Jawaharlal Nehru Technological University Hyderabad MCA V WEB SERVICES Previous Question Paper (August - 2017 - R09)

The Client-Server model is a centralized architecture where specific nodes (servers) provide resources or services to requesting nodes (clients). The server is typically always active, waiting for requests, while the client initiates communication. It is easier to manage and secure but creates a single point of failure and potential bottlenecks at the server.

The Peer-to-Peer (P2P) model is a decentralized architecture where every node (peer) acts as both a client and a server. Each node can share resources directly with others without a central authority. This model is highly scalable and resilient to failures, as the network does not rely on a single central server, but it is significantly more complex to manage, secure, and maintain consistency across the network.

Microsoft Distributed Component Object Model (DCOM) is a proprietary technology that extends the Component Object Model (COM) to allow software components to communicate across different computers in a network. It functions as an extension of Remote Procedure Call (RPC) and provides the underlying infrastructure for distributed applications on Windows platforms.

Key features include:

• Location Transparency: DCOM allows an application to access a component on a remote machine as if it were local, handling the underlying network communication automatically.
• Security: It integrates with the Windows NT security model, allowing administrators to control access to components using Access Control Lists (ACLs).
• Language Independence: Since it is built on COM, components can be written in any language that supports COM, such as C++, Visual Basic, or Java.
• Lifecycle Management: DCOM uses reference counting and pinging mechanisms to manage the lifecycle of remote objects, ensuring that resources are cleaned up when no longer in use.