source: TI05-delivery/ows_framework/branches/ows_framework-refactor/ows_common/ows_common/pylons/ows_controller.py @ 3553

Subversion URL: http://proj.badc.rl.ac.uk/svn/ndg/TI05-delivery/ows_framework/branches/ows_framework-refactor/ows_common/ows_common/pylons/ows_controller.py@3553
Revision 3553, 7.7 KB checked in by spascoe, 13 years ago (diff)

Moved all the model classes into their own sub-module.

Line 
1"""
2Base controller for OGC Web Services (OWS).
3
4@author: Stephen Pascoe
5@todo: Add pluggable security so replicate what was previously implemented
6    for the NDG discovery portal in ows_server.lib.BaseController.
7"""
8
9
10from pylons import request, response, config, c
11from pylons.controllers import WSGIController
12from pylons.templating import render
13from webhelpers import url_for
14
15from ows_common import exceptions as OWS_E
16from ows_common.util import negotiate_version, check_updatesequence
17from ows_common.builder import loadConfigFile
18from ows_common import helpers
19
20from ows_common.model import *
21
22from genshi.template import TemplateLoader
23from pkg_resources import resource_filename
24
25try:
26    from xml.etree import ElementTree as ET
27except ImportError:
28    from elementtree import ElementTree as ET
29
30import logging
31logger = logging.getLogger(__name__)
32
33# Instantiate Genshi template loader
34templateLoader = TemplateLoader(
35    resource_filename('ows_common.pylons', 'templates'),
36    auto_reload=True,
37    )
38
39# Configure
40#!TODO: rename this configuration object to something non-NDG specific
41#EXCEPTION_TYPE = request.environ['ndgConfig'].get('OWS_SERVER', 'exception_type', 'ogc').lower()
42EXCEPTION_TYPE = config.get('ows_server.exception_type', 'ogc')
43
44
45
46class OWSControllerBase(WSGIController):
47    """
48    @ivar owsParams: A dictionary of parameters passed to the service.
49        Initially these comes from the query string but could come from
50        a HTTP POST in future.
51    @cvar owsOperations: A list of operation names
52   
53    """
54
55    owsOperations = []
56   
57    def __call__(self, environ, start_response):
58
59        self._loadOwsParams()
60
61        # If the EXCEPTION_TYPE is 'pylons' let Pylons catch any exceptions.
62        # Otherwise send an OGC exception report for any OWS_E.OwsError
63        if 'pylons' in EXCEPTION_TYPE:
64            self._fixOwsAction(environ)
65            return super(OWSControllerBase, self).__call__(environ, start_response)
66        else:
67            try:
68                self._fixOwsAction(environ)
69                return super(OWSControllerBase, self).__call__(environ, start_response)
70            except OWS_E.OwsError, e:
71                logger.exception(e)
72
73                tmpl = templateLoader.load('exception_report.xml')
74                response.write(tmpl.generate(report=e.report).render('xml'))
75                response.headers['content-type'] = 'text/xml'
76                return response
77
78    def _loadOwsParams(self):
79        # All OWS parameter names are case insensitive.
80        self._owsParams = {}
81        for k in request.params:
82            self._owsParams[k.lower()] = request.params[k]
83
84    def _fixOwsAction(self, environ):
85        rdict = environ['pylons.routes_dict']
86       
87        # Override the Routes action from the request query parameter
88        action = self.getOwsParam('request')
89
90        # Check action is a method in self and is defined as an OWS operation
91        if action not in self.owsOperations:
92            raise OWS_E.InvalidParameterValue('request=%s not supported' % action,
93                                              'REQUEST')
94        rdict['action'] = action
95
96    def getOwsParam(self, param, **kwargs):
97        """
98        Returns the value of a OWS parameter passed to the operation.
99        If argv['default'] is given it is taken to be the default
100        value otherwise the parameter is treated as manditory and an
101        exception is raised if the parameter is not present.
102
103        """
104        try:
105            return self._owsParams[param.lower()]
106        except KeyError:
107            if 'default' in kwargs:
108                return kwargs['default']
109            else:
110                raise OWS_E.MissingParameterValue('%s parameter is not specified' % param,
111                                                  param)
112
113#-----------------------------------------------------------------------------
114# Functions that populate c.capabilities
115
116def addOperation(opName, formats=[]):
117    ops = c.capabilities.operationsMetadata.operationDict
118    ops[opName] = helpers.operation(url_for(qualified=True, action="index")+'?', formats=formats)
119
120def addLayer(name, title, abstract, srss, bbox, dimensions={}):
121    """
122    @param dimensions: Dictionary of dictionaries D[k1][k2]=val where
123        k1 is dimension name, k2 is a keyword parameter to send to
124        helpers.wms_dimension and val is it's value.
125
126    @todo: The helpers interface is leaking through.  Could make cleaner.
127
128    """
129       
130    if c.capabilities.contents is None:
131        c.capabilities.contents = Contents()
132
133    layer = helpers.wms_layer(name, title, srss, bbox, abstract)
134
135    for k1, kwargs in dimensions.items():
136        dim = helpers.wms_dimension(**kwargs)
137        layer.dimensions[k1] = dim
138
139    c.capabilities.contents.datasetSummaries.append(layer)
140
141def initCapabilities():
142    """
143    Initialise the capabilities object c.capabilities.
144
145    By default the server-wide configuration file is loaded and
146    used to populate some standard metadata.  The GetCapabilites
147    operation is added.
148
149    """
150    # Load the basic ServiceMetadata from a config file
151    configFile = config.get('ows_server.capabilities_config')
152    c.capabilities = loadConfigFile(configFile)
153
154    om = OperationsMetadata(operationDict={})
155    c.capabilities.operationsMetadata = om
156
157    addOperation('GetCapabilities', formats=['text/xml'])
158
159#-----------------------------------------------------------------------------
160
161class OWSController(OWSControllerBase):
162    """
163    Adds basic GetCapabilities response to OWSControllerBase.
164
165    @cvar service: If None does not enforce the SERVICE parameter.  Otherwise
166        raises exception if SERVICE is not correct on GetCapabilities request.
167    @cvar validVersions: A list of supported version numbers.  Automatic
168        version negotiation is performed according to this attribute.
169   
170    @ivar updateSequence: None if cache-control is not supported or an
171        updateSequence identifier.  This attribute should be set in the
172        controller's __before__() method.
173    """
174
175    owsOperations = ['GetCapabilities']
176
177    # Override these attributes to control how OWSController responds to
178    # GetCapabilities
179    service = None
180    validVersions = NotImplemented
181
182    # To enable cache control set this instance attribute in self.__before__().
183    updateSequence = None
184   
185    def GetCapabilities(self):
186
187        # Retrieve Operation parameters
188        service = self.getOwsParam('service')
189        version = self.getOwsParam('version', default=None)
190        format = self.getOwsParam('format', default='text/xml')
191        updateSequence = self.getOwsParam('updatesequence', default=None)
192
193        # Check update sequence
194        check_updatesequence(self.updateSequence, updateSequence)
195
196        # Do version negotiation
197        version = negotiate_version(self.validVersions, version)
198
199        # Get information required for the capabilities document
200        initCapabilities()
201        self._loadCapabilities()
202       
203        # Render the capabilities document       
204        response.headers['content-type'] = format
205        return self._renderCapabilities(version, format)
206
207
208    def _loadCapabilities(self):
209        """
210        Override in subclasses to populate c.capabilities with
211        operation and contents metadata.
212
213        """
214        pass
215
216    def _renderCapabilities(self, version, format):
217        """
218        Override in subclases to render the capabilities document.
219        The response mime-type will already have been set.  Raise an
220        OWS exception if the format is not supported.
221
222        @param version: the version as a string
223        @param format: the format as a string
224       
225        @return: a template as expected by pylons.render()
226        """
227        raise NotImplementedError
228
229   
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