There are five things we need to cover to understand how the vector layer works:
How the vector layer is rendered
The vector layer class itself
The vector source class and related format classes
The Feature and Geometry classes
The styling vector layers, which we won't look at until the next chapter
Recall from Chapter 3, Charting the Map Class that OpenLayers supports three separate renderer technologies, WebGL, Canvas, and DOM. When OpenLayers draws the layers in a map, it uses one of these renderers to do the actual work of drawing. The renderer requests data from the layer's source for the area being displayed, and then transforms this into the final map image. For raster layers, images are fetched from a remote server and are composited into a Canvas element (for WebGL and Canvas renderers) or <img> tags (for the DOM render). Vector layers work in the same way, but are only supported by the Canvas renderer at the time this book...