Dynamic Distributed Systems Using JINI

1
Dynamic Distributed Systems Using JINI

• By
• Ahmed. H. Al-Theneyan
• Computer Science Department
• Old Dominion University

2
Outline

• What is JINI ?
• Goals and Objectives
• Architectural Overview
• Infrastructure
• Programming Model
• Services
• Conclusion

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What is JINI (TM) ?

• Brand new distributed systems architecture
  brought out by SUN (TM).
• It enables the building of
• Dynamic
• Flexible
• Easily administered
• distributed system
• Simply, it enables Plug and Play networks

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What does the word "JINI" stands for ?

• It is not an acronym, it does not stand for
  anything. It is pronounced as 'Genie. As
  in "JINI in a bottle." or "JINI of the lamp" in
  Aladdin. That was one guess.
• Bill Joy, one of JINIs project leaders, came up
  with the name, because he liked the sound.

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Goals and objectives

• Resources
• Management
• Sharing
• and access is more simple
• Distributed Programming is more easy
• Easy connection, no need for complicated setup
  procedures
• Simply, Dynamic Distributed Systems

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Architectural Overview

• The whole technology can be segmented into
• Infrastructure
• Programming Model
• Services

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Infrastructure

• Set of components, includes the minimal JINI
  technology core, that enables building of the
  system.
• It includes
• Lookup Service
• Discovery/Join Protocol
• Distributed Security System

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Lookup Service

• Central storage of services available within the
  system
• It is the fundamental part of the infrastructure.
• It organizes services into groups.
• Service can be a member of multiple groups.
• Multiple Lookup Services can maintain the same
  group.
• This helps to achieve fault tolerance.

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How things work (Service Side)?

• When a new service is created, it register itself
  with a Lookup Service (Join).
• It must first locate the appropriate Lookup
  service (Discovery).
• This done using the Discovery/Join Protocol.

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How things work (Client Side)?

• Client locate the appropriate Lookup Service
  (Discovery).
• It locates a service by querying the Lookup
  Service (Lookup)
• This done using the Discovery/Lookup Protocol.
• Then, Client and service can communicate
  directly.

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Discovery Protocol

• It can be
• Multicast Discovery Protocol.
• (looking for an appropriate Lookup Service)
• Unicast Discovery Protocol.
• (looking for a specific Lookup Service or
  non-local Lookup service)
• Multicast Announcement Protocol.
• (Allow Lookup services to advertise their
  presence)

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Multicast Request Protocol
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Unicast Discovery Protocol
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Multicast Announcement Protocol
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Join Protocol

• A service discovers the appropriate Lookup
  Service.
• It connects via the Lookup Service registrar.
• The Service sends some info about itself.
• The Lookup Service stores the information and
  associate it with the requested group, if any.

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Join Protocol
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Lookup Protocol

• A Client discovers the appropriate Lookup
  Service.
• Itll query for the service.
• If found, the object reference of the requested
  service will be loaded into the client.
• Finally, client invoke the service.

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Lookup Protocol
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Distributed Security System

• Define how entities got the right to perform
  actions on their behalf or on behalf of others.
• It extends JDK1.2 platforms security model to
  the world of distributed systems.

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Programming Model

• Set of interfaces that enables the construction
  of reliable services.
• These interfaces make up the distributed
  extension of Java.
• All interfaces are written in Java
• Free source code.
• Has no limit, and it can be extended.

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Programming Model Cont..

• These interfaces include
• Leasing interface
• Events interface
• Transaction interface

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Leasing interface

• Access to many services in the JINI system is
  lease based.
• Lease grant guaranteed access to the service over
  a period of time.
• It is negotiable.
• Can be exclusive or non-exclusive.
• Can be renewed.

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Example

• When a service registers with the lookup service,
  it receives a lease.
• It need to renew periodically.
• When service failed or lease get expired, service
  will be removed.

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Distributed Events Interface

• It extends JavaBeans Event Model to the world of
  Distributed Systems.
• One object, Event Listener, registers an interest
  in event of another object, Event Generator.
• Listener will be notified in a timely and
  reliable fashion.
• Registration of interest is lease based

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Transaction Interface

• Transactions enables operation grouping. Either
  all Succeed or all Fail.
• The JINIs Transaction Interface supply a service
  protocol needed to coordinate 2-Phase commit
  protocol.

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Service

• Something that can be used by a person, program
  or another service.
• It can be Computational, Storage, Software,
  Hardware or Communication Channel.
• It has an interface which define the operations
  that can be requested.

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Services Cont..

• Service objects can be written in any language.
  Client does not care.
• But the interface has to be written in Java.
• One of them is JavaSpaces which can be used for
  simple communication and storage of related
  groups of objects.

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Conclusion

• JINI is the feature of distributed systems
• The dynamic nature of JINI allows resources to be
  added, subtracted at anytime without bothering
  other components.
• Open Source Code is available for download. Thus
  it has no limit.

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Questions
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References

• The main JINI page at Sun http//java.sun.com/pro
  ducts/jini/
• JINI specifications
  http//java.sun.com/products/jini/specs/
• JINI-USERS mailing list archives
  http//archives.java.sun.com/archives/jini-users.h
  tml
• Bill Venners' JINI/JavaSpaces talk
  http//www.artima.com/javaseminars/modules/JINI/Ha
  ndout.html
• JINI Community Web Site, devoted to JINI
  http//www.jinivision.com