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python paste_Python Paste.deploy 笔记

阎功
2023-12-01

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=value13 key2=value24 key3=values5 [composite:pdl]6 use=egg:Paste#urlmap

7 /:root8 /calc:calc9 [pipeline:root]10 pipeline =logrequest showversion11 [pipeline:calc]12 pipeline =logrequest calculator13 [filter:logrequest]14 username =root15 password =root12316 paste.filter_factory =pastedeploylab:LogFilter.factory17 [app:showversion]18 version = 1.0.019 paste.app_factory =pastedeploylab:ShowVersion.factory20 [app:calculator]21 description = This is an "+-*/"Calculator22 paste.app_factory = pastedeploylab:Calculator.factory

pastedeploylab.py

1 Created on 2011-6-12

2 @author: Sonic3 '''

4 import os5 import webob6 from webob import Request7 from webob import Response8 from paste.deploy import loadapp9 from wsgiref.simple_server import make_server10 #Filter11 class LogFilter():12 def __init__(self,app):13 self.app = app14 pass15 def __call__(self,environ,start_response):16 print "filter:LogFilter is called."17 return self.app(environ,start_response)18 @classmethod19 def factory(cls, global_conf, **kwargs):20 print "in LogFilter.factory", global_conf, kwargs21 return LogFilter22 class ShowVersion():23 def __init__(self):24 pass25 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 @classmethod29 def factory(cls,global_conf,**kwargs):30 print "in ShowVersion.factory", global_conf, kwargs31 return ShowVersion()32 class Calculator():33 def __init__(self):34 pass35

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 operands42 operator = req.GET.get("operator", None)43 operand1 = req.GET.get("operand1", None)44 operand2 = req.GET.get("operand2", None)45 print req.GET46 opnd1 = int(operand1)47 opnd2 = int(operand2)48 if operator == u'plus':49 opnd1 = opnd1 + opnd250 elif operator == u'minus':51 opnd1 = opnd1 - opnd252 elif operator == u'star':53 opnd1 = opnd1 * opnd254 elif operator == u'slash':55 opnd1 = opnd1 / opnd256 res.body = "%s /nRESULT= %d" % (str(req.GET) , opnd1)57 return res(environ,start_response)58 @classmethod59 def factory(cls,global_conf,**kwargs):60 print "in Calculator.factory", global_conf, kwargs61 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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