diff --git a/tiles/ISSUES.md b/tiles/ISSUES.md
index 95f4cd8..dece3ba 100644
--- a/tiles/ISSUES.md
+++ b/tiles/ISSUES.md
@@ -11,16 +11,16 @@
 - [x] IndexedDB not supported in iOS Safari (see https://developer.mozilla.org/en-US/docs/IndexedDB#Browser_compatibility and https://github.com/axemclion/IndexedDBShim, or http://nparashuram.com/IndexedDBShim/)
 - [x] Andy: We may want to look at limiting the tiles to two or three levels to help manage size/performance issues.
 	+ limit maxLevel to current zoomLevel + 3 (no problem to include all levels up to level 0, it will be only 1 or 2 tiles per level)
-
-- [ ] better tile estimation and limits
-- [ ] unit testing
-- [ ] reorganize code
+- [x] reorganize code
 	+ partially done
 	+ better dependency management
-- [ ] remove unused files (ioWorker, OfflineTileStore)
+- [x] remove unused files (ioWorker, OfflineTileStore)
+- [x] test iPad/iPhone **DONE**, it works!
+
+- [ ] unit testing
+- [ ] better tile estimation and limits
 
 - [ ] allow naming caches?
-- [ ] test iPad/iPhone
 - [ ] more general proxy.php
 
 - [ ] non-rectangular area
diff --git a/tiles/index.html b/tiles/index.html
index 109bca8..b700e59 100644
--- a/tiles/index.html
+++ b/tiles/index.html
@@ -35,7 +35,8 @@
 					<span class="icon-bar"></span>
 					<span class="icon-bar"></span>
 				</button>
-				<a class="navbar-brand" href=""><i class="fa fa-globe"></i> esri</a>
+				<a class="navbar-brand" href="http://github.com/Esri/offline-editor-js"><i class="fa fa-html5"></i> JS Offline Mapping</s>
+				<a class="navbar-brand" href="http://developers.arcgis.com"><i class="fa fa-globe"></i> esri</a>
 			</div>
 		<!--
 		<div class="collapse navbar-collapse">
@@ -50,19 +51,11 @@
 </div>
 
 <div class="container">
-	<div class="row">
-		<div class="col-xs-12">
-			<div class="page-header">
-				<h2><i class="fa fa-html5"></i> JS Offline Mapping</h2>
-			</div>
-		</div>
-	</div>
-
 	<div class="row">
 		<div class="col-sm-4">
 		</div>
 		<div class="col-sm-8">
-			<h3 id="mapTitle"></h3>			
+			<h3>Map:<span id="mapTitle">[none]</span></h3>
 		</div>
 	</div>
 
@@ -145,9 +138,6 @@
 <script src="../vendor/offline/offline.min.js"></script>
 <script src="../vendor/IndexedDBShim/dist/IndexedDBShim.min.js"></script>
 <script src="offlineProbe.js"></script>
-<script src="tilingScheme.js"></script>
-<script src="src/_base.js"></script>
-<script src="src/dbStore2.js"></script>
 <script src="main.js"></script>
 
 	<!-- Bootstrap core JavaScript
diff --git a/tiles/main.js b/tiles/main.js
index 69faae2..5bf4bd1 100644
--- a/tiles/main.js
+++ b/tiles/main.js
@@ -1,28 +1,28 @@
 "use strict"
 
 var map;
+var basemapLayer;
 var graphics;
 var cancelRequested, startTime;
 var showTiles = false;
 
 require(["esri/map", 
 	"esri/layers/GraphicsLayer", "esri/graphic", "esri/symbols/SimpleFillSymbol",
-	"esri/dijit/Scalebar", 
-	"esri/arcgis/utils", 
-	"esri/geometry",
-	"dojo/dom", 
-	"dojo/on", 
-	"dojo/query", 
+	"esri/dijit/Scalebar", "esri/arcgis/utils", "esri/geometry",
+	"dojo/dom", "dojo/on", "dojo/query", 
 	"../vendor/bootstrap-map-js/src/js/bootstrapmap.js",
-	"esri/urlUtils",
-	"esri/geometry/webMercatorUtils",
+	"esri/urlUtils", "esri/geometry/webMercatorUtils",
 	"src/offlineEnabler.js",
-	"dojo/dom-construct",
-	"dojo/domReady!"], 
-	function(Map, GraphicsLayer, Graphic, SimpleFillSymbol, Scalebar, esriUtils, geometry, dom, on, query, BootstrapMap, urlUtils, webMercatorUtils, 
+	"dojo/dom-construct", "dojo/domReady!"], 
+	function(Map, 
+		GraphicsLayer, Graphic, SimpleFillSymbol, 
+		Scalebar, esriUtils, geometry, 
+		dom, on, query, 
+		BootstrapMap, 
+		urlUtils, webMercatorUtils, 
 		offlineEnabler,
 		domConstruct) 
-	{  
+	{
 		var scalebar;
 		var symbol;
 
@@ -58,18 +58,18 @@ require(["esri/map",
 
 				if(map.loaded)
 				{
+					basemapLayer = map.getLayer( map.layerIds[0] );
 					initMapParts();
 					initEvents();
-					updateTileSizeEstimation();
 					initOffline();
 				}
 				else
 				{
 					on(map,"load",function()
 					{
+						basemapLayer = map.getLayer( map.layerIds[0] );
 						initMapParts();
 						initEvents();
-						updateTileSizeEstimation();
 						initOffline();
 					});
 				}
@@ -105,18 +105,17 @@ require(["esri/map",
 
 		function initEvents()
 		{
-			map.on('extent-change', updateTileSizeEstimation );
-			on(dojo.byId('minLevel'),'change', updateTileSizeEstimation);
-			on(dojo.byId('maxLevel'),'change', updateTileSizeEstimation);
+			map.on('extent-change', updateTileCountEstimation );
+			on(dojo.byId('minLevel'),'change', updateTileCountEstimation);
+			on(dojo.byId('maxLevel'),'change', updateTileCountEstimation);
 
-			var basemapLayer = map.getLayer( map.layerIds[0] );
-			dojo.byId('minLevel').value = basemapLayer.tileInfo.lods[0].level;
-			dojo.byId('maxLevel').value = basemapLayer.tileInfo.lods[basemapLayer.tileInfo.lods.length-1].level;
+			dojo.byId('minLevel').value = basemapLayer.minLevel = basemapLayer.tileInfo.lods[0].level;
+			dojo.byId('maxLevel').value = basemapLayer.maxLevel = basemapLayer.tileInfo.lods[basemapLayer.tileInfo.lods.length-1].level;
 		}
 
 		function initOffline()
 		{
-			var basemapLayer = offlineEnabler.getBasemapLayer(map);
+			console.log("extending");
 			offlineEnabler.extend(basemapLayer,function(success)
 			{
 				if(success)
@@ -131,6 +130,7 @@ require(["esri/map",
 					esri.show(dojo.byId('ready-to-download-ui'));
 					esri.hide(dojo.byId('downloading-ui'));
 					updateOfflineUsage();
+					updateTileCountEstimation();
 				}
 				else
 				{	
@@ -147,7 +147,6 @@ require(["esri/map",
 		function updateOfflineUsage()
 		{
 			dojo.byId('offline-usage').innerHTML = "updating...";
-			var basemapLayer = offlineEnabler.getBasemapLayer(map);
 			basemapLayer.getOfflineUsage(function(usage)
 			{
 				console.log(usage);
@@ -157,14 +156,7 @@ require(["esri/map",
 			});		
 		}
 
-		function estimateTileSize(tiledLayer)
-		{
-			var tileInfo = tiledLayer.tileInfo;
-
-			return 14000; // TODO - come up with a more precise estimation method
-		}
-
-		function updateTileSizeEstimation()
+		function updateTileCountEstimation()
 		{
 			console.log('updating');
 			var zoomLevel = map.getLevel();
@@ -173,30 +165,19 @@ require(["esri/map",
 			var minLevel = parseInt(dojo.byId('minLevel').value);
 			var maxLevel = parseInt(dojo.byId('maxLevel').value);
 			
-			if( maxLevel > zoomLevel + 3)
+			if( maxLevel > zoomLevel + 3 || maxLevel > basemapLayer.maxLevel)
 			{
-				maxLevel = zoomLevel + 3;
+				maxLevel = Math.min(basemapLayer.maxLevel, zoomLevel + 3);
 				dojo.byId('maxLevel').value = maxLevel;
 			}
 
-			var basemapLayer = map.getLayer( map.layerIds[0] );
-			var tileSize = estimateTileSize(basemapLayer);
-
-			var tilingScheme = new TilingScheme(basemapLayer,geometry);
+			var totalEstimation = { tileCount:0, sizeBytes:0 }
 
 			domConstruct.empty('tile-count-table-body');
 
-			var totalEstimation = { tileCount:0, sizeBytes:0 }
-
 			for(var level=minLevel; level<=maxLevel; level++)
 			{
-				var cellIds = tilingScheme.getAllCellIdsInExtent(map.extent,level);
-
-				var levelEstimation = { 
-					level: level,
-					tileCount: cellIds.length,
-					sizeBytes: cellIds.length * tileSize
-				}
+				var levelEstimation = basemapLayer.getLevelEstimation(map.extent,level);
 
 				totalEstimation.tileCount += levelEstimation.tileCount;
 				totalEstimation.sizeBytes += levelEstimation.sizeBytes;
@@ -228,7 +209,6 @@ require(["esri/map",
 			dojo.byId('go-offline-btn').disabled = true;
 			dojo.byId('go-online-btn').disabled = undefined;
 
-			var basemapLayer = map.getLayer( map.layerIds[0] );
 			basemapLayer.goOffline();
 		}
 
@@ -237,13 +217,11 @@ require(["esri/map",
 			dojo.byId('go-offline-btn').disabled = undefined;
 			dojo.byId('go-online-btn').disabled = true;
 
-			var basemapLayer = map.getLayer( map.layerIds[0] );
 			basemapLayer.goOnline();
 		}
 
 		function deleteAllTiles() 
 		{
-			var basemapLayer = map.getLayer( map.layerIds[0] );
 			basemapLayer.deleteAllTiles(function(success, err)
 			{
 				console.log("deleteAllTiles():", success,err);
@@ -251,7 +229,7 @@ require(["esri/map",
 				if( success )
 					alert("All tiles deleted");
 				else
-					alert("Can't delete tiles");
+					alert("Can't delete tiles: " + err);
 
 				setTimeout(updateOfflineUsage,0); // request execution in the next turn of the event loop
 			});
@@ -269,7 +247,6 @@ require(["esri/map",
 			/* launch offline preparation process */
 			var minLevel = parseInt(dojo.byId('minLevel').value);
 			var maxLevel = parseInt(dojo.byId('maxLevel').value);
-			var basemapLayer = map.getLayer( map.layerIds[0] );
 			basemapLayer.prepareForOffline(minLevel, maxLevel, map.extent, reportProgress, finishedDownloading);
 		}
 
@@ -321,7 +298,6 @@ require(["esri/map",
 
 			if( showTiles )
 			{
-				var basemapLayer = map.getLayer( map.layerIds[0] );
 				basemapLayer.getTilePolygons(function(polygon,err)
 				{
 					if(polygon)
diff --git a/tiles/src/OfflineTileStore.js b/tiles/src/OfflineTileStore.js
deleted file mode 100644
index 75b7a72..0000000
--- a/tiles/src/OfflineTileStore.js
+++ /dev/null
@@ -1,203 +0,0 @@
-/**
- * Library for handling the storage of map tiles.
- * Can use localStorage or IndexedDB. Local storage is supported in
- * more browsers (caniuse.com) however it is significantly more
- * limited in size.
- * NOTE: Uses localStorage by default. Override with useIndexedDB property.
- * NOTE: if you use IndexedDB be sure to verify if its available for use.
- * @param map
- * @constructor
- *
- * Author: Andy Gup (@agup)
- */
-var OfflineTileStore = function(/* Map */ map) {
-
-    this.ioWorker = null;
-    this.extend = null;
-    this.storage = 0;
-    this.map = map;
-    this.dbStore = null //indexedDB
-    this.useIndexedDB = false;
-
-    /**
-     * Provides control over allow/disallow values to be
-     * written to storage. Can be used for testing as well.
-     * @type {boolean}
-     */
-    this.allowCache = true;
-
-    /**
-     * Private Local ENUMs (Constants)
-     * Contains required configuration info.
-     * @type {Object}
-     * @returns {*}
-     * @private
-     */
-    this._localEnum = (function(){
-        var values = {
-            TIMEOUT : 20,                                      /* Seconds to wait for all tile requests to complete */
-            LOCAL_STORAGE_MAX_LIMIT : 4.75, /* MB */           /* Most browsers offer default storage of ~5MB */
-            LS_TILE_COUNT : "tile_count",
-            WORKER_URL : "./src/ioWorker.js"                   /* child process for gathering tiles */
-        }
-
-        return values;
-    });
-
-    /**
-     * Determines total storage used for this domain.
-     * @returns Number MB's
-     */
-    this.getlocalStorageUsed = function(){
-        var mb = 0;
-
-        //IE hack
-        if(window.localStorage.hasOwnProperty("remainingspace")){
-            //http://msdn.microsoft.com/en-us/library/ie/cc197016(v=vs.85).aspx
-            mb = window.localStorage.remainingSpace/1024/1024;
-        }
-        else{
-            for(var x in localStorage){
-                //Uncomment out console.log to see *all* items in local storage
-                //console.log(x+"="+((localStorage[x].length * 2)/1024/1024).toFixed(2)+" MB");
-                mb += localStorage[x].length
-            }
-        }
-
-        return Math.round(((mb * 2)/1024/1024) * 100)/100;
-    }
-
-    /**
-     * Refreshes base map and stores tiles.
-     * If they are already in database they are ignored.
-     */
-    this.storeLayer = function(){
-        this.tileCount = 0;
-        this.extendLayer(function(/* boolean */ evt){
-            var ids = map.layerIds;
-            var layer = map.getLayer(ids[0]);
-            layer.refresh();
-        }.bind(this));
-    }
-
-    this.extendLayer = function(callback){
-        if(this.extend == null){
-            var count = 0;
-
-            var allow = this.allowCache;
-            var worker = this.ioWorker;
-            var db = database;
-            var indexDB = this._useIndexedDB;
-
-            this.extend = dojo.extend(esri.layers.ArcGISTiledMapServiceLayer, {  //extend ArcGISTiledMapServiceLayer to use localStorage if available, else use worker to request tile and store in local storage.
-
-                getTileUrl : function(level, row, col) {
-                    this.tileCount++;
-                    count++;   //count number of tiles
-                    console.log("Count " + count);
-                    localStorage.setItem("tile_count",count);
-
-                    var url = this._url.path + "/tile/" + level + "/" + row + "/" + col;
-
-                    if(indexDB == true){
-                        database.get(url,function(event,result){
-                            console.log("img: " + result.img + ", event.url: " + result.url);
-                            if(event == true){
-                                console.log("in indexed db storage");
-                                return "data:image;base64," + result.img;
-                            }
-                            else{
-                                console.log("not in indexed db storage, pass url and load tile", url);
-                                worker.postMessage([url]);
-                                return url;
-                            }
-                        }.bind(this))
-                    }
-
-                    else{
-                        if(localStorage.getItem(url) !== null) {
-                            console.log("in local storage");
-                            return "data:image;base64," + localStorage.getItem(url);
-                        }
-                        else if(allow == true) {
-                            console.log("not in local storage, pass url and load tile", url);
-                            worker.postMessage([url]);
-                            return url;
-                        }
-                    }
-                }});
-            callback(true);
-        }
-        else{
-            callback(false);
-        }
-    }
-
-    /**
-     * Load src
-     * TO-DO: Needs to be made AMD compliant!
-     * @param urlArray
-     * @param callback
-     * @private
-     */
-    this._loadScripts = function(/* Array */ urlArray, callback)
-    {
-        count = 0;
-        for(var i in urlArray){
-            try{
-                var head = document.getElementsByTagName('head')[0];
-                var script = document.createElement('script');
-                script.type = 'text/javascript';
-                script.src = urlArray[i];
-                script.onreadystatechange = function(){
-                    count++;
-                    console.log("Script loaded. " + this.src);
-                    if(count == urlArray.length) callback();
-                };
-                script.onload = function(){
-                    count++;
-                    console.log("Script loaded. " + this.src);
-                    if(count == urlArray.length) callback();
-                };
-                head.appendChild(script);
-            }
-            catch(err){
-                console.log("_loadScripts: " + err.stack);
-            }
-        }
-    }
-
-    this.initLocalStorage = function() {
-        var tempArray = [];
-        var tempCount = 0;
-        this.dbStore = new dbStore();
-        this.ioWorker = new Worker(this._localEnum().WORKER_URL);
-        this.ioWorker.onmessage = function(evt) {
-
-            this.storage = this.getlocalStorageUsed();
-            console.log("Worker to Parent: ", evt.data[0]);
-            console.log("localStorage used: " + this.getlocalStorageUsed());
-
-            try {
-                localStorage.setItem(evt.data[0], evt.data[1]);
-                tempCount++;
-                tempArray.push({url:evt.data[0],img: evt.data[1]});
-            } catch(error) {
-                console.log('Problem adding tile to local storage. Storage might be full');
-            }
-
-            var count = parseFloat(localStorage.getItem(this._localEnum().LS_TILE_COUNT));
-            if(tempCount == count){
-                localStorage.setItem(this._localEnum().LS_TILE_COUNT,0);
-                database.add(tempArray,function(evt,err){
-                    evt == true ? console.log("Done") : console.log("init " + err);
-                });
-            }
-        }.bind(this);
-    }
-
-    this._init = function(){
-        this.initLocalStorage();
-    }.bind(this)()
-
-}
diff --git a/tiles/src/_base.js b/tiles/src/base64utils.js
similarity index 79%
rename from tiles/src/_base.js
rename to tiles/src/base64utils.js
index c4f3184..02377da 100644
--- a/tiles/src/_base.js
+++ b/tiles/src/base64utils.js
@@ -1,14 +1,16 @@
-var Base64Utils = (function(){
+"use strict"
 
-	var d={};
-	d.outputTypes={ 
+define([],function()
+{
+	var Base64Utils={};
+	Base64Utils.outputTypes={ 
 		//	summary:
 		//		Enumeration for input and output encodings.
 		Base64:0, Hex:1, String:2, Raw:3 
 	};
 
 	//	word-based addition
-	d.addWords=function(/* word */a, /* word */b){
+	Base64Utils.addWords=function(/* word */a, /* word */b){
 		//	summary:
 		//		add a pair of words together with rollover
 		var l=(a&0xFFFF)+(b&0xFFFF);
@@ -22,7 +24,7 @@ var Base64Utils = (function(){
 	var chrsz=8;	//	16 for Unicode
 	var mask=(1<<chrsz)-1;
 
-	d.stringToWord=function(/* string */s){
+	Base64Utils.stringToWord=function(/* string */s){
 		//	summary:
 		//		convert a string to a word array
 
@@ -33,7 +35,7 @@ var Base64Utils = (function(){
 		return wa;	//	word[]
 	};
 
-	d.wordToString=function(/* word[] */wa){
+	Base64Utils.wordToString=function(/* word[] */wa){
 		//	summary:
 		//		convert an array of words to a string
 		var s=[];
@@ -42,7 +44,7 @@ var Base64Utils = (function(){
 		}
 		return s.join("");	//	string
 	}
-	d.wordToHex=function(/* word[] */wa){
+	Base64Utils.wordToHex=function(/* word[] */wa){
 		//	summary:
 		//		convert an array of words to a hex tab
 		var h="0123456789abcdef", s=[];
@@ -51,7 +53,7 @@ var Base64Utils = (function(){
 		}
 		return s.join("");	//	string
 	}
-	d.wordToBase64=function(/* word[] */wa){
+	Base64Utils.wordToBase64=function(/* word[] */wa){
 		//	summary:
 		//		convert an array of words to base64 encoding, should be more efficient
 		//		than using dojox.encoding.base64
@@ -69,5 +71,5 @@ var Base64Utils = (function(){
 		return s.join("");	//	string
 	};
 
-  return d;
-})();
\ No newline at end of file
+	return Base64Utils;
+});
diff --git a/tiles/src/dbStore.js b/tiles/src/dbStore.js
new file mode 100644
index 0000000..6691328
--- /dev/null
+++ b/tiles/src/dbStore.js
@@ -0,0 +1,253 @@
+"use strict"
+
+/**
+ * Library for handling the storing of map tiles in IndexedDB.
+ *
+ * Author: Andy Gup (@agup)
+ * Contributor: Javier Abadia (@javierabadia)
+ */
+define([],function()
+{
+    var DbStore = function()
+    {
+        /**
+         * Internal reference to the local database
+         * @type {null}
+         * @private
+         */
+        this._db = null;
+
+        /**
+         * Private Local ENUMs (Constants)
+         * Contains required configuration info.
+         * @type {Object}
+         * @returns {*}
+         * @private
+         */
+        this._localEnum = (function(){
+            var values = {
+                DB_NAME : "offline_tile_store"
+            }
+
+            return values;
+        });
+
+        /**
+         * Determines if indexedDB is supported
+         * @returns {boolean}
+         */
+        this.isSupported = function(){
+            window.indexedDB = window.indexedDB || window.mozIndexedDB || window.webkitIndexedDB || window.msIndexedDB;
+
+            if(!window.indexedDB){
+                return false;
+            }
+
+            return true;
+        }
+
+        /**
+         * Adds an object to the database
+         * @param urlDataPair
+         * @param callback callback(boolean, err)
+         */
+        this.add = function(urlDataPair,callback){
+            try{
+                //console.log("add()",urlDataPair);
+                var transaction = this._db.transaction(["tilepath"],"readwrite");
+
+                transaction.oncomplete = function(event) {
+                    callback(true);
+                };
+
+                transaction.onerror = function(event) {
+                    callback(false,event.target.error.message)
+                };
+
+                var objectStore = transaction.objectStore("tilepath");
+                var request = objectStore.put(urlDataPair);
+                request.onsuccess = function(event) {
+                    //console.log("item added to db " + event.target.result);
+                };
+            }
+            catch(err){
+                console.log("dbstore: " + err.stack);
+                callback(false,err.stack);
+            }
+        }
+
+        /**
+         * Retrieve a record.
+         * @param url
+         * @param callback
+         */
+        this.get = function(/* String */ url,callback){
+            if(this._db != null){
+
+                var objectStore = this._db.transaction(["tilepath"]).objectStore("tilepath");
+                var request = objectStore.get(url);
+                request.onsuccess = function(event)
+                {
+                    var result = event.target.result;
+                    if(result == null){
+                        callback(false,"not found");
+                    }
+                    else{
+                        callback(true,result);
+                    }
+                }
+                request.onerror = function(err){
+                    callback(false,err);
+                }
+            }
+        }
+
+        /**
+         * Deletes entire database
+         * @param callback callback(boolean, err)
+         */
+        this.deleteAll = function(callback){
+            if(this._db != null){
+                var request = this._db.transaction(["tilepath"],"readwrite")
+                    .objectStore("tilepath")
+                    .clear();
+                request.onsuccess = function(event){
+                    callback(true);
+                }
+                request.onerror = function(err){
+                    callback(false,err);
+                }
+            }
+            else{
+                callback(false,null);
+            }
+        }
+
+        /**
+         * Delete an individual entry
+         * @param url
+         * @param callback callback(boolean, err)
+         */
+        this.delete = function(/* String */ url,callback){
+            if(this._db != null){
+                var request = this._db.transaction(["tilepath"],"readwrite")
+                    .objectStore("tilepath")
+                    .delete(url);
+                request.onsuccess = function(event){
+                    callback(true);
+                }
+                request.onerror = function(err){
+                    callback(false,err);
+                }
+            }
+            else{
+                callback(false,null);
+            }
+        }
+
+        /**
+         * Retrieve all tiles from indexeddb
+         * @param callback callbakck(url, err)
+         */
+        this.getAllTiles = function(callback){
+            if(this._db != null)
+            {
+                var transaction = this._db.transaction(["tilepath"])
+                    .objectStore("tilepath")
+                    .openCursor();
+
+                transaction.onsuccess = function(event)
+                {
+                    var cursor = event.target.result;
+                    if(cursor){
+                        var url = cursor.value.url;
+                        callback(url);
+                        cursor.continue();
+                    }
+                    else{
+                        callback(null, "end");
+                    }
+                }.bind(this);
+                transaction.onerror = function(err){
+                    callback(null, err);
+                }
+            }
+            else
+            {
+                callback(null, "no db");
+            }     
+        }
+
+        /**
+         * Provides a rough, approximate size of database in MBs.
+         * @param callback callback(size, null) or callback(null, error)
+         */
+        this.size = function(callback){
+            if(this._db != null){
+                var usage = { size: 0, tileCount: 0 };
+
+                var transaction = this._db.transaction(["tilepath"])
+                    .objectStore("tilepath")
+                    .openCursor();
+
+                transaction.onsuccess = function(event){
+                    var cursor = event.target.result;
+                    if(cursor){
+                        var storedObject = cursor.value;
+                        var json = JSON.stringify(storedObject);
+                        usage.size += this.stringBytes(json);
+                        usage.tileCount += 1;
+                        cursor.continue();
+                    }
+                    else{
+                        usage.size = Math.round((usage.size/1024/1024) * 100)/100; /* JAMI: *2 */
+                        callback(usage,null);
+                    }
+                }.bind(this);
+                transaction.onerror = function(err){
+                    callback(null,err);
+                }
+            }
+            else{
+                callback(null,null);
+            }
+        }
+
+        this.stringBytes = function(str) {
+            var b = str.match(/[^\x00-\xff]/g);
+            return (str.length + (!b ? 0: b.length));
+        }
+
+        this.init = function(callback)
+        {
+            var request = indexedDB.open(this._localEnum().DB_NAME, 4);
+            callback = callback? callback : function(success) { console.log("DbStore::init() success:", success)}.bind(this);
+
+            request.onerror = function(event) 
+            {
+                console.log("indexedDB error: " + event.target.errorCode);
+                callback(false,event.target.errorCode);
+            }.bind(this);
+
+            request.onupgradeneeded = function(event) 
+            {
+                var db = event.target.result;
+
+                if( db.objectStoreNames.contains("tilepath")) 
+                {
+                    db.deleteObjectStore("tilepath");
+                }            
+
+                var objectStore = db.createObjectStore("tilepath", { keyPath: "url" });
+            }.bind(this);
+
+            request.onsuccess = function(event)
+            {
+                this._db = event.target.result;
+                console.log("database opened successfully");
+                callback(true);
+            }.bind(this);
+        }
+    }
+    return DbStore;    
+});
diff --git a/tiles/src/dbStore2.js b/tiles/src/dbStore2.js
deleted file mode 100644
index dbbc874..0000000
--- a/tiles/src/dbStore2.js
+++ /dev/null
@@ -1,247 +0,0 @@
-/**
- * Library for handling the storing of map tiles in IndexedDB.
- *
- * Author: Andy Gup (@agup)
- * Contributor: Javier Abadia (@javierabadia)
- */
-var DbStore = function(){
-
-    /**
-     * Internal reference to the local database
-     * @type {null}
-     * @private
-     */
-    this._db = null;
-
-    /**
-     * Private Local ENUMs (Constants)
-     * Contains required configuration info.
-     * @type {Object}
-     * @returns {*}
-     * @private
-     */
-    this._localEnum = (function(){
-        var values = {
-            DB_NAME : "offline_tile_store"
-        }
-
-        return values;
-    });
-
-    /**
-     * Determines if indexedDB is supported
-     * @returns {boolean}
-     */
-    this.isSupported = function(){
-        window.indexedDB = window.indexedDB || window.mozIndexedDB || window.webkitIndexedDB || window.msIndexedDB;
-
-        if(!window.indexedDB){
-            return false;
-        }
-
-        return true;
-    }
-
-    /**
-     * Adds an object to the database
-     * @param urlDataPair
-     * @param callback callback(boolean, err)
-     */
-    this.add = function(urlDataPair,callback){
-        try{
-            //console.log("add()",urlDataPair);
-            var transaction = this._db.transaction(["tilepath"],"readwrite");
-
-            transaction.oncomplete = function(event) {
-                callback(true);
-            };
-
-            transaction.onerror = function(event) {
-                callback(false,event.target.error.message)
-            };
-
-            var objectStore = transaction.objectStore("tilepath");
-            var request = objectStore.put(urlDataPair);
-            request.onsuccess = function(event) {
-                //console.log("item added to db " + event.target.result);
-            };
-        }
-        catch(err){
-            console.log("dbstore: " + err.stack);
-            callback(false,err.stack);
-        }
-    }
-
-    /**
-     * Retrieve a record.
-     * @param url
-     * @param callback
-     */
-    this.get = function(/* String */ url,callback){
-        if(this._db != null){
-
-            var objectStore = this._db.transaction(["tilepath"]).objectStore("tilepath");
-            var request = objectStore.get(url);
-            request.onsuccess = function(event)
-            {
-                var result = event.target.result;
-                if(result == null){
-                    callback(false,"not found");
-                }
-                else{
-                    callback(true,result);
-                }
-            }
-            request.onerror = function(err){
-                callback(false,err);
-            }
-        }
-    }
-
-    /**
-     * Deletes entire database
-     * @param callback callback(boolean, err)
-     */
-    this.deleteAll = function(callback){
-        if(this._db != null){
-            var request = this._db.transaction(["tilepath"],"readwrite")
-                .objectStore("tilepath")
-                .clear();
-            request.onsuccess = function(event){
-                callback(true);
-            }
-            request.onerror = function(err){
-                callback(false,err);
-            }
-        }
-        else{
-            callback(false,null);
-        }
-    }
-
-    /**
-     * Delete an individual entry
-     * @param url
-     * @param callback callback(boolean, err)
-     */
-    this.delete = function(/* String */ url,callback){
-        if(this._db != null){
-            var request = this._db.transaction(["tilepath"],"readwrite")
-                .objectStore("tilepath")
-                .delete(url);
-            request.onsuccess = function(event){
-                callback(true);
-            }
-            request.onerror = function(err){
-                callback(false,err);
-            }
-        }
-        else{
-            callback(false,null);
-        }
-    }
-
-    /**
-     * Retrieve all tiles from indexeddb
-     * @param callback callbakck(url, err)
-     */
-    this.getAllTiles = function(callback){
-        if(this._db != null)
-        {
-            var transaction = this._db.transaction(["tilepath"])
-                .objectStore("tilepath")
-                .openCursor();
-
-            transaction.onsuccess = function(event)
-            {
-                var cursor = event.target.result;
-                if(cursor){
-                    var url = cursor.value.url;
-                    callback(url);
-                    cursor.continue();
-                }
-                else{
-                    callback(null, "end");
-                }
-            }.bind(this);
-            transaction.onerror = function(err){
-                callback(null, err);
-            }
-        }
-        else
-        {
-            callback(null, "no db");
-        }     
-    }
-
-    /**
-     * Provides a rough, approximate size of database in MBs.
-     * @param callback callback(size, null) or callback(null, error)
-     */
-    this.size = function(callback){
-        if(this._db != null){
-            var usage = { size: 0, tileCount: 0 };
-
-            var transaction = this._db.transaction(["tilepath"])
-                .objectStore("tilepath")
-                .openCursor();
-
-            transaction.onsuccess = function(event){
-                var cursor = event.target.result;
-                if(cursor){
-                    var storedObject = cursor.value;
-                    var json = JSON.stringify(storedObject);
-                    usage.size += this.stringBytes(json);
-                    usage.tileCount += 1;
-                    cursor.continue();
-                }
-                else{
-                    usage.size = Math.round((usage.size/1024/1024) * 100)/100; /* JAMI: *2 */
-                    callback(usage,null);
-                }
-            }.bind(this);
-            transaction.onerror = function(err){
-                callback(null,err);
-            }
-        }
-        else{
-            callback(null,null);
-        }
-    }
-
-    this.stringBytes = function(str) {
-        var b = str.match(/[^\x00-\xff]/g);
-        return (str.length + (!b ? 0: b.length));
-    }
-
-    this.init = function(callback)
-    {
-        var request = indexedDB.open(this._localEnum().DB_NAME, 4);
-        callback = callback? callback : function(success) { console.log("DbStore::init() success:", success)}.bind(this);
-
-        request.onerror = function(event) 
-        {
-            console.log("indexedDB error: " + event.target.errorCode);
-            callback(false,event.target.errorCode);
-        }.bind(this);
-
-        request.onupgradeneeded = function(event) 
-        {
-            var db = event.target.result;
-
-            if( db.objectStoreNames.contains("tilepath")) 
-            {
-                db.deleteObjectStore("tilepath");
-            }            
-
-            var objectStore = db.createObjectStore("tilepath", { keyPath: "url" });
-        }.bind(this);
-
-        request.onsuccess = function(event)
-        {
-            this._db = event.target.result;
-            console.log("database opened successfully");
-            callback(true);
-        }.bind(this);
-    }
-}
diff --git a/tiles/src/ioWorker.js b/tiles/src/ioWorker.js
deleted file mode 100644
index 16f5335..0000000
--- a/tiles/src/ioWorker.js
+++ /dev/null
@@ -1,34 +0,0 @@
-// Base64 conversion functions
-importScripts("_base.js");
-
-var PROXY_URL = "../proxy.php?";
-
-// Parent to worker
-onmessage = function(evt) {
-  getImages(evt.data);
-};
-
-function getImages(urls) {
-  for (var i = 0; i < urls.length; i++) {
-    var imgBytes = getImage(urls[i]);
-    if (imgBytes) {
-      var encoded = Base64Utils.wordToBase64(Base64Utils.stringToWord(imgBytes));
-      postMessage([ urls[i], encoded ]);
-    }
-  } // loop
-}
-
-function getImage(url) {
-  url = PROXY_URL + url;
-
-  var req = new XMLHttpRequest();
-  req.open("GET", url, false);
-  req.overrideMimeType("text/plain; charset=x-user-defined");
-  req.send(null);
-
-  if (req.status != 200) {
-    return "";
-  }
- 
-  return req.responseText;
-}
\ No newline at end of file
diff --git a/tiles/src/offlineEnabler.js b/tiles/src/offlineEnabler.js
index dfbfe96..c48e8a2 100644
--- a/tiles/src/offlineEnabler.js
+++ b/tiles/src/offlineEnabler.js
@@ -1,10 +1,12 @@
-/*
- * depends upon "_base.js"
- */
+"use strict"
+
 define([
 	"dojo/query",
-	"esri/geometry"
-	], function(query, geometry)
+	"esri/geometry",
+	"src/base64utils.js",
+	"src/dbStore.js",
+	"src/tilingScheme.js"
+	], function(query, geometry,Base64Utils,DbStore,TilingScheme)
 	{
 		return {
 			/*
@@ -85,10 +87,31 @@ define([
 					return tileid;
 				};
 
+				layer.estimateTileSize = function()
+				{
+					var tileInfo = this.tileInfo;
+
+					return 14000; // TODO - come up with a more precise estimation method
+				};
+
+				layer.getLevelEstimation = function(extent, level)
+				{
+					var tilingScheme = new TilingScheme(this,geometry);
+				 	var cellIds = tilingScheme.getAllCellIdsInExtent(extent,level);
+					var tileSize = this.estimateTileSize();
+
+					var levelEstimation = { 
+						level: level,
+						tileCount: cellIds.length,
+						sizeBytes: cellIds.length * tileSize
+					}
+
+					return levelEstimation;
+				};
+
 				layer.prepareForOffline = function(minLevel, maxLevel, extent, reportProgress, finishedDownloading)
 				{
 					/* create list of tiles to store */
-					var basemapLayer = map.getLayer( map.layerIds[0] );
 					var tilingScheme = new TilingScheme(this,geometry);
 					var cells = [];
 
diff --git a/tiles/src/tilingScheme.js b/tiles/src/tilingScheme.js
new file mode 100644
index 0000000..260a497
--- /dev/null
+++ b/tiles/src/tilingScheme.js
@@ -0,0 +1,69 @@
+"use strict"
+
+define([
+	"esri/geometry"
+	], function(geometry)
+	{
+
+	var TilingScheme = function(layer)
+	{
+		this.tileInfo = layer.tileInfo;
+	}
+
+	TilingScheme.prototype = 
+	{
+		getCellIdFromXy: function(x,y,level)
+		{
+			var col = Math.floor((x-this.tileInfo.origin.x) / (this.tileInfo.cols*this.tileInfo.lods[level].resolution));
+			var row = Math.floor((this.tileInfo.origin.y-y) / (this.tileInfo.rows*this.tileInfo.lods[level].resolution));
+			return [col,row];
+		},
+
+		getCellPolygonFromCellId: function(cellId,level)
+		{
+		    var col1 = cellId[0];
+		    var row1 = cellId[1];
+		    var col2 = col1+1;
+		    var row2 = row1+1;
+
+		    var x1 = this.tileInfo.origin.x + (col1 * this.tileInfo.cols * this.tileInfo.lods[level].resolution);
+		    var y1 = this.tileInfo.origin.y - (row1 * this.tileInfo.rows * this.tileInfo.lods[level].resolution);
+		    var x2 = this.tileInfo.origin.x + (col2 * this.tileInfo.cols * this.tileInfo.lods[level].resolution);
+		    var y2 = this.tileInfo.origin.y - (row2 * this.tileInfo.rows * this.tileInfo.lods[level].resolution);
+
+		    var polygon = new geometry.Polygon(this.tileInfo.spatialReference);
+		    polygon.addRing([
+				[x1,y1],  // clockwise
+				[x2,y1],
+				[x2,y2],
+				[x1,y2],
+				[x1,y1],
+			]);
+		    return polygon;
+		},
+
+		getAllCellIdsInExtent : function(extent, gridLevel)
+		{
+			var cellId0 = this.getCellIdFromXy(extent.xmin, extent.ymin, gridLevel);
+			var cellId1 = this.getCellIdFromXy(extent.xmax, extent.ymax, gridLevel);
+
+			var i,j;
+			var i0 = Math.max(Math.min(cellId0[0], cellId1[0]), this.tileInfo.lods[gridLevel].startTileCol);
+			var i1 = Math.min(Math.max(cellId0[0], cellId1[0]), this.tileInfo.lods[gridLevel].endTileCol);
+			var j0 = Math.max(Math.min(cellId0[1], cellId1[1]), this.tileInfo.lods[gridLevel].startTileRow);
+			var j1 = Math.min(Math.max(cellId0[1], cellId1[1]), this.tileInfo.lods[gridLevel].endTileRow);
+
+			var cellIds = [];
+
+			for(i=i0; i<=i1; i++)
+				for(j=j0; j<=j1; j++)
+				{
+					cellIds.push([i,j]);
+				}
+
+			return cellIds;
+		},
+	}
+
+	return TilingScheme;
+});
\ No newline at end of file
diff --git a/tiles/tilingScheme.js b/tiles/tilingScheme.js
deleted file mode 100644
index 328b80b..0000000
--- a/tiles/tilingScheme.js
+++ /dev/null
@@ -1,62 +0,0 @@
-"use strict";
-
-var TilingScheme = function(layer,geometry)
-{
-  this.tileInfo = layer.tileInfo;
-  this.geometry = geometry;
-}
-
-TilingScheme.prototype = 
-{
-  getCellIdFromXy: function(x,y,level)
-  {
-    var col = Math.floor((x-this.tileInfo.origin.x) / (this.tileInfo.cols*this.tileInfo.lods[level].resolution));
-    var row = Math.floor((this.tileInfo.origin.y-y) / (this.tileInfo.rows*this.tileInfo.lods[level].resolution));
-    return [col,row];
-  },
-
-  getCellPolygonFromCellId: function(cellId,level)
-  {
-      var col1 = cellId[0];
-      var row1 = cellId[1];
-      var col2 = col1+1;
-      var row2 = row1+1;
-
-      var x1 = this.tileInfo.origin.x + (col1 * this.tileInfo.cols * this.tileInfo.lods[level].resolution);
-      var y1 = this.tileInfo.origin.y - (row1 * this.tileInfo.rows * this.tileInfo.lods[level].resolution);
-      var x2 = this.tileInfo.origin.x + (col2 * this.tileInfo.cols * this.tileInfo.lods[level].resolution);
-      var y2 = this.tileInfo.origin.y - (row2 * this.tileInfo.rows * this.tileInfo.lods[level].resolution);
-
-      var polygon = new this.geometry.Polygon(this.tileInfo.spatialReference);
-      polygon.addRing([
-        [x1,y1],  // clockwise
-        [x2,y1],
-        [x2,y2],
-        [x1,y2],
-        [x1,y1],
-        ])
-      return polygon;
-  },
-
-  getAllCellIdsInExtent : function(extent, gridLevel)
-  {
-    var cellId0 = this.getCellIdFromXy(extent.xmin, extent.ymin, gridLevel);
-    var cellId1 = this.getCellIdFromXy(extent.xmax, extent.ymax, gridLevel);
-
-    var i,j;
-    var i0 = Math.max(Math.min(cellId0[0], cellId1[0]), this.tileInfo.lods[gridLevel].startTileCol);
-    var i1 = Math.min(Math.max(cellId0[0], cellId1[0]), this.tileInfo.lods[gridLevel].endTileCol);
-    var j0 = Math.max(Math.min(cellId0[1], cellId1[1]), this.tileInfo.lods[gridLevel].startTileRow);
-    var j1 = Math.min(Math.max(cellId0[1], cellId1[1]), this.tileInfo.lods[gridLevel].endTileRow);
-
-    var cellIds = [];
-
-    for(i=i0; i<=i1; i++)
-      for(j=j0; j<=j1; j++)
-      {
-        cellIds.push([i,j]);
-      }
-
-    return cellIds;
-  },
-}