Lightweight HTTP Server Nginx: module and Working principle

Wind Network (ithov.com) original article: Nginx by the kernel and modules, in which the design of the kernel is very small and concise, the completion of the work is very simple, only through the lookup configuration file to map client requests to a location Block (location is an instruction in the Nginx configuration for URL matching), and each instruction configured in this location will start a different module to do the work accordingly.

The Nginx modules are divided into core modules, basic modules and Third-party modules, HTTP modules, event modules and mail modules are core modules, HTTP access modules, HTTP fastcgi modules, HTTP proxy modules, and HTTP The rewrite module belongs to the base module, while the HTTP upstream Request hash module, notice module, and HTTP Access key module are third-party modules, and the modules that users develop according to their needs belong to third party modules. It is with so many modules of support, Nginx function will be so powerful.

&http://www.aliyun.com/zixun/aggregation/37954.html ">NBSP; The Nginx modules are divided into three functional categories.

Port handlers (processor module). Such modules directly handle requests, and output content and modify headers information operations. Handlers processor modules generally can only have one.
Port filters (filter module). This kind of module mainly to the other processor module output meat volume modification operation, finally by Nginx output.
Port proxies (proxy class module). Such modules are nginx HTTP upstream modules, which interact with some of the backend services such as fastcgi, to achieve Service Broker and load balancing functions.

Figure I-i shows the process of Nginx module general HTTP requests and responses.

Figure 1-1 HTTP request and response process for Nginx modules

In the way of work, Nginx is divided into two modes: single work process and multiple worker process. In single worker process mode, there is a worker process in addition to the main process, the worker process is single-threaded, and in multiple worker process mode, each worker process contains multiple threads. Nginx default to single worker process mode.

Nginx modules are compiled directly into the Nginx and therefore belong to the static compilation method. After starting the Nginx, the Nginx module is automatically loaded, unlike Apache, which first compiles the module to a so file and then specifies whether to load it in the configuration file. When parsing a configuration file, each module of Nginx is likely to process a request, but the same processing request can only be completed by one module.