slide 5 web eng

Software pattern

A reusable solution to a recurring software design problem

Application Layers Pattern

Separates concerns into presentation, application logic, and resource layers

Presentation layer

Handles rendering, user interaction, and communication logic

Application logic layer

Contains the core business logic of the application

Resource layer

Manages access to data sources such as databases and files

Monolithic application

A self-contained application deployed as a single unit

Main drawback of monolithic applications

Difficult to scale and evolve as system size grows

Client–Server architectural style

Clients request services and servers provide them

Tier

A physical deployment unit in a system architecture

Layer

A logical functional unit in a system architecture

Difference between tiers and layers

Tiers are physical; layers are logical and orthogonal to tiers

Client thickness

The amount of functionality executed on the client

Thin client

Client with little or no presentation or application logic

Thick client

Client that executes part of the presentation or application logic

2-tier architecture

Client and server communicate directly in a centralized system

3-tier architecture

Separates presentation, application logic, and data across physical tiers

N-tier architecture

Uses multiple tiers to improve scalability and maintainability

Remote presentation applications

Thick clients where UI logic runs on the client and data comes from APIs

Distributed applications

Applications where logic is split between client and server

Model–View–Controller (MVC)

Separates data, presentation, and control logic

Main benefit of MVC

Separation of concerns improves maintainability and testability

Model–View–Presenter (MVP)

Presenter mediates between View and Model through interfaces

Model–View–ViewModel (MVVM)

ViewModel exposes data and behavior without referencing the View

Key difference between MVC, MVP, and MVVM

How Views interact with Models and logic layers

Service-Oriented Architecture (SOA)

Architectural style for building distributed systems using services

Service

An encapsulated unit of functionality with a well-defined interface

Loose coupling

Minimizing dependencies between services to improve flexibility and scalability

SOA interaction roles

Provider, Consumer, and Registry

Purpose of a service registry

Enable discovery of available services

Web service (WS-*)

A machine-to-machine service using SOAP and WSDL

Main difference between REST and WS-*

REST is lightweight and resource-oriented; WS-* is protocol-heavy and operation-oriented

When WS-* is preferable

Complex enterprise workflows with strict contracts and QoS requirements

When REST is preferable

Scalable, lightweight Web-based systems