Markdown Syntax

Overview Nearly all Markdown applications support the basic syntax outlined in John Gruber’s original design document. There are minor variations and discrepancies between Markdown processors, those are noted inline wherever possible. Headings To create a heading, add number signs (#) in front of a word or phrase. The number of number signs you use should… Continue reading Markdown Syntax

YAML Syntax

Introduction YAML is used for configuration files, blueprints, and also in page settings. YAML is to configuration what markdown is to markup. It’s basically a human-readable structured data format. It is less complex and ungainly than XML or JSON, but provides similar capabilities. It essentially allows you to provide powerful configuration settings, without having to… Continue reading YAML Syntax

ProviewR – An open source process control

可能是市场上唯一能够以真正的面向对象方式设计和编程的开源过程控制系统。Powered By SSAB. General ProviewR is an Open Source Process Control System. It is modern, powerful and general and contains all functions normally required for successful sequential control, adjustment, data acquisition, communication, supervision, etc. The configuration of a ProviewR system is done graphically, making the application adaptation simple, reliable, and flexible. ProviewR is a distributed… Continue reading ProviewR – An open source process control

老生常谈,TCP三次握手、四次挥手过程及原理

本文来自于互联网,原始出处已无法考证 TCP 协议简述 TCP 提供面向有连接的通信传输,面向有连接是指在传送数据之前必须先建立连接,数据传送完成后要释放连接。 无论哪一方向另一方发送数据之前,都必须先在双方之间建立一条连接。在TCP/IP协议中,TCP协议提供可靠的连接服务,连接是通过三次握手进行初始化的。 同时由于TCP协议是一种面向连接的、可靠的、基于字节流的运输层通信协议,TCP是全双工模式,所以需要四次挥手关闭连接。 TCP包首部 网络中传输的数据包由两部分组成:一部分是协议所要用到的首部,另一部分是上一层传过来的数据。首部的结构由协议的具体规范详细定义。在数据包的首部,明确标明了协议应该如何读取数据。反过来说,看到首部,也就能够了解该协议必要的信息以及所要处理的数据。包首部就像协议的脸。 所以我们在学习TCP协议之前,首先要知道TCP在网络传输中处于哪个位置,以及它的协议的规范,下面我们就看看TCP首部的网络传输起到的作用: 下面的图是TCP头部的规范定义,它定义了TCP协议如何读取和解析数据: TCP首部承载这TCP协议需要的各项信息,下面我们来分析一下: