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

1. Processes

A process is a program in execution. It is a unit of work within the system. A program is a passive entity, while a process is an active one. A process needs resources to accomplish its task (CPU, memory, I/O, files). Process termination requires the reclamation of any reusable resources. A single-threaded process has one program counter, specifying the location of the next instruction to execute. The process executes instructions sequentially, one at a time, until completion. A multithreaded process has one program counter per thread. Concurrency is achieved by multiplexing the CPUs among the processes or threads.

2. Process States

As a process executes, it changes its state:

• New: The process is being created.
• Running: Instructions

Logic Bombs and Resource Exhaustion Attacks

Logic Bombs

A logic bomb is a program that performs an action violating the site security policy when a specific external event occurs. These are typically associated with insider threats.

Example: A program that deletes a company’s payroll records when one particular record is deleted.

• The "particular record" is usually that of the person who created the logic bomb.
• The idea is that if (or when) the creator is fired and their payroll record is deleted, the company loses all those records.

Rabbits and Bacteria (Resource Exhaustion)

Rabbits or Bacteria refer to programs designed to absorb all of a specific class of system resources, leading to denial of service or system instability.

Example: For a UNIX... Continue reading "Malicious Software: Types, Threats, and Advanced Viruses" »

Pseudo Classes

Pseudo classes are selectors that can be used to style elements based on their state or position in the document. For example, the :hover pseudo class can be used to style an element when the user hovers over it with the mouse.

:nth-of-type(an+b || even || a || an)

The :nth-of-type pseudo class is used to select elements based on their position in a group of siblings. It takes an argument that specifies which elements to select. The argument can be one of the following:

• an+b: Selects every nth element, starting with the bth element. For example, 2n would select every other element, and 2n+1 would select every odd element.
• even: Selects every even-numbered element.
• odd: Selects every odd-numbered element.
• a: Selects every element.

For... Continue reading "Web Development Fundamentals" »

1. What is a Public Blockchain?

Public blockchains are open networks that allow anyone to participate. This permissionless nature means anyone can join the network and read, write, or participate in the blockchain.

Public blockchains are decentralized, meaning no single entity controls the network. Data on a public blockchain is secure because it is virtually impossible to modify or alter data once validated on the blockchain.

Features of Public Blockchains:

• High Security: Secured by mining and the 51% rule.
• Open Environment: Open for anyone to join.
• Anonymous Nature: Participants can remain anonymous, enhancing privacy.
• No Regulations: No strict regulations on platform usage.
• Full Transparency: The ledger is publicly viewable, ensuring transparency.

PL/SQL

PL/SQL is a procedural language designed specifically to embrace SQL statements within its syntax. PL/SQL program units are compiled by the Oracle Database server and stored inside the database. And at run-time, both PL/SQL and SQL run within the same server process, bringing optimal efficiency. PL/SQL includes procedural language elements like conditions and loops. It allows declaration of constants and variables, procedures and functions, types and variable of those types and triggers. It can support Array and handle exceptions (runtime errors).

Differences between SQL and PL/SQL

• SQL is a single query that is used to perform DML and DDL operations.
• PL/SQL is a block of codes that used to write the entire program blocks/ procedure/ function,

Data Storage Conversion:

• 1 gigabyte (GB) equals 1,024 megabytes (MB).
• 1 megabyte (MB) equals 1,024 kilobytes (KB).
• To convert gigabytes to kilobytes, multiply by 1,024 twice. For example: 1 GB = 1,024 MB * 1,024 KB = 1,048,576 KB.
• To convert gigabytes to megabytes, multiply by 1,024. For example: 1 GB = 1,024 MB
• To convert 20 megabytes to bytes: 20 MB = 20 * 1,024 KB * 1,024 bytes = 20,971,520 bytes
• To convert 2 gigabytes to kilobytes: 2 GB = 2 * 1,024 MB * 1,024 KB = 2,097,152 KB

Example: SHKRONJA A has a value of 1010, B - 1011, C - 1100, D - 1101, E - 1110, F - 1111.

Binary Number Representations

There are three main ways to represent signed numbers in binary:

1. Signed Magnitude

• Positive Numbers: Standard binary representation.
• Negative Numbers: The

Mechatronics engineers are responsible for designing mechanical equipment. Combining their knowledge of computer, mechanical, and electrical engineering, they develop various automated products, such as cameras, cars, and aircraft. The engineering process typically involves designing and assembling components, testing products in development, making improvements, and evaluating finished products. Engineers must also assess equipment and publish reports outlining production factors, such as practical use, safety, and cost.

Work Areas:

• Electronics Development Unit
• Software Development Unit
• Project Management Unit
• Biomechanical Development Unit including our Mechanical Shop and Scientific Glassblower

Mechanical Engineer Job Duties:

• Evaluates mechanical

Network Fundamentals: LANs and WANs

• A Local Area Network (LAN) covers a small geographical area, such as a single site or building (e.g., a school or a college).

• A Wide Area Network (WAN) covers a large geographical area. Most WANs are formed by connecting several LANs, with the internet being a prime example.

Virtual Private Networks (VPNs) Explained

A Virtual Private Network (VPN) is programming that creates a safe, encrypted connection over a less secure network. It provides business travelers with secure access to software applications hosted on proprietary networks. To gain access to a restricted resource through a VPN, the user must be authorized to use the VPN application and provide one or more authentication factors, such as a password.... Continue reading "Networking Essentials: Devices, Protocols, Topologies" »

10LayerModelSecurity,10Security policies and mandates.9,Oversight of end-to-end processes to ensure compliance with enterprise security policies. Audit trails for the threads.8Security roles and responsibilities. Standard security practices as they relate to activities and exchanges. Security Architecture. Personnel security requirements. 3.10. Management7Application service security (e.g., integrity of the service and application code) and content security (e.g., security labels). Security of user access to IT. Privilege management. 6Framework service security (e.g., integrity of the service and application code of the framework). Content security labeling service and label checking service. Software-based content encryption/decryption services... Continue reading "Layered Security Model and IT Infrastructure Best Practices" »

Module 9: Firebase Application

Realtime Database

A cloud-hosted database. Data is stored as JSON and synchronized in real-time to every connected client. Provides easy-to-use services for authentication (email/password, 3rd-party providers like Google/Facebook).

Cloud Firestore

A flexible and scalable database for mobile, web, and development. It offers synchronization, offline support, and ACID transactions.

Cloud Functions

...

Hosting

CSS/JavaScript

Cloud Storage

Provides robust, secure file uploads and downloads for Firebase apps.

Module 10: UML Diagrams

Structural Diagrams

• Class Diagram: Shows class hierarchy, fields/attributes, and relevant methods.

How to Read

• Visibility:
  • +: Public
  • -: Private
  • #: Protected (accessed only by child classes)
• Relationships: