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.
Lookup Service Each lookup service provides a list of available services, communication procedure and attributes. Printer Database Calendar Printer Database Disk Storage Lookup Service A Client B Client C Disk Storage Lookup Service B
Discovery/Join Protocol Service sends a looking for lookup services Lookup Services respond Join Printer 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.
Proxy – Currency Converter Proxy – Case 1 Currency. Conv Currency Conv Client Lookup Service
Proxy – Currency Converter Proxy – Case 2 RMI 500 dollars Currency Conv Client 365 UK Pounds Currency Conv Service
Proxy – Currency Converter Proxy – Case 3 RMI, CORBA, Socket, SOAP Dollar to UK pounds Currency Conv Client 0. 75 Currency Conv Service
Client Any entity that needs to use a service. Goes through a matching protocol: Client sends a looking for lookup services Lookup Services respond Client searches for type of services. Lookup Services return the proxies. Printer Lookup Services
The Whole Process Registering the service: Lookup Service Printer Interface Proxy registration
The Whole Process (Cont’d) Looking up for services : Lookup Service Printer Interface Looking up for printerface Proxy Client
The Whole Process (Cont’d) Using the service: Client
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.
Leasing (cont’d) Lookup Service Printer Interface X
Leasing (cont’d) Lookup Service Printer Interface Leasing Renewal Yes, Leasing Time Printerface Client
References www. jini. org www. sun. com/software/jini/ www. kedwards. com/jini/
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