XACML Attribute Provider that provides attributes not already provided in the XACML request from PEP, e.g. from external sources. There must be one and only one Java class on the classpath - say com.example.FooAttributeProviderFactory - implementing interface org.ow2.authzforce.core.pdp.api.CloseableDesignatedAttributeProvider.Factory<CONF_T> with zero-arg constructor, where CONF_T is the JAXB type bound to this XML element type. This Attribute Provider may also depend on previously defined attributeProviders, to find dependency attributes, i.e. attributes that this Provider does not support itself, but requires to find its supported attributes. Therefore, if an attributeProvider AP1 requires/depends on an attribute A that is not to be provided in the XACML request from the PEP, another attributeProvider AP2 providing this attribute A must be declared before AP1.

More info about Attribute Providers (how to make/use one) is available on AuthzForce wiki.

Such configurations (XML instances of this schema) may use placeholders enclosed between ${ and } for the following properties:

• the global property PARENT_DIR for defining - in a generic way - a path relative to the parent directory to the XML file where this is used;
• Java system properties;
• System environment variables.

Implementation classes can use org.ow2.authzforce.pd.api.EnvironmentProperties#replacePlaceholders() to replace ${property_name} placeholders with such properties. You may use ! (exclamation mark) as a separating character between the placeholder property name and a default value that is used if the property is undefined. E.g. ${PARENT_DIR!/home/foo/conf} will be replaced with /home/foo/conf if PARENT_DIR is undefined.

In the location, you may use placeholders enclosed between ${ and } for the following properties:

• the global property PARENT_DIR for defining - in a generic way - a path relative to the parent directory to the XML file where this is used;
• Java system properties;
• System environment variables.