# ======================================================================== # Copyright (c) 2007, Metaweb Technologies, Inc. # All rights reserved. # # Redistribution and use in source and binary forms, with or without # modification, are permitted provided that the following conditions # are met: # * Redistributions of source code must retain the above copyright # notice, this list of conditions and the following disclaimer. # * Redistributions in binary form must reproduce the above # copyright notice, this list of conditions and the following # disclaimer in the documentation and/or other materials provided # with the distribution. # # THIS SOFTWARE IS PROVIDED BY METAWEB TECHNOLOGIES AND CONTRIBUTORS # ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS # FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL METAWEB # TECHNOLOGIES OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, # BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; # LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER # CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN # ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE # POSSIBILITY OF SUCH DAMAGE. # ======================================================================== # # declarations for external metaweb api. # # # from metaweb.api import HTTPMetawebSession # # mss = HTTPMetawebSession('sandbox.freebase.com') # print mss.mqlread([dict(name=None, type='/type/type')]) # # # __all__ = ['MetawebError', 'MetawebSession', 'HTTPMetawebSession', 'attrdict'] __version__ = '0.1' import os, sys, re import urllib2 import cookielib import simplejson from urllib import quote as urlquote import pprint import socket import logging log = logging.getLogger() log.setLevel(logging.DEBUG) log.addHandler(logging.StreamHandler()) try: import httplib2 from httplib2cookie import CookiefulHttp except ImportError: httplib2 = None CookiefulHttp = None log.info('freebase.api: you can install httplib2 for better performance') import simplejson.encoder simplejson.JSONEncoder.item_separator = ',' simplejson.JSONEncoder.key_separator = ':' #delattr(simplejson.encoder.ESCAPE_DCT, '/') def urlencode_weak(s): return urlquote(s, safe='{}[],"/:$') # from http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/361668 class attrdict(dict): """A dict whose items can also be accessed as member variables. >>> d = attrdict(a=1, b=2) >>> d['c'] = 3 >>> print d.a, d.b, d.c 1 2 3 >>> d.b = 10 >>> print d['b'] 10 # but be careful, it's easy to hide methods >>> print d.get('c') 3 >>> d['get'] = 4 >>> print d.get('a') Traceback (most recent call last): TypeError: 'int' object is not callable """ def __init__(self, *args, **kwargs): dict.__init__(self, *args, **kwargs) self.__dict__ = self # TODO expose the common parts of the result envelope class MetawebError(Exception): """ an error report from the metaweb service. """ pass # TODO right now this is a completely unnecessary superclass. # is there enough common behavior between session types # to justify it? class MetawebSession(object): """ MetawebSession is the base class for MetawebSession, subclassed for different connection types. Only http is available externally. This is more of an interface than """ # interface definition here... # from httplib2 NORMALIZE_SPACE = re.compile(r'(?:\r\n)?[ \t]+') def _normalize_headers(headers): return dict([ (key.lower(), NORMALIZE_SPACE.sub(value, ' ').strip()) for (key, value) in headers.iteritems()]) class HTTPMetawebSession(MetawebSession): """ a MetawebSession is a request/response queue. this version uses the HTTP api, and is synchronous. """ # share cookies across sessions, so that different sessions can # see each other's writes immediately. _cookies = cookielib.CookieJar() def __init__(self, service_url, username=None, password=None, prev_session=None): """ create a new MetawebSession for interacting with the Metaweb. a new session will inherit state from prev_session if present, """ super(HTTPMetawebSession, self).__init__() assert not service_url.endswith('/') if not '/' in service_url: # plain host:port service_url = 'http://' + service_url self.service_url = service_url self.username = username self.password = password self.tid = None if prev_session: self.service_url = prev.service_url if CookiefulHttp is not None: self.httpclient = CookiefulHttp(cookiejar=self._cookies) else: cookiespy = urllib2.HTTPCookieProcessor(self._cookies) self.opener = urllib2.build_opener(cookiespy) def _httpreq(self, service_path, method='GET', body=None, form=None, headers=None): """ make an http request to the service. form arguments are encoded in the url, even for POST, if a non-form content-type is given for the body. returns a pair (resp, body) resp is the response object and may be different depending on whether urllib2 or httplib2 is in use? """ if method == 'POST': assert body is not None or form is not None elif method == 'GET': assert body is None else: assert 0, 'unknown method %s' % method log.debug('HTTPREQ: %s %s %s', service_path, method, self._cookies) url = self.service_url + service_path if headers is None: headers = {} else: headers = _normalize_headers(headers) # XXX This is a lousy way to parse Content-Type, where is # the library? ct = headers.get('content-type', None) if ct is not None: ct = ct.split(';')[0] if body is not None: # if body is provided, content-type had better be too assert ct is not None if form is not None: qstr = '&'.join(['%s=%s' % (urlencode_weak(k), urlencode_weak(v)) for k,v in form.items()]) if method == 'POST': # put the args on the url if we're putting something else # in the body. this is used to add args to raw uploads. if body is not None: url += '?' + qstr else: if ct is None: # XXX encoding and stuff ct = 'application/x-www-form-urlencoded' headers['content-type'] = ct if ct == 'multipart/form-encoded': # XXX fixme raise NotImplementedError elif ct == 'application/x-www-form-urlencoded': body = qstr else: # for all methods other than POST, use the url url += '?' + qstr # assure the service that this isn't a CSRF form submission headers['x-metaweb-request'] = 'Python' if 'user-agent' not in headers: headers['user-agent'] = 'python freebase.api-%s' % __version__ #if self.tid is not None: # headers['x-metaweb-tid'] = self.tid if CookiefulHttp is not None: return self._httplib2_request(url, method, body, headers) else: return self._urllib2_request(url, method, body, headers) def _urllib2_request(self, url, method, body, headers): req = urllib2.Request(url, body, headers) try: resp = self.opener.open(req) except socket.error, e: log.error('SOCKET FAILURE: %s', e.fp.read()) raise MetawebError, 'failed contacting %s: %s' % (url, str(e)) except urllib2.HTTPError, e: if e.code == 400 and e.info().type == 'application/json': r = self._loadjson(e.fp.read()) for msg in r.messages: if msg.get('level', 'error') == 'error': raise MetawebError(u'%s %s %r' % (msg.get('code',''), msg.message, msg.info)) # some 400 we don't recognize. hmm. raise MetawebError(u'%r' % r) raise MetawebError, 'request failed: %s: %r %r' % (url, str(e), e.fp.read()) for header in resp.info().headers: log.debug('HTTP HEADER %s', header) name, value = re.split("[:\n\r]", header, 1) if name.lower() == 'x-metaweb-tid': self.tid = value.strip() return (resp, resp.read()) def _httplib2_request(self, url, method, body, headers): try: resp, content = self.httpclient.request(url, method=method, body=body, headers=headers) except socket.error, e: log.error('SOCKET FAILURE: %s', e.fp.read()) raise MetawebError, 'failed contacting %s: %s' % (url, str(e)) #tid = resp.get('x-metaweb-tid', None) return (resp, content) def _httpreq_json(self, *args, **kws): resp, body = self._httpreq(*args, **kws) return self._loadjson(body) def _loadjson(self, json): # TODO really this should be accomplished by hooking # simplejson to create attrdicts instead of dicts. def struct2attrdict(st): """ copy a json structure, turning all dicts into attrdicts. copying descends instances of dict and list, including subclasses. """ if isinstance(st, dict): return attrdict([(k,struct2attrdict(v)) for k,v in st.items()]) if isinstance(st, list): return [struct2attrdict(li) for li in st] return st if json == '': log.error('the empty string is not valid json') raise MetawebError('the empty string is not valid json') try: r = simplejson.loads(json) except ValueError, e: log.error('error parsing json string %r' % json) raise MetawebError, 'error parsing JSON string: %s' % e return struct2attrdict(r) def _check_mqlerror(self, r): if r.code != '/api/status/ok': for msg in r.messages: log.error('mql error: %s %s' % (msg.code, msg.message)) raise MetawebError, 'query failed: %s' % r.messages[0].code def _mqlresult(self, r): self._check_mqlerror(r) return r.result def login(self): """sign in to the service""" assert self.username is not None assert self.password is not None log.debug('LOGIN USERNAME: %s', self.username) try: r = self._httpreq_json('/api/account/login', 'POST', form=dict(username=self.username, password=self.password)) except urllib2.HTTPError, e: raise MetawebError("login error: %s", e) if r.code != '/api/status/ok': raise MetawebError(u'%s %r' % (r.get('code',''), r.messages)) log.debug('LOGIN RESP: %r', r) log.debug('LOGIN COOKIES: %s', self._cookies) def mqlreaditer(self, sq): """read a structure query""" cursor = True while 1: subq = dict(query=[sq], cursor=cursor, escape=False) qstr = simplejson.dumps(dict(c0=subq)) service = '/api/service/mqlread' r = self._httpreq_json(service, form=dict(queries=qstr)) r = r['c0'] for item in self._mqlresult(r): yield item if r['cursor']: cursor = r['cursor'] log.info('CONTINUING with %s', cursor) else: return def mqlread(self, sq): """read a structure query""" subq = dict(query=sq, escape=False) if isinstance(sq, list): subq['cursor'] = True qstr = simplejson.dumps(dict(c0=subq)) log.debug('MQLREAD: %s', qstr) service = '/api/service/mqlread' r = self._httpreq_json(service, form=dict(queries=qstr)) r = r['c0'] return self._mqlresult(r) def trans(self, guid): """translate blob from guid """ url = '/api/trans/raw/' + urlquote(guid) resp = self._httpreq(url) content = resp.read() return content def mqlwrite(self, sq): """do a mql write""" query = dict(q=dict(query=sq, escape=False)) qstr = simplejson.dumps(query) log.debug('MQLWRITE: %s', qstr) service = '/api/service/mqlwrite' r = self._httpreq_json(service, 'POST', form=dict(queries=qstr)) log.debug('MQLWRITE RESP: %r', r) return self._mqlresult(r['q']) def mqlflush(self): """ask the service not to hand us old data""" log.debug('MQLFLUSH') service = '/api/service/mqlwrite' r = self._httpreq_json(service, 'POST', form={}) self._check_mqlerror(r) return r def upload(self, body, content_type): """upload to the metaweb""" log.debug('UPLOAD %s', content) service = '/api/service/upload' r = self._httpreq_json(service, 'POST', headers={'content-type': content_type}, body=qstr) return self._mqlresult(r) if __name__ == '__main__': console = logging.StreamHandler() console.setLevel(logging.INFO) mss = HTTPMetawebSession('sandbox.freebase.com') print mss.mqlread([dict(name=None, type='/type/type')])