Jini Architecture

Alessandro Brawerman

Contents

Jini definitionAdvantagesArchitectureHow it worksWebsites to check

Distributed system - federating groups of users and the resources required by those users.Enables users to share services and resources over a network.Services can join or leave in a robust way, and clients can rely upon the availability of visible services until clear failure detections.

What is Jini?

Moving to client-client model.Network plug-and-work, dynamic configuration.Easy access to resources anywhere on the network.

Jini - Advantages

Erase the hard/software distinction.

Simplifies maintaining and altering a network.

Jini – Advantages (cont’d)

Based on JavaDynamically download and run codeBuilt-in securityRMIDepends on the Java environment rather programming.

Jini – Java technology-centered

ServiceProxyLookup Service Client

Jini – Architecture

Entity to be used by a person, program or another service.No hardware/software distinction.Dynamic nature – they can be added or withdrawal from a federation at any time.Examples: printers, disks, applications, databases, etc.

Services

Each lookup service provides a list of available services, communication procedure and attributes.

Lookup Service

Lookup Service A Lookup Service BClient A Client B Client C

Printer

Database

Calendar

Printer

Database

Printer Database Disk StorageDisk Storage

Discovery/Join Protocol

Lookup Services

Service sends a looking for lookup services

Lookup Services

Lookup Services respond

Join

Printer

Printer

Printer

It’s an object that teaches the client how to communicate with the service.The proxy is downloaded to the lookup services and then to clients.It can be the service itself.It can be an RMI stub.It can act as a smart adapter.

Proxy

Proxy – Currency Converter

CurrencyConv

Lookup ServiceClient

Proxy – Case 1

CurrencyConv

Client

CurrencyConv

Proxy – Currency Converter

Proxy – Case 2

Client

CurrencyConv

Service

CurrencyConv

RMI

500 dollars

365 UK Pounds

Proxy – Currency Converter

Proxy – Case 3

Client

CurrencyConv

Service

CurrencyConv

Dollar to UK pounds

0.75

RMI, CORBA, Socket, SOAP

Any entity that needs to use a service.Goes through a matching protocol:

Client

Lookup Services

Client sends a looking for lookup services

Lookup Services

Lookup Services respond

Lookup Services

Client searches fortype of services.

Printer

Printer

Lookup Services

Lookup Services return the proxies.

Printer

Printer

The Whole Process

Lookup Service

registration

Proxy

Printer Interface

Registering the service:

The Whole Process (Cont’d)

Lookup ServicePrinter Interface

Client

Looking up for printer interface

Proxy

Looking up for services :

The Whole Process (Cont’d)

Client

Using the service:

Services are registered for a bounded time. Special messages or Heartbeats.Proxies are leased for a bounded time.Clients can renew their proxies, if service permits.The leasing process takes care of fault detection.

Leasing

Leasing (cont’d)

Lookup ServicePrinter Interface

X

Lookup Service

Leasing (cont’d)

Lookup ServicePrinter Interface

Client

Printer interface

Leasing Renewal

Yes, Leasing Time

www.jini.orgwww.sun.com/software/jini/www.kedwards.com/jini/

References