JINI Java Intelligent Network Infra-structure Gijung Yun © Realtime Embedded Systems Laboratory Inha University

JINIJINI

Java Intelligent Network Infra-structure

Gijung Yun© Realtime Embedded Systems Laboratory

Inha University

© 2002, Gijung Yun, RESL, Inha University Page : 2

JINI

Contents

Introduction – Vision and Charicteristic

Jini Environment Jini Infrastructure Jini Architecture

1. RMI 2. Discovery, join and lookup3. Leasing 4. Events5. Transaction 6. Services7. Entry 8. Security


JINI

Introduction

Jini Goals– Network plug and work– Enable spontaneous networking– Promote service-based architecture– Simplicity– Resources can be implemented as

either hardware devices, software programs, or a combination of the two.


JINI


JINI

관련 기술– UPnP

MS, Compaq, Intel, Philips…

– HAVi Sony, Philips, Samsung, Sun… 가정내 AV 기기를 접속하는 기술


JINI

Characteristic – 100% Pure Java – Collection of API’s and Protocols

Infrastructure Built on RMI Discovery, Join and Service Protocols Lookup Service

Programming Model Leasing Interface Event and Notification Interfaces Transaction Interfaces

Services Fundamental entity of Jini

– Reference Implementations Supplied


JINI

Jini Environment

Java 2 compatible VM Network of reasonable speed

– Multicast support preferable– Initial support for TCP/IP only

Class file server– HTTP most commonly used

Dynamic address allocation– DHCP

Devices should have some memory and CPU– Can use a ‘proxy’ as an alternative


JINI

Jini Infrastructure

Windows UnixOther OS or Devices

Java VM

Boot, Discover, Join

RMI

JavaSpaces

Directory Services

Jini

It is a set of software layers that together create a federation of computer devices and services


JINI

Jini Architecture

RMI Discovery, Join & Lookup Leasing Events Transactions Services


JINI

RMI

Remote Method Invocation Object-Oriented RPC

– Similar to CORBA Distinguished by ability to parse

objects by value


JINI

Discovery, Join and Lookup

Discovery– Find a Lookup Service

Multicast UDP for nearby Lookup services Unicast TCP for known Lookup services

Join– Used by services to register with a Lookup S

ervice– Registration Utility Classes

LookupDiscover for multicast discovery LookupLocator for unicast discovery


JINI

Lookup

– Repository of available services– Stores each service as Java objects– Clients and services use to request a

service type from a Lookup service Search by type(Java Interface), not

name Closer to CORBA Trader service than

CORBA Naming service


JINI

Discovery and Join

Jini LookupService

J

J

ServiceProvider

512 byteDiscoveryMulticast

RMIReferenceJoin Upload

출처 : Sun


JINI

Lookup

RMIReference

LookupDownload

Jini LookupService

ServiceConsumer

J

J

ServiceProvider

Discovery

J

출처 : Sun


JINI

DiscovererLookupService

Request Message(sent via UDP multicast)

Response Message(sent via TCP unicast)

DiscovererLookupService

Announcement Message(sent via UDP multicast)

Request Message(sent via TCP unicast)

Response Message(sent via TCP unicast)


JINI

Vers<int>

Port<int>

GroupLen

<int>

Group 1<string>

Group 2<string>

…

Where the discoverer wants repliesSent to

Desired groups(length == 0 all)

HeardLen

<int>

Heard 1<svc id>

Heard 2<svc id>

…Known LookupServices

Request packet format


JINI

Announcement packet format

Vers<int>

Host<string>

Port<int>

My Id<svc id>

GroupLen

<int>

Group 1<string>

Group 2<string>

…

Service information(header)

Groups that I am amember of


JINI

Lookup Services

Maps interfaces indicating the functionality provided by a service to sets of objects that implement the service

JJ

Object

StorePrint

CopierFaxPrinter

HPCanon

BJC-70LBP-1260

BJ-100J

Service must be serialisableand implement Entry

출처 : Sun


JINI

May be federated with other lookup services

Lookup service interface provides:– Registration, Access, Search,

Removal


JINI

Network Issue– IP-based– Request Packet size limitation

(512Byte)– Limiting the scope of multicast

TTL ( recommend 15 )


JINI

Distributed Leasing

A form of Distributed ‘Garbage Collection’– Enables stability and resilience

Service is ‘loaned’ to a client for a certain period of time

Delegation of Lease Renewal– Allows clients/services to delegate

lease renewal to a third party object


JINI

Attribute Modification– If a service is asked to change the set

of attributes with which it registers itself,

– it saves the changed set in a persistent store, then performs the requested change at each lookup service with which it is registered.


JINI

Registering and Unregistering with Lookup Services– register with lookup service

adds that lookup service to the persistent set of lookup services it should join,

and then registers itself with that lookup service.

– unregister from lookup service service is in the persistent set of lookup

services to join, it should be removed from that set.

the service cancels the leases for all entries it maintains at that lookup service.


JINI

join a group– it adds the name of that group to the

persistent set of groups to join,– and either starts or continues to

perform multicast discovery using this augmented group.


JINI

leaving a group– It removes that group from the persistent

set of groups to join.– It removes all lookup services that match

only that group in the set of groups it is interested in from the set it has discovered using multicast discovery, and unregisters from those lookup services.

– It either continues to perform multicast discovery with the reduced set of groups or, if the set has been reduced to empty, ceases multicast discovery.


JINI

Distributed Events

Extends the standard Java event model– Adds features to provide resilience and determinati

on in a distributed environment Registration for event notifications is lease based Unique event identifiers assigned to every event supplier Event sequence numbers assigned to every event Event types

– Marshaled Object enables: Store-and-forward Notification filter Notification MailBox


JINI

Transactions

Set of Interfaces that support the implementation of a two-phase commit protocol– Designed to be lightweight

Left to developer to implement as much (or as little) of the transactional semantics as they need

Lease based - transaction will fail if not completed within leased period

– Supports distributed transactions– Sample Implementation supplied in Jini distribution


JINI

출처 : Sun


JINI

Services Services are defined by their interface Services must:

– Discover and register with a lookup service(s)– Maintain the following across failures:

ServiceID(128bit) assigned by a lookup service The service attributes that define its lookup entry The group(s) the service participates in Specific lookup services it must participate in

– Maintain all leases with lookup services they have registered with

Utility Classes provided to manage these responsibilities


JINI

Using a Service– Communication is between service

and its proxy– Independent of wire protocol– Protocol can change without affecting

client– RMI semantics core to functionality


JINI

Entry

Typed set of objects, for matching Provides extra information about services A service may have any number of entries Clients request services by class and/or by

entries, using a simple matching system Drawback:

– relational operators such as < and != are not supported


JINI

There are some convenience subclasses of Entry:– Address: the address of the physical component of a

service.

– Location: the location of the physical component of a service. It can be used alone in a small, local organization.

– Comment: a free-form comment about the service.

– Name: name(s) of the service as seen by users.

– ServiceInfo: generic information about a service. Includes the name of the manufacturer, the product, and the vendor.

– ServiceType: human-oriented information about the "type" of a service. This is not related to its data or class types.

– Status: the base class from which other status-related entry classes may be derived.


JINI

Security The design of the security model for Jini

technology is built on the twin notions of a principal and an access control list.

Jini services are accessed on behalf of some entity—the principal—which generally traces back to a particular user of the system.

Whether access to a service is allowed depends on the contents of an access control list that is associated with the object (entity).


JINI

The Sun Community Source License (SCSL)

Three Levels of Participation– Research and Education

Source code freely available Can be used in any way other than deployment

– Internal Deployment Deployed code must pass a compatibility test

– Commercialisation Source code available with Jini trademark for a branding fe

e Branding fee covers cost of trademark protection and com

patibility testing Low cost fee is based on either annual fee or royalty per d

evice/service sold - whichever is the lower


JINI

Summary

Jini limitations– TCP/IP, multicast, Java RMI, Java 2 VM

Jini philosophy is useful


JINI

Reference

Web Sites– http://www.jini.org/– http://java.sun.com/jini– http://java.sun.com/products/javaspaces

Documents

JINI Java Intelligent Network Infra-structure Gijung Yun © Realtime Embedded Systems Laboratory Inha University