Question

Giving reasons for your answer, suggest an appropriate structural model for the following systems: An automated ticket-issuing system used by passengers at a railway station A computer-controlled video conferencing system that allows video, audio and computer data to be visible to several participants at the same time A robot floor-cleaner that is intended to clean relatively clear spaces such as corridors. The cleaner must be able to sense walls and other obstructions.

Short answer

Client-Server, Peer-to-Peer, and Layered Architecture models are suitable respectively.

Step-by-step solution

Understanding the Systems

First, we need to understand the basic functionality and requirements of each system: 1. **Automated Ticket-Issuing System:** This system issues tickets to passengers and interacts with a central database to fetch train schedules, availability, and booking. 2. **Computer-Controlled Video Conferencing System:** Facilitates communication between users through video, audio, and shared data. 3. **Robot Floor-Cleaner:** Cleans floors autonomously by detecting walls and obstacles, potentially using sensors for navigation.

Identifying Main Components

Identify the main components for each system: 1. **Automated Ticket-Issuing System:** User interface for input/output, payment processing, central server/database communication, and printer. 2. **Video Conferencing System:** Input devices (camera, microphone), output devices (screen, speakers), data exchange hardware, and network connectivity. 3. **Robot Floor-Cleaner:** Sensors (for detecting obstacles), navigation system, cleaning mechanism, and power supply.

Choosing an Appropriate Model

Choose a structural model based on system components and behaviors: 1. **Automated Ticket-Issuing System:** Suitable for a **Client-Server Model** since the system requires constant interaction with a central server database. 2. **Video Conferencing System:** Best suited for a **Peer-to-Peer Model** due to the distributed nature of the system requiring direct connections between participants. 3. **Robot Floor-Cleaner:** A **Layered Architecture Model** is appropriate as it aligns with sensor input processing, navigation, and cleaning tasks done in distinct layers.

Key concepts

Structural Models

When designing software systems, choosing the right structural model is crucial for the system's functionality and efficiency. Structural models help define how different components of a system interact with each other. This not only aids in system organization but also enhances maintainability and scalability. For instance, in the **automated ticket-issuing system**, a client-server model is utilized to manage the interaction between user interfaces (clients) and the central database (server). This model is ideal due to the need for a centralized approach to handle transaction processing and data management.

By understanding the key elements of each system like user interfaces, input devices, sensors, and databases, appropriate structural models can be determined. Each model brings its unique advantages, allowing for optimized interaction, data flow, and operational efficiency. Considerations such as network architecture, processing requirements, and system distribution play significant roles in deciding the best fit for each system.

Client-Server Architecture

The client-server architecture is a popular model where systems are divided into two main components: clients and servers. Clients are user-facing interfaces that request services or information, while servers are responsible for processing these requests and providing responses.

In the context of an **automated ticket-issuing system**, this architecture is highly suitable. Here's why:

• Centralized Data Management: The server holds all the train schedules, availability data, and booking information in a central database.
• Scalability: As the number of users increases, additional servers can be added to handle more requests, ensuring a responsive system.
• Security: Sensitive information like payment details can be more securely managed on a centralized server.

This architecture supports efficient processing of tasks by distributing workloads appropriately between clients and the central server.

Peer-to-Peer Network

A peer-to-peer (P2P) network is a distributed system architecture where each participant, or "peer," operates both as a client and a server. This model is characterized by direct communication among peers without the need for a centralized server.

For the **computer-controlled video conferencing system**, a P2P network is ideal due to its distributed nature:

• Direct Communication: Participants can directly share video, audio, and data without intermediaries, reducing latency and enhancing user experience.
• Reliability and Resilience: The absence of a central server minimizes single points of failure, improving overall system robustness.
• Scalability: P2P networks can easily handle numerous participants without significant additional infrastructure, as each peer contributes resources to the network.

This structure ensures seamless connectivity and interaction, making it a perfect choice for real-time communication systems like video conferencing.

Layered Architecture

Layered architecture is a structural model that divides system functionality into distinct "layers," each responsible for specific tasks. This is particularly useful in complex systems where operations are interdependent but can be structured in a sequential manner.

The **robot floor-cleaner system** exemplifies how layered architecture can be effectively used:

• Sensor Layer: Handles data collection from the environment, detecting walls and obstructions.
• Navigation Layer: Processes sensor input to guide movement and avoid obstacles.
• Cleaning Layer: Executes cleaning tasks based on navigation data, ensuring efficient coverage of space.

By isolating responsibilities into layers, maintenance and debugging become simpler. This model supports system flexibility, allowing developers to modify or upgrade individual layers without impacting others. Layered architecture also encourages reusability, as modules performing specific functions can be adapted for use in different systems.