.. _filter_encoding: ***************************************************************************** WFS Filter Encoding ***************************************************************************** :Author: Jeff McKenna :Contact: jmckenna at gatewaygeomatics.com :Author: Yewondwossen Assefa :Contact: assefa at dmsolutions.ca :Revision: $Revision$ :Date: $Date$ :Last Updated: 2005/09/23 .. contents:: Table of Contents :depth: 2 :backlinks: top Introduction ============ This document describes the procedures for taking advantage of the Filter Encoding (FE) support in WFS GetFeature requests, which was added to MapServer in version 4.2. This document assumes that you are already familiar with the following aspects of MapServer: - MapServer application development and setting up .map files. - Familiarity with the WFS specification would be an asset. Links to the MapServer WFS documents are included in the next section. Links to SLD-related Information -------------------------------- - `Filter Encoding Implementation Specification`_. - :ref:`MapServer WFS Client Howto `. - :ref:`MapServer WFS Server Howto `. - `MapServer OGC Web Services Workshop`_. - `Open GIS Consortium (OGC) home page`_. .. _`Filter Encoding Implementation Specification`: http://www.opengeospatial.org/docs/02-059.pdf .. _`Open GIS Consortium (OGC) home page`: http://www.opengeospatial.org .. _`MapServer OGC Web Services Workshop`: http://ms-ogc-workshop.maptools.org/ Currently Supported Features ============================ The following table lists the currently supported features for FE. **Table 1. Currently Supported Features** +----------------------+-------------------------------------+ | Feature Set | Feature | +======================+=====================================+ | Spatial Capabilities | | +----------------------+-------------------------------------+ | | Equals | +----------------------+-------------------------------------+ | | Disjoint | +----------------------+-------------------------------------+ | | Touches | +----------------------+-------------------------------------+ | | Within | +----------------------+-------------------------------------+ | | Overlaps | +----------------------+-------------------------------------+ | | Crosses | +----------------------+-------------------------------------+ | | Intersects | +----------------------+-------------------------------------+ | | Contains | +----------------------+-------------------------------------+ | | DWithin | +----------------------+-------------------------------------+ | | BBOX | +----------------------+-------------------------------------+ | Scalar Capabilities | | +----------------------+-------------------------------------+ | | | +----------------------+-------------------------------------+ | Logical Operators | | +----------------------+-------------------------------------+ | | And | +----------------------+-------------------------------------+ | | Or | +----------------------+-------------------------------------+ | | Not | +----------------------+-------------------------------------+ | Comparison Operators | | +----------------------+-------------------------------------+ | | PropertyIsEqualTo (=) | +----------------------+-------------------------------------+ | | PropertyIsNotEqualTo (<>) | +----------------------+-------------------------------------+ | | PropertyIsLessThan (<) | +----------------------+-------------------------------------+ | | PropertyIsGreaterThan (>) | +----------------------+-------------------------------------+ | | PropertyIsLessThanOrEqualTo (<=) | +----------------------+-------------------------------------+ | | PropertyIsGreaterThanOrEqualTo (>=) | +----------------------+-------------------------------------+ | | PropertyIsLike | +----------------------+-------------------------------------+ | | PropertyIsBetween (range) | +----------------------+-------------------------------------+ Get and Post Requests ===================== MapServer already has the capability to receive and parse Get requests and URL-encoded Post requests. The ability for MapServer to be able to receive Post requests with XML-encoded information sent in the body of the request has been added. Also, the ability to generate XML-encoded Post requests for WFS layers has been added. Both Get and Post request are now supported for all WFS requests: - GetCapabilities - GetFeatures - DescribeFeatureType Supporting these WFS requests in Post was implemented to keep consistency between all supported WFS requests. When sending requests, the default request method used is Post. To change this behavior, we have introduced a layer level meta data, wfs_request_method, which can be set to "GET". Use of Filter Encoding in MapServer =================================== This section describes how to use FE on both the server and client sides. Server Side ----------- To be able to use Filter Encoding, you need to create a valid WFS server using MapServer. Please refer to the :ref:`WFS Server HOWTO ` for specifics. There is nothing special that should be added to a WFS server for Filter Encoding, but you should note that, when requesting the capabilities of your WFS server, the document returned should contain the supported filters. Here is part of a Capabilities document as well as the Post support: .. code-block:: guess :linenos: MapServer WFS GMap WMS Demo Server http://localhost/cgi-bin/mapserv.exe?map= c:/msapps/wfs_filter/htdocs/ns_wfsserver.map& ... ... Client Side ----------- To be able to generate a Filter to a WFS server, a layer level metadata called *wfs_filter* has been added, which should contain the filter to be sent to the server. Following is an example of a valid WFS client layer with a filter: .. code-block:: mapfile LAYER NAME popplace METADATA "wfs_version" "1.0.0" "wfs_typename" "popplace" "wfs_filter" "POP_RANGE 4" END TYPE POINT STATUS ON PROJECTION "init=epsg:42304" END CONNECTIONTYPE WFS CONNECTION "http://www2.dmsolutions.ca:8090/cgi-bin/mswfs_filter?" LabelItem "Name" CLASSITEM "Capital" CLASS SYMBOL 2 SIZE 8 NAME "Cities" LABEL COLOR 255 0 0 FONT fritqat-italic TYPE truetype SIZE 8 POSITION AUTO OUTLINECOLOR 255 255 255 FORCE TRUE END COLOR 0 0 0 END END # Layer *Note:* - The filter given as a value of the wfs_filter metadata should not contain start and end tags. - The CONNECTION points to a valid WFS server supporting filters - The returned shapes will be drawn using the class defined in the layer. Limitations =========== - A limited set of spatial operators are supported. Tests ===== Here are some test URLs for the different supported filters: - `PropertyIsEqualTo`_ :: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature& TYPENAME=popplace&Filter=NAME Digby - `PropertyIsNotEqualTo`_ :: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature& TYPENAME=popplace&Filter=NAME Digby - `PropertyIsLessThan`_ :: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature& TYPENAME=popplace&Filter=POP_RANGE 2 - `PropertyIsGreaterThan`_ :: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature& TYPENAME=popplace&Filter=POP_RANGE 5 - `PropertyIsLessThanOrEqualTo`_ :: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature& TYPENAME=popplace&Filter=POP_RANGE 2 - `PropertyIsGreaterThanOrEqualTo`_ :: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature& TYPENAME=popplace&Filter=POP_RANGE 5 - `PropertyIsBetween`_ :: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature& TYPENAME=popplace&Filter=POP_RANGE 56 - `PropertyIsLike`_ :: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature& TYPENAME=popplace&Filter= NAMESyd* - `Logical operator OR`_ :: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature& TYPENAME=popplace&Filter=NAME SydneyNAME Digby - `Logical operator AND`_ :: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature& TYPENAME=popplace&Filter= NAMESyd* POP_RANGE4 - `Logical operator NOT`_ :: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature& TYPENAME=popplace&Filter=POP_RANGE 2POP_RANGE 3 - `Spatial operator BBOX`_ :: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature&TYPENAME=popplace& Filter=Name>NAME 2518000,150000 2918000,450000 - `Spatial operator Dwithin`_ :: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature&TYPENAME=popplace&Filter= Geometry2587598.000000,404010.531250 1000 - `Spatial operator Intersects`_ :: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature&TYPENAME=popplace&Filter= Geometry 2488789,289552 2588789,289552 2588789,389552 2488789,389552 2488789,289552 .. _`PropertyIsEqualTo`: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature&TYPENAME=popplace&Filter=NAMEDigby .. _`PropertyIsNotEqualTo`: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature&TYPENAME=popplace&Filter=NAMEDigby .. _`PropertyIsLessThan`: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature&TYPENAME=popplace&Filter=POP_RANGE2 .. _`PropertyIsGreaterThan`: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature&TYPENAME=popplace&Filter=POP_RANGE5 .. _`PropertyIsLessThanOrEqualTo`: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature&TYPENAME=popplace&Filter=POP_RANGE2 .. _`PropertyIsGreaterThanOrEqualTo`: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature&TYPENAME=popplace&Filter=POP_RANGE5 .. _`PropertyIsBetween`: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature&TYPENAME=popplace&Filter=POP_RANGE56 .. _`PropertyIsLike`: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature&TYPENAME=popplace&Filter=NAMESyd* .. _`Logical operator OR`: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature&TYPENAME=popplace&Filter=NAMESydneyNAMEDigby .. _`Logical operator AND`: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature&TYPENAME=popplace&Filter=NAMESyd*POP_RANGE4 .. _`Logical operator NOT`: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature&TYPENAME=popplace&Filter=POP_RANGE2POP_RANGE3 .. _`Spatial operator BBOX`: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature&TYPENAME=popplace&Filter=Name>NAME2518000,150000%202918000,450000 .. _`Spatial operator Dwithin`: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature&TYPENAME=popplace&Filter=Geometry2587598.000000,404010.5312501000 .. _`Spatial operator Intersects`: http://www2.dmsolutions.ca/cgi-bin/mswfs_filter?&VERSION=1.0.0&SERVICE=WFS&REQUEST=GetFeature&TYPENAME=popplace&Filter=Geometry2488789,289552%202588789,289552%202588789,389552%202488789,389552%202488789,289552 - Tests using MapServer as a WFS client and a WFS server are available at http://www2.dmsolutions.ca/msapps/wfs_fe/. - The OGC conformance tests (http://cite.occamlab.com/tsOGC/) have been run on the FE support. The following table and notes reflect the current status. **Table 2. WFS OGC test suite (over the HTTP Get and Post method)** ======== ========================================================= ========== ================= Test # Description # of Tests # of Failed Tests ======== ========================================================= ========== ================= 1 Basic WFS tests over the HTTP Get and Post method 402 281 1.1 GetCapabilities 16 0 1.2 DescribeFeatureType 18 0 1.3 GetFeature 368 281 1.3.1 Basic WFS tests 20 1 1.3.2 Complex WFS tests 18 18 1.3.3 Arithmetic filter WFS tests 8 8 1.3.4 Comparison WFS tests 50 26 1.3.4.1 GetFeature PropertyIsGreaterThanOrEqualTo filter 2 0 1.3.4.2 GetFeature PropertyIsBetween filter 6 2 1.3.4.3 GetFeature PropertyIsEqualTo filter 4 0 1.3.4.4 GetFeature PropertyIsGreaterThan filter 4 2 1.3.4.5 GetFeature PropertyIsGreaterThanOrEqualTo filter 6 6 1.3.4.6 GetFeature PropertyIsLessThan filter 6 4 1.3.4.7 GetFeature PropertyIsLessThanOrEqualTo filter 6 4 1.3.4.8 GetFeature PropertyIsLike filter 2 0 1.3.4.9 GetFeature PropertyIsNotEqualTo filter 6 0 1.3.4.10 GetFeature PropertyIsNull filter 8 8 1.3.5 Logical WFS test 20 0 1.3.5.1 GetFeature AND PropertyIsEqualTo PropertyIsEqualTo filter 8 0 1.3.5.2 GetFeature OR PropertyIsEqualTo PropertyIsEqualTo filter 8 0 1.3.5.3 GetFeature NOT PropertyIsNotEqualTo filter 4 0 1.3.6 Spatial operator WFS test 252 228 1.3.6.1 GetFeature BBOX filter 36 12 1.3.6.2 GetFeature with other filter types 216 216 2 Transactional WFS test 69 69 ======== ========================================================= ========== ================= The OGC Cite WFS test suite can be found on the `OGC Cite portal`_. .. _`OGC Cite portal`: http://cite.occamlab.com/test_engine/wfs_1_0_0/wfs_1_0_0.html Following are some MapServer specific notes on this test suite: 1. *Test number 1.3.1*: - There is a contradiction between the wfs/1.0.0/basic/getfeature/post/3 assertion and the XPath expected value of the test. The assertion says: "Test that a GetFeature request with no output format defined returns a wfs:FeatureCollection with GML data." and the expected XPath value for this request: "boolean(/ogc:ServiceExceptionReport)" is supposed to be true. So, the assertion means that when a WFS server receives a request which contains an undefined output format or no output format at all, the WFS server must return a WFS collection containing GML data. The XPath expected value means that when a WFS server receives a request with an undefined output format or no output format at all, the WFS server must return a service exception report. 2. *Tests number 1.3.2 and 1.3.3*: - Not supported. 3. *Tests number 1.3.4.2, 1.3.4.4 to 1.3.4.7*: - The string comparison is not supported using >, <, >=, <=. - The date comparison is not supported. .. seealso:: `bug 461`_ 4. *Test number 1.3.4.10*: - This property is not supported in MapServer. 5. *Test number 1.3.6.1*: - The returned feature xml won't validate because the validation is done against a specific xsd (geomatry.xsd). - The data conversion on multipoints and multilayers are not supported within GDAL. .. seealso:: `bug 461`_ 6. *Test number 2*: - The transaction requests are not supported. .. _`bug 461`: http://trac.osgeo.org/mapserver/ticket/461