--- title: "JINI goals, CORBA services, OS support" subject: "Distributed System" chapter: 3 key: "semester_7/distributed_system:os-support-jini-corba" source: https://www.bctengineer.com/q/semester_7/distributed_system/os-support-jini-corba site: BCT Engineering --- # JINI goals, CORBA services, OS support Distributed System · Chapter 3: Operating System Support - Asked in: 2071 Chaitra, 4+2+2 marks - Video: [CORBA : What is CORBA in Distributed System ? : Distributed System](https://www.youtube.com/watch?v=PpbJq5OA66Y) — Computer Science Academy By Dinesh Sir - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_7/distributed_system/os-support-jini-corba - Whole chapter: https://www.bctengineer.com/md/semester_7/distributed_system/chapter-3 ## Question List the goals of JINI. What are CORBA services? How does operating system support for distributed system? ## Short answer JINI enables network plug-and-play, service discovery, and leasing. CORBA services cover naming, events, transactions, security, etc. The OS provides processes/threads, communication (sockets/IPC), memory management, protection, and device access, often using a microkernel design. ## Answer #### Goals of JINI JINI is Sun Microsystems' Java-based technology for building networked services that join and leave a network spontaneously. Its goals are: - **Network plug and play**: a device or software service can be attached to the network and used without manual installation or configuration. - **Simplicity of use**: users get services on demand; administration is minimal. - **Reliable, self-healing network**: services are leased; if a service fails or leaves, its lease expires and it is removed automatically. - **Service discovery and lookup**: clients find services through a lookup service by type, not by address. - **Platform independence**: any device with a Java Virtual Machine can take part; code (proxy) is downloaded dynamically. - **Scalability and flexibility**: small devices and large servers can be federated in one community. #### CORBA services CORBA services (COSS, Common Object Services) are a set of standard, IDL-defined, general-purpose services that every distributed object application needs. Main ones: - **Naming service**: binds names to object references. - **Event and Notification service**: asynchronous communication between objects (suppliers and consumers). - **Life-cycle service**: create, copy, move and delete objects. - **Persistent object service**: store object state on disk. - **Transaction service**: atomic operations across objects. - **Concurrency control service**: locks. - **Security service**: authentication, access control, encryption. - **Trading service**: find objects by properties. - **Relationship, Query and Time services**. #### Operating system support for distributed systems The OS gives the base on which middleware and applications run: - **Processes and threads**: concurrent servers handle many clients at once. - **Communication primitives**: sockets, message passing, RPC support (kernel IPC). - **Memory management**: virtual memory and shared memory for fast local communication. - **Protection**: address spaces and kernel/user mode, access rights on resources. - **Naming, file and device access**: network file systems and remote devices. - **Scheduling and synchronisation** of threads and processes. - A **microkernel** design provides only the basic mechanisms (threads, IPC, memory) so that other services run as user-level servers and can be replaced. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Which is a goal of JINI? A. Network plug and play with no manual configuration B. Replacing Java C. Requiring fixed addresses D. Forbidding service discovery Answer: A. JINI lets services join and leave the network spontaneously. (Key point: JINI goal) 2. In JINI, what happens when a service fails and stops renewing its lease? A. It stays registered forever B. The network crashes C. The user must remove it D. The lease expires and it is removed automatically Answer: D. Leasing makes the network self-healing. (Key point: Leasing) 3. What is the difference between CORBA Naming and Trading services? A. Naming binds names to references; Trading finds objects by properties B. Naming finds by properties; Trading binds names C. Both only handle transactions D. They are the same Answer: A. Naming is like white pages, trading like yellow pages. (Key point: CORBA naming vs trading) 4. What does a microkernel provide for distributed systems? A. All services in the kernel B. Only basic mechanisms (threads, IPC, memory), other services run as replaceable user-level servers C. Only a GUI D. Only file systems Answer: B. This keeps the kernel small and services replaceable. (Key point: Microkernel support) ## Related in Distributed System - [CORBA invocation methods and services](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Acorba-invocation-services) — Distributed System, chapter 4, asked 3× - [Short note: CORBA services](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Acorba-services-note) — Distributed System, chapter 4 - [CORBA services; object adapter functions](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Acorba-services-object-adapter) — Distributed System, chapter 4 - [IDL and CORBA RMI with services](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Aidl-corba-rmi) — Distributed System, chapter 4 - [Middleware role; CORBA and services](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Amiddleware-corba-services) — Distributed System, chapter 4 - [Short note: JINI distributed event spec](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Ajini-event-note) — Distributed System, chapter 2 ## Related in other subjects - [Multiprogramming, multiprocessing, distributed OS](https://www.bctengineer.com/question.md?key=semester_6%2Foperating_system%3Amultiprog-multiproc-distributed-os) — Operating System, chapter 1 - [OS abstraction, extended machine, system call](https://www.bctengineer.com/question.md?key=semester_6%2Foperating_system%3Aos-abstraction-system-call) — Operating System, chapter 1 - [Features of a typical operating system](https://www.bctengineer.com/question.md?key=semester_4%2Fmicroprocessor%3Afeatures-of-operating-system) — Microprocessor, chapter 6, asked 3× - [Real-time system and real-time OS components](https://www.bctengineer.com/question.md?key=semester_5%2Fsoftware_engineering%3Areal-time-os) — Software Engineering, chapter 4