---
title: "Short note: CORBA services"
subject: "Distributed System"
chapter: 4
key: "semester_7/distributed_system:corba-services-note"
source: https://www.bctengineer.com/q/semester_7/distributed_system/corba-services-note
site: BCT Engineering
---

# Short note: CORBA services

Distributed System · Chapter 4: Distributed Heterogeneous Applications and CORBA

- Asked in: 2072 Kartik, 4 marks
- Video: [CORBA | Service | Advantages |  Disadvantages | Distributed System | Lec-47 | Bhanu Priya](https://www.youtube.com/watch?v=eJqJFk7Gp8k) — Education 4u
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/distributed_system/corba-services-note
- Whole chapter: https://www.bctengineer.com/md/semester_7/distributed_system/chapter-4

## Question

Write a short note on CORBA services.

## Short answer

CORBA services are standard IDL-defined system-level services providing naming (white pages), trading (yellow pages), event/notification, life cycle, persistence, transactions, concurrency control, and security. They are accessed through the ORB like any other CORBA object, forming the reusable middleware layer for distributed applications.

## Answer

CORBA services (also called CORBAservices or COSS) are a collection of standard, IDL-specified system-level services that support distributed objects. They are defined by the OMG so that every ORB vendor offers the same interfaces and applications need not reimplement them.

Main services:
1. **Naming service**: maps human-readable names to object references (like a white pages directory).
2. **Trading service**: finds objects by the properties they offer (yellow pages).
3. **Event and Notification services**: asynchronous communication between supplier and consumer objects through event channels; notification adds filtering and quality of service.
4. **Life cycle service**: create, copy, move, remove objects through factories.
5. **Persistent state service**: saves object state to storage and restores it.
6. **Transaction service**: atomic, consistent execution of a group of operations with two-phase commit.
7. **Concurrency control service**: locking to coordinate simultaneous access.
8. **Security service**: authentication, authorisation, auditing, encryption.
9. **Relationship, Externalization, Query, Licensing, Time, Collection and Property services**.

Applications call these services like any other CORBA object, through their IDL interfaces. Together they form the standard middleware layer of CORBA.

## Check yourself

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

1. What are CORBA services?
   A. Standard IDL-specified system-level services defined by OMG for distributed objects
   B. Vendor-specific add-ons
   C. Programming languages
   D. Hardware standards
   Answer: A. They make every ORB vendor offer the same interfaces. (Key point: COSS)

2. What does the Trading service do?
   A. Maps names to references
   B. Finds objects by the properties they offer
   C. Saves state
   D. Locks objects
   Answer: B. Naming is white pages; trading is yellow pages. (Key point: Trading service)

3. What does the Life cycle service handle?
   A. Authentication
   B. Locking
   C. Create, copy, move and remove objects through factories
   D. Time
   Answer: C. Persistent state service saves state. (Key point: Life cycle)

4. What mechanism does the Transaction service use?
   A. Locks only
   B. Event channels
   C. Name binding
   D. Atomic execution of a group of operations with two-phase commit
   Answer: D. Concurrency control uses locking. (Key point: Transaction service)

## 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×
- [JINI goals, CORBA services, OS support](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Aos-support-jini-corba) — Distributed System, chapter 3
- [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
- [Heterogeneous vs homogeneous; CORBA](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Ahetero-homo-corba) — Distributed System, chapter 4