Extensions/wms/parser.py

# Copyright (c) 2004 by Intevation GmbH
# Authors:
# Martin Schulze <[email protected]>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

"""
Inspect WMS Capabilities for later processing.

Information should only be retrieved with the proper get*() methods.

class WMSCapabilitiesParser:
    __init__()

    grok(string)

    getTitle()
    getAbstract()
    getFees()
    getAccessConstraints()
    getFormats()
    getLayers()
    getSRS()

    getLayerTitle(layer)
    getLayerSRS(layer)
    getLayerLatLonBBox(layer)
    getLayerBBox(layer, srs)

    isQueryable(layer)

    get_srs_discrepancies()
"""

__version__ = "$Revision$"
# $Source$
# $Id$

import xml.dom.minidom

from domutils import getElementsByName, getElementByName

from Thuban import _

class WMSCapabilitiesParser:
    """
    Thuban class to parse capabilities supplied as large string.

    This class provides methods to parse and retrieve particular
    information from the WMS capabilities XML.  Information should
    only be extracted by the respective get*() methods.
    """

    layers = None
    title = None
    abstract = None
    fees = None
    access = None
    formats = None
    srs_discrepancies = None
    error = None


    def __init__(self):
        """
        Initialises an instance in this class.
        """

        # Note that we must not initialise internal variables of the
        # class in a mutable way or it will be shared among all
        # instances.  None is immutable, [] is not.
        self.error = []


    def grok(self, data):
        """
        Parses the XML response to a WMS GetCapabilities request.

        Internal datastructure of the class will be filled.
        Information should only be retrieved with the respective
        get*() methods.
        """
        xml_dom = xml.dom.minidom.parseString(data)
        root = xml_dom.documentElement

        # Extract the title
        foo = getElementByName(getElementByName(root, 'Service'), 'Title')
        if foo:
            self.title = foo.childNodes[0].data
        
        # Extract the abstract
        foo = getElementByName(getElementByName(root, 'Service'), 'Abstract')
        if foo and len(foo.childNodes[0].data):
            self.abstract = foo.childNodes[0].data
        
        # Extract fees information
        foo = getElementByName(getElementByName(root, 'Service'), 'Fees')
        if foo and len(foo.childNodes[0].data) \
               and foo.childNodes[0].data.lower() != 'none':
            self.fees = foo.childNodes[0].data
        
        # Extract access information
        foo = getElementByName(getElementByName(root, 'Service'),
                               'AccessConstraints')
        if foo and len(foo.childNodes[0].data) \
               and foo.childNodes[0].data.lower() != 'none':
            self.access = foo.childNodes[0].data
        
        # Extract output format information
        foo = getElementsByName(
            getElementByName(getElementByName(getElementByName(
            root, 'Capability'), 'Request'), 'GetMap'), 'Format')
        self.formats = map((lambda i: i.childNodes[0].data), foo)

        # Extract layer names
        self.layers = []
        self.peekLayers(getElementByName(getElementByName(
            root, 'Capability'), 'Layer'), -1)

        xml_dom.unlink()


    def peekLayers(self, top, parent):
        """
        Inspect the provided DOM fragment referenced as top.

        This method will inspect all included layers and traverse the
        tree recursively in order to fill the internal datastructure.

        Note that SRS other than EPSG:* are not yet supported,
        especially there is no support for AUTO and NONE.
        """

        index = len (self.layers)
        self.layers.append({})
        self.layers[index]['parent'] = parent

        for foo in top.attributes.keys():
            if foo == 'queryable':
                self.layers[index]['queryable'] \
                    = int(top.attributes.get(foo).nodeValue)

        foo = getElementByName(top, 'Title')
        if foo and len(foo.childNodes[0].data):
            self.layers[index]['title'] = foo.childNodes[0].data
        else:
            # A <Title> is required for each layer, <name> is optional
            # See OGC 01-068r3, 7.1.4.5.1 and 7.1.4.5.2
            self.error.append(_("No title found for layer #%d") % index)

        foo = getElementByName(top, 'Name')
        if foo and len(foo.childNodes[0].data):
            self.layers[index]['name'] = foo.childNodes[0].data

        # These values are only used for an integrity check
        for foo in getElementsByName(top, 'SRS'):
            for srs in foo.childNodes[0].data.split(" "):
                if srs[0:5] == 'EPSG:':
                    srs = srs[5:]
                try:
                    self.layers[index]['srs'].append(srs)
                except KeyError:
                    self.layers[index]['srs'] = [srs]

        foo = getElementByName(top, 'LatLonBoundingBox')
        if foo is not None:
            self.layers[index]['llbbox'] = {}
            for corner in ['minx', 'miny', 'maxx', 'maxy']:
                self.layers[index]['llbbox'][corner] \
                    = foo.attributes.get(corner).nodeValue

        boxes = getElementsByName(top, 'BoundingBox')
        if boxes != []:
            self.layers[index]['bbox'] = {}
        for foo in boxes:
            srs = foo.attributes.get('SRS').nodeValue
            if srs[0:5] == 'EPSG:':
                srs = srs[5:]
            self.layers[index]['bbox'][srs] = {}
            for corner in ['minx', 'miny', 'maxx', 'maxy']:
                self.layers[index]['bbox'][srs][corner] \
                    = foo.attributes.get(corner).nodeValue
            
        # Traverse subsidiary layers
        sublayer = getElementsByName(top, 'Layer')
        for l in sublayer:
            self.peekLayers(l, index)


    def getTitle(self):
        """
        Returns the main title of the WMS object.

        If no title is provided in the capabilities, an empty string
        is returned.
        """
        if self.title is None:
            return ''
        else:
            return self.title


    def getAbstract(self):
        """
        Returns the abstract of the WMS object.

        If no abstract is provided in the capabilities, an empty
        string is returned.
        """
        if self.abstract is None:
            return ''
        else:
            return self.abstract


    def getFees(self):
        """
        Returns the fees information of the WMS object.

        If no information is provided in the capabilities or if it is
        set to 'none', an empty string is returned.
        """
        if self.fees is None:
            return ''
        else:
            return self.fees


    def getAccessConstraints(self):
        """
        Returns information about access constraints for the WMS object.

        If no information is provided in the capabilities or if it is
        set to 'none', an empty string is returned.
        """
        if self.access is None:
            return ''
        else:
            return self.access


    def getFormats(self):
        """
        Returns a list of supported output formats.

        These are used in the GetMap request.  This method will
        default to 'image/jpeg' if no format is recognised in XML
        Capabilities, assuming that JPEG will always be supported on
        the server side.
        """
        if self.formats is None:
            return ['image/jpeg']
        else:
            return self.formats

    def getLayers(self):
        """
        Returns a list of layer names.

        Only named layers will be returned, since a layer may have a
        title but doesn't have to have a name associated to it as
        well.  If no layers were found, an empty list is returned.
        """
        result = []
        for layer in self.layers:
            if 'name' in layer:
                result.append(layer['name'])

        return result


    def getSRS(self):
        """
        Returns the root list of spatial reference systems (SRS).

        This list is taken from the root layer.  Those SRS are common
        to all subsidiary layers.  If no SRS are common to all layers,
        an empty list is returned.  If no layers were detected, an
        empty list is returned as well.
        """
        if len(self.layers) == 0:
            return []

        # index 0 denotes the root layer by design
        if 'srs' in self.layers[0].keys():
            return self.layers[0]['srs']


    def getLayerTitle(self, name):
        """
        Returns the title of the named layer.

        If no such title or no such layer exists, an empty string is
        returned.
        """
        for layer in self.layers:
            if 'name' in layer:
                if layer['name'] == name:
                    if 'title' in layer:
                        return layer['title']

        return ''


    def getLayerSRS(self, name):
        """
        Returns a list of spacial reference systems (SRS).

        The SRS are specified by the European Petroleum Survey Group
        (EPSG).  There should be at least one SRS per layer, though.
        The prefix 'EPSG:' will be stripped.  If none exists, an empty
        list is returned.

        The specification [OGC 01-068r3] says about inheritance of
        SRS:

        - Every layer is available in one or more SRS (or in an
          undefined SRS)

        - Geographic information whose SRS is undefined
          (e.g. digitised historical maps) shall use 'NONE'
          (case-sensitive).  This implementation does not support
          this.

        - Every layer shall have at least one SRS element that is
          either stated explicitly or inherited from a parent layer.

        - The root layer element shall include a sequence of zero or
          more SRS elements listing all SRS which are common for to
          all subsidiary layers.

        - Layers may optionally add to the global SRS list, or to the
          list inherited from a parent layer.

        - A server which has the ability to transform data to
          different SRSes may choose not to provide an explicit
          BoundingBox for every possible SRS available for each Layer.
          Thus the list of <SRS> elements are authoritative.

        This implementation returns the list of SRS for the given
        layer, calculated by looking at BoundingBoxes defined in the
        named layer and all layers higher in the hierarchy up to the
        root layer which weren't overwritten.
        """
        for i in range(len(self.layers)):
            if 'name' in self.layers[i]:
                if self.layers[i]['name'] == name:
                    pivot = i
                    break
        else:
            return []

        result = []
        while pivot != -1:
            if 'srs' in self.layers[pivot]:
                for srs in self.layers[pivot]['srs']:
                    if srs not in result:
                        result.append(srs)
            pivot = self.layers[pivot]['parent']

        return result


    def getLayerLatLonBBox(self, name):
        """
        Returns a dictionary of the LatLonBoundingBox.

        ... for the named layer if it exists.  The SRS is always
        EPSG:4326 per convention.  There should be at least one,
        though, inherited from the root layer at least.  If none
        exists, the value None is returned.
        """
        for layer in self.layers:
            if 'name' in layer:
                if layer['name'] == name:
                    if 'llbbox' in layer:
                        return layer['llbbox']
                    else:
                        # No LatLonBoundingBox found in current layer,
                        # so traverse the hierarchy upwards and check
                        # again until there is one.
                        pivot = layer
                        while pivot['parent'] != -1:
                            pivot = self.layers[pivot['parent']]
                            if 'llbbox' in pivot:
                                return pivot['llbbox']

        return None


    def getLayerBBox(self, name, srs):
        """
        Returns a dictionary of the BoundingBox.

        If no such BoundingBox exists, None is returned.

        The specification [OGC 01-068r3] says about BoundingBoxes:

        - Layers may have zero or more BoundingBox elements what are
          either stated explicitly or inherited from a parent layer.

        - A layer may have multiple BoundingBox elements, but each one
          shall state a different SRS.

        - A layer inherits any BoundingBoxes defined by its
          parents.

        - A BoundingBox inherited from the parent layer for a
          particular SRS is replaced by any declaration for the same
          SRS in the current layer.

        - A BoundingBox in the child layer for a new SRS which is not
          already declared by the parent, is added to the list of
          BoundingBoxes for the child layer.

        - A single layer shall not contain more than one BoundingBox
          element for the same SRS.
        """
        for layer in self.layers:
            if 'name' in layer:
                if layer['name'] == name:
                    if 'bbox' in layer:
                        if srs in layer['bbox']:
                            return layer['bbox'][srs]
                    
                    # No BoundingBox for the given SRS found in
                    # current layer, so traverse the hierarchy upwards
                    # and check again until there is one.
                    pivot = layer
                    while pivot['parent'] != -1:
                        pivot = self.layers[pivot['parent']]
                        if 'bbox' in pivot:
                            if srs in pivot['bbox']:
                                return pivot['bbox'][srs]

        return None


    def isQueryable(self, name):
        """
        Returns the value of the queryable attribute of a layer.

        This attribute denotes whether this layer can be queried
        through the GetFeatureInfo request.  The default value is 0.

        The specification [OGC 01-068r3] this attribute can be
        inherited.
        """

        for layer in self.layers:
            if 'name' in layer:
                if layer['name'] == name:
                    try:
                        return layer['queryable']
                    except KeyError:
                        # No attribute in this layer, so traverse the
                        # hierarchy upwards
                        pivot = layer
                        while pivot['parent'] != -1:
                            pivot = self.layers[pivot['parent']]
                            if 'queryable' in pivot:
                                return pivot['queryable']
        return 0


    def get_srs_discrepancies(self):
        """
        Returns a list of layer identifications where the denoted SRS
        values differ from the calculated ones through BoundingBox
        elements.
        """
        return self.srs_discrepancies


if __name__ == "__main__":
    print "This module cannot be executed standalone."

    import os

    sample = "test/sample.xml"
    try:
        f = open(sample, "r")
    except IOError:
        try:
            f = open(os.path.dirname(__file__) + "/" + sample, "r")
        except IOError:
            print "Cannot open %s for reading" % sample

    if f is not None:
        sample = f.read();
        f.close()
        
        ina = WMSCapabilitiesParser()
        ina.grok(sample)
1	joey	2133	# Copyright (c) 2004 by Intevation GmbH
2			# Authors:
3			# Martin Schulze <[email protected]>
4			#
5			# This program is free software; you can redistribute it and/or modify
6			# it under the terms of the GNU General Public License as published by
7			# the Free Software Foundation; either version 2 of the License, or
8			# (at your option) any later version.
9			#
10			# This program is distributed in the hope that it will be useful,
11			# but WITHOUT ANY WARRANTY; without even the implied warranty of
12			# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13			# GNU General Public License for more details.
14			#
15			# You should have received a copy of the GNU General Public License
16			# along with this program; if not, write to the Free Software
17			# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18
19			"""
20			Inspect WMS Capabilities for later processing.
21
22			Information should only be retrieved with the proper get*() methods.
23
24			class WMSCapabilitiesParser:
25			__init__()
26
27			grok(string)
28
29			getTitle()
30			getAbstract()
31			getFees()
32			getAccessConstraints()
33			getFormats()
34			getLayers()
35			getSRS()
36
37			getLayerTitle(layer)
38			getLayerSRS(layer)
39			getLayerLatLonBBox(layer)
40			getLayerBBox(layer, srs)
41
42			isQueryable(layer)
43
44			get_srs_discrepancies()
45			"""
46
47			__version__ = "$Revision$"
48			# $Source$
49			# $Id$
50
51			import xml.dom.minidom
52
53			from domutils import getElementsByName, getElementByName
54
55	joey	2165	from Thuban import _
56
57	joey	2133	class WMSCapabilitiesParser:
58			"""
59			Thuban class to parse capabilities supplied as large string.
60
61			This class provides methods to parse and retrieve particular
62			information from the WMS capabilities XML. Information should
63			only be extracted by the respective get*() methods.
64			"""
65
66			layers = None
67			title = None
68			abstract = None
69			fees = None
70			access = None
71			formats = None
72			srs_discrepancies = None
73	joey	2165	error = None
74	joey	2133
75
76			def __init__(self):
77			"""
78			Initialises an instance in this class.
79			"""
80
81			# Note that we must not initialise internal variables of the
82			# class in a mutable way or it will be shared among all
83			# instances. None is immutable, [] is not.
84	joey	2165	self.error = []
85	joey	2133
86
87			def grok(self, data):
88			"""
89			Parses the XML response to a WMS GetCapabilities request.
90
91			Internal datastructure of the class will be filled.
92			Information should only be retrieved with the respective
93			get*() methods.
94			"""
95	joey	2153	xml_dom = xml.dom.minidom.parseString(data)
96			root = xml_dom.documentElement
97	joey	2133
98			# Extract the title
99			foo = getElementByName(getElementByName(root, 'Service'), 'Title')
100			if foo:
101			self.title = foo.childNodes[0].data
102
103			# Extract the abstract
104			foo = getElementByName(getElementByName(root, 'Service'), 'Abstract')
105			if foo and len(foo.childNodes[0].data):
106			self.abstract = foo.childNodes[0].data
107
108			# Extract fees information
109			foo = getElementByName(getElementByName(root, 'Service'), 'Fees')
110			if foo and len(foo.childNodes[0].data) \
111	joey	2155	and foo.childNodes[0].data.lower() != 'none':
112	joey	2133	self.fees = foo.childNodes[0].data
113
114			# Extract access information
115			foo = getElementByName(getElementByName(root, 'Service'),
116			'AccessConstraints')
117			if foo and len(foo.childNodes[0].data) \
118	joey	2155	and foo.childNodes[0].data.lower() != 'none':
119	joey	2133	self.access = foo.childNodes[0].data
120
121			# Extract output format information
122			foo = getElementsByName(
123			getElementByName(getElementByName(getElementByName(
124			root, 'Capability'), 'Request'), 'GetMap'), 'Format')
125			self.formats = map((lambda i: i.childNodes[0].data), foo)
126
127			# Extract layer names
128			self.layers = []
129			self.peekLayers(getElementByName(getElementByName(
130			root, 'Capability'), 'Layer'), -1)
131
132	joey	2153	xml_dom.unlink()
133	joey	2133
134	joey	2153
135	joey	2133	def peekLayers(self, top, parent):
136			"""
137			Inspect the provided DOM fragment referenced as top.
138
139			This method will inspect all included layers and traverse the
140			tree recursively in order to fill the internal datastructure.
141
142			Note that SRS other than EPSG:* are not yet supported,
143			especially there is no support for AUTO and NONE.
144			"""
145
146			index = len (self.layers)
147			self.layers.append({})
148			self.layers[index]['parent'] = parent
149
150			for foo in top.attributes.keys():
151			if foo == 'queryable':
152			self.layers[index]['queryable'] \
153			= int(top.attributes.get(foo).nodeValue)
154
155			foo = getElementByName(top, 'Title')
156			if foo and len(foo.childNodes[0].data):
157			self.layers[index]['title'] = foo.childNodes[0].data
158	joey	2165	else:
159			# A <Title> is required for each layer, <name> is optional
160			# See OGC 01-068r3, 7.1.4.5.1 and 7.1.4.5.2
161			self.error.append(_("No title found for layer #%d") % index)
162	joey	2133
163			foo = getElementByName(top, 'Name')
164			if foo and len(foo.childNodes[0].data):
165			self.layers[index]['name'] = foo.childNodes[0].data
166
167			# These values are only used for an integrity check
168			for foo in getElementsByName(top, 'SRS'):
169			for srs in foo.childNodes[0].data.split(" "):
170			if srs[0:5] == 'EPSG:':
171			srs = srs[5:]
172			try:
173			self.layers[index]['srs'].append(srs)
174			except KeyError:
175			self.layers[index]['srs'] = [srs]
176
177			foo = getElementByName(top, 'LatLonBoundingBox')
178			if foo is not None:
179			self.layers[index]['llbbox'] = {}
180			for corner in ['minx', 'miny', 'maxx', 'maxy']:
181			self.layers[index]['llbbox'][corner] \
182			= foo.attributes.get(corner).nodeValue
183
184			boxes = getElementsByName(top, 'BoundingBox')
185			if boxes != []:
186			self.layers[index]['bbox'] = {}
187			for foo in boxes:
188			srs = foo.attributes.get('SRS').nodeValue
189			if srs[0:5] == 'EPSG:':
190			srs = srs[5:]
191			self.layers[index]['bbox'][srs] = {}
192			for corner in ['minx', 'miny', 'maxx', 'maxy']:
193			self.layers[index]['bbox'][srs][corner] \
194			= foo.attributes.get(corner).nodeValue
195
196			# Traverse subsidiary layers
197			sublayer = getElementsByName(top, 'Layer')
198			for l in sublayer:
199			self.peekLayers(l, index)
200
201
202			def getTitle(self):
203			"""
204			Returns the main title of the WMS object.
205
206			If no title is provided in the capabilities, an empty string
207			is returned.
208			"""
209			if self.title is None:
210			return ''
211			else:
212			return self.title
213
214
215			def getAbstract(self):
216			"""
217			Returns the abstract of the WMS object.
218
219			If no abstract is provided in the capabilities, an empty
220			string is returned.
221			"""
222			if self.abstract is None:
223			return ''
224			else:
225			return self.abstract
226
227
228			def getFees(self):
229			"""
230			Returns the fees information of the WMS object.
231
232			If no information is provided in the capabilities or if it is
233			set to 'none', an empty string is returned.
234			"""
235			if self.fees is None:
236			return ''
237			else:
238			return self.fees
239
240
241			def getAccessConstraints(self):
242			"""
243			Returns information about access constraints for the WMS object.
244
245			If no information is provided in the capabilities or if it is
246			set to 'none', an empty string is returned.
247			"""
248			if self.access is None:
249			return ''
250			else:
251			return self.access
252
253
254			def getFormats(self):
255			"""
256			Returns a list of supported output formats.
257
258			These are used in the GetMap request. This method will
259			default to 'image/jpeg' if no format is recognised in XML
260			Capabilities, assuming that JPEG will always be supported on
261			the server side.
262			"""
263			if self.formats is None:
264			return ['image/jpeg']
265			else:
266			return self.formats
267
268			def getLayers(self):
269			"""
270			Returns a list of layer names.
271
272			Only named layers will be returned, since a layer may have a
273			title but doesn't have to have a name associated to it as
274			well. If no layers were found, an empty list is returned.
275			"""
276			result = []
277			for layer in self.layers:
278			if 'name' in layer:
279			result.append(layer['name'])
280
281			return result
282
283
284			def getSRS(self):
285			"""
286			Returns the root list of spatial reference systems (SRS).
287
288			This list is taken from the root layer. Those SRS are common
289			to all subsidiary layers. If no SRS are common to all layers,
290			an empty list is returned. If no layers were detected, an
291			empty list is returned as well.
292			"""
293			if len(self.layers) == 0:
294			return []
295
296			# index 0 denotes the root layer by design
297			if 'srs' in self.layers[0].keys():
298			return self.layers[0]['srs']
299
300
301			def getLayerTitle(self, name):
302			"""
303			Returns the title of the named layer.
304
305			If no such title or no such layer exists, an empty string is
306			returned.
307			"""
308			for layer in self.layers:
309			if 'name' in layer:
310			if layer['name'] == name:
311			if 'title' in layer:
312			return layer['title']
313
314			return ''
315
316
317			def getLayerSRS(self, name):
318			"""
319			Returns a list of spacial reference systems (SRS).
320
321			The SRS are specified by the European Petroleum Survey Group
322			(EPSG). There should be at least one SRS per layer, though.
323			The prefix 'EPSG:' will be stripped. If none exists, an empty
324			list is returned.
325
326			The specification [OGC 01-068r3] says about inheritance of
327			SRS:
328
329			- Every layer is available in one or more SRS (or in an
330			undefined SRS)
331
332			- Geographic information whose SRS is undefined
333			(e.g. digitised historical maps) shall use 'NONE'
334			(case-sensitive). This implementation does not support
335			this.
336
337			- Every layer shall have at least one SRS element that is
338			either stated explicitly or inherited from a parent layer.
339
340			- The root layer element shall include a sequence of zero or
341			more SRS elements listing all SRS which are common for to
342			all subsidiary layers.
343
344			- Layers may optionally add to the global SRS list, or to the
345			list inherited from a parent layer.
346
347	joey	2144	- A server which has the ability to transform data to
348			different SRSes may choose not to provide an explicit
349			BoundingBox for every possible SRS available for each Layer.
350			Thus the list of <SRS> elements are authoritative.
351
352	joey	2133	This implementation returns the list of SRS for the given
353			layer, calculated by looking at BoundingBoxes defined in the
354			named layer and all layers higher in the hierarchy up to the
355			root layer which weren't overwritten.
356			"""
357			for i in range(len(self.layers)):
358			if 'name' in self.layers[i]:
359			if self.layers[i]['name'] == name:
360			pivot = i
361			break
362			else:
363			return []
364
365			result = []
366			while pivot != -1:
367	joey	2144	if 'srs' in self.layers[pivot]:
368			for srs in self.layers[pivot]['srs']:
369	joey	2133	if srs not in result:
370			result.append(srs)
371			pivot = self.layers[pivot]['parent']
372
373			return result
374
375
376			def getLayerLatLonBBox(self, name):
377			"""
378			Returns a dictionary of the LatLonBoundingBox.
379
380			... for the named layer if it exists. The SRS is always
381			EPSG:4326 per convention. There should be at least one,
382			though, inherited from the root layer at least. If none
383			exists, the value None is returned.
384			"""
385			for layer in self.layers:
386			if 'name' in layer:
387			if layer['name'] == name:
388			if 'llbbox' in layer:
389			return layer['llbbox']
390			else:
391			# No LatLonBoundingBox found in current layer,
392			# so traverse the hierarchy upwards and check
393			# again until there is one.
394			pivot = layer
395			while pivot['parent'] != -1:
396			pivot = self.layers[pivot['parent']]
397			if 'llbbox' in pivot:
398			return pivot['llbbox']
399
400			return None
401
402
403			def getLayerBBox(self, name, srs):
404			"""
405			Returns a dictionary of the BoundingBox.
406
407			If no such BoundingBox exists, None is returned.
408
409			The specification [OGC 01-068r3] says about BoundingBoxes:
410
411			- Layers may have zero or more BoundingBox elements what are
412			either stated explicitly or inherited from a parent layer.
413
414			- A layer may have multiple BoundingBox elements, but each one
415			shall state a different SRS.
416
417			- A layer inherits any BoundingBoxes defined by its
418			parents.
419
420			- A BoundingBox inherited from the parent layer for a
421			particular SRS is replaced by any declaration for the same
422			SRS in the current layer.
423
424			- A BoundingBox in the child layer for a new SRS which is not
425			already declared by the parent, is added to the list of
426			BoundingBoxes for the child layer.
427
428			- A single layer shall not contain more than one BoundingBox
429			element for the same SRS.
430			"""
431			for layer in self.layers:
432			if 'name' in layer:
433			if layer['name'] == name:
434			if 'bbox' in layer:
435			if srs in layer['bbox']:
436			return layer['bbox'][srs]
437
438			# No BoundingBox for the given SRS found in
439			# current layer, so traverse the hierarchy upwards
440			# and check again until there is one.
441			pivot = layer
442			while pivot['parent'] != -1:
443			pivot = self.layers[pivot['parent']]
444			if 'bbox' in pivot:
445			if srs in pivot['bbox']:
446			return pivot['bbox'][srs]
447
448			return None
449
450
451			def isQueryable(self, name):
452			"""
453			Returns the value of the queryable attribute of a layer.
454
455			This attribute denotes whether this layer can be queried
456			through the GetFeatureInfo request. The default value is 0.
457
458			The specification [OGC 01-068r3] this attribute can be
459			inherited.
460			"""
461
462			for layer in self.layers:
463			if 'name' in layer:
464			if layer['name'] == name:
465			try:
466			return layer['queryable']
467			except KeyError:
468			# No attribute in this layer, so traverse the
469			# hierarchy upwards
470			pivot = layer
471			while pivot['parent'] != -1:
472			pivot = self.layers[pivot['parent']]
473			if 'queryable' in pivot:
474			return pivot['queryable']
475			return 0
476
477
478			def get_srs_discrepancies(self):
479			"""
480			Returns a list of layer identifications where the denoted SRS
481			values differ from the calculated ones through BoundingBox
482			elements.
483			"""
484			return self.srs_discrepancies
485
486
487			if __name__ == "__main__":
488			print "This module cannot be executed standalone."
489
490			import os
491
492	joey	2164	sample = "test/sample.xml"
493	joey	2133	try:
494	joey	2164	f = open(sample, "r")
495	joey	2133	except IOError:
496			try:
497	joey	2164	f = open(os.path.dirname(__file__) + "/" + sample, "r")
498	joey	2133	except IOError:
499	joey	2164	print "Cannot open %s for reading" % sample
500	joey	2133
501			if f is not None:
502			sample = f.read();
503			f.close()
504
505			ina = WMSCapabilitiesParser()
506			ina.grok(sample)
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