JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech IV Year DISTRIBUTED SYSTEMS Previous Question Paper (July/August - 2022 - R18)

Distributed systems face several inherent challenges due to the separation of components across a network:

• Heterogeneity: Systems consist of diverse hardware, operating systems, networks, and programming languages, requiring middleware to provide a uniform interface.
• Openness: Systems must be extensible and interoperable, allowing new services to be added or replaced without disrupting existing components.
• Security: Protecting resources and ensuring secure communication is difficult because the network is open and components are geographically dispersed.
• Scalability: Systems must maintain performance as the number of users or resources grows, avoiding bottlenecks in centralized components.
• Failure Handling: Partial failures are inevitable; the system must detect, mask, or recover from individual component failures without crashing the entire system.
• Concurrency: Multiple processes access shared resources simultaneously, necessitating synchronization mechanisms to ensure data consistency.
• Transparency: The system should hide its distributed nature from users and applications, appearing as a single coherent entity.

The evolution of distributed systems is categorized into four main generations:

• First Generation (Early Distributed Systems): Emerged in the 1970s and 80s with the development of Local Area Networks (LANs). These systems focused on resource sharing, such as file servers and print servers, using basic protocols like early Ethernet and TCP/IP.
• Second Generation (Client-Server Systems): Dominant in the 1990s, these systems utilized the client-server model to separate processing tasks. This era introduced distributed databases and the World Wide Web, relying on middleware like RPC (Remote Procedure Call) and CORBA to manage communication.
• Third Generation (Intranet and Enterprise Systems): Focused on integrating various enterprise applications. These systems introduced web services, service-oriented architecture (SOA), and mobile computing, emphasizing interoperability across different platforms and the use of XML/SOAP for data exchange.
• Fourth Generation (Cloud and Ubiquitous Systems): The current era characterized by cloud computing, virtualization, and massive scalability. Systems are now defined by service-oriented models (SaaS, PaaS, IaaS), peer-to-peer networks, IoT (Internet of Things), and edge computing, where resources are dynamically provisioned and accessed globally.