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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>Can someone please explain the “Sub-Layers” section of this tutorial (<a href="http://www.geoext.org/tutorials/layertree-tutorial.html#sub-layers">http://www.geoext.org/tutorials/layertree-tutorial.html#sub-layers</a>)? Specifically I’m wondering how the param property in the loader works. I understand that the loader is a LayerParamLoader but the underlying mechanics are unclear. I was originally under the assumption that this was used as a read-only mechanism to grab data from an already configured/retrieved layer as in using "LAYERS" in order to retrieve the following layers from groupLayer:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'> layers: [<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'> "topp:tasmania_state_boundaries",<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'> "topp:tasmania_water_bodies",<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'> "topp:tasmania_cities",<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'> "topp:tasmania_roads"<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'> ],<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>After reading the note about using the “CQL_FILTER” param I became confused. Here are some questions that can hopefully clear things up for me (and possibly others):<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>1 - Is this used to create a new “CQL_FILTER” and/or modify an existing one or just to read one that already exists? <o:p></o:p></p><p class=MsoNormal>2 - What would be the use case for reading a “CQL_FILTER” that already exists? <o:p></o:p></p><p class=MsoNormal>3 - If creating/modifying a “CQL_FILTER”, does this reinitiate a WMS etc. request in order to fulfill the new filter? <o:p></o:p></p><p class=MsoNormal>4 - If this is not used for just read-only purposes, can you also create/modify a layer list using "LAYERS"?<o:p></o:p></p><p class=MsoNormal>5 - What is the lifecycle of the LayerParamLoader and the underlying (in this case) OpenLayers.Layer.WMS? i.e. Does the LayerParamLoader trigger the WMS request from the server or is that request initiated separately?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Is there a working example showing the use of “CQL_FILTER” in this manner? (I couldn’t find one)<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>BTW, I was even more confused when playing around with a value other than "LAYERS" for the param property. For instance, when I changed it as follows:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:8.0pt;font-family:"Courier New";color:black'> loader: {</span><span style='font-size:8.0pt;font-family:"Courier New"'><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:8.0pt;font-family:"Courier New";color:black'> param: </span><span style='font-size:8.0pt;font-family:"Courier New";color:#2A00FF'>"FORMAT"</span><span style='font-size:8.0pt;font-family:"Courier New"'><o:p></o:p></span></p><p class=MsoNormal style='text-autospace:none'><span style='font-size:8.0pt;font-family:"Courier New";color:black'> }</span><span style='font-size:8.0pt;font-family:"Courier New"'><o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>the group layer node was populated with a single node displaying the text “image/gif” but the map displayed all 4 layers when I clicked the checkbox. Can anyone explain this behavior?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thanks!<o:p></o:p></p><p class=MsoNormal>Gary<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>