Notes, abstracts, papers, exams and problems of Computers

Design of Webpages

There are 2 distinct phases:

• Layout: it organizes written and multimedia spaces and contents.
• Interface: is the set of commands and methods that facilitate the interaction between the user and the system

We cannot move ahead with the creation of a web page without knowing what we want to show, the topic and the quantity of information that we will put in it. We shall also decide the title of the web page, its header and its logo, since they will give a sensation of continuity and greater professionalism.

CMS

The Content Management Systems (CMS) are applications installed on the server that enable us the creation of dynamic web pages and allow us to design the site independently of the content. When we administer a CMS, we define... Continue reading "Webpage Design and Security Threats" »

Chapter 1 Introduction to Services

3.1. Service Terminology Service

a service is a software program that makes its functionality available via a technical interface, called a service contract.

Figure 3.1. The symbol used to represent an abstract service.

Service Contract

The symbol used to represent a service contract is displayed in Figure 3.2.

Service Capability

A service contract can be broken down into a set of service capabilities, each of which expresses a function offered by the service to other software programs.

Figure 3.4. A Purchase Order service contract with four service capabilities.

Service Consumer

A service consumer is software program when it accesses and invokes a service—or, when it sends a message to a service capability

Service

Initialization: Prior to the first iteration of the loop, we have k = p, so that the subarray A[p..K-1]is empty. This empty subarray contains the k – p = 0 smallest elements of L and R, and since i = j = 1, both L[i] and R[j] are the smallest elements of their arrays that have not been copied back into A. Maintenance: To see that each iteration maintains the loop invariant, let us first suppose that L[i] <= R[j]. Then L[i] is the smallest element not yet copied back into A. Because A[p..K-1]contains the k - p smallest elements, after line 14 copies L[i]into A[k], the subarray A[p..K] will contain the k – p + 1 smallest elements. Incrementing k (in the for loop update) and i (in line 15) reestablishes the loop invariant for the next iteration.... Continue reading "Action disvalue" »

WEEK 1: Software that Manages Computer Hardware

Operating System as an Abstract Machine, Service Provider, and Resource Manager. OS Objectives: Convenience, Efficiency, and Ability to Evolve.

Performance Indices

Arrival Time, Service Time, Turnaround Time, Normalized Turnaround Time. First-Come-First-Served (FCFS) Scheduling Policy.

Microprocessor and DMA Activity

Impact of Microprocessor Bus Configuration and DMA Activity on System Speed.

Memory System and Cache

Cache and Main Memory Access Time, Average Access Time Calculation.

iOS and Android

Similarities and Differences between iOS and Android.

Job Execution and CPU Utilization

CPU Utilization for Uniprogramming and Multiprogramming.

Direct Memory Access (DMA)

Coordination, Memory Operations Completion,... Continue reading "Understanding Operating Systems: Functions, Performance, and Multithreading" »

Security:

This principle requires the person or agency in control of the personal data to implement organizational and technical measures to ensure the data is secure. It requires the controller to offer protection against:

• Unlawful destruction or accidental loss
• Alteration
• Unauthorized disclosure or access
• All other form of unlawful processing

In particular when the data is transmitted over a network. If the controller is not doing the processing themselves they must provide guarantees that the specified security measures are being carried out.

Pre Processing a Biometrics Image for Feature Extraction:

Case Study: Finger Prints:

Fingerprint ID is often based on minutiae and or the location or the direction of fingerprint of the ridge endings and bifurcations... Continue reading "eyes" »

To start a backend project.

- npm init

Then make a file with whatever entry point you named it as, for example, server.js

Once package.json is created:

• npm i <package>
• connect-mongo (store sessions in DB)
• dotenv (for config files, environment variables)
• express
• mongoose
• express-sessions (sessions and cookies)
• method-override (to use PUT, UPDATE, DELETE requests)
• moments (date formatting)
• morgan (logging)
• passport (authentication)

npm i -D <package>

• nodemon (Update every file change instantly without having to restart the server)
• cross-env (To update environment variables in script definition itself)

After installing the dependencies, edit the scripts in package.json

Types definition

#include <stdbool.h>

#include <stdlib.h>

Struct Definition

typedef int tItemL;
typedef struct tNode* tPosL; //Ptr to tNode
struct tNode {
tItemL data;
tPosL next;
tPosL prev;
};
typedef tPosL tList;

Prototypes

void createEmptyList(tList *L);
bool createNode(tPosL* p);
bool insertItem(tItemL d, tPosL p, tList *L);
void updateItem(tItemL d, tPosL p, tList* L);
tPosL findItem(tItemL d,tList L);
bool isEmptyList(tList L);
tItemL getItem(tPosL p, tList L);
tPosL first(tList L);
tPosL last(tList L);
tPosL previous(tPosL p, tList L);
tPosL next(tPosL p,tList L);
void deleteAtPosition(tPosL p , tList *L);
void deleteList(tList *L);

Function Definitions

#include "doubly_linked_list.h"
bool isEmptyList(tList L) { return (L == NULL); }
void... Continue reading "Doubly Linked List Implementation in C" »