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Jini Architecture. Alessandro Brawerman. Contents. Jini definition Advantages Architecture How it works Websites to check. What is Jini?. Distributed system - federating groups of users and the resources required by those users.
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Jini Architecture Alessandro Brawerman
Contents • Jini definition • Advantages • Architecture • How it works • Websites to check
What is Jini? • 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.
Jini - Advantages • Moving to client-client model. • Network plug-and-work, dynamic configuration. • Easy access to resources anywhere on the network.
Jini – Advantages (cont’d) • Erase the hard/software distinction. • Simplifies maintaining and altering a network.
Jini – Java technology-centered • Based on Java • Dynamically download and run code • Built-in security • RMI • Depends on the Java environment rather programming.
Jini – Architecture • Service • Proxy • Lookup Service • Client
Services • 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.
Disk Storage Database Printer Disk Storage Lookup Service • Each lookup service provides a list of available services, communication procedure and attributes. Printer Printer Database Database Calendar Lookup Service A Lookup Service B Client A Client B Client C
Service sends a looking for lookup services Join Lookup Services respond Discovery/Join Protocol Printer Printer Printer Lookup Services Lookup Services
Proxy • 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.
CurrencyConv Currency Conv Currency Conv Client Client Lookup Service Proxy – Currency Converter Proxy – Case 1
500 dollars Currency Conv Currency Conv 365 UK Pounds Service Client Proxy – Currency Converter Proxy – Case 2 RMI
Dollar to UK pounds Currency Conv Currency Conv 0.75 Service Client Proxy – Currency Converter Proxy – Case 3 RMI, CORBA, Socket, SOAP
Client sends a looking for lookup services Client searches for type of services. Lookup Services respond Lookup Services return the proxies. Client • Any entity that needs to use a service. • Goes through a matching protocol: Printer Printer Printer Printer Lookup Services Lookup Services Lookup Services Lookup Services
Printer Interface Proxy registration The Whole Process • Registering the service: Lookup Service
Lookup Service Printer Interface Looking up for printer interface Proxy The Whole Process (Cont’d) • Looking up for services : Client
Client The Whole Process (Cont’d) • Using the service:
Leasing • 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.
Printer Interface Lookup Service Leasing (cont’d) Lookup Service X
Printer Interface Leasing Renewal Yes, Leasing Time Leasing (cont’d) Lookup Service Printer interface Client
References • www.jini.org • www.sun.com/software/jini/ • www.kedwards.com/jini/