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/* Copyright (c) 2006-2013 by OpenLayers Contributors (see authors.txt for
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* full list of contributors). Published under the 2-clause BSD license.
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* See license.txt in the OpenLayers distribution or repository for the
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* full text of the license. */
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/**
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* @requires OpenLayers/Layer.js
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*/
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/**
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* Class: OpenLayers.Layer.HTTPRequest
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*
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* Inherits from:
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* - <OpenLayers.Layer>
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*/
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OpenLayers.Layer.HTTPRequest = OpenLayers.Class(OpenLayers.Layer, {
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/**
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* Constant: URL_HASH_FACTOR
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* {Float} Used to hash URL param strings for multi-WMS server selection.
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* Set to the Golden Ratio per Knuth's recommendation.
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*/
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URL_HASH_FACTOR: (Math.sqrt(5) - 1) / 2,
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/**
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* Property: url
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* {Array(String) or String} This is either an array of url strings or
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* a single url string.
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*/
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url: null,
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/**
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* Property: params
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* {Object} Hashtable of key/value parameters
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*/
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params: null,
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/**
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* APIProperty: reproject
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* *Deprecated*. See http://docs.openlayers.org/library/spherical_mercator.html
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* for information on the replacement for this functionality.
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* {Boolean} Whether layer should reproject itself based on base layer
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* locations. This allows reprojection onto commercial layers.
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* Default is false: Most layers can't reproject, but layers
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* which can create non-square geographic pixels can, like WMS.
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*
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*/
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reproject: false,
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/**
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* Constructor: OpenLayers.Layer.HTTPRequest
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*
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* Parameters:
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* name - {String}
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* url - {Array(String) or String}
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* params - {Object}
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* options - {Object} Hashtable of extra options to tag onto the layer
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*/
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initialize: function(name, url, params, options) {
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OpenLayers.Layer.prototype.initialize.apply(this, [name, options]);
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this.url = url;
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if (!this.params) {
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this.params = OpenLayers.Util.extend({}, params);
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}
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},
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/**
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* APIMethod: destroy
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*/
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destroy: function() {
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this.url = null;
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this.params = null;
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OpenLayers.Layer.prototype.destroy.apply(this, arguments);
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},
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/**
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* APIMethod: clone
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*
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* Parameters:
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* obj - {Object}
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*
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* Returns:
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* {<OpenLayers.Layer.HTTPRequest>} An exact clone of this
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* <OpenLayers.Layer.HTTPRequest>
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*/
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clone: function (obj) {
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if (obj == null) {
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obj = new OpenLayers.Layer.HTTPRequest(this.name,
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this.url,
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this.params,
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this.getOptions());
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}
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//get all additions from superclasses
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obj = OpenLayers.Layer.prototype.clone.apply(this, [obj]);
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// copy/set any non-init, non-simple values here
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return obj;
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},
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/**
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* APIMethod: setUrl
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*
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* Parameters:
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* newUrl - {String}
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*/
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setUrl: function(newUrl) {
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this.url = newUrl;
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},
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/**
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* APIMethod: mergeNewParams
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*
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* Parameters:
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* newParams - {Object}
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*
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* Returns:
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* redrawn: {Boolean} whether the layer was actually redrawn.
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*/
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mergeNewParams:function(newParams) {
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this.params = OpenLayers.Util.extend(this.params, newParams);
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var ret = this.redraw();
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if(this.map != null) {
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this.map.events.triggerEvent("changelayer", {
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layer: this,
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property: "params"
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});
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}
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return ret;
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},
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/**
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* APIMethod: redraw
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* Redraws the layer. Returns true if the layer was redrawn, false if not.
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*
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* Parameters:
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* force - {Boolean} Force redraw by adding random parameter.
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*
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* Returns:
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* {Boolean} The layer was redrawn.
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*/
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redraw: function(force) {
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if (force) {
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return this.mergeNewParams({"_olSalt": Math.random()});
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} else {
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return OpenLayers.Layer.prototype.redraw.apply(this, []);
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}
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},
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/**
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* Method: selectUrl
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* selectUrl() implements the standard floating-point multiplicative
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* hash function described by Knuth, and hashes the contents of the
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* given param string into a float between 0 and 1. This float is then
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* scaled to the size of the provided urls array, and used to select
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* a URL.
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*
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* Parameters:
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* paramString - {String}
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* urls - {Array(String)}
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*
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* Returns:
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* {String} An entry from the urls array, deterministically selected based
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* on the paramString.
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*/
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selectUrl: function(paramString, urls) {
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var product = 1;
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for (var i=0, len=paramString.length; i<len; i++) {
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product *= paramString.charCodeAt(i) * this.URL_HASH_FACTOR;
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product -= Math.floor(product);
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}
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return urls[Math.floor(product * urls.length)];
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},
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/**
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* Method: getFullRequestString
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* Combine url with layer's params and these newParams.
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*
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* does checking on the serverPath variable, allowing for cases when it
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* is supplied with trailing ? or &, as well as cases where not.
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*
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* return in formatted string like this:
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* "server?key1=value1&key2=value2&key3=value3"
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*
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* WARNING: The altUrl parameter is deprecated and will be removed in 3.0.
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*
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* Parameters:
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* newParams - {Object}
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* altUrl - {String} Use this as the url instead of the layer's url
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*
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* Returns:
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* {String}
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*/
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getFullRequestString:function(newParams, altUrl) {
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// if not altUrl passed in, use layer's url
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var url = altUrl || this.url;
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// create a new params hashtable with all the layer params and the
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// new params together. then convert to string
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var allParams = OpenLayers.Util.extend({}, this.params);
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allParams = OpenLayers.Util.extend(allParams, newParams);
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var paramsString = OpenLayers.Util.getParameterString(allParams);
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// if url is not a string, it should be an array of strings,
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// in which case we will deterministically select one of them in
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// order to evenly distribute requests to different urls.
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//
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if (OpenLayers.Util.isArray(url)) {
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url = this.selectUrl(paramsString, url);
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}
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// ignore parameters that are already in the url search string
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var urlParams =
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OpenLayers.Util.upperCaseObject(OpenLayers.Util.getParameters(url));
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for(var key in allParams) {
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if(key.toUpperCase() in urlParams) {
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delete allParams[key];
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}
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}
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paramsString = OpenLayers.Util.getParameterString(allParams);
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return OpenLayers.Util.urlAppend(url, paramsString);
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},
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CLASS_NAME: "OpenLayers.Layer.HTTPRequest"
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});
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