BitComet

BitComet (originally named SimpleBT client from versions 0.11 to 0.37) is a cross-protocol BitTorrent, HTTP and FTP client written in C++ for Microsoft Windows and available in 43 different languages.[1] Its first public release was version 0.28. The current BitComet logo has been used since version 0.50.[2]

Features

The BitComet program is a multi-threaded multi-protocol hybrid download manager and BitTorrent Peer-to-peer (P2P) file-sharing application. It supports simultaneous download tasks. To complete a particular download, it can draw parts of files from many sources across different P2P and Client-server protocols.
BitComet's chief features include an embedded Internet Explorer window for the purpose of allowing users to search for torrents within the program. Along with the features typical of contemporary BitTorrent clients, it supports UPnP gateway configuration, bandwidth scheduling, Webseeding, selecting downloads inside a torrent package, and NAT traversal.[3]
When downloading, BitComet prioritizes the first and last portions of media files so that files may be previewed before they are completely downloaded. BitComet also allows users to share their torrent files on a searchable P2P network. BitComet uses the Kademlia (mainline) DHT to operate even when the tracker is offline. BitComet is capable of downloading files over HTTP and FTP as well as bittorrent, and it includes download plugins for Firefox, Internet Explorer, and Maxthon.[3]
An optional plugin is available to connect to the eD2K network. The plugin is a modified version of the GPL eMule program. When installed, it connects automatically to a server.[4]

BitComet FLV Player version 1.3
The software includes a application to play Flash Video files (.flv and .swf files). [5]

Optional Standalone Software
BitComet.com offers a BitTorrent tracker available for download from the official site.[6] The FLV player program can also be downloaded separately and used independent of the BitComet software.

Controversy and Criticism

Hash reporting
Since version 0.86 BitComet includes discussion and stat-tracking features which send information about torrents to the Bitcomet.com servers, including the torrent hash.[7][verification needed].

Adware
The official BitComet website claims that "BitComet does not contain any adware or spyware"[8]. However, versions 0.85 to 0.97 contained advertising[9]. The current versions no longer contain advertising, except in the web-based search window[10][verification needed].

DHT Exploit
During version 0.60, BitComet received bad publicity because its implementation of the DHT feature, which was new at the time, could be exploited to not respect the private flag of a tracker. This allowed users to avoid download and upload ratio restrictions, which are common on private trackers. Some private trackers responded to this by blacklisting version 0.60.[11] BitComet developer RnySmile reverted the client back to version 0.59 in response to the blacklisting.[12]
The DHT exploit was fixed in version 0.61.[13][14]

Super-seeding
In early 2007, John Hoffman, the creator of super-seeding and author of the BitTornado client, harshly criticized BitComet for using abusive tactics to "game" and "cheat" super-seeding at the expense of other peers: "Since BitComet has proven itself to be a harmful codebase, and since they have forced me to take steps I’d rather not have, I will also be banning connections from that client to my own client and tracker codebases." [15]

Padding Files
Starting with version 0.85 (Early 2007), BitComet added an option to its torrent maker that ensures that no two data files in a multi-file torrent occupy the same BitTorrent "piece." This helps enable BitComet to download different parts of a multi-file torrent from non-BitTorrent sources such as http/ftp servers or the ED2K network. To accomplish this, BitComet fills the remainder of each last "piece" with an intervening padding file. While these small and harmless files are transparent to the BitComet user, they can be an annoyance to users of other clients who must deal with them both during and after the download. [16] Creation of padding files was enabled by default in version 0.85, and disabled by default in version 0.86 onward.[verification needed]

Validity of criticism
In July 2007 professional networking specialist Robb Topolski conducted an independent analysis of most accusations leveled against BitComet including the DHT Exploit and Super-seeding controversies mentioned above. He found all but one of the claims to be false or unverifiable. He found that BitComet is not detrimental or malicious to the download or upload speeds of a BitTorrent swarm or the tracker.[17]
The one claim he verified as partially correct was that, "BitComet is a poor peer due to no upload slot control; upload bandwidth is stretched too thin.". Topolski's tests indicated that BitComet does lack upload slot control, but only when BitComet is initially seeding a torrent—that is, when BitComet is the only seeding peer in a swarm, it tends to seed less efficiently than the two other clients he tested. Topolski asserts that when BitComet is not the only seeding peer in the swarm, or when it is a non-seeding peer, upload slot control is managed exceptionally well.[18]

Server (computing)

A server is a computer dedicated to running a server application. A server application is a computer program that accepts network connections in order to service requests by sending back responses.[1] Examples of server applications include mail servers, file servers, and proxy servers.

Term usage in information technology

A server is simply a computer that provides services or resources to other computers.[2]
Server is an adjective in the term server operating system. A server operating system is intended or better enabled to run server applications. The differences between the server version and the workstation version of an operating system vary. Sometimes the difference can be the removal of an arbitrary limit due to licensing, as in the case of Windows 2000, or it can be the addition of bundled applications as in Mac OS X Server. Some server applications (e.g. Microsoft IIS) impose arbitrary limits on the number of HTTP connections they will accept, depending on whether they are running under a server operating system or not.
A server is a computer system that has been designated for running a specific server application. A computer that is designated for only one server application is often named for that application. For example, when the software Apache HTTP Server is used as the web server for a company's website, the computer running Apache is also called the web server. Server applications can be divided among server computers over an extreme range, depending upon the workload. Every server application can run concurrently on a single computer under light loading, but multiple server computers may be required for each application under a heavy load. Under medium loading, it is common to use one server computer per server application, in order to limit the amount of damage caused by failure of any single server computer or security breach of any single server application. Any server computer can also be used as a workstation, but it is avoided in practice, again to contain risk.
Server is also a designation for computer models intended for use in running server applications, often under heavy workloads, unattended, for an extended period of time. While any workstation computer can run server operating systems and server applications, a server computer usually has special features intended to make it more suitable. These features can include a faster CPU, faster and more plentiful RAM, and larger hard drives, but these traits are shared with high-end desktops. More obvious distinctions include redundancy in power supplies, network connections, and storage devices as well as modular design. Blade servers are an example of the latter and are often used in server farms.
The name server or server appliance also applies to network-connected computer appliances or "appliance hardware" that provide specific services for other clients on the network. Though the appliance is a server computer, loaded with a server operating system and running a server application, the user need not configure any of it — it is a black box that does a specific job. The simplest servers are most often sold as appliances, like switches, routers, gateways, and print servers.

Server hardware

Hardware requirements for servers vary, depending on the server application. Absolute CPU speed is not as critical to a server as it is to a desktop. Servers' duties to provide service to many users over a network lead to different requirements like fast network connections and high I/O throughput. Since servers are typically accessed over a network, servers emphasize function over form, without regard to aesthetics like appearance and noise level, because users may never lay eyes on the machine itself. Servers may accordingly run in headless mode without a monitor in order to free up processing cycles for other tasks. In general, a server becomes more specialized and therefore more efficient as unnecessary and unused services are eliminated. For this reason, many servers lack a graphical user interface, or GUI, because it consumes resources that could be allocated elsewhere. Similarly, servers often lack audio and USB interfaces.
By definition, servers provide services, but it is not always possible to predict when users will need those services. For this reason, servers are often online for weeks or months without interruption, making hardware durability extremely important. Although servers can be built from commodity computer parts, mission-critical servers use specialized hardware with low failure rates in order to maximize uptime. For example, servers may incorporate faster, higher-capacity hard drives, larger computer fans or water cooling to help remove heat, and uninterruptible power supplies that ensure the servers continue to function in the event of a power failure. These components offer higher performance and reliability at a correspondingly higher price. The dominant paradigm in servers is parallel computing, and thus high-performance servers are often placed in rack-mounted configurations to save space inside server rooms or "closets." These special rooms help mute the large amount of noise produced and also restrict physical access to the system administrators for security purposes.
Servers have a unique property in that, the more powerful and complex the system, the longer it takes for the hardware to turn on and begin loading the operating system. Servers often do extensive preboot memory testing and verification and start up of remote management services. The hard drive controllers then start up banks of drives sequentially, rather than all at once, so as not to overload the power supply, and afterwards they initiate RAID system prechecks for correct operation of redundancy. It is not uncommon for a machine to take several minutes to turn on and yet not require a restart for the next calendar year.

Server operating system

Some popular operating systems for servers — such as FreeBSD, Solaris, and Linux — are derived from or are similar to UNIX. UNIX was originally a minicomputer operating system, and as servers gradually replaced traditional minicomputers, UNIX was a logical and efficient choice of operating system for the servers. UNIX-based systems, many of which are free in both senses, are the most popular.
Server-oriented operating systems tend to have certain features in common that make them more suitable for the server environment, such as
an optional or absent GUI,
ability to reconfigure both hardware and software to some extent without restart,
advanced backup facilities to permit online backups of critical data at regular and frequent intervals,
transparent data transfer between different volumes or devices,
flexible and advanced networking capabilities,
automation capabilities like daemons in UNIX and services in Windows, and
tight system security, with advanced user, resource, data, and memory protection.
Server-oriented operating systems can in many cases interact with hardware sensors to detect conditions such as overheating, processor and disk failure, and consequently alert an operator and/or take remedial measures itself.
Because the requirements of servers are, in some cases, almost diametrically opposed to those of desktop computers,[citation needed] it is extremely difficult to design an operating system that handles both environments well; thus, operating systems that are well suited to the desktop may not be ideal for servers and vice versa. Regardless of OS vendor, system configurations that are ideal for servers may be unsatisfactory for desktop use, and configurations that perform well on the desktop may leave much to be desired on servers. This results in many operating systems' release in both server and desktop versions. Nevertheless, the desktop versions of the Windows and Mac OS X operating systems are deployed on a minority of servers, as are some proprietary mainframe operating systems, such as z/OS. The dominant operating systems among servers are UNIX-based and open source kernel distributions.[citation needed]
The rise of the microprocessor-based server was facilitated by the development of Unix to run on the x86 microprocessor architecture. The Microsoft Windows family of operating systems also runs on x86 hardware, and versions beginning with Windows NT have incorporated features that making them suitable for use as server operating systems.
While the role of server and desktop operating systems remains distinct, improvements in the reliability of both hardware and operating systems have blurred the distinction between the two classes. Today, many desktop and server operating systems share similar code bases, differing mostly in configuration. The shift towards web applications and middleware platforms has also lessened the demand for specialist application servers.

Java (programming language)

Java is a programming language originally developed by Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities. Java applications are typically compiled to bytecode that can run on any Java virtual machine (JVM) regardless of computer architecture.
The original and reference implementation Java compilers, virtual machines, and class libraries were developed by Sun from 1995. As of May 2007, in compliance with the specifications of the Java Community Process, Sun made available most of their Java technologies as free software under the GNU General Public License. Others have also developed alternative implementations of these Sun technologies, such as the GNU Compiler for Java and GNU Classpath.

Syntax

The syntax of Java is largely derived from C++. Unlike C++, which combines the syntax for structured, generic, and object-oriented programming, Java was built exclusively as an object oriented language. As a result, almost everything is an object and all code is written inside a class. The exceptions are the intrinsic data types (ordinal and real numbers, boolean values, and characters), which are not classes for performance reasons.

Hello world program
This is a minimal Hello world program in Java with syntax highlighting:


// HelloWorld.java
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello, world!");
}
}


A more comprehensive example

// OddEven.java
import javax.swing.JOptionPane;

public class OddEven {
public static void main(String[] args) {
// This is the main method. It gets called when this class is run through a Java interpreter.
OddEven number = new OddEven();
/* This line of code creates a new instance of this class called "number" and
* initializes it, and the next line of code calls the "showDialog()" method,
* which brings up a prompt to ask you for a number
*/
number.showDialog();
}
private int input; // A whole number("int" means integer)
// "input" is the number that the user gives to the computer

public OddEven() {
/* This is the constructor method. It gets called when an object of the OddEven type
* is created.
*/
}

public void showDialog() {
try
/* This makes sure nothing goes wrong. If something does,
* the interpreter skips to "catch" to see what it should do.
*/
{
input = Integer.parseInt(JOptionPane.showInputDialog("Please Enter A Number"));
calculate();
/*
* The code above brings up a JOptionPane, which is a dialog box
* The String returned by the "showInputDialog()" method is converted into
* an integer, making the program treat it as a number instead of a word.
* After that, this method calls a second method, calculate() that will
* display either "Even" or "Odd."
*/
}
catch (NumberFormatException e)
/* This means that there was a problem with the format of the number
* (Like if someone were to type in 'Hello world' instead of a number).
*/
{
System.err.println("ERROR: Invalid input. Please type in a numerical value.");
}
}

private void calculate() {
if (input % 2 == 0)
System.out.println("Even");
/* When this gets called, it sends a message to the interpreter.
* The interpreter usually shows it on the command prompt (For Windows users)
* or the terminal (For Linux users).(Assuming it's open)
*/
else
System.out.println("Odd");
}
}

WinRAR

WinRAR (a.k.a. RAR) is a shareware file archiver and data compression utility developed by Eugene Roshal. It is one of the few applications that is able to create RAR archives natively, as the encoding method is held to be proprietary.

WinRAR supports the following features:
-Complete support for RAR and ZIP archives, and unpacking of ARJ, LZH, TAR, GZ, ACE, UUE, BZ2, JAR, ISO, 7z and Z archives. Future versions of WinRAR are planned to include 7z creation.[1]
-The ability to create self-extracting and multi-volume (split) archives.
-Data redundancy is provided via recovery records and recovery volumes, even allowing reconstruction of damaged archives.
-Support for advanced NTFS file system options and Unicode in file names.
Optional archive encryption using AES (Advanced Encryption Standard) with a 128-bit key.

Wi-Fi

Wi-Fi (IPA: /ˈwaɪfaɪ/) is the trade name for a popular wireless technology used in home networks, mobile phones, video games and more. Wi-Fi is supported by nearly every modern personal computer operating system and most advanced game consoles.

Windows XP

Windows XP is a line of operating systems developed by Microsoft for use on personal computers, including home and business desktops, notebook computers, and media centers. The name "XP" stands for eXPerience.[2] Windows XP is the successor to both Windows 2000 Professional and Windows Me, and is the first consumer-oriented operating system produced by Microsoft to be built on the Windows NT kernel (version 5.1) and architecture. Windows XP was first released on October 25, 2001, and over 400 million copies were in use in January 2006, according to an estimate in that month by an IDC analyst.[3] It is succeeded by Windows Vista, which was released to volume license customers on November 8, 2006, and worldwide to the general public on January 30, 2007.
The most common editions of the operating system are Windows XP Home Edition, which is targeted at home users, and Windows XP Professional, which has additional features such as support for Windows Server domains and two physical processors, and is targeted at power users and business clients. Windows XP Media Center Edition has additional multimedia features enhancing the ability to record and watch TV shows, view DVD movies, and listen to music. Windows XP Tablet PC Edition is designed to run ink-aware applications built using the Tablet PC platform. Two separate 64-bit versions of Windows XP were also released, Windows XP 64-bit Edition for IA-64 (Itanium) processors and Windows XP Professional x64 Edition for x86-64.
Windows XP is known for its improved stability and efficiency over the 9x versions of Microsoft Windows. It presents a significantly redesigned graphical user interface, a change Microsoft promoted as more user-friendly than previous versions of Windows. New software management capabilities were introduced to avoid the "DLL hell" that plagued older consumer-oriented 9x versions of Windows. It is also the first version of Windows to use product activation to combat software piracy, a restriction that did not sit well with some users and privacy advocates. Windows XP has also been criticized by some users for security vulnerabilities, tight integration of applications such as Internet Explorer 6 and Windows Media Player, and for aspects of its default user interface. Later versions with Service Pack 2, and Internet Explorer 7 addressed some of these concerns.
During development, the project was codenamed "Whistler", after Whistler, British Columbia, as many Microsoft employees skied at the Whistler-Blackcomb ski resort.

BIOS

BIOS (pronounced /ˈbaɪoʊs/), in computing, stands for Basic Input/Output System.[1] [2]
The term is incorrectly known as Binary Input/Output System, Basic Integrated Operating System and occasionally Built In Operating System. BIOS refers to the firmware code run by an IBM PC when first powered on. The primary function of the BIOS is to identify and initiate component hardware (such as hard disk, floppy and optical disk drives). This is to prepare the machine so other software programs stored on various media can load, execute, and assume control of the PC.[3] This process is known as booting, or booting up, which is short for bootstrapping.
BIOS can also be said to be a coded program embedded on a chip that recognizes and controls various devices that make up x86 personal computers. Among other classes of computers, the generic terms boot monitor, boot loader or boot ROM were commonly used. Some Sun and Macintosh PowerPC computers used Open Firmware for this purpose. There are a few proposed alternatives for Legacy BIOS in the x86 world: Extensible Firmware Interface, Open Firmware (used on the OLPC XO-1) and coreboot.
The term first appeared in the CP/M operating system, describing the part of CP/M loaded during boot time that interfaced directly with the hardware (CP/M machines usually had a simple boot loader in ROM, and nothing else). Most versions of DOS have a file called "IBMBIO.COM" or "IO.SYS" that is analogous to the CP/M disk BIOS.

Mac OS X

Mac OS X (pronounced /mæk oʊ ɛs tɛn/)[1] is a line of graphical operating systems developed, marketed, and sold by Apple Inc., the latest of which is pre-loaded on all currently shipping Macintosh computers. Mac OS X is the successor to the original Mac OS, which had been Apple's primary operating system since 1984. Unlike its predecessors, Mac OS X is a Unix-based operating system[2] built on technology that had been developed at NeXT through the second half of the 1980s until Apple purchased the company in early 1997.
The first version released was Mac OS X Server 1.0 in 1999, and a desktop-oriented version, Mac OS X v10.0 followed in March 2001. Since then, five more distinct "end-user" and "server" versions have been released, most recently Mac OS X v10.5 in October 2007. Releases of Mac OS X are named after big cats, for example Mac OS X v10.5 is usually referred to by Apple and users as "Leopard".
The server edition, Mac OS X Server, is architecturally very similar to its desktop counterpart but includes workgroup management and administration software tools that provide simplified access to common network services, including a mail transfer agent, a Samba server, an LDAP server, a domain name server, and others. It is included with Apple's Xserve server hardware, but is designed to run on most of Apple's computer models.
Apple also produces specialized versions of OS X for use on three of its consumer devices, the Apple TV,[3] the iPhone and the iPod touch

IP address

An IP address (or Internet Protocol address) is a unique address that certain electronic devices use in order to identify and communicate with each other on a computer network utilizing the Internet Protocol standard (IP)—in simpler terms, a computer address. Any participating network device—including routers, switches, computers, infrastructure servers (e.g., NTP, DNS, DHCP, SNMP, etc.), printers, Internet fax machines, and some telephones—can have its own address that is unique within the scope of the specific network. Some IP addresses are intended to be unique within the scope of the global Internet, while others need to be unique only within the scope of an enterprise.
The IP address acts as a locator for one IP device to find another and interact with it. It is not intended, however, to act as an identifier that always uniquely identifies a particular device. In current practice, an IP address is not always a unique identifier, due to technologies such as dynamic assignment and network address translation.
On the public Internet, as opposed to private internets or intranets, IP addresses are managed and created by the Internet Assigned Numbers Authority (IANA). The IANA generally allocates super-blocks to Regional Internet Registries, who in turn allocate smaller blocks to Internet service providers and enterprises.

Networking and the Internet

Visualization of a portion of the routes on the Internet.

Computers have been used to coordinate information between multiple locations since the 1950s. The U.S. military's SAGE system was the first large-scale example of such a system, which led to a number of special-purpose commercial systems like Sabre.
In the 1970s, computer engineers at research institutions throughout the United States began to link their computers together using telecommunications technology. This effort was funded by ARPA (now DARPA), and the computer network that it produced was called the ARPANET. The technologies that made the Arpanet possible spread and evolved. In time, the network spread beyond academic and military institutions and became known as the Internet. The emergence of networking involved a redefinition of the nature and boundaries of the computer. Computer operating systems and applications were modified to include the ability to define and access the resources of other computers on the network, such as peripheral devices, stored information, and the like, as extensions of the resources of an individual computer. Initially these facilities were available primarily to people working in high-tech environments, but in the 1990s the spread of applications like e-mail and the World Wide Web, combined with the development of cheap, fast networking technologies like Ethernet and ADSL saw computer networking become almost ubiquitous. In fact, the number of computers that are networked is growing phenomenally. A very large proportion of personal computers regularly connect to the Internet to communicate and receive information. "Wireless" networking, often utilizing mobile phone networks, has meant networking is becoming increasingly ubiquitous even in mobile computing environments.

Information technology

Information and communication

technology spending in 2005

Information Technology (IT), as defined by the Information Technology Association of America (ITAA), is "the study, design, development, implementation, support or management of computer-based information systems, particularly software applications and computer hardware." IT deals with the use of electronic computers and computer software to convert, store, protect, process, transmit, and securely retrieve information.

Today, the term information technology has ballooned to encompass many aspects of computing and technology, and the term is more recognizable than ever before. The information technology umbrella can be quite large, covering many fields. IT professionals perform a variety of duties that range from installing applications to designing complex computer networks and information databases. A few of the duties that IT professionals perform may include data management, networking, engineering computer hardware, database and software design, as well as the management and administration of entire systems. When computer and communications technologies are combined, the result is information technology, or "infotech". Information Technology (IT) is a general term that describes any technology that helps to produce, manipulate, store, communicate, and/or disseminate information. Presumably, when speaking of Information Technology (IT) as a whole, it is noted that the use of computers and information are associated.

Computer

The NASA Columbia Supercomputer.

This article is about the machine. For other uses, see Computer (disambiguation).
"Computer technology" redirects here. For the company, see Computer Technology Limited.

A computer is a machine that manipulates data according to a list of instructions.
The first devices that resemble modern computers date to the mid-20th century (around 1940 - 1945), although the computer concept and various machines similar to computers existed earlier. Early electronic computers were the size of a large room, consuming as much power as several hundred modern personal computers.[1] Modern computers are based on tiny integrated circuits and are millions to billions of times more capable while occupying a fraction of the space.[2] Today, simple computers may be made small enough to fit into a wristwatch and be powered from a watch battery. Personal computers, in various forms, are icons of the Information Age and are what most people think of as "a computer"; however, the most common form of computer in use today is the embedded computer. Embedded computers are small, simple devices that are used to control other devices — for example, they may be found in machines ranging from fighter aircraft to industrial robots, digital cameras, and children's toys.

The ability to store and execute lists of instructions called programs makes computers extremely versatile and distinguishes them from calculators. The Church–Turing thesis is a mathematical statement of this versatility: any computer with a certain minimum capability is, in principle, capable of performing the same tasks that any other computer can perform. Therefore, computers with capability and complexity ranging from that of a personal digital assistant to a supercomputer are all able to perform the same computational tasks given enough time and storage capacity.