503 error when trying to access Google Patents using python

问题

Earlier today I was able to pull data from Google Patents using the code below

import urllib2

url = 'http://www.google.com/search?tbo=p&q=ininventor:"John-Mudd"&hl=en&tbm=pts&source=lnt&tbs=ptso:us'
req = urllib2.Request(url, headers={'User-Agent' : "foobar"})

response = urllib2.urlopen(req)

Now when I go to run it I get the following 503 error. I had only looped through this code maybe 30 times on it (i'm trying to get all the patents owned by a list of 30 people).

HTTPError                                 Traceback (most recent call last)
<ipython-input-4-01f83e2c218f> in <module>()
----> 1 response = urllib2.urlopen(req)

C:\Python27\lib\urllib2.pyc in urlopen(url, data, timeout)
    124     if _opener is None:
    125         _opener = build_opener()
--> 126     return _opener.open(url, data, timeout)
    127 
    128 def install_opener(opener):

C:\Python27\lib\urllib2.pyc in open(self, fullurl, data, timeout)
    404         for processor in self.process_response.get(protocol, []):
    405             meth = getattr(processor, meth_name)
--> 406             response = meth(req, response)
    407 
    408         return response

C:\Python27\lib\urllib2.pyc in http_response(self, request, response)
    517         if not (200 <= code < 300):
    518             response = self.parent.error(
--> 519                 'http', request, response, code, msg, hdrs)
    520 
    521         return response

C:\Python27\lib\urllib2.pyc in error(self, proto, *args)
    436             http_err = 0
    437         args = (dict, proto, meth_name) + args
--> 438         result = self._call_chain(*args)
    439         if result:
    440             return result

C:\Python27\lib\urllib2.pyc in _call_chain(self, chain, kind, meth_name, *args)
    376             func = getattr(handler, meth_name)
    377 
--> 378             result = func(*args)
    379             if result is not None:
    380                 return result

C:\Python27\lib\urllib2.pyc in http_error_302(self, req, fp, code, msg, headers)
    623         fp.close()
    624 
--> 625         return self.parent.open(new, timeout=req.timeout)
    626 
    627     http_error_301 = http_error_303 = http_error_307 = http_error_302

C:\Python27\lib\urllib2.pyc in open(self, fullurl, data, timeout)
    404         for processor in self.process_response.get(protocol, []):
    405             meth = getattr(processor, meth_name)
--> 406             response = meth(req, response)
    407 
    408         return response

C:\Python27\lib\urllib2.pyc in http_response(self, request, response)
    517         if not (200 <= code < 300):
    518             response = self.parent.error(
--> 519                 'http', request, response, code, msg, hdrs)
    520 
    521         return response

C:\Python27\lib\urllib2.pyc in error(self, proto, *args)
    442         if http_err:
    443             args = (dict, 'default', 'http_error_default') + orig_args
--> 444             return self._call_chain(*args)
    445 
    446 # XXX probably also want an abstract factory that knows when it makes

C:\Python27\lib\urllib2.pyc in _call_chain(self, chain, kind, meth_name, *args)
    376             func = getattr(handler, meth_name)
    377 
--> 378             result = func(*args)
    379             if result is not None:
    380                 return result

C:\Python27\lib\urllib2.pyc in http_error_default(self, req, fp, code, msg, hdrs)
    525 class HTTPDefaultErrorHandler(BaseHandler):
    526     def http_error_default(self, req, fp, code, msg, hdrs):
--> 527         raise HTTPError(req.get_full_url(), code, msg, hdrs, fp)
    528 
    529 class HTTPRedirectHandler(BaseHandler):

HTTPError: HTTP Error 503: Service Unavailable

回答1:

Shot in the dark guess:

Did you look to see if there was a "Retry-After header" in the response. It's a real possibility with 503.

From RFC 2616:

14.37 Retry-After

The Retry-After response-header field can be used with a 503 (Service Unavailable) response to indicate how long the service is expected to be unavailable to the requesting client. This field MAY also be used with any 3xx (Redirection) response to indicate the minimum time the user-agent is asked wait before issuing the redirected request. The value of this field can be either an HTTP-date or an integer number of seconds (in decimal) after the time of the response. Retry-After = "Retry-After" ":" ( HTTP-date | delta-seconds )

Two examples of its use are Retry-After: Fri, 31 Dec 1999 23:59:59 GMT Retry-After: 120

In the latter example, the delay is 2 minutes.

回答2:

Google's TOS bans automated queries, sadly enough. It almost certainly detected that you were "up to no good."

source: https://support.google.com/websearch/answer/86640?hl=en

来源：https://stackoverflow.com/questions/15506651/503-error-when-trying-to-access-google-patents-using-python