Configuration interfaces
At the heart of Saxon is the object net.sf.saxon.Configuration. This contains all the current settings
of configuration options. All Saxon tasks, such as compiling and running queries and transformations, or building and
validating source documents, happen under the control of a Configuration. Many resources are owned
by the Configuration, meaning that related tasks must run under the same Configuration.
Most notably, the Configuration holds a NamePool, which is a table allocating integer
codes to the qualified names that appear in stylesheets, queries, schemas, and source documnets, and during the execution
of a stylesheet or query all the resources used (for example, the stylesheet, all its input documents, and any schemas
it uses) must all use the same NamePool to ensure that they all use the same integer codes for the same
qualified names. However, two Saxon tasks that are unrelated can run under different Configurations.
There are subclasses of Configuration containing resources associated with the capabilities of the
different Saxon editions: specifically, com.saxonica.config.ProfessionalConfiguration and
com.saxonica.config.EnterpriseConfiguration. In many cases the Configuration is used
as a factory class to deliver services associated with the different capability levels, for example the
method getOptimizer() returns the query optimizer appropriate to the loaded Saxon edition.
Many configuration options have direct setter and getter methods on the Configuration object,
for example setAllowExternalFunctions() and isAllowExternalFunctions(). Some other options
have setters and getters on objects reachable from the Configuration, for example defaults for XSLT
processing can be controlled using methods such as getDefaultXsltCompilerInfo().setXsltVersion(),
while defaults for XQuery processing can be controlled using methods such as
getDefaultStaticQueryContext().setLanguageVersion().
The most general mechanism for getting and setting configuration properties, however, is provided by the methods
getConfigurationProperty(name) and setConfigurationProperty(name, value). In these methods
the name of the configuration property is always a string in the form of a URI (for example,
"http://saxon.sf.net/feature/initialTemplate"), and the strings available are all defined by constants in the
class net.sf.saxon.lib.FeatureKeys (for example, FeatureKeys.INITIAL_TEMPLATE).
The value is of various types depending on the property. In the vast majority of cases, the property
can be supplied as a string, or it has an alternative, equivalent property that can be supplied as a string.
For properties that are essentially boolean in nature the value can be supplied either as one of the Java constants
Boolean.TRUE or Boolean.FALSE, or as one of the strings "true", "1", "yes", "on", or
"false", "0", "no", "off". These choices are designed to suit the conventions of different APIs in which the
configuration options are exposed.
In many APIs for controlling Saxon activities, the Configuration object is not exposed
directly, but is hidden below some similar object acting as the root object for that particular API. Many
of these objects provide a direct way to set the configuration options. These are discussed in the following
sections.