Jusene's Blog

从wsgi起构建web框架(一)

python
字数统计: 1k阅读时长: 5 min
2018/07/08 Share

WSGI(Web Server Gateway Interface)，简单来说就是Python Web服务网关接口，是实现Python Web服务的统一接口，如Flask, Django都是基于该接口实现的框架，从wsgi出发一步步了解框架的构建过程。

首先,Python原生为我们提供了wsgi的实现,WSGI的实现非常简单:

1
def application(environ, start_response):
2
    start_response('200 OK',[("Content-type","text/plain")])
3
    return ["hello world".encode()]
  • environ: 一个包含本地环境变量和http请求的dict对象
  • start_response: 一个发送http响应的函数

简单的echo服务

1
from wsgiref.simple_server import make_server
2
3
def application(environ, start_response):
4
    start_response('200 OK',[("Content-type","text/plain")])
5
    return ["hello world".encode()]
6
7
if __name__ == "__main__":
8
    server = make_server('0.0.0.0',8000,application)
9
    try:
10
        server.serve_forever()
11
    except KeyboardInterrupt:
12
        server.shutdown()

params解析

  • GET请求
1
from wsgiref.simple_server import make_server
2
from urllib.parse import parse_qs
3
4
def application(environ, start_response):
5
    params = parse_qs(environ["QUERY_STRING"]) # 针对GET请求的请求参数解析
6
    name = params.get('name', ['anonymous'])[0]
7
    start_response('200 OK',[("Content-type","text/plain")])
8
    return ["hello {}".format(name).encode()]
9
10
if __name__ == "__main__":
11
    server = make_server('0.0.0.0',8000,application)
12
    try:
13
        server.serve_forever()
14
    except KeyboardInterrupt:
15
        server.shutdown()
  • POST请求
1
from wsgiref.simple_server import make_server
2
from urllib.parse import parse_qs
3
4
def application(environ, start_response):
5
    request_body = environ.get('wsgi.input').read(int(environ.get('CONTENT_LENGTH',0)))
6
    params = parse_qs(request_body)
7
    name = params.get(b'name', ['anonymous'])[0]
8
    start_response('200 OK',[("Content-type","text/plain")])
9
    return ["hello {}".format(name.decode()).encode()]
10
11
if __name__ == "__main__":
12
    server = make_server('0.0.0.0',8000,application)
13
    try:
14
        server.serve_forever()
15
    except KeyboardInterrupt:
16
        server.shutdown()

使用webob对象化wsgi的environ

1
from wsgiref.simple_server import make_server
2
import webob
3
4
def application(environ, start_response):
5
    request = webob.Request(environ)
6
    name = request.params.get("name","anoymous")
7
    response = webob.Response()
8
    response.text = u'hello {}'.format(name)
9
    response.status_code = 200
10
    response.content_type = 'text/plain'
11
    return response(environ, start_response)
12
13
if __name__ == "__main__":
14
    server = make_server('0.0.0.0',8000,application)
15
    try:
16
        server.serve_forever()
17
    except KeyboardInterrupt:
18
        server.shutdown()
  • 装饰器优化
1
from wsgiref.simple_server import make_server
2
import webob
3
from webob.dec import wsgify
4
5
@wsgify
6
def application(request: webob.Request) -> webob.Response:    
7
    name = request.params.get("name","anoymous")
8
    response = webob.Response()
9
    response.text = u'hello {}'.format(name)
10
    response.status_code = 200
11
    response.content_type = 'text/plain'
12
    return response
13
    
14
if __name__ == "__main__":
15
    server = make_server('0.0.0.0',8000,application)
16
    try:
17
        server.serve_forever()
18
    except KeyboardInterrupt:
19
        server.shutdown()
  • 自己实现wsgify
1
from webob import Request
2
from functools  import wraps
3
4
def Wsgify(fn):
5
    @wraps(fn)
6
    def wrap(environ, start_response):
7
        request = Request(environ)
8
        response = fn(request)
9
        return response(environ, start_response)
10
    return wrap
11
``` 
12
13
### 路由
14
15
一个web框架最重要的一部分是路由，所以学习框架的时候，只需要清楚如何路由基本都可以上手
16
17
- 静态路由
18
19
```python
20
from wsgiref.simple_server import make_server
21
import webob
22
from webob.dec import wsgify
23
24
def hello(request: webob.Request) -> webob.Response:
25
    name = request.params.get('name', 'anonymous')
26
    response = webob.Response()
27
    response.text = u'hello {}'.format(name)
28
    response.status_code = 200
29
    response.content_type = 'text/plain'
30
    return response
31
32
def index(request: webob.Request) -> webob.Response:
33
    return webob.Response(body='hello world', content_type='text/plain')
34
35
router = {
36
    '/hello': hello,
37
    '/': index}
38
39
@wsgify
40
def application(request: webob.Request) -> webob.Response:
41
    return router.get(request.path,index)(request)
42
43
if __name__ == "__main__":
44
    server = make_server('0.0.0.0',8000,application)
45
    try:
46
        server.serve_forever()
47
    except KeyboardInterrupt:
48
        server.shutdown()

动态路由

1
from wsgiref.simple_server import make_server
2
import webob
3
from webob.dec import wsgify
4
5
def hello(request: webob.Request) -> webob.Response:
6
    name = request.params.get('name', 'anonymous')
7
    response = webob.Response()
8
    response.text = u'hello {}'.format(name)
9
    response.status_code = 200
10
    response.content_type = 'text/plain'
11
    return response
12
13
def index(request: webob.Request) -> webob.Response:
14
    return webob.Response(body='hello world', content_type='text/plain')
15
16
class Application:
17
    ROUTER = {}
18
19
    @classmethod
20
    def register(cls, path, view):
21
        cls.ROUTER[path] = view    
22
23
    def default_view(self, request: webob.Request) -> webob.Response:
24
        # return webob.Response(bosy='Not Found', status=404)
25
        raise webob.exc.HTTPNotFound()
26
27
    @wsgify    
28
    def __call__(self, request: webob.Request) -> webob.Response:
29
        return self.ROUTER.get(request.path, self.default_view)(request)
30
31
if __name__ == "__main__":
32
    Application.register('/hello', hello)
33
    Application.register('/', index)
34
    server = make_server('0.0.0.0',8000,Application())
35
    try:
36
        server.serve_forever()
37
    except KeyboardInterrupt:
38
        server.shutdown()
  • 封装成装饰器
1
from wsgiref.simple_server import make_server
2
import webob
3
from webob.dec import wsgify
4
class Application:
5
    ROUTER = {}
6
    @classmethod
7
    def register(cls, path):
8
        def wrap(view)
9
            cls.ROUTER[path] = view            
10
            return view        
11
        return wrap    
12
        
13
    def default_view(self, request: webob.Request) -> webob.Response:
14
        # return webob.Response(bosy='Not Found', status=404)
15
        raise webob.exc.HTTPNotFound()
16
17
    @wsgify    
18
    def __call__(self, request: webob.Request) -> webob.Response:
19
        return self.ROUTER.get(request.path, self.default_view)(request)
20
21
@Application.register('/hello')
22
def hello(request: webob.Request) -> webob.Response:
23
    name = request.params.get('name', 'anonymous')
24
    response = webob.Response()
25
    response.text = u'hello {}'.format(name)
26
    response.status_code = 200
27
    response.content_type = 'text/plain'
28
    return response
29
30
@Application.register('/')
31
def index(request: webob.Request) -> webob.Response:
32
    return webob.Response(body='hello world', content_type='text/plain')
33
34
if __name__ == "__main__":
35
    server = make_server('0.0.0.0',8000,Application())
36
    try:
37
        server.serve_forever()
38
    except KeyboardInterrupt:
39
        server.shutdown()

原文作者：Zhang Jusene

原文链接：http://jusene.github.io/2018/07/08/wsgi/

发表日期：July 8th 2018, 11:08:49 pm

更新日期：November 30th 2019, 1:54:24 am

版权声明：本文采用知识共享署名-非商业性使用 4.0 国际许可协议进行许可

CATALOG
  1. 1. 简单的echo服务
  2. 2. params解析
  3. 3. 使用webob对象化wsgi的environ
  4. 4. 动态路由
Total : 190
2020
2019
2018
2017
python boot troubshooting docker drbd ssh web ELK kubernetes Kubernetes git ansible tools dns corosync consul Django etcd security ftp Go bash bigdata grub heartbeat Java kickstart kvm lvs mongodb mysql mesh nc nfs mogilefs openresty upgrade puppet rabbitmq saltstack rsync screen socat svn tcpdump fastdfs haproxy iscsi keepalived cache openssl vpn optimization prometheus redis RPM cncf supervisord kernel JAVA
python Linux troubshooting Docker docker storage nginx Nosql kubernetes Flask Kubernetes ansible Shell cluster Django Go bigdata boot Java hypervisor mysql mesh tools openresty puppet rabbitmq saltstack optimization cncf varnish tomcat JAVA