If you have used nginx, you may know that nginx supports hot update, which means you can update your nginx without stopping and restarting it. It serves old connections with old version, and accepts new connections with new version. Notice that hot compiling is different from hot update, where hot compiling is monitoring your source files and recompile them when the content changes, it requires stop and restart your applications, `bee start` is a tool for hot compiling.
##Is hot update necessary?
## Is hot update necessary?
Some people says that hot update is not as useful as its cool name. In my opinion, this is absolutely necessary because zero-down server is our goal for our services. Even though sometimes some errors or hardware problems may occur, but it belongs to design of high availability, don't mix them up. Service update is a known issue, so we need to fix this problem.
##How Beego support hot update?
## How Beego support hot update?
The basic principle of hot update: main process fork a process, and child process execute corresponding programs. So what happens? We know that after forked a process, main process will have all handles, data and stack, etc, but all handles are saved in `CloseOnExec`, so all copied handles will be closed when you execute it unless you clarify this, and we need child process to reuse the handle of `net.Listener`. Once a process calls exec functions, it is "dead", system replaces it with new code. The only thing it left is the process ID, which is the same number but it is a new program after executed.
Therefore, the first thing we need to do is that let child process fork main process and through `os.StartProcess` to append files that contains handle that is going to be inherited.
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Above are three problems that we need to solve, you can see my code logic for specific implementation.
##Show time
## Show time
1. Write code in your Get method:
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One execute: ` ps -ef|grep <application name>`
Another one execute：`curl "http://127.0.0.1:8080/?sleep=20"`
Another one execute：`curl "http://127.0.0.1:8080/?sleep=20"`
Beego is a simple web framework, but it uses many third-party packages, so you have to install all dependency packages also.
- Before anything you do, you have to check that you installed Go in your computer, see more detail about Go installation in my book: [Chapter 1](https://github.com/Unknwon/build-web-application-with-golang_EN/blob/master/eBook/01.1.md)
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Beego is a lightweight, open source, non-blocking and scalable web framework for the Go programming language. It's like tornado in Python. This web framework has already been using for building web server and tools in SNDA's CDN system. Documentation and downloads available at [http://astaxie.github.com/beego](http://astaxie.github.com/beego)
It has following main features:
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Beego is licensed under the Apache Licence, Version 2.0
People may ask me why I want to build a new web framework rather than use other good ones. I know there are many excellent web frameworks on the internet and almost all of them are open source, and I have my reasons to do this.
Remember when I was writing the book about how to build web applications with Go, I just wanted to tell people what were my valuable experiences with Go in web development, especially I have been working with PHP and Python for almost ten years. At first, I didn't realize that a small web framework can give great help to web developers when they are learning to build web applications in a new programming language, and it also helps people more by studying its source code. Finally, I decided to write a open source web framework called Beego as supporting materiel for my book.
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2. Learn more about languages by studying their source code, it's not hard to read and understand them because they are both lightweight frameworks.
3. It's quite easy to make secondary development of these frameworks for specific purposes.
Those reasons are my original intention of implementing Beego, and used two chapters in my book to introduce and design this lightweight web framework in GO.
Those reasons are my original intention of implementing Beego, and used two chapters in my book to introduce and design this lightweight web framework in Go.
Then I started to design logic execution of Beego. Because Go and Python have somewhat similar, I referenced some ideas from tornado to design Beego. As you can see, there is no different between Beego and tornado in RESTful processing; they both use GET, POST or some other methods to implement RESTful. I took some ideas from [https://github.com/drone/routes](https://github.com/drone/routes) at the beginning of designing routes. It uses regular expression in route rules processing, which is an excellent idea that to make up for the default Mux router function in Go. However, I have to design my own interface in order to implement RESTful and use inherited ideas in Python.
