# ================================================================== # 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 cookielib try: import simplejson except ImportError: try: # appengine provides simplejson at django.utils.simplejson from django.utils import simplejson except ImportError: raise Error("unable to import simplejson") try: from urllib import quote as urlquote except ImportError: from urlib_stub import quote as urlquote import pprint import socket import logging class Delayed(object): """ Wrapper for callables in log statements. Avoids actually making the call until the result is turned into a string. A few examples: simplejson.dumps is never called because the logger never tries to format the result >>> logging.debug(Delayed(simplejson.dumps, q)) This time simplejson.dumps() is actually called: >>> logging.warn(Delayed(simplejson.dumps, q)) """ def __init__(self, f, *args, **kwds): self.f = f self.args = args self.kwds = kwds def __str__(self): return str(self.f(*self.args, **self.kwds)) def logformat(result): """ Format the dict/list as a json object """ rstr = simplejson.dumps(result, indent=2) if rstr[0] == '{': rstr = rstr[1:-2] return rstr from httpclients import Httplib2Client, Urllib2Client, UrlfetchClient # Check for urlfetch first so that urlfetch is used when running the appengine SDK try: import google.appengine.api.urlfetch from cookie_handlers import CookiefulUrlfetch http_client = UrlfetchClient except ImportError: try: import httplib2 from cookie_handlers import CookiefulHttp http_client = Httplib2Client except ImportError: import urllib2 httplib2 = None CookiefulHttp = None http_client = Urllib2Client # remove whitespace from json encoded output simplejson.JSONEncoder.item_separator = ',' simplejson.JSONEncoder.key_separator = ':' # don't escape slashes, we're not pasting into script tags here. if simplejson.encoder.ESCAPE_DCT.get('/', None) == r'\/': 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 a class """ # 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. _default_cookiejar = cookielib.CookieJar() def __init__(self, service_url, username=None, password=None, prev_session=None, cookiejar=None, cookiefile=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__() self.log = logging.getLogger() 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 cookiefile is not None: cookiejar = self.open_cookie_file(cookiefile) if cookiejar is not None: self.cookiejar = cookiejar elif prev_session: self.cookiejar = prev_session.cookiejar else: self.cookiejar = self._default_cookiejar self._http_request = http_client(self.cookiejar, self._raise_service_error) def open_cookie_file(self, cookiefile=None): if cookiefile is None or cookiefile == '': if os.environ.has_key('HOME'): cookiefile = os.path.join(os.environ['HOME'], '.pyfreebase/cookiejar') else: raise MetawebError("no cookiefile specified and no $HOME/.pyfreebase directory" % cookiefile) cookiejar = cookielib.LWPCookieJar(cookiefile) if os.path.exists(cookiefile): cookiejar.load(ignore_discard=True) return cookiejar 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 url = self.service_url + service_path if headers is None: headers = {} else: headers = _normalize_headers(headers) # 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: ct = 'application/x-www-form-urlencoded' headers['content-type'] = ct + '; charset=utf-8' if ct == 'multipart/form-encoded': # TODO handle this case 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 ####### DEBUG MESSAGE - should check log level before generating if form is None: formstr = '' else: formstr = '\nFORM:\n ' + '\n '.join(['%s=%s' % (k,v) for k,v in form.items()]) if headers is None: headerstr = '' else: headerstr = '\nHEADERS:\n ' + '\n '.join([('%s: %s' % (k,v)) for k,v in headers.items()]) self.log.info('%s %s%s%s', method, url, formstr, headerstr) ####### return self._http_request(url, method, body, headers) def _raise_service_error(self, url, status, ctype, body): is_jsbody = (ctype.endswith('javascript') or ctype.endswith('json')) if str(status) == '400' and is_jsbody: r = self._loadjson(body) msg = r.messages[0] raise MetawebError(u'%s %s %r' % (msg.get('code',''), msg.message, msg.info)) raise MetawebError, 'request failed: %s: %r %r' % (url, status, body) 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 == '': self.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: self.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: self.log.error('mql error: %s %s %r' % (msg.code, msg.message, msg.get('query', None))) raise MetawebError, 'query failed: %s\n%r' % (r.messages[0].code, r.messages[0].get('query', None)) def _mqlresult(self, r): self._check_mqlerror(r) self.log.info('result: %s', Delayed(logformat, r)) return r.result def login(self): """sign in to the service""" assert self.username is not None assert self.password is not None self.log.debug('LOGIN USERNAME: %s', self.username) r = self._httpreq_json('/api/account/login', 'POST', form=dict(username=self.username, password=self.password)) if r.code != '/api/status/ok': raise MetawebError(u'%s %r' % (r.get('code',''), r.messages)) self.log.debug('LOGIN RESP: %r', r) self.log.debug('LOGIN COOKIES: %s', self.cookiejar) def mqlreaditer(self, sq, asof=None): """read a structure query""" cursor = True while 1: subq = dict(query=[sq], cursor=cursor, escape=False) if asof: subq['as_of_time'] = asof qstr = simplejson.dumps(subq) service = '/api/service/mqlread' r = self._httpreq_json(service, form=dict(query=qstr)) for item in self._mqlresult(r): yield item if r['cursor']: cursor = r['cursor'] self.log.info('CONTINUING with %s', cursor) else: return def mqlread(self, sq, asof=None): """read a structure query""" subq = dict(query=sq, escape=False) if asof: subq['as_of_time'] = asof if isinstance(sq, list): subq['cursor'] = True service = '/api/service/mqlread' self.log.info('%s: %s', service, Delayed(logformat, sq)) qstr = simplejson.dumps(subq) r = self._httpreq_json(service, form=dict(query=qstr)) return self._mqlresult(r) def mqlreadmulti(self, queries, asof=None): """read a structure query""" keys = [('q%d' % i) for i,v in enumerate(queries)]; envelope = {} for i,sq in enumerate(queries): subq = dict(query=sq, escape=False) if asof: subq['as_of_time'] = asof # XXX put this back once mqlreadmulti is working in general #if isinstance(sq, list): # subq['cursor'] = True envelope[keys[i]] = subq service = '/api/service/mqlread' self.log.info('%s: %s', service, Delayed(logformat, envelope)) qstr = simplejson.dumps(envelope) rs = self._httpreq_json(service, form=dict(queries=qstr)) self.log.info('%s result: %s', service, Delayed(simplejson.dumps, rs, indent=2)) return [self._mqlresult(rs[key]) for key in keys] def trans(self, guid): """translate blob from guid """ url = '/api/trans/raw' + urlquote(guid) self.log.info(url) resp, body = self._httpreq(url) self.log.info('%d bytes' % len(body)) return body def mqlwrite(self, sq): """do a mql write""" query = dict(query=sq, escape=False) qstr = simplejson.dumps(query) self.log.debug('MQLWRITE: %s', qstr) service = '/api/service/mqlwrite' self.log.info('%s: %s', service, Delayed(logformat,sq)) r = self._httpreq_json(service, 'POST', form=dict(query=qstr)) self.log.debug('MQLWRITE RESP: %r', r) return self._mqlresult(r) def mqlcheck(self, sq): """ See if a write is valid, and see what would happen, but do not actually do the write """ query = dict(query=sq, escape=False) qstr = simplejson.dumps(query) self.log.debug('MQLCHECK: %s', qstr) service = '/api/service/mqlcheck' self.log.info('%s: %s', service, Delayed(logformat, sq)) r = self._httpreq_json(service, 'POST', form=dict(query=qstr)) self.log.debug('MQLCHECK RESP: %r', r) return self._mqlresult(r) def mqlflush(self): """ask the service not to hand us old data""" self.log.debug('MQLFLUSH') service = '/api/service/touch' r = self._httpreq_json(service) self._check_mqlerror(r) return True def touch(self): return self.mqlflush() def upload(self, body, content_type, document_id=False, permission_of=False): """upload to the metaweb""" service = '/api/service/upload' self.log.info('POST %s: %s (%d bytes)', service, content_type, len(body)) headers = {} if content_type is not None: headers['content-type'] = content_type form = None if document_id is not False: if document_id is None: form = { 'document': '' } else: form = { 'document': document_id } if permission_of is not False: if form: form['permission_of'] = permission_of else: form = { 'permission_of' : permission_of } # note the use of both body and form. # form parameters get encoded into the URL in this case r = self._httpreq_json(service, 'POST', headers=headers, body=body, form=form) return self._mqlresult(r) def reconcile(self, name, etype=['/common/topic']): """reconcile name to guid""" service = '/dataserver/reconciliation' r = self._httpreq_json(service, 'GET', form={'name':name, 'types':','.join(etype)}) # TODO non-conforming service, fix later #self._mqlresult(r) return r if __name__ == '__main__': console = logging.StreamHandler() console.setLevel(logging.DEBUG) mss = HTTPMetawebSession('sandbox.freebase.com') self.mss.log.setLevel(logging.DEBUG) self.mss.log.addHandler(console) print mss.mqlread([dict(name=None, type='/type/type')])