(四)Openstack学习之WSGI:自己动手写例子
(四)Openstack学习之WSGI:自己动手写例子
WSGI 是Web Services Gateway Interface的缩写. 如果想深入了解,可以阅读 PEP 333 文档,包含有任何你想要的:)community errata, .这篇文章将手把手教你写一个简单的WSGI例子。
注意:我用的Python版本是.2.7.x.
最经典,最简答的WSGI样当属 Hello World app.
咱们将要用到 virtualenv 去创建一个封闭的Python项目环境:
$
virtualenv wsgi-example
$
cd wsgi-example
$
source bin/activate
|
然后在该目录下新建一个文件: wsgi_app.py 并且添加如下的代码 :
from
__future__ import
print_function
from
wsgiref.simple_server import
make_server
def
myapp(environ, start_response):
response_headers
=
[( 'content-type' ,
'text/plain' )]
start_response( '200
OK' ,
response_headers)
return
[ 'Hello
World' ]
app
=
myapp
httpd
=
make_server('', 8080 ,
app)
print ( "Starting
the server on port 8080" )
httpd.serve_forever()
|
把项目跑起来:
$
python wsgi_app.py
|
之后就可以测试啦,测试有浏览器或者命令cURL两种方式,返回的应该是hello world 哦:
$
curl http://localhost:8080 -v
|
上面这个例子虽然清晰,但是一点都不爽啊so easy。let's high 起来。接下来我们继续往里面赛一条消息 。
修改 wsgi_app.py 文件成下面这个样纸:
from
__future__ import
print_function
from
wsgiref.simple_server import
make_server
from
urlparse import
parse_qs
def
myapp(environ, start_response):
msg
=
'No Message!'
response_headers
=
[( 'content-type' ,
'text/plain' )]
start_response( '200
OK' ,
response_headers)
qs_params
=
parse_qs(environ.get( 'QUERY_STRING' ))
if
'msg'
in
qs_params:
msg
=
qs_params.get( 'msg' )[ 0 ]
return
[ 'Your
message was: {}' . format (msg)]
app
=
myapp
httpd
=
make_server('', 8080 ,
app)
print ( "Starting
the server on port 8080" )
httpd.serve_forever()
|
把程序跑起来,测试还是刚才那样。如果程序还在运行中,可以CTRL+C快捷键暂停并且重启。
$
curl http://localhost:8080/?msg=Hello -v
|
接下来,让我们继续聊中间件。你可以在这里 获得一些信息。这里我会写一个添加了HTTP 头回复的中间层例子。中间件可以做任何你能够想象的到的事情,例如session,认证等等。
中间件例子:
from
__future__ import
print_function
from
wsgiref.simple_server import
make_server
def
myapp(environ, start_response):
response_headers
=
[( 'content-type' ,
'text/plain' )]
start_response( '200
OK' ,
response_headers)
return
[ 'Check
the headers!' ]
class
Middleware:
def
__init__( self ,
app):
self .wrapped_app
=
app
def
__call__( self ,
environ, start_response):
def
custom_start_response(status, headers, exc_info = None ):
headers.append(( 'X-A-SIMPLE-TOKEN' ,
"1234567890" ))
return
start_response(status, headers, exc_info)
return
self .wrapped_app(environ,
custom_start_response)
app
=
Middleware(myapp)
httpd
=
make_server('', 8080 ,
app)
print ( "Starting
the server on port 8080" )
httpd.serve_forever()
|
访问终端:
$
curl http://localhost:8080/ -v
|
结果差不多应该是介个样子的:
*
Connected to localhost (127.0.0.1) port 8080 (#0)
>
GET / HTTP/1.1
>
User-Agent: curl/7.30.0
>
Host: localhost:8080
>
Accept: */*
>
*
HTTP 1.0, assume close after body
<
HTTP/1.0 200 OK
<
Date: Sat, 08 Feb 2014 00:16:00 GMT
<
Server: WSGIServer/0.1 Python/2.7.5
<
content-type: text/plain
<
X-A-SIMPLE-TOKEN: 1234567890
<
Content-Length: 18
<
*
Closing connection 0
|
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