reorganize package inorder to emphasize freebase-api as the main one

git-svn-id: http://freebase-python.googlecode.com/svn/trunk@88 5914aa95-5b3a-0410-a3b5-7b719e7fe9b2

1 files changed, 469 insertions, 0 deletions

diff --git a/metaweb.py b/metaweb.py
new file mode 100644
index 0000000..e75ee0b
--- /dev/null
+++ b/metaweb.py
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+#========================================================================
+# 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 ``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 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.
+# ========================================================================
+#
+# This is the full "metaweb.py" module from the Metaweb API documentation
+#
+# In the documentation, each function is presented as a separate
+# example.  This is the whole file.
+#
+# If you find any errors or have suggestions for improving this module,
+# send them to the Freebase developers mailing list: developers@freebase.com
+# You can subscribe to the mailing list at http://lists.freebase.com/
+#
+
+import httplib
+import urllib        # URL encoding
+import urllib2       # Higher-level URL content fetching
+import simplejson    # JSON serialization and parsing
+import cookielib     # Cookie handling
+import os
+
+#
+# When experimenting, use the sandbox.freebase.com service.
+# Every Monday, sandbox.freebase.com is erased and it is updated
+# with a fresh copy of data from www.freebase.com.  This makes
+# it an ideal place to experiment.
+#
+host = 'sandbox.freebase.com'              # The Metaweb host
+readservice = '/api/service/mqlread'   # Path to mqlread service
+loginservice = '/api/account/login'     # Path to login service
+writeservice = '/api/service/mqlwrite'  # Path to mqlwrite service
+uploadservice = '/api/service/upload'   # Path to upload service
+searchservice = '/api/service/search'   # Path to search service
+                 
+credentials = None      # default credential from login()
+escape = False          # default escape, set to 'html' for HTML escaping
+permission = None       # default permission used when creating new objects
+debug = False           # default debug setting
+
+# Install a CookieProcessor
+cookiefile = os.path.join(os.environ["HOME"], ".metaweb.cookies.txt")
+cookiejar = cookielib.LWPCookieJar()
+if os.path.isfile(cookiefile):
+    cookiejar.load(cookiefile)
+
+urllib2.install_opener(
+    urllib2.build_opener(
+        urllib2.HTTPCookieProcessor(cookiejar)))
+
+# If anything goes wrong when talking to a Metaweb service, we raise MQLError.
+class MQLError(Exception):
+    def __init__(self, value):     # This is the exception constructor method
+        self.value = value
+    def __str__(self):             # Convert error object to a string
+        return repr(self.value)
+
+# Submit the MQL query q and return the result as a Python object.
+# If authentication credentials are supplied, use them in a cookie.
+# Raises MQLError if the query was invalid. Raises urllib2.HTTPError if
+# mqlread returns an HTTP status code other than 200 (which should not happen).
+def read(q, credentials=credentials, escape=escape):
+    # Put the query in an envelope
+    envelope = {'query':q}
+
+    # Add escape if needed
+    if escape != 'html':
+        envelope['escape'] = False if not escape else escape
+
+    # Encode the result
+    encoded = urllib.urlencode({'query': simplejson.dumps(envelope)})
+
+    # Build the URL and create a Request object for it
+    url = 'http://%s%s' % (host, readservice)
+    req = urllib2.Request(url)
+
+    # The body of the POST request is encoded URL parameters
+    req.add_header('Content-type', 'application/x-www-form-urlencoded')
+
+    # Send our authentication credentials, if any, as a cookie.
+    # The need for mqlread authentication is a temporary restriction.
+    if credentials: req.add_header('Cookie', credentials)
+
+    # Use the encoded envelope as the value of the q parameter in the body
+    # of the request.  Specifying a body automatically makes this a POST.
+    req.add_data(encoded)
+
+    # Now upen the URL and and parse its JSON content
+    f = urllib2.urlopen(req)        # Open the URL
+    inner = simplejson.load(f)      # Parse JSON response to an object
+
+    # If anything was wrong with the invocation, mqlread will return an HTTP
+    # error, and the code above with raise urllib2.HTTPError.
+    # If anything was wrong with the query, we won't get an HTTP error, but
+    # will get an error status code in the response envelope.  In this case
+    # we raise our own MQLError exception.
+    if not inner['code'].startswith('/api/status/ok'):
+        if debug: print q
+        if debug: print inner
+        if debug: print f.info()['X-Metaweb-Cost']
+        if debug: print f.info()['X-Metaweb-TID']
+        error = inner['messages'][0]
+        raise MQLError('%s: %s' % (error['code'], error['message']))
+
+    # If there was no error, then just return the result from the envelope
+    return inner['result']
+
+# Submit the MQL query q and return the result as a Python object
+# This function behaves like read() above, but uses cursors so that
+# it works even for very large result sets. See also the cursor class below.
+def readall(q, credentials=credentials, escape=escape):
+    # This is the start of the mqlread URL.
+    # We just need to append the envelope to it
+    url = 'http://%s%s' % (host, readservice)
+
+    # The query and most of the envelope are constant. We just need to append
+    # the encoded cursor value and some closing braces to this prefix string
+    jsonq = simplejson.dumps(q)
+
+    # Add escape if needed
+    if escape != 'html':
+        jsonq += ',"escape":' + ('false' if not escape else escape)
+ 
+    cursor = 'true'   # This is the initial value of the cursor
+    results = []      # We accumulate results in this array
+
+    # Loop until mqlread tells us there are no more results
+    while cursor:
+        # append the cursor and the closing braces to the envelope
+        envelope = urllib.urlencode({'query': '{"query":' + jsonq + ',"cursor":' + cursor + '}'})
+
+        # Begin an HTTP request for the URL
+        req = urllib2.Request(url)
+
+        # The body of the POST request is encoded URL parameters
+        req.add_header('Content-type', 'application/x-www-form-urlencoded')
+
+        # Send our authentication credentials, if any, as a cookie.
+        # The need for mqlread authentication is a temporary restriction.
+        if credentials: 
+            req.add_header('Cookie', credentials)
+
+        # Use the encoded envelope as the value of the q parameter in the body
+        # of the request.  Specifying a body automatically makes this a POST.
+        req.add_data(envelope)
+
+        # Read and parse the URL contents
+        f = urllib2.urlopen(req)          # Open URL
+        inner = simplejson.load(f)        # Parse JSON response
+
+        # Raise a MQLError if there were errors
+        if not inner['code'].startswith('/api/status/ok'):
+            if debug: print q
+            if debug: print inner
+            if debug: print f.info()['X-Metaweb-Cost']
+            if debug: print f.info()['X-Metaweb-TID']
+            error = inner['messages'][0]
+            raise MQLError('%s: %s' % (error['code'], error['message']))
+
+        # Append this batch of results to the main array of results.
+        results.extend(inner['result'])
+
+        # Finally, get the new value of the cursor for the next iteration
+        cursor = inner['cursor']
+        if cursor:                        # If it is not false, put it
+            cursor = '"' + cursor + '"'   #  in quotes as a JSON string
+
+    # Now that we're done with the loop, return the results array
+    return results
+
+# Submit multiple MQL queries and return the result as a Python array.
+# If authentication credentials are supplied, use them in a cookie.
+# Raises MQLError if the query was invalid. Raises urllib2.HTTPError if
+# mqlread returns an HTTP status code other than 200 (which should not happen).
+def readmulti(queries, credentials=credentials, escape=escape):
+    encoded = ""
+    for i in range(0, len(queries)):
+        # Put the query in an envelope
+        envelope = {'query':queries[i]}
+        # Add escape if needed
+        if escape != 'html':
+            envelope['escape'] = False if not escape else escape
+        if i > 0:
+            encoded += ","
+        encoded += '"q%d":%s' % (i, simplejson.dumps(envelope))
+
+    # URL encode the outer envelope
+    encoded = urllib.urlencode({'queries': "{" + encoded + "}"})
+
+    # Build the URL and create a Request object for it
+    url = 'http://%s%s' % (host, readservice)
+    req = urllib2.Request(url)
+
+    # The body of the POST request is encoded URL parameters
+    req.add_header('Content-type', 'application/x-www-form-urlencoded')
+
+    # Send our authentication credentials, if any, as a cookie.
+    # The need for mqlread authentication is a temporary restriction.
+    if credentials: req.add_header('Cookie', credentials)
+
+    # Use the encoded envelope as the value of the q parameter in the body
+    # of the request.  Specifying a body automatically makes this a POST.
+    req.add_data(encoded)
+
+    # Now upen the URL and and parse its JSON content
+    f = urllib2.urlopen(req)        # Open the URL
+    inner = simplejson.load(f)      # Parse JSON response to an object
+
+    # If anything was wrong with the invocation, mqlread will return an HTTP
+    # error, and the code above with raise urllib2.HTTPError.
+    # If anything was wrong with the query, we won't get an HTTP error, but
+    # will get an error status code in the response envelope.  In this case
+    # we raise our own MQLError exception.
+    if not inner['code'].startswith('/api/status/ok'):
+        if debug: print queries
+        if debug: print inner
+        if debug: print f.info()['X-Metaweb-Cost']
+        if debug: print f.info()['X-Metaweb-TID']
+        error = inner['messages'][0]
+        raise MQLError('%s: %s' % (error['code'], error['message']))
+
+    # extract the results
+    results = []
+    for i in range(0, len(queries)):
+        result = inner["q%d" % i]
+        if not result['code'].startswith('/api/status/ok'):
+            if debug: print queries[i]
+            if debug: print result
+            if debug: print f.info()['X-Metaweb-Cost']
+            if debug: print f.info()['X-Metaweb-TID']
+            error = result['messages'][0]
+            raise MQLError('%s: %s' % (error['code'], error['message']))
+        results.append(result['result'])
+    
+    # If there was no error, then just return the result from the envelope
+    return results
+
+# Submit the specified username and password to the Metaweb login service.
+# Return opaque authentication credentials on success. 
+# Raise MQLError on failure.
+def login(username, password):
+    # Establish a connection to the server and make a request.
+    # Note that we use the low-level httplib library instead of urllib2.
+    # This allows us to manage cookies explicitly.
+    conn = httplib.HTTPConnection(host)
+    conn.request('POST',                   # POST the request
+                 loginservice,             # The URL path /api/account/login
+                 # The body of the request: encoded username/password
+                 urllib.urlencode({'username':username, 'password':password}),
+                 # This header specifies how the body of the post is encoded.
+                 {'Content-type': 'application/x-www-form-urlencoded'})
+
+    # Get the response from the server
+    response = conn.getresponse()
+
+    if response.status == 200:  # We get HTTP 200 OK even if login fails
+        # Parse response body and raise a MQLError if login failed
+        body = simplejson.loads(response.read())
+        if not body['code'].startswith('/api/status/ok'):
+            if debug: print inner
+            if debug: print f.info()['X-Metaweb-Cost']
+            if debug: print f.info()['X-Metaweb-TID']
+            error = body['messages'][0]
+            raise MQLError('%s: %s' % (error['code'], error['message']))
+
+        # Otherwise return cookies to serve as authentication credentials.
+        # The set-cookie header holds one or more cookie specifications,
+        # separated by commas. Each specification is a name, an equal
+        # sign, a value, and one or more trailing clauses that consist
+        # of a semicolon and some metadata.  We don't care about the
+        # metadata. We just want to return a comma-separated list of
+        # name=value pairs.
+        cookies = response.getheader('set-cookie').split(',')
+        return ';'.join([c[0:c.index(';')] for c in cookies])
+    else:                      # This should never happen
+        raise MQLError('HTTP Error: %d %s' % (response.status,response.reason))
+
+
+# Submit the MQL write q and return the result as a Python object.
+# Authentication credentials are required, obtained from login()
+# Raises MQLError if the query was invalid. Raises urllib2.HTTPError if
+# mqlwrite returns an HTTP status code other than 200
+def write(query, credentials=credentials, escape=escape, permission=permission):
+    # We're requesting this URL
+    req = urllib2.Request('http://%s%s' % (host, writeservice))
+    # Send our authentication credentials as a cookie
+    if credentials:
+        req.add_header('Cookie', credentials)
+    # This custom header is required and guards against XSS attacks
+    req.add_header('X-Metaweb-Request', 'True')
+    # The body of the POST request is encoded URL parameters
+    req.add_header('Content-type', 'application/x-www-form-urlencoded')
+    # Wrap the query object in a query envelope
+    envelope = {'qname': {'query': query}}
+    # Add escape if needed
+    if escape != 'html':
+        envelope['qname']['escape'] = (False if not escape else escape)
+    # Add permissions if needed
+    if permission:
+        envelope['qname']['use_permission_of'] = permission
+    # JSON encode the envelope
+    encoded = simplejson.dumps(envelope)
+    # Use the encoded envelope as the value of the q parameter in the body
+    # of the request.  Specifying a body automatically makes this a POST.
+    req.add_data(urllib.urlencode({'queries':encoded}))
+
+    # Now do the POST
+    f = urllib2.urlopen(req)
+    response = simplejson.load(f)   # Parse HTTP response as JSON
+    inner = response['qname']       # Open outer envelope; get inner envelope
+
+    # If anything was wrong with the invocation, mqlwrite will return an HTTP
+    # error, and the code above with raise urllib2.HTTPError.
+    # If anything was wrong with the query, we will get an error status code
+    # in the response envelope.
+    # we raise our own MQLError exception.
+    if not inner['code'].startswith('/api/status/ok'):
+        if debug: print query
+        if debug: print inner
+        if debug: print f.info()['X-Metaweb-Cost']
+        if debug: print f.info()['X-Metaweb-TID']
+        error = inner['messages'][0]
+        raise MQLError('%s: %s' % (error['code'], error['message']))
+
+    # save cookie
+    cookiejar.save(cookiefile)
+
+    # If there was no error, then just return the result from the envelope
+    return inner['result']
+
+# Upload the specified content (and give it the specified type).
+# Return the guid of the /type/content object that represents it.
+# The returned guid can be used to retrieve the content with /api/trans/raw.
+def upload(content, type, credentials=credentials):
+    # This is the URL we POST content to
+    url = 'http://%s%s'%(host,uploadservice)
+    # Build the HTTP request
+    req = urllib2.Request(url, content)         # URL and content to POST
+    req.add_header('Content-Type', type)        # Content type header
+    if credentials:
+        req.add_header('Cookie', credentials)       # Authentication header
+    req.add_header('X-Metaweb-Request', 'True') # Guard against XSS attacks
+    f = urllib2.urlopen(req)                # POST the request
+    response = simplejson.load(f)           # Parse the response
+    if not response['code'].startswith('/api/status/ok'):
+        if debug: print inner
+        if debug: print f.info()['X-Metaweb-Cost']
+        if debug: print f.info()['X-Metaweb-TID']
+        error = response['messages'][0]
+        raise MQLError('%s: %s' % (error['code'], error['message']))
+    return response['result']['id']         # Extract and return content id
+
+# Search for topics
+def search(query, type=None, start=0, limit=0):
+    args = {"query": query}
+    if type:
+        args["type"] = type
+    if start > 0:
+        args["start"] = start
+    if limit > 0:
+        args["limit"] = limit
+    url = 'http://%s%s?%s'%(host, searchservice, urllib.urlencode(args))
+    f = urllib2.urlopen(url)
+    response = simplejson.load(f)           # Parse the response
+    if not response['code'].startswith('/api/status/ok'):
+        if debug: print query
+        if debug: print inner
+        if debug: print f.info()['X-Metaweb-Cost']
+        if debug: print f.info()['X-Metaweb-TID']
+        error = response['messages'][0]
+        raise MQLError('%s: %s' % (error['code'], error['message']))
+    return response['result']
+
+# Cursor for iterating over large data sets
+# For example:
+#    query = {"name": None, "type":"/type/media_type"}
+#    for row in metaweb.cursor([query]):
+#        print row
+class cursor:
+    def __init__(self, query, credentials=credentials, escape=escape):
+        self.query = query
+        self.credentials = credentials
+        self.index = 0
+        self.results = []
+        self.cursor = 'true'
+        self.url = 'http://%s%s' % (host, readservice)
+        self.jsonq = simplejson.dumps(self.query)
+        if escape != 'html':
+            self.jsonq += ',"escape":' + ('false' if not escape else escape)
+ 
+    def __iter__(self):
+        return self
+
+    def next(self):
+        # return the next value
+        if self.index < len(self.results):
+            result = self.results[self.index]
+            self.index = self.index + 1
+            return result
+
+        # check if there is more
+        if not self.cursor:
+            raise StopIteration
+        
+        # append the cursor and the closing braces to the envelope
+        envelope = urllib.urlencode({'query': '{"query":' + self.jsonq + ',"cursor":' + self.cursor + '}'})
+
+        # Begin an HTTP request for the URL
+        req = urllib2.Request(self.url)
+
+        # The body of the POST request is encoded URL parameters
+        req.add_header('Content-type', 'application/x-www-form-urlencoded')
+
+        # Send our authentication credentials, if any, as a cookie.
+        # The need for mqlread authentication is a temporary restriction.
+        if self.credentials: req.add_header('Cookie', self.credentials)
+
+        # Use the encoded envelope as the value of the q parameter in the body
+        # of the request.  Specifying a body automatically makes this a POST.
+        req.add_data(envelope)
+
+        # Read and parse the URL contents
+        f = urllib2.urlopen(req)          # Open URL
+        inner = simplejson.load(f)        # Parse JSON response
+
+        # Raise a MQLError if there were errors
+        if not inner['code'].startswith('/api/status/ok'):
+            if debug: print self.query
+            if debug: print inner
+            if debug: print f.info()['X-Metaweb-Cost']
+            if debug: print f.info()['X-Metaweb-TID']
+            error = inner['messages'][0]
+            raise MQLError('%s: %s' % (error['code'], error['message']))
+
+        # Remember the next cursor
+        self.cursor = inner['cursor']
+        if self.cursor:                             # If it is not false, put it
+            self.cursor = '"' + self.cursor + '"'   #  in quotes as a JSON string
+
+        # Append this batch of results to the main array of results.
+        self.results = inner['result']
+        if len(self.results) == 0:
+            raise StopIteration
+
+        # Return the first result
+        self.index = 1
+        return self.results[0]