policy.java

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     * @param id the policy identifier
     * @param version the policy version or null for the default (this must
     *                always be null for XACML 1.x policies)
     * @param combiningAlg the <code>CombiningAlgorithm</code> used on the
     *                     rules in this set
     * @param description a <code>String</code> describing the policy or
     *                    null if there is no description
     * @param target the <code>Target</code> for this policy
     * @param defaultVersion the XPath version to use or null if there is
     *                       no default version
     * @param ruleElements a list of <code>RuleCombinerElement</code> objects
     *                     or null if there are no rules
     * @param obligations a set of <code>Obligations</code> objects or null
     *                    if there are no obligations
     * @param definitions a set of <code>VariableDefinition</code> objects
     *                    that must provide all definitions referenced by
     *                    all <code>VariableReference</code>s in the policy
     * @param parameters the <code>List</code> of
     *                   <code>CombinerParameter</code>s provided for general
     *                   use by the combining algorithm
     *
     * @throws IllegalArgumentException if the <code>List</code> of rules
     *                                  contains an object that is not a
     *                                  <code>RuleCombinerElement</code>
     */
    public Policy(URI id, String version, RuleCombiningAlgorithm combiningAlg,
                  String description, Target target, String defaultVersion,
                  List ruleElements, Set obligations, Set definitions,
                  List parameters) {
        super(id, version, combiningAlg, description, target, defaultVersion,
              obligations, parameters);

        // check that the list contains only RuleCombinerElements
        if (ruleElements != null) {
            Iterator it = ruleElements.iterator();
            while (it.hasNext()) {
                Object o = it.next();
                if (! (o instanceof RuleCombinerElement))
                    throw new IllegalArgumentException("non-Rule in rules");
            }
        }

        setChildren(ruleElements);

        // save the definitions
        if (definitions == null)
            this.definitions = Collections.EMPTY_SET;
        else
            this.definitions = Collections.
                unmodifiableSet(new HashSet(definitions));
    }

    /**
     * Creates a new Policy based on the given root node. This is 
     * private since every class is supposed to use a getInstance() method
     * to construct from a Node, but since we want some common code in the
     * parent class, we need this functionality in a constructor.
     */
    private Policy(Node root) throws ParsingException {
        super(root, "Policy", "RuleCombiningAlgId");

        List rules = new ArrayList();
        HashMap parameters = new HashMap();
        HashMap variableIds = new HashMap();
        PolicyMetaData metaData = getMetaData();

        // first off, go through and look for any definitions to get their
        // identifiers up front, since before we parse any references we'll
        // need to know what definitions we support
        NodeList children = root.getChildNodes();
        for (int i = 0; i < children.getLength(); i++) {
            Node child = children.item(i);
            if (child.getNodeName().equals("VariableDefinition")) {
                String id = child.getAttributes().
                    getNamedItem("VariableId").getNodeValue();

                // it's an error to have more than one definition with the
                // same identifier
                if (variableIds.containsKey(id))
                    throw new ParsingException("multiple definitions for " +
                                               "variable " + id);

                variableIds.put(id, child);
            }
        }

        // now create a manager with the defined variable identifiers
        VariableManager manager = new VariableManager(variableIds, metaData);
        definitions = new HashSet();

        // next, collect the Policy-specific elements
        for (int i = 0; i < children.getLength(); i++) {
            Node child = children.item(i);
            String name = child.getNodeName();

            if (name.equals("Rule")) {
                rules.add(Rule.getInstance(child, metaData, manager));
            } else if (name.equals("RuleCombinerParameters")) {
                String ref = child.getAttributes().getNamedItem("RuleIdRef").
                    getNodeValue();

                // if we found the parameter before than add it the end of
                // the previous paramters, otherwise create a new entry
                if (parameters.containsKey(ref)) {
                    List list = (List)(parameters.get(ref));
                    parseParameters(list, child);
                } else {
                    List list = new ArrayList();
                    parseParameters(list, child);
                    parameters.put(ref, list);
                }
            } else if (name.equals("VariableDefinition")) {
                String id = child.getAttributes().
                    getNamedItem("VariableId").getNodeValue();

                // parsing definitions is a little strange, since they can
                // contain references to definitions we haven't yet parsed
                // or circular references, but we still want to verify the
                // references and the types...so, for each definition, we
                // ask the manager though getDefinition, which takes care
                // of loading any forward references, handles loops, etc.
                // It also handles caching definitions, so we don't end
                // up parsing the same definitions multiple times
                definitions.add(manager.getDefinition(id));
            }
        }

        definitions = Collections.unmodifiableSet(definitions);

        // now make sure that we can match up any parameters we may have
        // found to a cooresponding Rule...
        List elements = new ArrayList();
        Iterator it = rules.iterator();

        while (it.hasNext()) {
            Rule rule = (Rule)(it.next());
            String id = rule.getId().toString();
            List list = (List)(parameters.remove(id));

            elements.add(new RuleCombinerElement(rule, list));
        }

        // ...and that there aren't extra parameters
        if (! parameters.isEmpty())
            throw new ParsingException("Unmatched parameters in Rule");

        // finally, set the list of Rules
        setChildren(elements);
    }

    /**
     * Helper method that parses out a collection of combiner parameters.
     */
    private void parseParameters(List parameters, Node root)
        throws ParsingException
    {
        NodeList nodes = root.getChildNodes();

        for (int i = 0; i < nodes.getLength(); i++) {
            Node node = nodes.item(i);
            if (node.getNodeName().equals("CombinerParameter"))
                parameters.add(CombinerParameter.getInstance(node));
        }
    }

    /**
     * Creates an instance of a <code>Policy</code> object based on a
     * DOM node. The node must be the root of PolicyType XML object,
     * otherwise an exception is thrown.
     *
     * @param root the DOM root of a PolicyType XML type
     *
     * @throws ParsingException if the PolicyType is invalid
     */
    public static Policy getInstance(Node root) throws ParsingException {
        // first off, check that it's the right kind of node
        if (! root.getNodeName().equals("Policy")) {
            throw new ParsingException("Cannot create Policy from root of " +
                                       "type " + root.getNodeName());
        }

        return new Policy(root);
    }

    /**
     * Returns the variable definitions in this Policy.
     *
     * @return a <code>Set</code> of <code>VariableDefinition</code>s
     */
    public Set getVariableDefinitions() {
        return definitions;
    }

    /**
     * Encodes this <code>Policy</code> into its XML representation and writes
     * this encoding to the given <code>OutputStream</code> with no
     * indentation.
     *
     * @param output a stream into which the XML-encoded data is written
     */
    public void encode(OutputStream output) {
        encode(output, new Indenter(0));
    }

    /**
     * Encodes this <code>Policy</code> into its XML representation and writes
     * this encoding to the given <code>OutputStream</code> with
     * indentation.
     *
     * @param output a stream into which the XML-encoded data is written
     * @param indenter an object that creates indentation strings
     */
    public void encode(OutputStream output, Indenter indenter) {
        PrintStream out = new PrintStream(output);
        String indent = indenter.makeString();

        out.println(indent + "<Policy PolicyId=\"" + getId().toString() +
                    "\" RuleCombiningAlgId=\"" +
                    getCombiningAlg().getIdentifier().toString() +
                    "\">");
        
        indenter.in();
        String nextIndent = indenter.makeString();

        String description = getDescription();
        if (description != null)
            out.println(nextIndent + "<Description>" + description +
                        "</Description>");

        String version = getDefaultVersion();
        if (version != null)
            out.println("<PolicyDefaults><XPathVersion>" + version +
                        "</XPathVersion></PolicyDefaults>");

        getTarget().encode(output, indenter);

        Iterator it = definitions.iterator();
        while (it.hasNext())
            ((VariableDefinition)(it.next())).encode(output, indenter);
        
        encodeCommonElements(output, indenter);

        indenter.out();
        out.println(indent + "</Policy>");
    }

}