/*
* @(#)StandardCombiningAlgFactory.java
*
* Copyright 2004-2006 Sun Microsystems, Inc. All Rights Reserved.
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package com.sun.xacml.combine;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import java.util.logging.Logger;
import com.sun.xacml.PolicyMetaData;
import com.sun.xacml.UnknownIdentifierException;
/**
* This factory supports the standard set of algorithms specified in XACML 1.x and 2.0. It is the
* default factory used by the system, and imposes a singleton pattern insuring that there is only
* ever one instance of this class.
* <p>
* Note that because this supports only the standard algorithms, this factory does not allow the
* addition of any other algorithms. If you call <code>addAlgorithm</code> on an instance of this
* class, an exception will be thrown. If you need a standard factory that is modifiable, you should
* create a new <code>BaseCombiningAlgFactory</code> (or some other <code>CombiningAlgFactory</code>
* ) and configure it with the standard algorithms using <code>getStandardAlgorithms</code> (or, in
* the case of <code>BaseAttributeFactory</code>, by providing the datatypes in the constructor).
*
* @since 1.2
* @author Seth Proctor
*/
public class StandardCombiningAlgFactory extends BaseCombiningAlgFactory {
// the single factory instance
private static StandardCombiningAlgFactory factoryInstance = null;
// the algorithms supported by this factory
private static Set<CombiningAlgorithm> supportedAlgorithms = null;
// identifiers for the supported algorithms
private static Set<String> supportedAlgIds;
// the logger we'll use for all messages
private static final Logger logger = Logger.getLogger(StandardCombiningAlgFactory.class
.getName());
/**
* Default constructor.
*/
private StandardCombiningAlgFactory() {
super(supportedAlgorithms);
}
/**
* Private initializer for the supported algorithms. This isn't called until something needs
* these values, and is only called once.
*/
private static void initAlgorithms() {
logger.config("Initializing standard combining algorithms");
supportedAlgorithms = new HashSet<CombiningAlgorithm>();
supportedAlgIds = new HashSet<String>();
supportedAlgorithms.add(new DenyOverridesRuleAlg());
supportedAlgIds.add(DenyOverridesRuleAlg.algId);
supportedAlgorithms.add(new DenyOverridesPolicyAlg());
supportedAlgIds.add(DenyOverridesPolicyAlg.algId);
supportedAlgorithms.add(new OrderedDenyOverridesRuleAlg());
supportedAlgIds.add(OrderedDenyOverridesRuleAlg.algId);
supportedAlgorithms.add(new OrderedDenyOverridesPolicyAlg());
supportedAlgIds.add(OrderedDenyOverridesPolicyAlg.algId);
supportedAlgorithms.add(new PermitOverridesRuleAlg());
supportedAlgIds.add(PermitOverridesRuleAlg.algId);
supportedAlgorithms.add(new PermitOverridesPolicyAlg());
supportedAlgIds.add(PermitOverridesPolicyAlg.algId);
supportedAlgorithms.add(new OrderedPermitOverridesRuleAlg());
supportedAlgIds.add(OrderedPermitOverridesRuleAlg.algId);
supportedAlgorithms.add(new OrderedPermitOverridesPolicyAlg());
supportedAlgIds.add(OrderedPermitOverridesPolicyAlg.algId);
supportedAlgorithms.add(new FirstApplicableRuleAlg());
supportedAlgIds.add(FirstApplicableRuleAlg.algId);
supportedAlgorithms.add(new FirstApplicablePolicyAlg());
supportedAlgIds.add(FirstApplicablePolicyAlg.algId);
supportedAlgorithms.add(new OnlyOneApplicablePolicyAlg());
supportedAlgIds.add(OnlyOneApplicablePolicyAlg.algId);
supportedAlgIds = Collections.unmodifiableSet(supportedAlgIds);
}
/**
* Returns an instance of this factory. This method enforces a singleton model, meaning that
* this always returns the same instance, creating the factory if it hasn't been requested
* before. This is the default model used by the <code>CombiningAlgFactory</code>, ensuring
* quick access to this factory.
*
* @return the factory instance
*/
public static StandardCombiningAlgFactory getFactory() {
if (factoryInstance == null) {
synchronized (StandardCombiningAlgFactory.class) {
if (factoryInstance == null) {
initAlgorithms();
factoryInstance = new StandardCombiningAlgFactory();
}
}
}
return factoryInstance;
}
/**
* A convenience method that returns a new instance of a <code>CombiningAlgFactory</code> that
* supports all of the standard algorithms. The new factory allows adding support for new
* algorithms. This method should only be used when you need a new, mutable instance (eg, when
* you want to create a new factory that extends the set of supported algorithms). In general,
* you should use <code>getFactory</code> which is more efficient and enforces a singleton
* pattern.
*
* @return a new factory supporting the standard algorithms
*/
public static CombiningAlgFactory getNewFactory() {
// first we make sure everything's been initialized...
getFactory();
// ...then we create the new instance
return new BaseCombiningAlgFactory(supportedAlgorithms);
}
/**
* Returns the identifiers supported for the given version of XACML. Because this factory
* supports identifiers from all versions of the XACML specifications, this method is useful for
* getting a list of which specific identifiers are supported by a given version of XACML.
*
* @param xacmlVersion
* a standard XACML identifier string, as provided in <code>PolicyMetaData</code>
*
* @return a <code>Set</code> of identifiers
*
* @throws UnknownIdentifierException
* if the version string is unknown
*/
public static Set<String> getStandardAlgorithms(String xacmlVersion)
throws UnknownIdentifierException {
if ((xacmlVersion.equals(PolicyMetaData.XACML_1_0_IDENTIFIER))
|| (xacmlVersion.equals(PolicyMetaData.XACML_2_0_IDENTIFIER)))
return supportedAlgIds;
throw new UnknownIdentifierException("Unknown XACML version: " + xacmlVersion);
}
/**
* Throws an <code>UnsupportedOperationException</code> since you are not allowed to modify what
* a standard factory supports.
*
* @param alg
* the combining algorithm to add
*
* @throws UnsupportedOperationException
* always
*/
public void addAlgorithm(CombiningAlgorithm alg) {
throw new UnsupportedOperationException("a standard factory cannot "
+ "support new algorithms");
}
}