This demo shows how to create a map that displays a single vector layer loaded from the geoJson file ca_counties.json. With the Oracle Maps HTML5 API, you can create an interactive vector layer from a variety of data sources and formats. For instance you can create and display a layer based on an external GeoRSS feed, or based on the result set of a dynamic geospatial query posted to a MapViewer server instance, or on a pre-defined MapViewer theme. The easist way to display a layer however is based on some geoJson file, such as the bundled cacounties.json file with all the counties of California, USA. Such geoJson files (also known as _datapacks in the HTML5 API) typically contain a set of features of the same type, with each feature composed of a geometry or shape definition plus addtional attributes. They can be obtained from a variety of sources, including any 11g+ MapViewer server using its Map Data Server (which can generate and stream your Oracle Spatial managed geographic data in geoJson formats). Creates the map instance based on an instance of the WorldMercatorUniverse. This universe is based on the popular world mercator map projection used by many online map services. the universe property can actually be skipped if you add a Tile Layer to the map such as shown in the tile layer demo. Defines the vector layer options that are unique to the datapack type, since we are creating the vector layer based on a datapack geoJson file. optional label column that will provide the label text for each displayed polygon. It must come from the properties tag in the geoJSON file. Creates a Color type style object that will be applied to all the polygons in the layer. This is how we change the drawing style of any vector layers. For instance if a layer’s geometries are all points, then you will want to create a Marker type style and apply it to the layer. now create another Color style to applied to the polygon being hovered on. Notice it changes the polygon to use a thicker border and different fill. next let’s create a different style to be used on selected polygons. The style has a different fill and stroke color. User can select polygons by clicking on it, or by using various selection tools such as the Rectangle selection tool. Now we can complete the initialization of the map. You must only call this method once. Note however map contents (features and layers) can be added even after calling this method. Source.