JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech IV MIDDLEWARE TECHNOLOGIES Previous Question Paper (September - 2020 - R15)

Client/server computing has evolved significantly due to advancements in both hardware and software. The hardware trends focus on increasing processing power, storage capacity, and network bandwidth, while software trends emphasize modularity, distributed architectures, and interoperability.

Hardware Trends:

1. Increased Processing Power: The shift from mainframe-centric computing to powerful microprocessors and multi-core architectures allows servers to handle complex concurrent requests efficiently.
2. Storage Evolution: The transition from traditional hard disk drives to Solid State Drives (SSDs) and high-speed storage area networks (SAN) has drastically reduced latency in data retrieval.
3. Network Infrastructure: The deployment of high-speed fiber optics, 10Gbps+ Ethernet, and software-defined networking (SDN) has minimized bottlenecks between clients and servers.
4. Virtualization and Cloud Hardware: Hardware is now designed to support hypervisors, enabling multiple virtual servers to run on a single physical machine, optimizing resource utilization.

Software Trends:

1. Service-Oriented Architecture (SOA) and Microservices: Applications have moved from monolithic structures to loosely coupled services that communicate via APIs, facilitating independent scaling and maintenance.
2. Middleware Layering: The use of robust middleware (such as message-oriented middleware, ORBs, and application servers) has become essential to abstract the complexities of heterogeneous network environments.
3. Containerization: Technologies like Docker and Kubernetes allow applications to be packaged with all dependencies, ensuring consistency across development, testing, and production environments.
4. Cloud-Native Development: Software is increasingly designed to leverage cloud-specific features like auto-scaling, serverless computing, and managed database services, shifting the focus from infrastructure management to application logic.
5. Security and Interoperability: Modern software trends prioritize standardized communication protocols (like REST and gRPC) and advanced security frameworks (OAuth, TLS) to ensure secure data exchange between diverse client platforms and backend services.

Remote Method Invocation (RMI) enables an object on one Java Virtual Machine (JVM) to invoke methods on an object in another JVM. The implementation relies on the Stub, Skeleton, and Remote Reference Layer to abstract the network communication.

The process follows these steps:

1. The Client invokes a method on the Stub, which acts as a local proxy for the remote object.
2. The Stub marshals (serializes) the method arguments into a stream of bytes and sends them to the server via the Remote Reference Layer.
3. The server-side Remote Reference Layer receives the request and passes it to the Skeleton.
4. The Skeleton unmarshals the arguments and invokes the actual method on the Remote Object implementation.
5. The result of the method execution is returned to the Skeleton, which marshals the return value or exception and sends it back to the Stub.
6. The Stub unmarshals the result and returns it to the Client.

Diagrammatic Representation:

In modern Java RMI (post-JDK 5.0), the Skeleton is implicitly handled by the RMI runtime, and stubs are generated dynamically, removing the need for manual compilation using rmic.