Chapter 2: Issues of Web Technology – Exam Revision Notes

1. Introduction

• Web technology involves multiple layers and components to deliver content and services over the Internet.
  
• Understanding architectural issues helps in efficient web application design, scalability, and maintenance.
  

2. Architectural Issues of Web Layer

Web applications are divided into tiers or layers for better management and performance:

2.1 Two-Tier Architecture

• Client Tier: User interface, collects user input, presents results
  
• Server Tier: Database or business logic server
  
• Characteristics:
  
  • Simple design
    
  • Limited scalability
    
  • Direct connection between client and server
    

2.2 Three-Tier Architecture

• Presentation Tier: Front-end (HTML/CSS/JS), interacts with users
  
• Application Tier: Business logic, processes requests, performs computations
  
• Data Tier: Database server, manages data storage and retrieval
  
• Advantages:
  
  • Improved scalability
    
  • Easier maintenance
    
  • Security control between tiers
    

2.3 N-Tier Architecture

• Extends three-tier into multiple layers, e.g., caching servers, web services, middleware
  
• Advantages:
  
  • High scalability
    
  • Flexibility to integrate multiple services
    
  • Supports enterprise-level applications
    

3. Key Web Technology Issues

1. Performance:
   
   • Response time, server load, and bandwidth usage
     
   • Use caching, compression, and content delivery networks (CDNs)
     
2. Security:
   
   • User authentication and authorization
     
   • Secure communication: SSL/TLS
     
   • Protect against common attacks (SQL injection, XSS, CSRF)
     
3. Scalability:
   
   • Ability to handle increasing number of users
     
   • Load balancing and distributed servers
     
4. Interoperability:
   
   • Support for multiple browsers and devices
     
   • Use of standards like HTML, CSS, XML, JSON
     
5. Maintainability:
   
   • Modular design, separation of concerns
     
   • Use of frameworks and libraries
     
6. Reliability & Availability:
   
   • System should work consistently without failures
     
   • Redundant servers and failover mechanisms
     

4. Tier Technology in Web Applications

• 2-Tier: Client ↔ Server (simple apps)
  
• 3-Tier: Client ↔ Application Server ↔ Database Server (business apps)
  
• n-Tier: Multiple layers for complex, enterprise applications
  
• Selection Criteria:
  
  • Application size and complexity
    
  • Number of users
    
  • Security and maintenance requirements
    

5. Key Takeaways

• Web technology design requires understanding tiers, architecture, and system issues.
  
• Choosing the right tier architecture improves performance, scalability, and maintainability.
  
• Addressing security, interoperability, and reliability is critical for successful web applications.
  
• Proper architecture ensures separation of presentation, logic, and data layers for easier upgrades and management.