# JAXP Source Types

This section is relevant to the Java platform only.

When a user application invokes Saxon via the Java API, then a source document is supplied as an instance of the JAXP `Source` class. This is true whether invoking an XSLT transformation, an XQuery query, or a free-standing XPath expression. The `Source` class is essentially a marker interface. The `Source` that is supplied must be a kind of `Source` that Saxon recognizes.

Saxon recognizes the three kinds of `Source` defined in JAXP: a `StreamSource`, a `SAXSource`, and a `DOMSource`. If a `DOMSource` is to be used, then the Saxon DOM support classes in `saxon8-dom.jar` must be on the class path.

Nodes in Saxon's implementation of the XPath data model are represented by the interface `net.sf.saxon.NodeInfo`. A `NodeInfo` is itself a `Source`, which means that any method in the API that requires a source object will accept any implementation of `net.sf.saxon.NodeInfo`.

Saxon also provides a class `net.sf.saxon.AugmentedSource` which implements the `Source` interface. This class encapsulates one of the standard `Source` objects, and allows additional processing options to be specified. These options include whitespace handling, schema and DTD validation, XInclude processing, error handling, choice of XML parser, and choice of Saxon tree model.

Saxon allows additional `Source` types to be supported by registering a `SourceResolver` with the `Configuration` object. The task of a `SourceResolver` is to convert a `Source` that Saxon does not recognize into a `Source` that it does recognize. For example, this may be done by building the document tree in memory and returning the `NodeInfo` object representing the root of the tree.

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