Question

What are the basic facilities that must be provided by an object request broker?

Short answer

An ORB provides object location transparency, object activation, interface definition via IDL, manages communications, and supports interoperability.

Step-by-step solution

Understanding Object Request Broker (ORB)

An Object Request Broker (ORB) is middleware that allows program calls to be made between computers in a network. It is a key component in distributed systems, enabling software applications to communicate with each other regardless of where they are located or who implemented them.

Identifying Core Facilities

The basic facilities provided by an ORB include Object Location Transparency, which allows clients to access objects without knowing their physical location. The ORB also provides Object Activation, enabling the creation or activation of objects on demand when a request is made.

Understanding Interface Definition

An ORB provides a mechanism for defining and implementing object interfaces, typically using an Interface Definition Language (IDL). This allows objects to be described abstractly, ensuring that different programming languages and environments can interact seamlessly.

Exploring Communication Handling

ORB handles the communication between clients and server objects, abstracting the underlying network protocols and providing a consistent interface. This involves marshalling and unmarshalling data, managing connections, and handling requests and responses.

Supporting Interoperability

An ORB must support interoperability between different ORBs and systems, ensuring that objects can interact across diverse environments and platforms. This is often achieved using standard protocols like Internet Inter-ORB Protocol (IIOP).

Key concepts

Distributed Systems

Distributed systems are a fundamental concept in computer science and engineering. They consist of multiple computers, which often reside in different physical locations but work together as a single cohesive unit to achieve common goals. The primary advantage of distributed systems is their ability to leverage the computing power of multiple machines, enabling them to perform complex tasks more efficiently than a single computer could manage.

• Fault Tolerance: Distributed systems are designed to continue functioning even if one or more of the components fail. This resilience is achieved through redundancy and failover strategies.
• Scalability: These systems can scale horizontally by adding more machines to accommodate increased loads, offering a way to handle growing data or user demands.
• Concurrency: Distributed systems enable concurrent operations, allowing multiple processes to happen simultaneously, which boosts performance and response time.

Distributed systems empower applications to be more available and reliable, making them a popular choice for modern software solutions that require high availability and real-time processing.

Interface Definition Language

An Interface Definition Language (IDL) is a crucial tool in software engineering, especially in the context of distributed systems. It serves as a common language to define the interfaces that software components use to communicate. By specifying the data types and method signatures in IDL, developers from different platforms or programming languages can work together seamlessly.

• Language Agnostic: IDL abstracts the interface definitions away from specific programming languages, fostering interoperability between systems.
• Version Control: Since interfaces can evolve, IDL provides a mechanism for managing versions, ensuring backward compatibility.
• Automation: IDL allows for tools that can automatically generate code stubs and skeletons, reducing manual coding efforts and errors.

IDLs play a pivotal role in bridging the gap between diverse systems and components, enhancing the modularity and robustness of distributed applications.

Interoperability

Interoperability is the ability of different systems and components, often developed independently, to work together efficiently. In the realm of distributed systems, interoperability is a critical requirement as it allows systems to communicate and function cohesively, regardless of the underlying technologies or platforms.

• Standard Protocols: Protocols such as HTTP, IIOP, or REST facilitate communication between disparate systems, ensuring data and request exchanges are understood universally.
• Compatibility: Interoperability ensures that updates or changes in one system do not adversely affect other connected systems, maintaining seamless operation.
• Cross-Platform Communication: Interoperability supports communication across different operating systems and hardware, crucial for businesses that rely on a heterogeneous technology stack.

When achieved, interoperability significantly reduces integration costs and complexity, enabling businesses to leverage existing systems across varied technologies.

Network Protocols

Network protocols are sets of rules and conventions that determine how data is transmitted over a network. They ensure reliable and orderly communication between devices in a distributed system. These protocols handle everything from addressing data packets to ensuring their correct delivery.

• TCP/IP: This is the foundational protocol suite for the internet and many local networks, offering reliable data transmission through error-checking and retransmission features.
• HTTP/HTTPS: Used primarily for web communications, these protocols ensure data security and integrity between browsers and servers.
• SMTP/IMAP: As protocols for email transmission and retrieval, they ensure reliable delivery of messages across networks.

Network protocols are indispensable for ensuring that multiple distributed systems can communicate efficiently, providing a structured way of exchanging information between devices.