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393 lines
14 KiB
Python
393 lines
14 KiB
Python
# =============================================================================
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# OWSLib. Copyright (C) 2005 Sean C. Gillies
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#
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# Contact email: sgillies@frii.com
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#
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# $Id: wfs.py 503 2006-02-01 17:09:12Z dokai $
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# =============================================================================
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import cgi
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from cStringIO import StringIO
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from urllib import urlencode
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from urllib2 import urlopen
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from owslib.util import openURL, testXMLValue, extract_xml_list, ServiceException, xmltag_split
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from owslib.etree import etree
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from owslib.fgdc import Metadata
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from owslib.iso import MD_Metadata
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from owslib.crs import Crs
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from owslib.namespaces import Namespaces
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from owslib.util import log
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n = Namespaces()
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WFS_NAMESPACE = n.get_namespace("wfs")
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OGC_NAMESPACE = n.get_namespace("ogc")
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#TODO: use nspath in util.py
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def nspath(path, ns=WFS_NAMESPACE):
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"""
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Prefix the given path with the given namespace identifier.
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Parameters
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----------
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path : string
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ElementTree API Compatible path expression
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ns : string
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The XML namespace. Defaults to WFS namespace.
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"""
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components = []
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for component in path.split("/"):
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if component != '*':
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component = "{%s}%s" % (ns, component)
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components.append(component)
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return "/".join(components)
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class WebFeatureService_1_0_0(object):
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"""Abstraction for OGC Web Feature Service (WFS).
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Implements IWebFeatureService.
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"""
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def __new__(self,url, version, xml, parse_remote_metadata=False):
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""" overridden __new__ method
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@type url: string
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@param url: url of WFS capabilities document
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@type xml: string
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@param xml: elementtree object
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@type parse_remote_metadata: boolean
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@param parse_remote_metadata: whether to fully process MetadataURL elements
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@return: initialized WebFeatureService_1_0_0 object
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"""
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obj=object.__new__(self)
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obj.__init__(url, version, xml, parse_remote_metadata)
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return obj
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def __getitem__(self,name):
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''' check contents dictionary to allow dict like access to service layers'''
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if name in self.__getattribute__('contents').keys():
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return self.__getattribute__('contents')[name]
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else:
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raise KeyError, "No content named %s" % name
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def __init__(self, url, version, xml=None, parse_remote_metadata=False):
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"""Initialize."""
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self.url = url
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self.version = version
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self._capabilities = None
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reader = WFSCapabilitiesReader(self.version)
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if xml:
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self._capabilities = reader.readString(xml)
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else:
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self._capabilities = reader.read(self.url)
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self._buildMetadata(parse_remote_metadata)
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def _buildMetadata(self, parse_remote_metadata=False):
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'''set up capabilities metadata objects: '''
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#serviceIdentification metadata
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serviceelem=self._capabilities.find(nspath('Service'))
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self.identification=ServiceIdentification(serviceelem, self.version)
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#serviceProvider metadata
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self.provider=ServiceProvider(serviceelem)
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#serviceOperations metadata
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self.operations=[]
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for elem in self._capabilities.find(nspath('Capability/Request'))[:]:
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self.operations.append(OperationMetadata(elem))
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#serviceContents metadata: our assumption is that services use a top-level
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#layer as a metadata organizer, nothing more.
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self.contents={}
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featuretypelist=self._capabilities.find(nspath('FeatureTypeList'))
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features = self._capabilities.findall(nspath('FeatureTypeList/FeatureType'))
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for feature in features:
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cm=ContentMetadata(feature, featuretypelist, parse_remote_metadata)
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self.contents[cm.id]=cm
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#exceptions
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self.exceptions = [f.text for f \
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in self._capabilities.findall('Capability/Exception/Format')]
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def getcapabilities(self, timeout=30):
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"""Request and return capabilities document from the WFS as a
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file-like object.
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NOTE: this is effectively redundant now"""
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reader = WFSCapabilitiesReader(self.version)
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return urlopen(reader.capabilities_url(self.url), timeout=timeout)
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def items(self):
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'''supports dict-like items() access'''
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items=[]
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for item in self.contents:
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items.append((item,self.contents[item]))
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return items
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def getfeature(self, typename=None, filter=None, bbox=None, featureid=None,
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featureversion=None, propertyname=['*'], maxfeatures=None,
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srsname=None, outputFormat=None, method='{http://www.opengis.net/wfs}Get'):
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"""Request and return feature data as a file-like object.
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Parameters
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----------
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typename : list
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List of typenames (string)
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filter : string
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XML-encoded OGC filter expression.
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bbox : tuple
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(left, bottom, right, top) in the feature type's coordinates.
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featureid : list
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List of unique feature ids (string)
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featureversion : string
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Default is most recent feature version.
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propertyname : list
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List of feature property names. '*' matches all.
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maxfeatures : int
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Maximum number of features to be returned.
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method : string
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Qualified name of the HTTP DCP method to use.
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srsname: string
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EPSG code to request the data in
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outputFormat: string (optional)
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Requested response format of the request.
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There are 3 different modes of use
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1) typename and bbox (simple spatial query)
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2) typename and filter (more expressive)
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3) featureid (direct access to known features)
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"""
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try:
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base_url = next((m.get('url') for m in self.getOperationByName('GetFeature').methods if m.get('type').lower() == method.lower()))
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except StopIteration:
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base_url = self.url
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request = {'service': 'WFS', 'version': self.version, 'request': 'GetFeature'}
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# check featureid
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if featureid:
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request['featureid'] = ','.join(featureid)
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elif bbox and typename:
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request['bbox'] = ','.join([repr(x) for x in bbox])
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elif filter and typename:
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request['filter'] = str(filter)
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if srsname:
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request['srsname'] = str(srsname)
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assert len(typename) > 0
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request['typename'] = ','.join(typename)
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if propertyname:
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request['propertyname'] = ','.join(propertyname)
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if featureversion: request['featureversion'] = str(featureversion)
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if maxfeatures: request['maxfeatures'] = str(maxfeatures)
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if outputFormat is not None:
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request["outputFormat"] = outputFormat
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data = urlencode(request)
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log.debug("Making request: %s?%s" % (base_url, data))
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u = openURL(base_url, data, method)
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# check for service exceptions, rewrap, and return
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# We're going to assume that anything with a content-length > 32k
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# is data. We'll check anything smaller.
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try:
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length = int(u.info()['Content-Length'])
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have_read = False
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except (KeyError, AttributeError):
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data = u.read()
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have_read = True
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length = len(data)
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if length < 32000:
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if not have_read:
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data = u.read()
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try:
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tree = etree.fromstring(data)
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except BaseException:
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# Not XML
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return StringIO(data)
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else:
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if tree.tag == "{%s}ServiceExceptionReport" % OGC_NAMESPACE:
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se = tree.find(nspath('ServiceException', OGC_NAMESPACE))
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raise ServiceException(str(se.text).strip())
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else:
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return StringIO(data)
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else:
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if have_read:
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return StringIO(data)
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return u
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def getOperationByName(self, name):
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"""Return a named content item."""
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for item in self.operations:
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if item.name == name:
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return item
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raise KeyError, "No operation named %s" % name
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class ServiceIdentification(object):
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''' Implements IServiceIdentificationMetadata '''
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def __init__(self, infoset, version):
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self._root=infoset
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self.type = testXMLValue(self._root.find(nspath('Name')))
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self.version = version
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self.title = testXMLValue(self._root.find(nspath('Title')))
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self.abstract = testXMLValue(self._root.find(nspath('Abstract')))
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self.keywords = [f.text for f in self._root.findall(nspath('Keywords'))]
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self.fees = testXMLValue(self._root.find(nspath('Fees')))
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self.accessconstraints = testXMLValue(self._root.find(nspath('AccessConstraints')))
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class ServiceProvider(object):
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''' Implements IServiceProviderMetatdata '''
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def __init__(self, infoset):
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self._root = infoset
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self.name = testXMLValue(self._root.find(nspath('Name')))
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self.url = testXMLValue(self._root.find(nspath('OnlineResource')))
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self.keywords = extract_xml_list(self._root.find(nspath('Keywords')))
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class ContentMetadata:
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"""Abstraction for WFS metadata.
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Implements IMetadata.
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"""
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def __init__(self, elem, parent, parse_remote_metadata=False, timeout=30):
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"""."""
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self.id = testXMLValue(elem.find(nspath('Name')))
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self.title = testXMLValue(elem.find(nspath('Title')))
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self.abstract = testXMLValue(elem.find(nspath('Abstract')))
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self.keywords = [f.text for f in elem.findall(nspath('Keywords'))]
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# bboxes
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self.boundingBox = None
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b = elem.find(nspath('BoundingBox'))
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if b is not None:
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self.boundingBox = (float(b.attrib['minx']),float(b.attrib['miny']),
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float(b.attrib['maxx']), float(b.attrib['maxy']),
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b.attrib['SRS'])
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self.boundingBoxWGS84 = None
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b = elem.find(nspath('LatLongBoundingBox'))
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if b is not None:
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self.boundingBoxWGS84 = (
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float(b.attrib['minx']),float(b.attrib['miny']),
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float(b.attrib['maxx']), float(b.attrib['maxy']),
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)
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# crs options
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self.crsOptions = [Crs(srs.text) for srs in elem.findall(nspath('SRS'))]
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# verbs
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self.verbOptions = [op.tag for op \
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in parent.findall(nspath('Operations/*'))]
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self.verbOptions + [op.tag for op \
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in elem.findall(nspath('Operations/*')) \
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if op.tag not in self.verbOptions]
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#others not used but needed for iContentMetadata harmonisation
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self.styles=None
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self.timepositions=None
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self.defaulttimeposition=None
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# MetadataURLs
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self.metadataUrls = []
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for m in elem.findall(nspath('MetadataURL')):
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metadataUrl = {
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'type': testXMLValue(m.attrib['type'], attrib=True),
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'format': testXMLValue(m.find('Format')),
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'url': testXMLValue(m)
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}
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if metadataUrl['url'] is not None and parse_remote_metadata: # download URL
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try:
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content = urlopen(metadataUrl['url'], timeout=timeout)
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doc = etree.parse(content)
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if metadataUrl['type'] is not None:
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if metadataUrl['type'] == 'FGDC':
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metadataUrl['metadata'] = Metadata(doc)
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if metadataUrl['type'] == 'TC211':
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metadataUrl['metadata'] = MD_Metadata(doc)
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except Exception, err:
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metadataUrl['metadata'] = None
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self.metadataUrls.append(metadataUrl)
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class OperationMetadata:
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"""Abstraction for WFS metadata.
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Implements IMetadata.
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"""
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def __init__(self, elem):
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"""."""
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self.name = xmltag_split(elem.tag)
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# formatOptions
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self.formatOptions = [f.tag for f in elem.findall(nspath('ResultFormat/*'))]
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self.methods = []
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for verb in elem.findall(nspath('DCPType/HTTP/*')):
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url = verb.attrib['onlineResource']
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self.methods.append({'type' : xmltag_split(verb.tag), 'url': url})
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class WFSCapabilitiesReader(object):
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"""Read and parse capabilities document into a lxml.etree infoset
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"""
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def __init__(self, version='1.0'):
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"""Initialize"""
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self.version = version
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self._infoset = None
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def capabilities_url(self, service_url):
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"""Return a capabilities url
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"""
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qs = []
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if service_url.find('?') != -1:
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qs = cgi.parse_qsl(service_url.split('?')[1])
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params = [x[0] for x in qs]
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if 'service' not in params:
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qs.append(('service', 'WFS'))
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if 'request' not in params:
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qs.append(('request', 'GetCapabilities'))
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if 'version' not in params:
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qs.append(('version', self.version))
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urlqs = urlencode(tuple(qs))
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return service_url.split('?')[0] + '?' + urlqs
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def read(self, url, timeout=30):
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"""Get and parse a WFS capabilities document, returning an
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instance of WFSCapabilitiesInfoset
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Parameters
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----------
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url : string
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The URL to the WFS capabilities document.
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timeout : number
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A timeout value (in seconds) for the request.
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"""
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request = self.capabilities_url(url)
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u = urlopen(request, timeout=timeout)
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return etree.fromstring(u.read())
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def readString(self, st):
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"""Parse a WFS capabilities document, returning an
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instance of WFSCapabilitiesInfoset
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string should be an XML capabilities document
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"""
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if not isinstance(st, str):
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raise ValueError("String must be of type string, not %s" % type(st))
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return etree.fromstring(st)
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