variety of application
areas. Few (if any) products based on Jini might have been shipped as
of today. Sun Microsystems is promoting Jini as the technology of the
future in a big way. "The Jini technology represents an important
advance in making home network devices as easy to use as the telephone
is today," said Robba Benjamin, Vice President and General Manager
of Cisco Systems' Consumer Line of Business. So, there is no doubt that
Jini is the technology that will create a "connected"
world.Web
Site Links Related to Jini:
Mailing ListsTo
subscribe to various mailing lists, visit http://www.jini.org/cgi-bin/show-mailing.
Circuit Cellar provides
up to date information for engineers, www.circuitcellar.com for more
information and additional articles.
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