Essential XML: Beyond Markup

Implementation vs Interface

The discussion so far has focused on DOM Level 2 core functionality. The DOM working group defines a base set of functionality that all implementations must fulfill. The DOM working group has also defined interfaces that model peripheral functionality that implementations can elect to implement or not implement as they see fit. Rather than use the well-known component development techniques^[11] for interface discovery, the DOM working group instead relies on a hard-coded method (DOMImplementation.hasFeature) to determine whether a given implementation supports some feature. DOMImplementation.hasFeature allows you to query for specific versions of DOM feature support. The following Java code tests if the DOM implementation ...