updated voila demo to work with updated client code

Author: jpswinski

examples/voila_demo.ipynb

@@ -174,23 +174,20 @@
    "outputs": [],
    "source": [
     "%matplotlib inline\n",
-    "# callback for handling results\n",
-    "def demoCB(resource, result, index, total):\n",
-    "    global parms, results\n",
-    "    print(f'SlideRule processing request... [{index}/{total}] {resource} returned {len(result)} elevations\\r', end=\"\")\n",
-    "    if len(result) > 0:\n",
-    "        results.append(result)\n",
+    "\n",
+    "# callbacks for events and exceptions\n",
+    "def demo_logeventrec(rec):\n",
+    "    print(f'{rec[\"attr\"]}                                                        \\r', end=\"\")\n",
+    "\n",
+    "def demo_exceptrec(rec):\n",
+    "    print(f'{rec[\"text\"]}                                                        \\r', end=\"\")\n",
     "\n",
     "# build and transmit requests to SlideRule\n",
     "def runSlideRule():\n",
     "    global url_textbox, parms, results\n",
     "    \n",
     "    # set the url for the sliderule service\n",
-    "    if url_textbox.value == 'local':\n",
-    "        url = 'host.docker.internal'\n",
-    "    else:\n",
-    "        url = url_textbox.value\n",
-    "    icesat2.init(url, loglevel=logging.WARNING, max_resources=1000)\n",
+    "    icesat2.init(url_textbox.value, loglevel=logging.WARNING, max_resources=1000)\n",
     "\n",
     "    # sliderule asset and data release\n",
     "    asset = SRwidgets.asset.value\n",
@@ -221,20 +218,17 @@
     "\n",
     "    # clear existing geodataframe\n",
     "    results = []\n",
-    "    rsps = icesat2.__emptyframe()\n",
+    "    gdf = icesat2.__emptyframe()\n",
     "\n",
     "    # for each region of interest\n",
     "    for poly in m.regions:\n",
     "        # add polygon from map to sliderule parameters\n",
     "        parms[\"poly\"] = poly \n",
     "        # make the request to the SlideRule (ATL06-SR) endpoint\n",
     "        # and pass it the request parameters to request ATL06 Data\n",
-    "        icesat2.atl06p(parms, asset, callback=demoCB)\n",
-    "\n",
-    "    if len(results) > 0:\n",
-    "        rsps = geopandas.pd.concat(results)\n",
+    "        gdf = gdf.append(icesat2.atl06p(parms, asset, callbacks={'eventrec': demo_logeventrec, 'exceptrec': demo_exceptrec}))\n",
     "    \n",
-    "    return rsps\n",
+    "    return gdf\n",
     "\n",
     "# run sliderule action\n",
     "def on_run_clicked(b):\n",
@@ -292,7 +286,7 @@
    "source": [
     "# url input text box\n",
     "url_textbox = widgets.Text(\n",
-    "    value='local',\n",
+    "    value='slideruleearth.io',\n",
     "    placeholder='Input box for SlideRule url',\n",
     "    description='URL:',\n",
     "    disabled=False\n",