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longchamppas

sac longchamps week end Un - 0 views

L'Europe abaisse les quotas de pêche pour 2014 Engagée à mener la bataille contre la surpêche, la Commission européenne vient d'annoncer des quotas 2014 à la baisse pour 45 espèces de poissons de ...

sac longchamps waterloo week end wikipedia

started by longchamppas on 22 Aug 14 no follow-up yet
knowuh not saying

Comparison of hex editors - Wikipedia, the free encyclopedia - 0 views

en.wikipedia.org/...Comparison_of_hex_editors

comparison editor hex list programming

shared by knowuh not saying on 04 Jun 08 - Cached
  • knowuh not saying on 04 Jun 08
     
    Wikipedia article which does a good job of comparing all the myriad of available hex editors. I found it very useful. I will be returning.
ma_haijin

TCP 的那些事儿（上） 酷壳 - CoolShell.cn | 酷 壳 - CoolShell.cn - 0 views

coolshell.cn/11564.html

shared by ma_haijin on 11 Aug 16 - No Cached
  • TCP的包是没有IP地址的，那是IP层上的事。但是有源端口和目标端口。
  • Sequence Number是包的序号，用来解决网络包乱序（reordering）问题。
  • Acknowledgement Number就是ACK——用于确认收到，用来解决不丢包的问题。
  • ...14 more annotations...
  • Window又叫Advertised-Window，也就是著名的滑动窗口（Sliding Window），用于解决流控的。
  • TCP Flag ，也就是包的类型，主要是用于操控TCP的状态机的。
  • 其实，网络上的传输是没有连接的，包括TCP也是一样的。而TCP所谓的“连接”，其实只不过是在通讯的双方维护一个“连接状态”，让它看上去好像有连接一样。所以，TCP的状态变换是非常重要的。
  • 这个号要作为以后的数据通信的序号，以保证应用层接收到的数据不会因为网络上的传输的问题而乱序（TCP会用这个序号来拼接数据）。
  • 关于建连接时SYN超时。试想一下，如果server端接到了clien发的SYN后回了SYN-ACK后client掉线了，server端没有收到client回来的ACK，那么，这个连接处于一个中间状态，即没成功，也没失败。于是，server端如果在一定时间内没有收到的TCP会重发SYN-ACK。在Linux下，默认重试次数为5次，重试的间隔时间从1s开始每次都翻售，5次的重试时间间隔为1s, 2s, 4s, 8s, 16s，总共31s，第5次发出后还要等32s都知道第5次也超时了，所以，总共需要 1s + 2s + 4s+ 8s+ 16s + 32s = 2^6 -1 = 63s，TCP才会把断开这个连接。
  • 请注意，请先千万别用tcp_syncookies来处理正常的大负载的连接的情况。因为，synccookies是妥协版的TCP协议，并不严谨。对于正常的请求，你应该调整三个TCP参数可供你选择，第一个是：tcp_synack_retries 可以用他来减少重试次数；第二个是：tcp_max_syn_backlog，可以增大SYN连接数；第三个是：tcp_abort_on_overflow 处理不过来干脆就直接拒绝连接了。
  • 一个ISN的周期大约是4.55个小时。因为，我们假设我们的TCP Segment在网络上的存活时间不会超过Maximum Segment Lifetime（缩写为MSL – Wikipedia语条），所以，只要MSL的值小于4.55小时，那么，我们就不会重用到ISN。
  • 为什么不直接给转成CLOSED状态呢？主要有两个原因：1）TIME_WAIT确保有足够的时间让对端收到了ACK，如果被动关闭的那方没有收到Ack，就会触发被动端重发Fin，一来一去正好2个MSL，2）有足够的时间让这个连接不会跟后面的连接混在一起（你要知道，有些自做主张的路由器会缓存IP数据包，如果连接被重用了，那么这些延迟收到的包就有可能会跟新连接混在一起）。
  • Again，使用tcp_tw_reuse和tcp_tw_recycle来解决TIME_WAIT的问题是非常非常危险的，因为这两个参数违反了TCP协议
  • 如果你的服务器是于HTTP服务器，那么设置一个HTTP的KeepAlive有多重要（浏览器会重用一个TCP连接来处理多个HTTP请求）
  • TCP要保证所有的数据包都可以到达，所以，必需要有重传机制。
  • 接收端给发送端的Ack确认只会确认最后一个连续的包，比如，发送端发了1,2,3,4,5一共五份数据，接收端收到了1，2，于是回ack 3，然后收到了4（注意此时3没收到），此时的TCP会怎么办？我们要知道，因为正如前面所说的，SeqNum和Ack是以字节数为单位，所以ack的时候，不能跳着确认，只能确认最大的连续收到的包，不然，发送端就以为之前的都收到了。
  • TCP引入了一种叫Fast Retransmit 的算法，不以时间驱动，而以数据驱动重传。也就是说，如果，包没有连续到达，就ack最后那个可能被丢了的包，如果发送方连续收到3次相同的ack，就重传。Fast Retransmit的好处是不用等timeout了再重传。
  • 注意：SACK会消费发送方的资源，试想，如果一个攻击者给数据发送方发一堆SACK的选项，这会导致发送方开始要重传甚至遍历已经发出的数据，这会消耗很多发送端的资源。
  • ma_haijin on 11 Aug 16
     
    TCP是一个巨复杂的协议，因为他要解决很多问题，而这些问题又带出了很多子问题和阴暗面。所以学习TCP本身是个比较痛苦的过程，但对于学习的过程却能让人有很多收获。关于TCP这个协议的细节，我还是推荐你去看W.Richard Stevens的《TCP/IP 详解 卷1：协议》（当然，你也可以去读一下RFC793以及后面N多的RFC）。另外，本文我会使用英文术语，这样方便你通过这些英文关键词来查找相关的技术文档。 之所以想写这篇文章，目的有三个， 一个是想锻炼一下自己是否可以用简单的篇幅把这么复杂的TCP协议描清楚的能力。 另一个是觉得现在的好多程序员基本上不会认认真真地读本书，喜欢快餐文化，所以，希望这篇快餐文章可以让你对TCP这个古典技术有所了解，并能体会到软件设计中的种种难处。并且你可以从中有一些软件设计上的收获。 最重要的希望这些基础知识可以让你搞清很多以前一些似是而非的东西，并且你能意识到基础的重要。 所以，本文不会面面俱到，只是对TCP协议、算法和原理的科普。 我本来只想写一个篇幅的文章的，但是TCP真TMD的复杂，比C++复杂多了，这30多年来，各种优化变种争论和修改。所以，写着写着就发现只有砍成两篇。 上篇中，主要向你介绍TCP协议的定义和丢包时的重传机制。 下篇中，重点介绍TCP的流迭、拥塞处理。 废话少说，首先，我们需要知道TCP在网络OSI的七层模型中的第四层--Transport层，IP在第三层--Network层，ARP在第二层--Data Link层，在第二层上的数据，我们叫Frame，在第三层上的数据叫Packet，第四层的数据叫Segment。 首先，我们需要知道，我们程序的数据首先会打到TCP的Segment中，然后TCP的Segment会打到IP的Packet中，然后再打到以太网Ethernet的Frame中
Kevin O'Neill

The 7 Software "-ilities" You Need To Know - 0 views

www.codesqueeze.com/tware-ilities-you-need-to-know

engineering ilities requirements software

shared by Kevin O'Neill on 13 Aug 08 - Cached
  • 1. Usability Software usability can be described as how effectively end users can use, learn, or control the system
  • 2. Maintainability ( or Flexibility / Testibility) The definition of maintainability [for me] implies how brittle the code is to change
  • 3. Scalability Scalability is the ability for your program to gracefully meet the demand of stress caused by increased usage
  • ...4 more annotations...
  • 4. Availability (or Reliability) How long the system is up and running and the Mean Time Between Failure (MTBF) is known as the availability of a program
  • 5. Extensibility Are there points in the system where changes can be made with (or without) program changes?
  • 6. Security I shouldn’t need to go into this one but to be thorough I like this definition of security: the measure of system’s ability to resist unauthorized attempts at usage or behavior modification, while still providing service to legitimate users.
  • 7. Portability Portability is the ability for your application to run on numerous platforms.
Joel Bennett

Expect - Wikipedia - 0 views

en.wikipedia.org/Expect

automation cli development scripting tcl testing

shared by Joel Bennett on 16 Oct 08 - Cached
  • Joel Bennett on 16 Oct 08
     
    Expect is an extension to the Tcl scripting language to create an automation and testing tool for CLI applications such as telnet, ftp, passwd, fsck, rlogin, tip, ssh, et., and because it wraps the standard command-line interface, it can be used to automate any arbitrary applications that are accessed over a terminal.
Joel Bennett

Comparison of JavaScript-based source code editors - Wikipedia, the free encyclopedia - 0 views

en.wikipedia.org/...ript-based_source_code_editors

Development WebDesign Javascript CodeEditor Syntax Highlighter

shared by Joel Bennett on 31 Mar 09 - Cached
  • Joel Bennett on 31 Mar 09
     
    EditArea and CodeMirror are clearly winners here.
Fabien Cadet

Herbert Simon - Wikipedia (en) - 2 views

en.wikipedia.org/...Herbert_Simon

CS AI sociology

shared by Fabien Cadet on 19 Sep 11 - Cached
  • Fabien Cadet on 19 Sep 11
     
    « Simon was among the founding fathers of several of today's important scientific domains, including artificial intelligence, information processing, decision-making, problem-solving, attention economics, organization theory, complex systems, and computer simulation of scientific discovery. He coined the terms bounded rationality and satisficing, and was the first to analyze the architecture of complexity and to propose a preferential attachment mechanism to explain power law distributions. »
Tarik Guney

Singleton pattern - Wikipedia, the free encyclopedia - 0 views

en.wikipedia.org/...Singleton_pattern

singleton-pattern programming

shared by Tarik Guney on 03 Nov 09 - Cached
  • the singleton pattern is a design pattern that is used to restrict instantiation of a class to one object.
  • Tarik Guney on 03 Nov 09
     
    In software engineering, the singleton pattern is a design pattern that is used to restrict instantiation of a class to one object. This is useful when exactly one object is needed to coordinate actions across the system. The concept is sometimes generalized to systems that operate more efficiently when only one object exists, or that restrict the instantiation to a certain number of objects (say, five). Some consider it an anti-pattern, judging that it is overused, introduces unnecessary limitations in situations where a sole instance of a class is not actually required, and introduces global state into an application.
Fabien Cadet

Duck typing - Wikipedia [en] - 0 views

en.wikipedia.org/Duck_typing

development coding OOP concept principle interface

shared by Fabien Cadet on 18 Jul 11 - Cached
  • When I see a bird that walks like a duck and swims like a duck and quacks like a duck, I call that bird a duck.
zenfone

Provider Vcc murah di Indonesia - 1 views

Taufan review vcc.co.id Provider Vcc murah di Indonesia Apakah Anda pernah mengetahui vcc atau virtual credit card?. Menurut Wikipedia vcc adalah kartu kredit virtual yang merupakan bentuk dari seb...

development web tools

started by zenfone on 14 Sep 14 no follow-up yet
Joel Bennett

Openserving - Free Content For All - 0 views

www.openserving.com

develop free hosting webdesign wiki

shared by Joel Bennett on 08 Feb 07 - Cached
  • Joel Bennett on 08 Feb 07
     

    Wikia's OpenServing service is giving away MediaWiki-derivative software hosting and bandwidth in exchange for links back to Wikia.  Not just that, but according to this article on eWeek they are hoping to become a sort of unified free hosting site based on open source website software ...
  • anonymous on 27 Sep 13
     
    Visit News www.killdo.de.gg. How to make the 1000 visitor from PR9 backlinks. Buy cheap service www.fiverr.com/radjaseotea/making-best-super-backlink-143445
Joel Bennett

html2wiki.pm - Convert HTML text to wiki markup - live preview - 0 views

diberri.dyndns.org/...index.html

@public development languages markup perl scripting webdesign

shared by Joel Bennett on 26 Mar 07 - Cached
  • Joel Bennett on 26 Mar 07
     
    A Perl Module to convert HTML to any of the many pseudo-markups in use by wiki's and blogs, including Textile (see "Confluence") and Markdown, MediaWiki, UseMod, SnipSnap, MoinMoin, etc.
  • Joel Bennett on 26 Mar 07
     
    At first I thought this could be the "back" part of TIM, but after trying it out on even simple example text, I'm a bit dissapointed. The nested lists, images, and URLs seem broken (although the links at least, work in Confluence).

    The worst problems are that it has no sense of %{style} span% or footnotes, and no concept AT ALL of tables.  It would be nice to at least get the {style} -- and therefore the spans -- working.
Matteo Spreafico

Classical Inheritance in JavaScript - 0 views

javascript.crockford.com/inheritance.html

javascript inheritance Scripting programming

shared by Matteo Spreafico on 13 Aug 09 - Cached
  • function ZParenizor2(value) { var that = new Parenizor(value); that.toString = function () { if (this.getValue()) { return this.uber('toString'); } return "-0-" }; return that; }
    • Matteo Spreafico
      Matteo Spreafico on 13 Aug 09
       
      This constructors lies, wondeful!
  • Again, we augment Function. We make an instance of the parent class and use it as the new prototype. We also correct the constructor field, and we add the uber method to the prototype as well.
  • This adds a public method to the Function.prototype, so all functions get it by Class Augmentation. It takes a name and a function, and adds them to a function's prototype object.
  • ...3 more annotations...
  • To make the examples above work, I wrote four sugar methods. First, the method method, which adds an instance method to a class. Function.prototype.method = function (name, func) { this.prototype[name] = func; return this; };
  • JavaScript can be used like a classical language, but it also has a level of expressiveness which is quite unique. We have looked at Classical Inheritance, Swiss Inheritance, Parasitic Inheritance, Class Augmentation, and Object Augmentation. This large set of code reuse patterns comes from a language which is considered smaller and simpler than Java.
  • I have been writing JavaScript for 8 years now, and I have never once found need to use an uber function. The super idea is fairly important in the classical pattern, but it appears to be unnecessary in the prototypal and functional patterns. I now see my early attempts to support the classical model in JavaScript as a mistake.
Fabien Cadet

Programming languages usage ::TIOBE Index - 9 views

www.tiobe.com/...index.html

programming language statistics ranking

shared by Fabien Cadet on 05 Dec 09 - Cached
  • yc c on 05 Dec 09
     
    The TIOBE Programming Community index gives an indication of the popularity of programming languages. The index is updated once a month. The ratings are based on the number of skilled engineers world-wide, courses and third party vendors. The popular search engines Google, MSN, Yahoo!, Wikipedia and YouTube are used to calculate the ratings. Observe that the TIOBE index is not about the best programming language or the language in which most lines of code have been written. The index can be used to check whether your programming skills are still up to date or to make a strategic decision about what programming language should be adopted when starting to build a new software system.
cerdigoo

pagina web - 0 views

es.wikipedia.org/...P%C3%A1gina_web

Que es una pagina web

shared by cerdigoo on 03 Sep 14 - No Cached
  • cerdigoo on 03 Sep 14
     
    Una página web o página electrónica, es un documento o información electrónica capaz de contener texto, sonido, vídeo, programas, enlaces, imágenes, y muchas otras cosas, adaptada para la llamada World Wide Web, y que puede ser accedida mediante un navegador.
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