Jini Architecture Alessandro Brawerman

Contents Jini definition Advantages Architecture How it works Websites 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 Java Dynamically download and run code Built-in security RMI Depends on the Java environment rather programming. Jini – Java technology-centered

Service Proxy Lookup 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 ALookup Service B Client A Client BClient C Printer Database Calendar Printer Database Printer Database Disk Storage

Discovery/Join Protocol Lookup Services Service sends a looking for lookup services Lookup Services respond Join 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 Service Client Proxy – Case 1 Currency Conv Client Currency Conv

Proxy – Currency Converter Proxy – Case 2 Client Currency Conv Service Currency Conv RMI 500 dollars 365 UK Pounds

Proxy – Currency Converter Proxy – Case 3 Client Currency Conv Service Currency Conv 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 respond Lookup Services Client searches for type of services. Printer Lookup Services return the proxies. Printer

The Whole Process Lookup Service registration Proxy Printer Interface Registering the service:

The Whole Process (Cont’d) Lookup Service Printer 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 Service Printer Interface X Lookup Service

Leasing (cont’d) Lookup Service Printer Interface Client Printer interface Leasing Renewal Yes, Leasing Time

References