Notes, summaries, assignments, exams, and problems for Computers

Client and Server Web Interaction

Steps for a Client (Browser)

• Determine the protocol (HTTP).
• Ask DNS for the IP address of the server.
• Make a TCP connection to the server.
• Send a request for the page; the server sends it back.
• Fetch other URLs as needed to display the page.
• Close idle TCP connections.

Steps for a Server

• Accept a TCP connection from the client.
• Get the page request and map it to a resource (e.g., file name).
• Get the resource (e.g., file from disk).
• Send the contents of the resource to the client.
• Release idle TCP connections.

Challenges in P2P Networking

1. How do peers find each other?
2. How do peers support rapid content downloads?
3. How do peers encourage each other to upload?

BitTorrent Protocol Download Steps

1. Start with the torrent description.

Computer Networks

What is a Network?

A network is a number of computers linked together to allow the sharing of resources. A server usually provides services like file storage and email.

Types of Networks

There are two main types of networks:

• Local Area Network (LAN): A LAN covers a small area, such as a home or office.
• Wide Area Network (WAN): A WAN covers a large geographical area. Most WANs are made from several LANs connected together. WANs can be connected together using the internet.

Email

There are two main types of email:

• Client-based email: Often used by business users, client-based email involves downloading email from a server to an application on the user's computer.
• Webmail: Accessed through a web browser, webmail can be accessed from any

Servers

A server stores data to be used by other computers on a network. A server could be a specialized machine, or it can be a normal PC running server software. The server stores data and responds to requests for data or files, such as web pages.

Types of Server

There are many different types of servers. Some popular examples follow.

Web Servers

Web servers host websites and generally handle requests for static information such as HTML pages or images. They are used to manage the website on the server and often include FTP software, which can easily host and share large files. The Apache web server is a popular type of open-source web server software.

Application Servers

Many websites are classed as web applications, which contain programming and... Continue reading "Introduction to Computer Networks" »

Caloreats

Functionality

The goal of Caloreats is to help users control their daily calorie intake. With an intuitive menu, users can select their preferred diet (e.g., gluten-free, vegetarian, vegan) and their daily calorie target. The app then generates a personalized meal plan for the day, including breakfast, lunch, and dinner, complete with detailed nutritional information.

All recipes are provided by the Spoonacular API, which features over 2,600 ingredients and 360,000 recipes. Each recipe includes pricing, health information, nutritional analysis, images, and cooking tips.

Navigation

Upon launching the app, users are directed to the login page, which supports email or Google account authentication. Once logged in, the user is taken to the... Continue reading "Caloreats: Personalized Daily Calorie and Meal Planning" »

Python Syntax

As we learned in the previous page, Python syntax can be executed by writing directly in the Command Line:

>>> print("Hello, World!")
Hello, World!

Python Indentation

Indentation refers to the spaces at the beginning of a code line.

Where in other programming languages the indentation in code is for readability only, the indentation in Python is very important.

Python uses indentation to indicate a block of code.

if5 > 2:
    print("Five is greater than two!")

Python will give you an error if you skip the indentation:

if5 > 2:
print("Five is greater than two!")

Python Comments

Comments can be used to explain Python code.

Comments can be used to make the code more readable.

Comments can be used to prevent execution when testing... Continue reading "Python Syntax, Indentation, Comments, Variables, Data Types, Numbers, Casting, and Strings" »

Java Student Management System: Core Concepts

This document presents a foundational Java program designed to manage student data. It demonstrates key Object-Oriented Programming (OOP) principles through a simple console-based application.

Prerequisites

• Basic understanding of Java programming.
• Familiarity with classes, objects, methods, and variables.

Core Components of the Student System

The Aluno Class: Student Data Model

The Aluno class serves as the blueprint for creating student objects. Each object encapsulates a student's name, course, and a unique registration number.

Class Attributes

• nome (String): Stores the student's name.
• curso (String): Stores the student's enrolled course.
• num_matricula (int): Represents the unique registration number (RA)

1. Telephone communication

it has been the medium used as the first contact with a company. It is used to arrange meetings , interviews or to ask for information, so the impression of the first telephone call is very important

2. Telephone means and equipment

Fixed individual devices

Private branch exchanges (PBX):  it connects calls between two destinations or ends

Mobile devices:

PDA (Personal Digital Assistant) it`s like a small computer (Internet and electronic mail)

Smartphone:  A PDA with video, camera, radio, MP3 player  or television

Services: Internet, e-mail, videoconference, camera, audio and  Video quality player, an agenda, GPS,....

3. Additional services offered by the telephone equipment

3.1 Common features(a,b,c,)

1. Fixed telephony: -

Notice

1. General Questions (35%)

1.1. (5%) What is the difference between a write-back cache and a write-through cache?

Write-back cache: A store only writes data to the cache and marks the corresponding line as dirty. The modified line is written to the lower level of the memory hierarchy only when it is evicted.

Write-through cache: Data is written to the caches and the memory every time a store is executed.

1.2. (15%) Name the 3 Cs in cache misses and provide a brief explanation for each C.

Compulsory miss: A cache miss caused by the first access, a cold start effect.

Capacity miss: A cache miss due to the capacity limitation. Even with full associativity, it cannot accommodate all the working sets of an application.

Conflict miss: A cache miss that... Continue reading "Understanding Cache Memory and CPU Hazards" »

Dimensions of Software Design

Software design involves several key dimensions:

• Problem solving
• Modeling
• Specification
• Organizing the solution
• Communication
• Economics and reuse
• Maintenance and evolution

Design Approaches

Divide-and-Conquer

A problem is decomposed into subproblems that are worked on independently. This approach can be applied recursively for complex problems and allows managers to allocate work to multiple people.

Procedural Design

Design is viewed as a set of procedures that are composed:

• Sequentially
• Conditionally
• Iteratively
• Hierarchically

Borderline Procedural Design

In this approach, the main steps are not fixed. The user has choices with few constraints, and there is typically a main loop to find the next operation.

Event-Driven Design

This... Continue reading "Software Design Principles and UML Diagrams Explained" »