zK++

A

ADL Search       Automatic Directory Listing Search (ADLSearch) is a tool for searching of file lists downloaded from users. Create a new ADLSearch entering 'avi' as search string for example.

ADSL       Acronym for "Asymmetric Digital Subscriber Line". This is a broadband connection that connected through your phone line. It usually has a very fast download speed and a considerably slower upload speed.

Anti-Fragmentation       When downloading, it creates a file of the expected target size with unspecified content. If the download fails, the file is truncated to the size zK++ thinks it has downloaded, and resume should work fine. If zK++ crashes, you'll lose the whole downloaded part + any resumed part as well, as there's no way to know how much valid data there is in the file. Fragmentation occurs when several downloads are running at the same time, and small bits of data are written to different files continously - causing the data to be scattered around on different locations on the drive. Anti-fragmentation will reserve space on the harddrive, thus putting all the file's data in the same physical space on the harddrive. Fragmented harddrives become slow, as the drive needs to jump around to collect the file's data. Run windows' defrag software to "fix" fragmented data.

ASCII       Acronym for the American Standard Code for Information Interchange. Pronounced ask-ee, ASCII is a code for representing English characters as numbers, with each letter assigned a number from 0 to 127. For example, the ASCII code for uppercase M is 77. Most computers use ASCII codes to represent text, which makes it possible to transfer data from one computer to another.

B

Ban       Being disconnected from a hub by an Operator for a specific period of time. Unlike a Kick, you cannot reconnect to the hub until the ban period has expired.

Bandwidth       The amount of data that can be transmitted in a fixed amount of time. This is also a measure of the speed that you can send or receive something.

bin       An ISO file type, .bin is a file that contains an image (ISO) of a disc. A .bin file is usually matched with a .cue file which cues tells the burning software how to burn the image. Originally, CDRWin was the only burning software able to burn .bin/cue files. Now most will including Nero. Load the cue file and it will do the rest.

Binary/Binaries       Usually it is a compiled file without installer (no instalation is needed).

Broadband        Broadband is a term desribed to difine any Internet connection greater than 128 Kilobits per second. Typical broadband connections include, but are not limited to DSL, Cable, T1 and T3.

C

Cable      A broadband (high bandwidth/speed) connection to the internet. Home computer users are increasingly ditching their phone modems and upgrading to cable or DSL service which is CONSIDERABLY faster.

Client      A client is a program that connects to another computer over a network to request information.

D

DirectConnect       DirectConnect (aka 'DC') is a P2P network that has a simultaneous population of approximately 650,000 users. This community has been around since the days of Napster and is well known for its quantity of CD/DVD images, music and movies.

F

File List       A file generated by zK++ which contains a listing of all the files in your shared directories.

G

GNU GPL       GNU is a recursive acronym for "GNU's Not Unix''; it is pronounced "guh-NEW". GLP is the associative "General Public License." Programs released under public domain, or open source, are protected under this license. Basically, it allows anyone to modify the program, however must give the original author due credit and release it for no cost. 

GUI       Acronym for Graphical User Interface. This is the visual part of the program, where you enter information, read information and so on.

H

Hashing       The process of creating a hash value (a unique identifier) for a file. This value is calculated from the contents of the file and means you no longer have to worry about file names when searching for alternate sources.  For example, if you have "Series 1 - Episode 3.mpg" in your queue and another user has the same file, but called Ǿ.mpeg" they will have the same hash value and can therefore be used as an alternate source.  Hashing was introduced in original DC++ version 0.307.
 
Hub       The DirectConnect system consists of two components - a client (such as zK++) and a hub. A hub is what users connect to in order to chat and find out what files other users have made available. A hub is a central server, much like its literal definition suggests. For example, on DirectConnect, the end user must connect to a "hub", where serveral dozens or serverl hundreds of other computers are linked to. In this situation, this hub acts as a conduit of information.

Hub List       A list of many available public hubs. Note that hub lists do not show all availble hubs. There are many different hub lists available.

K

Kick       Being disconnected from a hub by an Operator. Sometimes, you can reconnect immediately after a kick. See also: Ban.

Kademlia       KADEMLIA is a novel routing algorithm for peer-to-peer networks based on the XOR metric. The KADEMLIA project is a research effort to implement a full-featured peer-to-peer system based on the XOR metric routing. Topics of interest are efficient data storage and query; anonimity; network, content and user security and authentication. Currently, we are working on a Java implementation of KADEMLIA.

L

Leech       A file-sharing user that does not allow others to download from him and only takes from others is a LEECH. And remember folks, nobody likes a leech. 

M

Magnet Links      It is an open URI-scheme and supporting practices/code for enabling seamless integration between websites and locally-running utilities, such as file-management tools or peer to peer clients. Magnet links have been implemented in DC++ 0.4032.  Since this version of DC++, it will register, by default, to handle any magnet: links you click on in web pages. If you click on one of these links, zK++ will pop up and ask you if you want to search the DC network (or hubs you're connected to, at least) for this hash. You can create your own magnets in the search frame, file list window, and download queue by a new contextual menu choice - just right click on the file you want a magnet for, and select Copy magnet link to clipboard.  Since magnet links are an open standard for all (peer to peer) applications, there are hash types in some magnets that zK++ cannot handle. It can only handle magnets that contain a tiger tree hash.

Match Queue       A function to allow you to quickly queue a number of items. In some DC clients, the Match Queue button is found in the file list window. When you open a file list and hit the Match Queue button, if there are any items in the file list that match an entry in your download queue, that particular user is added as an alternate source for the download queue item.

Minimum Share       The minimum quanitity of files required to gain access to a particular hub. Sometimes known as MinShare.

N

Nick      A name that you use to identify yourself, short for nickname. Usually used in DC, IRC and other P2P chat rooms.

noob      Although originally designed to describe "newbies" to the gaming scene, this is now a general term to describe anyone who is consistent with being or acting stupid.

O

Op       An Op (or Operator) is a person within a hub who has control over aspects of the hub such as kicking/banning users, registering new users and so on. He also supervises relevance of chat and files being shared. Operators can temporary remove or permanently remove irrelevant users by their own consideration. You can recognize operators from the key icon in the user list (some users with keys can be bots).

P

Private Hub       A hub not available to the general public. Access to a private hub will require registering with the Hub Owner.

Protocol       A standard way of communicating across a network. Many P2P networks have their own protocol for the peers to communicate with each other. 

Public Hub       A hub available to the general public. This hub may or may not be located on a public hub list.

R

Ratio       Ratio is an easy way to determine how much you are contributing to the hub. In the lower section of the zK++ window you will find a couple of numbers, "D" states how much you have downloaded (total) and "U" states how much you have uploaded (total). In order for the hub to work properly everybody have to have the ambition to upload at least as much as they download and by doing this guarantee a possibility of getting hold of the things that you might want. Since the connection fee is most certainly fixed you will not loose anything if you upload a little more - don't hold back on something that's free!

Rollback checking       When DC clients resumes a file transfer, it will transfer a small amount of the file and then check that it matches with the end of the incomplete file already downloaded. This ensures that the correct file is resumed. If there is a discrepency between two pieces of data, then a Rollback Inconsistency has occurred and the particular source will be removed. The transfer will be attempted from the next available source. Note: Once the TTH implementation in DC client matures, rollback checking will become redundant and may therefore be phased out. 
 
Rollback Inconsistency       A Rollback Inconsistency is when there is a data mismatch during Rollback checking. The symptoms of rollback inconsistency are any of the following: The words "Rollback inconsistency, existing file does not match the one being downloaded" in either the Errors column of the Download queue or the transfer window. The transfer repeatedly starting, running for a few seconds and then disconnecting. 
 
Rollback value       The size of the data that will be checked for consistency during Rollback checking.

S

Search Spam       Sending a large number of search requests to a hub within a short period of time.

Search Spy       A function within zK++ that allows you to see the search requests that are arriving at your computer. It also shows you some statistics about the requests such as the number of requests that match a file in your share (a search "hit").

Scheduling       Enabling your DC client to start uploading and downloading at a set time period and to stop at a certain set time period.

Segmented Downloading       Also known as multisource downloading or swarming download, can be a more efficient way of downloading files from many peers at once. The one single file is downloaded, in parallel, from several distinct sources or uploaders of the file. This can help a group of users with asymmetric connections, such as ADSL to provide a high total bandwidth to one downloader, and to handle peaks in download demand. Segmented downloads probably have an origin with NASA and the magnetic tape based file systems used on Deep Space Network craft such as those in the Voyager Program. In this animation, the coloured bars beneath all of the clients represent individual pieces of the file. After the initial pieces transfer from the seed, the pieces are individually transferred from client to client. The original seeder only needs to send out one copy of the file for all the clients to receive a copy. 

Slot       A unit of file transfer. Each file being transferred in zK++ uses up one slot for downloading files from other users. The number of open download slots determines how any files can be downloaded simultaneously. See also: Upload slot.

Slot Ratio       The ratio of the number of slots to number of connected hubs. For example, a slot ratio of two would mean opening at least two slots for every hub you are connected to.

T

T1       A very high-speed connection to the internet allowing for up to 1.544 million bits per second (Mbps) of data transfer per second. Usually used by businesses or other large organizations due to the cost of having this type of connection.

Tag       A piece of text which provides information about your current zK++ session. The information that zK++ provides is the zK++ version number, the connection mode (Active or Passive), the number of hubs you are connected to and the number upload slots you have. Example: <zK++ V:0.720,M:A,H:0/0/1,S:3>.

Throttling       Artificially restricting network data transfer rates. This is a process which is carried out by some ISPs and/or universities in order to restrict certain traffic types, such as traffic created by file sharing applications. This can be simple restrictions based on source/destination IP addresses and port numbers or more sophisticated restrictions based on traffic analysis. Also known as "bandwidth throttling".
 
Transfer Window       The lower half of the zK++ screen. It display the current uploads, downloads and connection attempts.
 
TTH       There are many ways to do hashing. TTH (Tiger Tree Hashing) is the method used in zK++. It is used to verify the integrity of large chunks of data. The data is split into small pieces which are individually hashed, then hashed together until one, root hash is formed. DC++ 0.400 introduced mandatory TTH. Once zK++ hashes all of your share (yes this will take a while) it will only hash new files. The hashing thread in zK++ is set to low priority, so it shouldn't interfere too badly.  There are several benefits of file hashing:

• No longer does one need to pay attention to the name of the file when looking for alternative sources.  If the files are the same, they will have the same hash and thusly be chosen as an alternative source.  Just because two files are the exact same size does not mean they are the same bitwise!
• Magnet Links.  Implemented in DC++ 0.4032. 
• Segmented (aka 'multisource') downloading.  While it is currently not implemented, now there is a safe way to implement downloading files from multiple sources.  All clients at this point have been implementing segmented downloading in cowboy fashion.  They do not verify the files are the same (except for the size and partial name) which does result in corrupt files.  A file hash ensures the files are identical.

U

UDP       Acronym for User Datagram Protocol. This protocol allows data transfer much like TCP however does not have the strict error management features that slow TCP down.

Upload       When information (files) is transferred from your computer to another computer through a network. When information is being transferred to you from another computer on a network, that is called Downloading.

Upload Limiting       The ability to throttle your upload bandwidth via a setting in many clients. This can be a good or bad thing depending on your total upload bandwidth. It is mainly used to prevent your connection from being choked out. Some hubs ban clients that allow upload limiting.

Upload Slot       A slot allowing files to be uploaded from you, to other users.

D E F I N I T I O N

The Direct Connect network is a decentralized network, made up of individual servers (hubs) that users join to share files with other members on that hub. Each hub is individually run by a fellow user of the Direct Connect network, and may have certain themes to the content on the hub. Hub Owners set up rules to regulate their hub as they see fit. Direct Connect allows you to share files over the Internet without restrictions or limits. The client is completely free of advertisements and has a nice, easy to use interface. Firewall and router support is integrated and it is easy and convenient to use functionality like multi-hub connections, auto-connections and resuming of downloads.

Developed by Neo Modus, is one of the older file-sharing communities still in existence. What began as a small community of only a few thousand individuals has grown into a major P2P player with a speculative population over 500,000. Its network architechure and philosphy is similar to OpenNap. Like OpenNap, the DirectConnect development team creates the client and server software, however distributes the programs to the community. It is up to the DirectConnect community to maintain the network. DirectConnect is still living in the dark ages of file-sharing, as it has no multi-source swarming, official hashing system or connectivity of servers.

It offers a community-oriented, open, user-controlled network. Moreover, Direct Connects network architecture is built on a peer-to-peer foundation; users run, control, and maintain the network. Users are able to share any type of file - with some restrictions. These files are easily viewed through a familiar organized windows-explorer interface. To conveniently access the plethora of files, advanced searching capabilities and filters are provided. All of these features are integrated into Direct Connects unique communal file-sharing system.

It uses a hub-system where a user needs to connect to a hub (servers) to be able to share and download files. When connected to a hub the user can see all other users connected to the hub and a list of the files they share. To be able to download the user must find the file at a computer with a free slot. The design makes Direct Connect more like IRC than KaAaA. Lists of hubs are available from within the DirectConnect program. Many hubs have specialties, which include music, movies and CD images, etc. While music is quite prolific on this network, DirectConnect is best known for the latter two.

While the DirectConnect network may seem enticing, it is not for everyone. Many hub operators set strict entry criteria. This criterion is mostly based on the amount of information you share. For example, many hubs will not allow you to connect if you do not share at least 1 gigabyte of information. With such requirements, only those on broadband connections can take advantage of this network. Although these requirements may seem harsh to those on dialup, it has significantly reduced problems related to leeching, flaming and general lamership.

The much preferred client for the Direct Connect network is called DC++. It has many more features than the original Direct Connect client and has a nicer user interface. zK++ is the open source alternative to DC++. Both connect to the same network, but the experience is very different. Compared to DC++, zK++ has a lot of extra features and is very easy to use. Its streamlined interface makes this network usable for just about anyone. There are many advantages it has over DC++. They include, but are not limited to: detection data, segmented downloading, constant development, cool and smart window interface, better GUI, bandwidth management, smaller download and considerably more stable.

Therefore, Direct connect is a peer-to-peer file-sharing protocol. The most popular Windows client implementing this protocol currently is DC++. Direct connect clients connect to a central hub (usually on port 411) and can download files directly from one machine to another.

Hubs feature a list of clients or users connected to them. Users can search for files and download them from other clients, as well as chat with other users.

H U B

Direct Connect hubs are servers to which clients connect. A "hub" is a piece of software which routes chat, search requests/results and facilitates clients to connect each other. It's not called a server because it doesn't share any files. All file transfers are being made directly between clients, not through the hub. One can find hubs to connect to through the various hublists available in the client. A list of alternative hublists can be found in the end of this page. Hubs provide information about the clients, as well as file searching and chat capabilities. File transfers are done directly between clients, in true peer-to-peer fashion.

Hubs often have special areas of interest. Many have requirements on the total size of the files that their members share (share size), and restrictions on the content and quality of shares. Hubs can allow users to register and provide user authentication. Some private reghubs only let in users already registered.

Direct connect hubs have difficulty scaling, due to the broadcast-centricity of the protocol.

P R O T O C O L

The Direct connect protocol suffers from high bandwidth usage, unusual requirements for parsing, lacklustre internationalization support, and parts that seem to have been crafted to overcome network handling bugs in older versions of Microsoft Visual Basic (which NMDC was developed in). The protocol does not try to hide the identities of the peers, nor is it very optimized for swarm-downloading such as BitTorrent since it lacks partial file-sharing and (in many clients) segmented downloading.

Continued interest exists in features such as ratings and language packs. However, the authors of DC++ have been actively working on a complete replacement of the Direct connect protocol called ADC, designed to address the former's weaknesses.

One example of an added feature is Tiger-Tree Hashing of shared files (TTH). The advantages of this include verifying that a file is downloaded correctly, and the ability to find files independent of their names.