Questions: Chapter 1 Flashcards
Client-server architecture is a modular infrastructure intended to improve Usability, Flexibility, Interoperability, and Scalability. Explain each with an example, in each case, how it helps to improve the functionality of client-server architecture.
- Usability
Definition: Usability refers to how easy and user-friendly a system is for its users.
How it helps: In a client-server architecture, the client (user interface) is separate from the server (where the data and processing occur). This separation means that users can interact with the system through simple interfaces, while the server handles the complex tasks in the background.
Example: Think of an online shopping website. The client is your web browser (which shows you the website) and the server stores the products, user information, and handles purchases. The client makes it easy for you to browse products, add items to the cart, and check out without needing to know how all the data is being processed on the server.
Improvement: By separating tasks, users don’t need to worry about the underlying complexity, making the system easier to use.
- Flexibility
Definition: Flexibility refers to the system’s ability to adapt to changes, like supporting different devices or software versions.
How it helps: Since the client and server are independent, they can evolve separately. The client can change (like updating a mobile app) without affecting the server. Likewise, the server can be upgraded or replaced without requiring changes to the client.
Example: If you use a banking app on your phone, the app (client) can be updated with new features (like biometric login), while the server can continue to process transactions in the same way. The client update doesn’t break the system, and the server can manage the new features as well.
Improvement: This separation allows each part of the system to be updated and improved without disrupting the other parts, making the system more flexible and adaptable to changes.
- Interoperability
Definition: Interoperability refers to the ability of different systems or applications to work together.
How it helps: Client-server architecture allows different types of clients (e.g., web browsers, mobile apps, desktop applications) to interact with the same server. The server provides a standard way to access data, regardless of the client being used.
Example: Imagine a weather service where you can check the forecast on a website, in a mobile app, or through a smart device. All these different clients (browser, phone app, smart device) connect to the same server, which sends the weather data in a way that works for all types of devices.
Improvement: This compatibility across different platforms ensures that users can access services on whatever device they prefer, improving functionality by making the system more universal.
- Scalability
Definition: Scalability refers to the ability of a system to handle more users or data as it grows.
How it helps: In client-server architecture, the server can be scaled up (getting more powerful servers) or scaled out (adding more servers) to handle more clients. The client doesn’t need to change, so the system can grow without affecting the user’s experience.
Example: In an online game, as more people join, the game server can handle more players by adding more resources or servers. The players (clients) won’t notice any difference as long as the server can manage the increased load.
Improvement: The system can grow smoothly as more users or data are added, ensuring that it remains functional even as demand increases.
What are the Advantages and Disadvantages of Client-Server vs Mainframe Architecture
Client-Server Architecture:
Advantages:
Scalability: It’s easier to scale up because you can add more client machines or servers as needed.
Flexibility: Clients and servers can run on different types of hardware and software, making it more versatile and adaptable.
Disadvantages:
Network Dependency: The system relies on the network to communicate between clients and servers. If the network goes down, the entire system could be affected.
Security Risks: Since clients are distributed, there’s a higher risk of security breaches and unauthorized access if not properly managed.
Mainframe Architecture:
Advantages:
Centralized Control: All the data and processing are done on one mainframe computer, making it easier to manage and secure.
Reliable: Mainframes are known for being reliable and capable of handling large amounts of data and transactions at once.
Disadvantages:
Costly: Mainframes are expensive to maintain, both in terms of hardware and skilled personnel.
Limited Flexibility: Unlike client-server, mainframes are less flexible, and users often have to access it through dedicated terminals, limiting access methods.
Explain Client-server as a two-tier architecture.
Client/Server as a 2-Tier Architecture
Client-server architecture is often called a 2-tier architecture because there are two layers (or tiers) of interaction:
Client Layer: This is the “front-end,” where users interact with the system, usually on a personal computer or device. The client requests data or services from the server.
Server Layer: This is the “back-end,” where data is stored, and processing happens. The server listens for requests from clients and responds by sending the requested data or performing specific tasks.
In a 2-tier system, the client directly communicates with the server without any middle layer.
Explain the Work of Three-Tier Architecture with an Application Server
three-tier architecture has three layers:
Presentation Layer (Client): This is where the user interacts with the application, usually via a graphical user interface (GUI) like a web browser.
Application Layer (Application Server): This middle layer handles the business logic. When a client makes a request, it’s processed here before any data is retrieved or action is taken.
Data Layer (Database Server): This is where the data is stored and retrieved. The application layer communicates with this layer to fetch or update information.
In the case of an Application Server, it helps handle tasks like:
Authenticating users
Processing business rules
Sending the appropriate data to the client
Ensuring security and transaction management
Explain Client-Server Interaction with a Sketch
In client-server interaction, the client makes requests to the server, and the server processes the request and sends back a response.
Here’s how it works:
The client sends a request for data or services (like clicking a button to load a webpage).
The server receives the request, processes it (maybe by accessing a database or performing some logic), and sends a response back.
The client receives the response and displays it to the user.
Explain Server Function and Client Responsibility in Client-Server Architecture
Server Functions:
Data Management: The server stores and manages data, ensuring it’s accessible for clients.
Processing Requests: The server processes the requests it receives from clients, such as retrieving or updating data.
Security and Authentication: The server ensures that only authorized clients can access the data or services.
Client Responsibilities:
User Interaction: The client is where the user interacts with the system (e.g., inputting data, requesting information).
Sending Requests: The client sends requests to the server for data or services.
Displaying Responses: The client displays the server’s responses, like showing data, confirming actions, or updating the user interface.
Describe three-level schema architecture. Why do we need to map between schema levels?
The three-level schema architecture in database systems is designed to separate the physical storage of data from how users interact with it. It has three layers:
Internal schema: This layer deals with how data is stored physically in the database. It’s about how the data is organized and optimized on the storage device.
Conceptual schema: This is the logical view of the entire database. It defines the structure, relationships, and constraints of the data without worrying about how it’s stored physically.
External schema: This represents the user’s view of the data. Different users or applications can have different external schemas, which show only the parts of the database they are interested in.
Mapping between schema levels is needed because the data in the database can be stored in many different ways (internal schema), but users only care about how they see it (external schema). Mapping ensures that users can interact with the database in a way that makes sense to them, while the system optimizes storage and performance.
Differentiate between the transaction server and the data server system by providing examples.
Transaction server: A transaction server manages the execution of business transactions, ensuring they are processed correctly and reliably. It often handles complex logic like coordinating multiple operations that need to be completed successfully as a group (atomicity).
Example: In an online shopping website, the transaction server processes payments, stock updates, and order confirmations to ensure all steps happen successfully.
Data server: A data server primarily stores and manages the data in a database. It responds to requests from other servers or clients to retrieve or update data.
Example: A server running a database that stores customer details and order information for an e-commerce site.
How client/server computing environment is different from the mainframe-based computing environment?
Client/Server Computing: In this environment, the processing is divided between clients (users or devices) and servers. Clients send requests to servers, and the servers handle tasks like data storage, processing, and response. Each client has its own system and may interact with multiple servers.
Example: A typical web application where your browser (client) sends requests to a web server for information.
Mainframe Computing: In this older system, most of the processing and storage happens on a central mainframe computer. Clients (often terminals) are just interfaces that rely entirely on the mainframe for all computing tasks.
Example: A large corporation uses a mainframe to process payroll, where employees simply input their data on terminals.
The main difference is that client/server systems are more distributed, with processing happening across multiple systems, while mainframe systems centralize processing in one powerful machine.
In the online transaction processing environment, discuss how transaction processing monitor controls data transfer between client and server machines.
Transaction Processing Monitor (TPM) is responsible for managing and controlling the flow of data between clients and servers in an online transaction processing (OLTP) environment. It ensures that transactions are executed reliably, and it handles the communication between the client and the server, ensuring that the data is transferred correctly.
Here’s how it works:
When a client sends a request (e.g., a purchase or data query), the TPM acts as an intermediary.
The TPM ensures that the request is properly processed by the server.
It manages the ACID properties (Atomicity, Consistency, Isolation, Durability) of transactions, ensuring that data integrity is maintained.
If a transaction involves multiple servers or databases, the TPM coordinates these operations to make sure the transaction is completed successfully and consistently.
Example: In an online banking system, the TPM makes sure that when a customer transfers money, both the sender’s and receiver’s accounts are updated correctly without errors, and it ensures the system can handle interruptions (e.g., server crashes) without losing data.
