---
title: "Short note: JINI"
subject: "Distributed System"
chapter: 2
key: "semester_7/distributed_system:jini-note"
source: https://www.bctengineer.com/q/semester_7/distributed_system/jini-note
site: BCT Engineering
---

# Short note: JINI

Distributed System · Chapter 2: Distributed Objects and File System

- Asked in: 2072 Chaitra, 4 marks
- Video: [Introduction to Jini // Enterprise Application Development](https://www.youtube.com/watch?v=8oDzVFrHFX8) — Global Exploration Knowledge Hub 2.0
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/distributed_system/jini-note
- Whole chapter: https://www.bctengineer.com/md/semester_7/distributed_system/chapter-2

## Question

Write a short note on JINI.

## Short answer

Jini is a Java architecture for dynamic service federation. Services discover lookup services via multicast, register proxy objects with leases, and clients find them. It supports remote events, transactions, and JavaSpaces for spontaneous, self-healing networking.

## Answer

**Jini** is a network architecture from Sun Microsystems (now Apache River) for building distributed systems from services that can join and leave a network dynamically ("spontaneous networking"). It is written in Java and uses RMI, with services described by Java interfaces.

**Main parts**
- **Lookup service:** a registry where services register their proxies with attributes and where clients find them.
- **Discovery and join:** a new service uses multicast discovery to find lookup services, and joins by registering a service proxy object.
- **Leasing:** a registration is for a limited time and must be renewed, so services that become unavailable are removed automatically and the network heals itself.
- **Remote events:** distributed event notification between services.
- **Transactions:** two-phase commit across services.
- **JavaSpaces:** shared object space for coordination.

```text
 Service --discover/register--> Lookup service
 Client  --lookup--> Lookup --> download proxy --> call service
```

Jini supports plug-and-play devices, mobile code, and fault tolerance, and is used in networks of printers, phones and appliances.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is the role of the Jini lookup service?
   A. A device that executes services for clients
   B. A tool that compiles Java code
   C. A registry where services register proxies with attributes and clients find them
   D. A transaction log
   Answer: C. Services join by registering proxies at lookup services; clients search them. (Key point: Lookup service)

2. How does a new Jini service find lookup services?
   A. Polling every client
   B. Using multicast discovery
   C. Reading a fixed address in the code only
   D. Asking the user for an IP address
   Answer: B. Multicast discovery supports spontaneous networking. (Key point: Discovery)

3. What benefit does leasing give Jini?
   A. Unavailable services vanish automatically, giving self-healing
   B. Automatic code compilation
   C. Faster network transmission
   D. Services can never leave
   Answer: A. Registrations expire unless renewed, so dead services are removed. (Key point: Leasing)