Today is the first seven for Mr. Hawking. In memory of the martyrs, oh, No, is a pioneer. Oh well, maybe~!
Let's start with a paragraph on the Internet to popularize the old man Hawking who decorated the wall and the old man Yang who hit the elevator:
Physics is like this. Archimedes dug a cave where people could live. Galileo thought the cave was too primitive, so he dug a hole and wanted to build a house. Newton, the foreman, brought Kepler, Hooke, Descartes and a group of younger brothers to lay the foundation. A few hundred years later, a group of physicists, including Faraday, built a house that looked beautiful and perfect. Then Kelvin said that the house was finished, everyone should go to live, it was perfect, the physicist had nothing to do, but why was the sky so cloudy, and there were two dark clouds on the head? As a result, the creator of the dark cloud, Maxwell, struck two lightning bolts and the house collapsed. Maxwell said, Can Ganima's house have a long-term vision? "Actually, the dark clouds were not created by Maxwell, but Maxwell's equations predict that the speed of light will remain constant. As the fourth-year-old in physics, he must be given a domineering job, which is to demolish the house." So Einstein, the contractor, appeared, and he led the Lorenz and other younger brothers built a floor of "special relativity", and later his younger brother didn't use it, so he built an entire building by himself! This building was built but not renovated. The scientists behind, Schwarzschild, Hawking, were all decorated on the Einstein building. Hawking probably installed a wall. Contemporaries of Einstein, Planck, Bohr, Heisenberg and others, oh, and Einstein, they built another building, which is quantum mechanics, and these people built it together, without a contractor , This building seems to be more powerful now, and Yang Zhenning, built an elevator shaft in this building, and used a standard model to run through this building. Therefore, Yang Zhenning and Hawking can judge who is higher and who is lower. One has renovated the wall and the other has built the elevator shaft. As for Einstein who built the building and Newton who built the foundation, forget about it.
The paragraph is a bit long, take it slow~! hehe~! (My manuscript fee is coming again~!)
The beauty editor has been saying that Hapizhuang's writing level continues to decline. I often go to the Internet to find some so-called jokes, and make up the number of words to earn manuscript fees. Indeed, I have been a little shameless recently at Happy Zhuang. Haha~!
Closer to home, Mr. Hawking's wall decoration skills are still good, and our CDN sometimes needs to decorate the facade. As for Mr. Yang's advanced skills in taking elevators, our CDN also has them. Hahaha~! People walk in the rivers and lakes, how can there be no kitchen knife~!
On the day of 315 rights protection, we mentioned third-party performance testing. OK. Let me ask you a question first, a rough room, a room that has been renovated according to your expectations, which one do you choose to live in? The answer is obvious! For those of you who deliberately choose a rough house, there is one movie for you, One Flew Over the Cuckoo's Nest. Before the third-party test, we will do CDN decoration, that is, preheating the tested customer website files in advance. At this time, someone will jump out and raise their arms and shout, MD, you CDNs are cheating and cheating! Shameless Shameless Shameless! Here, only Hapizhuang shamelessly cheated and wrote down the same Chinese vocabulary three times in a row to make up the number of words for the manuscript. But CDN did not cheat, because CDN is the correct posture to test CDN edge distribution when the content has been cached. Then some people will say that the content should be brought back from the source site, and end-to-end testing is the correct way to open it. OK, here are two scenarios.
First of all, the static content itself should be tested for the service quality after caching. The unlucky person is only the person who drinks the soup first, that is, when the first user comes to request the content, the CDN temporarily misses when he requests the content. The content is retrieved from the source, and subsequent user visits are cached content. Customers should pay attention to the quality of this service. After all, there are many subsequent service users, which is the focus of attention.
Second, dynamic back-to-origin means that CDNs are not cached at the edge and must be back-to-origin every time. This is the time to test the quality of the CDN back-to-source service. It's time for Mr. Yang's kitchen knife to hit the elevator. CDN back-to-source is an advanced technology activity. Many CDN static services are of good quality, but dynamic back-to-source is so-so. Of course, sometimes, the CDN system cannot be completely relied on, because the customer origin system itself is also related to the quality of its own access network and the quality of the system's own service. For example, dynamic back-to-source generally queries from the origin database and returns the content. If the source database itself is not optimized in place, the query speed is slow, and the CDN cannot be faster. Aside from the source site factor, the network between the CDN and the origin site should be a factor that must be considered. A good CDN service provider will introduce a kitchen knife, which is the parent-level back-to-source optimization mechanism.
To put it simply, a CDN will have multiple parent-level servers, and within a period of time, they will dial to measure the network quality of the back-to-origin servers, and choose one or several parent-level servers with good back-to-origin quality as back-to-origin servers. Other CDN edges use this optimal back-to-origin server as the parent layer for dynamic back-to-origin. The advantage of doing this is to dynamically adjust the high-quality back-to-source link to ensure the quality of back-to-source services as much as possible. What do you think of this high-end kitchen knife~! It's a bit like SDN~! So fresh and mellow~!
Pictures from the Internet