scada protocols

The difference between get and post requests. 1, when the browser fallback and refresh, get harmless, but post will resubmit the data 2, get can be bookmarked, and post can not 3, get can be cached by the browser, and post can not 4. The encoding type of the GET request is application/x-www-form-urlencoded The encoding type of the POST request can be application/x-www-form-urlencoded and multipart/form-data 5, get parameters for the existence of browsing history, and post does not 6, get the url

transaction to be modified at all.Two-stage lock protocolThe database follows the "two-segment lock" protocol when scheduling concurrent transactions, which means that all transactions must lock and unlock data items in two stages Extended stage: Before you read or write any data item, apply and obtain a blockade of the data item. Shrink stage: In each transaction, all blocking requests must precede the unlock request. Mathematically, it can be proved that the scheduling with

Senior engineers teach you how to select Open Source protocols Practice open source Now open source is more than just a spirit, and many domestic and foreign companies have actually practiced it. Including FEX, more than 20 open-source products are supported by many front-end developers. The number of stars on GitHub is close to 3000. Therefore, we naturally face the issue of choosing open source protocols

Reprint Address: http://blog.jobbole.com/84429/TCP HTTP UDP:is the communication protocol, that is, the rules of communication, only the two parties in accordance with this rule "speak", the other party can understand or serve.The relationship between TCP HTTP UDP three:TCP/IP is a protocol group, which can be divided into four levels: network interface layer, network layer, Transport layer and application layer.At the network layer are IP protocols,

This article Reprinted from: http://www.ruanyifeng.com/blog/2012/05/internet_protocol_suite_part_ I .html We use the Internet every day. Have you ever wondered how it is implemented? Billions of computers around the world are connected together and communicate with each other. One Network Card in Shanghai sends a signal, and the other network card in Los Angeles actually receives the signal. The two actually do not know the physical location of the other. Do you think this is amazing? The core

Network protocols are the basis for the development of the Internet. If we want to control the network well, we must have a clear understanding of network protocols. Here we will explain some elements of the network protocol. A network protocol includes at least three elements: The syntax is used to specify the information format. The format, encoding, and electrical equality of data and control information

The OSI seven-layer model is a standard system and framework for interconnection between different computers or communication systems, including a range of standards and protocols in OSI, such as TCP/IP, UDP, HTTP, and so on, which provide implementation and support for these protocols in Node.js, such as: NET modules provide TCP, Socket encapsulation and support, the Dgram module provides a package and sup

LAN protocol is the most important part of our LAN. With the coexistence of LAN and Internet. These protocols have also been affected by the deepening of Internet protocols. Computer network applications have been applied in almost all fields of human activity. The core of all network applications is network protocols. Network protocol is a supporting software an

More and more developers and designers want to open-source their products so that others can do more on the basis of their code. The open-source community is also full of vigor. Open-source software exists in all the application fields we can think of (open-source CMS such as WordPress and Drupal ). However, many people do not know about open-source licenses. This article describes several license protocols commonly used in the open-source field and t

Route information protocol (RIP) The routing information protocol was originally designed for Xerox PUPPARC universal protocol. In 1981, the Xerox network system protocol was collectively referred to as "GWINFO" and defined as RFC 1988 in 1058 ". The routing information protocol is easy to configure and works very well in small networks. However, in large networks, the routing information protocol is inefficient. As I said to myself, the routing information protocol will split your network. In a

similar to the concept of the network information table in Digital Video broadcast Digital Video Broadcasting, DVB. RSVP uses this request to access each node of the network through the network. On each node, RSVP tries to reserve resources for the stream. This makes it possible to provide images with quality of service and other real-time services. What is an IPv6 network protocol conversion mechanism? Why is a conversion mechanism required? IPv6 cannot replace IPv4 immediately. Therefore, IPv

Redundancy is common point for today's topologies. Especially in mission-critical networks The It is isn't acceptable that using only one gateway to reach a point. Because One gateway means single point of failure.With multiple gateways, you can still reach the remote node even if that's connect fails. As soon as one of the gateway down, the link changes through and other gateway. Here with the word gateway. I mean the router that router so you use to reach a point, or with redundancy, multiply

The previous article mentions the use of the Windows Store protocol, in fact the Windows Store protocol is only a protocol rule built into the system. We can also define a set of specifications of the Uri-scheme, in addition to other applications can be called, the application can also be called, to solve some special scenes, this talk about the specific discussion of this issue.For the resolution and use of the Windows Store protocol, you can read the previous article: http://www.cnblogs.com/zh

At present, dynamic routing protocols are widely used. So I have studied the comprehensive comparison between the two commonly used dynamic routing protocols. Here I will share with you, hoping to help you. The earlier IGRP protocol was invented by Cisco and is a dynamic routing protocol based on the distance vector algorithm. The Enhanced Interior Gateway Routing Protocol is an Enhanced version of the IGRP

This article mainly introduces to you about the PHP Support Protocol and encapsulation Protocol related Materials, the text through the sample code introduced in very detailed, for everyone to learn or use PHP has a certain reference learning value, the need for friends below with the small series to learn together. Objective Today's Web program development technology is really a contention, ASP, PHP, Jsp,perl, AJAX and so on. Regardless of how web technologies evolve in the future, it is impor

Many of my friends are confused about the routing protocol. Here we will introduce all the routing protocols in detail. Let's take a look at the definition and classification of the routing protocol. A route consists of a static route table and a dynamic route table. The corresponding route table is called a static route table and a dynamic route table. The static route table is preset by the network administrator according to the network configuratio

network topology changes. Dynamic Routing is suitable for networks with large networks and complex network topologies. Of course, various dynamic routing protocols occupy network bandwidth and CPU resources to varying degrees. Static Routing and dynamic routing have their own characteristics and applicability. Therefore, dynamic routing is usually used as a supplement to Static Routing in the network. When a group is used to find the route in the vro

) 2014 Kenshin Cui. All rights reserved.//#import "Person.h" @implementation person-(void) eat{ NSLog (@ "eating ...");} @endHere are a few things to note: One protocol can be extended from another protocol, such as the above animaldelegate extension from NSObject, if you need to extend the middle of multiple protocols using commas separated; Unlike other high-level languages, the methods defined in the Protocol are not necessarily ne

A network protocol is a collection of rules, standards, or conventions that are established for data exchange in a computer network. It specifies the format in which information must be used in communication and the meaning of these formats. Most networks have a layered architecture, each layered on top of it, providing some service to its upper layer, and masking the details of how to implement the service. The rule that the nth layer on one device communicates with the nth layer on another dev

A network protocol is a collection of standards, rules, and norms that a computer uses to Exchange data over a network. Common protocols are TCP protocol, IP Protocol, UDP protocol, ICMP protocol. These are all transport protocols, as well as application layer protocols such as HTTP protocol, FTP protocol, etc. This application layer protocol is meant to tell oth