# 请求流程

## 1 Application 入口

![image](https://github.com/meetbill/butterfly/blob/master/images/wsgi_flow.png?raw=true)

wsgigw = httpgateway.WSGIGateway(httpgateway.get\_func\_name,logger.errlog,logger.acclog,apicube)

```
status, headders, content = wsgigw.process(environ)
start_response(status, headders)
return content
```

其中

> * httpgateway.get\_func\_name : 根据 environ\['PATH\_INFO'] 找到对应的 url
> * logger.errlog : 错误日志文件
> * logger.acclog : 访问日志文件
> * apicube : protocols 字典，key 为 func name，value 为 Protocol 实例

wsgigw\.process 主要就是做三件事

```
 1) 封装 request
 2) 路由查询
 3) 将请求 request 发到对应的 protocol 实例（对 handler 进行的封装）
```

> * 对 wsgienv 进行封装为 req
>   * req = Request(reqid, wsgienv, ip) : req 对 wsgienv 进行封装，此 req 会以参数传入后端 handler 函数中
> * 路由查询
> * 将 req 传给对 api 封装后的 protocol 实例
>   * protocol = `self._protocols.get(funcname)`
>   * httpstatus, headers, content = protocol(req)
>   * protocol 实例是对 handler 函数进行的包装，进行统一日志管理以及参数校验等操作

```
         +---------------------------------------------------------+
         |                       WEB brower                        |
         +---------------------------------------------------------+
             |                           ^       ^          ^
             |                           |       |          |
             |HTTP request               |       |          |
             |                           |       |          |
      -- +---V-----------------------------------------------------+
    /    |                       HTTPServer                        |  WSGI server
    |    |     +-------------------+ put +-------------------+     |
    |    |     |ThreadPool(Queue) <+-----+ HTTPConnection    |     |
    |    |     |+---------------+  |     | +---------------+ |     |
    |    |     ||WorkerThread   |  |     | |HTTPRequest    | |     |
    |    |     |+---------------+  |     | +---------------+ |     |
    |    |     +-------------------+     +-------------------+     |
    |    +---------------------------------------------------------+
    |          /------------\            ^       ^          ^
    |         |   environ    |           |       |          |
    |          \------------/            |       |          |
    |   .............|...................|.......|..........|.........WSGI
    |                |                   |       |          |
    |         +------V-------+           |       |          |
    |         |      req     |           |       |          |
    |         +--------------+           |       |          |
Butterfly            |                   |       |          |
    |         +------V-------+           |       |          |
    |         |apiname_getter|           |       |          |
    |         +--------------+           |       |          |
    |                |                   |       |          |
    |       +--------V--------+ False +--+--+    |          |
    |       |is_protocol_exist|------>| 400 |    |          |
    |       +-----------------+       +-----+    |          |
    |                |                           |          |
    |                | (protocol_process)        |          |
    |                V                           |          |
    |       +-----------------+                  |          |
    |       | protocol        |  Exception    +-----+       |
    |       | +-------------+ |---------------| 500 |       |
    |       | |/app1/handler| |               +-----+       |
    |       | |/app2/handler| |               +----------------------------+
    |       | +-------------+ |---------------|httpstatus, headers, content|
    \       +-----------------+               +----------------------------+
     ---
```


---

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