Python Paste.deploy 笔记

首先python paste是一个WSGI工具包,在WSGI的基础上包装了几层,让应用管理和实现变得方便。说实话,Python Paste的文档做的真差劲!加之python代码可读性本来就不怎么滴,真费劲。

 

paste.deploy关键部分留个抓印:

1)python paste.deploy不能只装个paste.deploy包就可以工作了,还需要paste.script包

2)python paste.deploy中loadapp给的路径可用os.path.abspath(配置文件相对路径)得到配置文件的绝对路径,否则报找不到relative_to path...没搞明白怎么回事,目前不重要,放过。

3)python paste.deploy中filter,filter_factory,app,app_factory的规范在文档中都没怎么写清楚,我来给你补上吧:

- app是一个callable object,接受的参数(environ,start_response),这是paste系统交给application的,符合

WSGI规范的参数. app需要完成的任务是响应envrion中的请求,准备好响应头和消息体,然后交给start_response处理,并返回响应消息体。

- filter是一个callable object,其唯一参数是(app),这是WSGI的application对象,见(1),filter需要完成的工作是将application包 装成另一个application(“过滤”),并返回这个包装后的application。

- app_factory是一个callable object,其接受的参数是一些关于application的配置信息:(global_conf,**kwargs),global_conf是在 ini文件中default section中定义的一系列key-value对,而**kwargs,即一些本地配置,是在ini文件中,app:xxx section中定义的一 系列key-value对。app_factory返回值是一个application对象

- filter_factory是一个callable object,其接受的参数是一系列关于filter的配置信息:(global_conf,**kwargs),global_conf是在ini文件 中default section中定义的一系列key-value对,而**kwargs,即一些本地配置,是在ini文件中,filter:xxx section中定 义的一系列key-value对。filter_factory返回一个filter对象

 

给个例子:

pastedeploylab.ini:

 1     [DEFAULT]  
 2     key1=value1  
 3     key2=value2  
 4     key3=values  
 5     [composite:pdl]  
 6     use=egg:Paste#urlmap  
 7     /:root  
 8     /calc:calc  
 9     [pipeline:root]  
10     pipeline = logrequest showversion  
11     [pipeline:calc]  
12     pipeline = logrequest calculator  
13     [filter:logrequest]  
14     username = root  
15     password = root123  
16     paste.filter_factory = pastedeploylab:LogFilter.factory  
17     [app:showversion]  
18     version = 1.0.0  
19     paste.app_factory = pastedeploylab:ShowVersion.factory  
20     [app:calculator]  
21     description = This is an "+-*/" Calculator   
22     paste.app_factory = pastedeploylab:Calculator.factory 

 

pastedeploylab.py

 1 Created on 2011-6-12 
 2 @author: Sonic 
 3 ‘‘‘  
 4 import os  
 5 import webob  
 6 from webob import Request  
 7 from webob import Response  
 8 from paste.deploy import loadapp  
 9 from wsgiref.simple_server import make_server  
10 #Filter  
11 class LogFilter():  
12     def __init__(self,app):  
13         self.app = app  
14         pass  
15     def __call__(self,environ,start_response):  
16         print "filter:LogFilter is called."  
17         return self.app(environ,start_response)  
18     @classmethod  
19     def factory(cls, global_conf, **kwargs):  
20         print "in LogFilter.factory", global_conf, kwargs  
21         return LogFilter  
22 class ShowVersion():  
23     def __init__(self):  
24         pass  
25     def __call__(self,environ,start_response):  
26         start_response("200 OK",[("Content-type", "text/plain")])  
27         return ["Paste Deploy LAB: Version = 1.0.0",]  
28     @classmethod  
29     def factory(cls,global_conf,**kwargs):  
30         print "in ShowVersion.factory", global_conf, kwargs  
31         return ShowVersion()  
32 class Calculator():  
33     def __init__(self):  
34         pass  
35       
36     def __call__(self,environ,start_response):  
37         req = Request(environ)  
38         res = Response()  
39         res.status = "200 OK"  
40         res.content_type = "text/plain"  
41         # get operands  
42         operator = req.GET.get("operator", None)  
43         operand1 = req.GET.get("operand1", None)  
44         operand2 = req.GET.get("operand2", None)  
45         print req.GET  
46         opnd1 = int(operand1)  
47         opnd2 = int(operand2)  
48         if operator == u‘plus‘:  
49             opnd1 = opnd1 + opnd2  
50         elif operator == u‘minus‘:  
51             opnd1 = opnd1 - opnd2  
52         elif operator == u‘star‘:  
53             opnd1 = opnd1 * opnd2  
54         elif operator == u‘slash‘:  
55             opnd1 = opnd1 / opnd2  
56         res.body = "%s /nRESULT= %d" % (str(req.GET) , opnd1)  
57         return res(environ,start_response)  
58     @classmethod  
59     def factory(cls,global_conf,**kwargs):  
60         print "in Calculator.factory", global_conf, kwargs  
61         return Calculator()  
62 if __name__ == ‘__main__‘:  
63     configfile="pastedeploylab.ini"  
64     appname="pdl"  
65     wsgi_app = loadapp("config:%s" % os.path.abspath(configfile), appname)  
66     server = make_server(‘localhost‘,8080,wsgi_app)  
67     server.serve_forever()  
68     pass  

 

使用:

http://127.0.0.1:8080/

输出:

Paste Deploy LAB: Version = 1.0.0

http://127.0.0.1:8080/calc?operator=plus&operand1=12&operand2=23

输出:

UnicodeMultiDict([(‘operator‘, u‘plus‘), (‘operand1‘, u‘12‘), (‘operand2‘, u‘23‘)])

RESULT= 35
====================================================
进一步猜测filter的使用过程:在paste deploy库中应该有类似这样的一段代码对application进行重组包装:
#
# 假设在ini文件中, 某条pipeline的顺序是filter1, filter2, filter3
# app, 那么,最终运行的app_real是这样组织的:
#
app_real = filter1(filter2(filter3(app)))
# 在app真正被调用的过程中,filter1.__call__(environ,start_response)被首先调用,若某种检查未通过,filter1做出反应;否则交给filter2__call__(environ,start_response)
进一步处理,若某种检查未通过,filter2做出反应,中断链条,否则交给filter3.__call__(environ,start_response)处理,若filter3的某种检查都通过了,最后交给
app.__call__(environ,start_response)进行处理。

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