📄 glossary.html
字号:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN"><html lang="en"><head><title>Winsock Programmer's FAQ: Glossary</title><link rel="Stylesheet" type="text/css" href="./faq.css"></head><body bgcolor="#ffffee" text="#000000" link="#491e00" vlink="#7d2e01" alink="#da7417"><!-- ---- Header Bar ---- --><table border="0" width="95%" bgcolor="#006000" cellpadding="5" cellspacing="3" align="center"> <tr> <td align="left" bgcolor="#e0e0c0"> <font size="2" face=Verdana,Arial,Helvetica> <b><a href="reviews/unp-v1.html"><<</a></b> </font> </td> <td align="center"> <font face=Verdana,Arial,Helvetica color="#ffffee"> <p align=center class=bigger3><b> Winsock Programmer's FAQ<br> Section 9: Glossary<br> </b></p> </font> </td> </tr></table><!-- ---- Body Table ---- --><table width="95%" border="0" cellpadding="10"> <tr valign="top"> <td><p>There's not much to say about this section, except that Ifrequently refer you to corresponding and related entries in an onlinecopy of <a href="http://locke.ccil.org/jargon/"><i>The New Hacker'sDictionary</i></a> (known online as <i>The Jargon File</i>), an excellentresource for understanding some of the culture and jargon of the originalInternet. I link you there when I think that the TNHD reference clarifiesor enhances the more straightforward definition I provide.</p><a name="asynchronous"><p><b>asynchronous</b> - In Winsock terms, an asynchronous callis one that returns before performing the requested function. (Youmake a socket asynchronous by calling the <code>WSAAsyncSelect()</code>function on it.) This allows your program to go about its businessuntil Winsock manages to complete the requested function. OnceWinsock completes the request, it notifies your program with awindow message. This is a Good Thing, because networks are so slowand unreliable, compared to the internals of a computer. Asynchronouscalls allow you to decouple the rest of your program from the networkportions, so that a network fault or delay does not unduly impact yourprogram's performance. See also <a href="#blocking">blocking</a> and<a href="#non-blocking">non-blocking</a>.</p><a name="blocking"><p><b>blocking</b> - A function is said to "block" when it waitsuntil it completes the requested operation (or fails trying) beforereturning. (Sockets are blocking by default under Winsock.) The main usefor blocking calls in a Winsock program are when your program's only jobin life is to communicate with the network, because while a call blocks,your program can do nothing else. This mode of operation is also called"synchronous." See also <a href="#asynchronous">asynchronous</a> and<a href="#non-blocking">non-blocking</a>.</p><a name="bridge"><p><b>bridge</b> - A bridge is a <a href="#multi-homed">multi-homed</a>host that operates at layers 1 and 2 of the <a href="#osi-model">OSImodel</a>. Bridges connect two networks, usually of the sametype. A bridge is somewhat smarter than a simple repeater, in thatit can make decisions about moving data from one network to theother. Some bridges even reach up into layers 3 and 4 (traditional <ahref="#router">router</a> and <a href="#gateway">gateway</a> territory)to add even more intelligence; these smarter devices are often called"brouters."</p><a name="BSD"><p><b>BSD Unix</b> - The Berkeley Software Distribution of Unix took anearly lead over originator AT&T's offerings by providing extra featuresand functionality that didn't appear in AT&T Unix (also called SystemV) until later. One of these features was the "sockets" system forcommunicating over TCP/IP networks. Between that and its adoptionby Sun Microsystems, Digital Equipment Corporation and others, BSDUnix was the most popular choice for Internet hosts from the mid 80'sthrough the early 90's. The early 90's saw AT&T sue the Computer SoftwareResearch Group, the University of California at Berkeley organization thatcreated BSD. The early 90's also saw System V adopt many traditional BSDfeatures (including sockets). For those reasons, all commercial Unixeseventually switched to System V. BSD is still available, however,in several lineal descendants: <a href="http://www.freebsd.org">FreeBSD</a>,<a href="http://www.netbsd.org">NetBSD</a>, <a href="http://www.openbsd.org">OpenBSD</a>and <a href="http://www.bsdi.com">BSD/OS</a>. See also the <a href="http://www.netmeg.net/jargon/terms/b/BSD.html">BSD</a> and<a href="http://www.netmeg.net/jargon/terms/u/Unix.html">Unix</a> entries in TNHD.</p><a name="client"><p><b>client</b> - A program that initiates a network connection. Byextension, a client program usually has some kind of user interface,often a GUI. In a typical client/server protocol, the clientis the active participant, in that it makes requests and the <ahref="#server">server</a> responds.</p><a name="datagram"><p><b>datagram protocol</b> - A datagram protocol, such as IP or UDP,delivers data in packets the same size as those that were sent. Forexample, if one host sends another two 50-byte datagrams, that host willreceive two discrete 50-byte datagrams. Compare <a href="#stream">streamprotocol</a>.</p><a name="DNS"><p><b>DNS</b> - The Domain Name Service is one of the core Internetprotocols and mechanisms. DNS is what translates human-readable names(e.g. "www.cyberport.com") into the binary IP addresses that are actuallyused to move data packets around on the Internet. Winsock accesses the DNSwhen you give the <code>gethostbyname()</code> and <code>gethostbyaddr()</code>calls.</p><a name="domain-name"><p><b>domain name</b> - Domain names are the human-readable addresses usedon the Internet (e.g., "www.cyberport.com"). The <a href="#DNS">DomainName Service</a> translates these names into <a href="#IP-address">IPaddresses</a> which TCP/IP programs use directly. Compare <ahref="#dotted-quad">dotted quad</a>.</p><a name="dotted-quad"><p><b>dotted quad</b> - An string representation of an <ahref="#IPv4">IPv4</a> address, in the form "172.16.3.52" <imgsrc="bitmaps/waist-dot.gif" alt="--" width=14 height=6 hspace=2> thatis, four decimal numbers separated by dots. Note that the future <ahref="#IPv6">IPv6</a> addresses are commonly written as a series of8 colon-separated 16-bit values in hexadecimal notation, with zeroessuppressed: "AC01:987C:::A39D::FF52:CC4C". Contrast this with the <ahref="#IP-address">IP address</a> and <a href="#domain-name">domainname</a> entries.</p><a name="gateway"><p><b>gateway</b> - A <a href="#multi-homed">multi-homed</a> network hostthat operates at layer 4 of the <a href="#osi-model">OSI model</a>. Agateway understands the transport layer protocols at the least (TCP,UDP, etc.) and sometimes understands elements from layer 5 (e.g. theFTP protocol). A gateway uses this information to filter data <imgsrc="bitmaps/waist-dot.gif" alt="--" width=14 height=6 hspace=2>for example, it can reject disallowed operations, for example; and totranslate items in the data stream <img src="bitmaps/waist-dot.gif"alt="--" width=14 height=6 hspace=2> for example, it can translate thenetwork addresses from an internal format to an external format. Relatedterms include "packet filter" and "firewall:" a packet filter can bepart of a gateway, and a gateway is one component of a firewall.</p><p>Also note that looser definitions exist, such as for a mail gateway,which lets people using one email system to send mail to people usinganother system.</p><a name="IP-address"><p><b>IP address</b> - A binary value used by the IP protocolto deliver packets to their destination hosts. See the entry <ahref="#dotted-quad">dotted-quad</a> for a common representation ofthese addresses.</p><a name="IPv4"><p><b>IPv4</b> - The Internet Protocol version 4. This is the currentversion, and it is distinguished with addresses that are 32 bitswide. Compare <a href="#IPv6">IPv6</a>.</p><a name="IPv6"><p><b>IPv6</b> - The Internet Protocol version 6. This isstill-experimental version of IP that is destined to replace version4 over the next few years. It is distinguished with many improvementsand features, including a much larger address space, at 128 bits peraddress. This protocol is also sometimes called "IPng", for "IP nextgeneration". Compare <a href="#IPv4">IPv4</a>.</p><a name="MTU"><p><b>MTU</b> - The Maximum Transmission Unit is the largest packet thata given network medium can carry. Ethernet, for example, has a fixed MTUof 1500 bytes, ATM has a fixed MTU of 48 bytes, and PPP has a negotiatedMTU that is usually between 500 and 2000 bytes.</p><a name="multi-homed"><p><b>multi-homed</b> - A host with more than one networkadapter. Sometimes a host is multi-homed to link two networks (as witha <a href="#router">router</a>). More commonly, a multi-homed host issimply connected to two networks, such as a machine on a LAN which alsohas a modem for connecting to an ISP.</p><a name="Nagle"><p><b>Nagle algorithm</b> - The Nagle algorithm delays sending smallpackets over the network on the theory that further packets might followsoon. If so, those packets can be transmitted as a single unit, thusreducing the impact of protocol overhead.</p>⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -