Brief introduction about the ideas of the Blockchain technology.
Written in Korean.
Starts with Hash function, Hashcash, proof-of-work, and how Blockchain adopted and extended the idea.
Brief introduction about the ideas of the Blockchain technology.
Written in Korean.
Starts with Hash function, Hashcash, proof-of-work, and how Blockchain adopted and extended the idea.
REST (REpresentational State Transfer) is a web service architecture that uses HTTP requests to GET, POST, PUT, PATCH, and DELETE data in a stateless manner. It focuses on resources instead of remote procedures. REST examples show making GET requests to retrieve XML data from a URI and using RESTful principles like addressability, connectedness, statelessness, and a homogeneous interface with standard HTTP methods.
This document discusses media server options for Ubuntu, including iTunes Media Server which uses Digital Audio Access Protocol (DAAP) and the mt-daap and FirePlay clients. It also mentions the Media Player Daemon (MPD) as an alternative media server that includes an MPD server and clients that can control streaming.
This document discusses implementing a file upload feature using open source technologies. It describes using HTML forms to upload files and a PHP script to handle the upload. It then recommends using the open source Plupload library to add multiple file selection, client-side validation, and progress bars. The Plupload library allows uploading files to a PHP script which can then store the files in a database.
This document discusses computer security and threats. It covers authentication through passwords, program threats like trojan horses and trap doors, system threats such as worms and viruses. It also discusses threat monitoring through audit logs and scans, and encryption techniques like public-key encryption. The goal is to protect systems from unauthorized access, malicious modification, and accidental inconsistencies.
This document provides an overview of the Linux operating system, including its history, design principles, and key components. It began in 1991 as a small kernel developed by Linus Torvalds and has grown through collaboration over the Internet. The core Linux kernel is original but can run existing UNIX software. Major versions have added support for new hardware, file systems, networking, and multiprocessing. Key components include the Linux kernel, system libraries, and system utilities. The kernel uses loadable modules and supports process management and scheduling.
This document discusses protection in operating systems. It covers the goals of protection, domains of protection, access matrices, implementation of access matrices, revocation of access rights, capability-based systems, and language-based protection. The key aspects are that protection ensures each object is only accessed by allowed processes, domains define access rights to objects, access matrices represent access permissions, and capabilities and access control lists are approaches to implementing and revoking access rights.
The document provides an overview of the Unix operating system, including its history, design principles, interfaces, and key components. It was originally developed in 1969 at Bell Labs and incorporated features from Multics. The C programming language was developed to support Unix. Key aspects include its process management, memory management using paging and swapping, file system storing files in blocks and fragments, and user interface through command line shells.
This document summarizes key aspects of distributed file systems (DFS), including their structure, naming and transparency, remote file access using caching, stateful versus stateless service models, file replication, and examples like the Sun Network File System (NFS). A DFS manages dispersed storage across a network, using caching to improve performance of remote file access and dealing with issues of consistency between cached and server copies. NFS provides a specific implementation of a DFS that integrates remote directories transparently and uses stateless remote procedure calls along with caching for efficiency.
This document discusses network structures and communication. It describes different types of network topologies including fully connected, partially connected, tree-structured, star, ring, and bus networks. It also describes different network types like local area networks (LANs) and wide area networks (WANs). Additionally, it discusses important aspects of network communication like naming and addressing, routing strategies, connection strategies, contention, and design strategies using a layered approach.
This document discusses secondary storage devices used by operating systems, including disk structure, disk scheduling algorithms, disk management, swap space management, and tertiary storage devices. It provides details on disk addressing, mapping, scheduling algorithms like FCFS, SSTF, SCAN and C-SCAN. It also summarizes disk reliability techniques, stable storage implementation, removable media like floppy disks, tapes, optical disks and their applications. Hierarchical storage management and performance factors like speed, reliability and cost of different storage devices are also overviewed.
This document discusses various techniques for distributed coordination including event ordering, mutual exclusion, atomicity, concurrency control, deadlock handling, election algorithms, and reaching agreement. It provides details on implementing happened-before relations for event ordering, centralized and distributed approaches for mutual exclusion, using two-phase commit for atomicity, locking protocols and timestamp ordering for concurrency control, deadlock prevention and detection methods, and election algorithms for determining where to restart a coordinator process.
This document discusses input/output (I/O) systems. It describes I/O hardware, including devices, ports, buses and controllers. It explains how I/O requests are handled using techniques like polling, interrupts and direct memory access. It also discusses the role of the operating system kernel in managing I/O through subsystems that interface with applications, transform requests, handle buffers and errors. The performance of I/O systems is also covered.
This document discusses key aspects of file systems including file concepts, directory structures, access methods, allocation methods, and file system performance and recovery. It covers topics such as file attributes, operations, types, structures, tree-structured and graph-based directories, protection methods, free space management, efficiency techniques, and consistency checking. The goal is to provide an overview of file system interfaces and how different components are organized and managed.
Virtual memory allows a program's logical address space to be larger than physical memory by swapping pages in and out of memory as needed. Demand paging brings pages into memory only when they are referenced. When a page is not in memory and is referenced, a page fault occurs which causes the OS to locate a free frame, swap in the page, and update tables. Page replacement algorithms like FIFO and LRU are used to determine which page to swap out when there is no free frame. Thrashing can occur if working set size is larger than physical memory.
Windows NT is a 32-bit preemptive multitasking operating system that uses a microkernel architecture. It has several key goals including portability, security, POSIX compliance, extensibility, and compatibility with MS-DOS and Windows applications. The document discusses Windows NT's history, design principles, system components including the kernel, executive subsystems, virtual memory manager, process manager, file system, and networking. It provides details on how Windows NT achieves reliability, performance, and international support through its layered architecture and object-oriented design.
This document discusses various memory management techniques including paging, segmentation, and swapping. Paging divides memory into fixed-size blocks called frames and logical memory into blocks called pages. It uses a page table to map logical to physical addresses. Segmentation divides programs into segments and uses segment tables to map logical segments to physical frames. Swapping temporarily moves processes out of memory to disk to allow other processes to run.
4. What is Bitcoin?
Satoshi Nakamoto (2009)
Digital Monay
No center processor
Method of transaction - Distribute Database on Peer to Peer Network
Public-Key Cryptosystem
anonymity and disclosure