Hi, It would be nice to be able to query WMS layers with GetFeatureInfo requests. DeeJUMP has implemented this feature but I have understood that it is utilising deegree libraries. As a non-programmer I am thinking that adding this feature to the existing WMS part of OpenJUMP should not be extra difficult. The OGC standard text is here: http://cite.opengeospatial.org/OGCTestData/wms/1.1.1/spec/wms1.1.1.html# wmsops.getfeatureinfo
What needs to be done for making GetFeatureInfo requests, starting from a situation of successfull WMS GetMap request and the returned image being in OJ map Window is about the following. 1. Get the service GetCapabilities document handy, let's say it is found here: http://myserver.fi/cgi-bin/WMS?REQUEST=GetCapabilities&SERVICE=WMS&VERSI ON=1.1.1 That is the initial query for using WMS get map so it is mostly implemented already but I will come back to this in section 3. 2. Take the WMS GetMap request as basis. Let's say it is like this: http://myserver.fi/cgi-bin/WMS?REQUEST=GetMap&SERVICE=WMS&VERSION=1.1.1&; WIDTH=600&HEIGHT=400&LAYERS=parcels2008,parcels2009&TRANSPARENT=TRUE&FOR MAT=image/png&BBOX=430000,6943000,430600,6943400&SRS=EPSG:3067&STYLES= 3. Read and parse the GetFeatureInfo part of the GetCapabilities document that was queried in step 1: <GetFeatureInfo> <Format>text/plain</Format> <Format>application/vnd.ogc.gml</Format> <DCPType> <HTTP> <Get><OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink"; xlink:href="http://myserver.fi/cgi-bin/WMS?"/></Get> <Post><OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink"; xlink:href="http://myserver.fi/cgi-bin/WMS?"/></Post> </HTTP> </DCPType> </GetFeatureInfo> 4. Build the GetFeatureInfo query from the following components: a) Base url from step 3 http://myserver.fi/cgi-bin/WMS? This online resource is usually the same that is used for GetCapabilities but according to the standard it may be something else, so the correct way would be to read and interpret the document. b) Version number of GetFeatureInfo request, I suppose it can always be the same that has been used for GetCapabilities and GetMap VERSION=1.1.1 c) Request name &REQUEST=GetFeatureInfo d) copy of the main part of GetMap request from the step 2 &SERVICE=WMS&WIDTH=600&HEIGHT=400&LAYERS=parcels2008,parcels2009&TRANSPA RENT=TRUE&FORMAT=image/png&BBOX=430000,6943000,430600,6943400&SRS=EPSG:3 067&STYLES= So it is the whole GetMap request exept base url, version and request. d) Add QUERY_LAYERS parameter. Standard says: This parameter shall contain at least one layer name, but may contain fewer layers than the original GetMap request. To make things a bit more simple I think it could always contain all the layers from the original GetMap request. e) Add INFO_FORMAT parameter. It is optional, but without giving it server returns its default format and standard does not say what it should be so perhaps it would be better if WMS client ask for a certain format. Possible values are listed in GetFeatureInfo report in step 3. f) Add FEATURE_COUNT parameter. It is optional but it is good to have, because the default is 1 and that gives, for example, feature info of just one of the overlapping polygons which are queried. g) Add X and Y which are the pixel coordinates of the point that is clicken on a map. h) EXCEPTIONS parameter is optional and only supported value seems to be "application/vnd.ogc.se_xml" so there is no need to include it. When everything is put together the request should look like this: http://myserver.fi/cgi-bin/WMS?VERSION=1.1.1&REQUEST=GetFeatureInfo&SERV ICE=WMS&WIDTH=600&HEIGHT=400&LAYERS=parcels2008,parcels2009&TRANSPARENT= TRUE&FORMAT=image/png&BBOX=430000,6943000,430600,6943400&SRS=EPSG:3067&S TYLES=&QUERY_LAYERS=parcels2008,parcels2009&INFO_FORMAT=text/plain&FEATU RE_COUNT=100&X=162&Y=225 This was the request part, another part would be to make OJ to parse what is sent back from WMS server. Standard does not order which formats must of should be supported, but most common are propably text/plain, text/html and INFO_FORMAT=application/vnd.ogc.gml which is returning gml. Well, after writing all this I believe it is not necessarily so simple to implement. -Jukka Rahkonen- ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Jump-pilot-devel mailing list Jump-pilot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
