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
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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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