public ProcessingNode buildNode(Configuration config) throws Exception 
{
        resourceName = config.getAttribute("resource", null);
        functionName = config.getAttribute("function", null);
        continuationId = config.getAttribute("continuation", null);
        if (resourceName == null) {
            // Building a CallFunction node
            if (functionName == null && continuationId == null) {
                throw new ConfigurationException(
                    "< map:call > must have either a 'resource', 'function' or 'continuation' attribute, at " +
                    config.getLocation());
            }
            node = new CallFunctionNode(
                VariableResolverFactory.getResolver(functionName, this.manager),
                VariableResolverFactory.getResolver(continuationId, this.manager)
            );
        } else {
            // Building a Call(Resource)Node
            if (functionName != null || continuationId != null) {
                throw new ConfigurationException(
                    "< map:call > cannot have both a 'resource' and a 'function' or 'continuation' attribute, at "
                    + config.getLocation()
                );
            }
            node = new CallNode();
        }
        this.treeBuilder.setupNode(this.node, config);
        if (node instanceof Configurable) {
            ((Configurable)this.node).configure(config);
        }
        return this.node;
}

 public  void linkNode() throws Exception 
{
        if (resourceName != null) {
            // We have a < map:call resource="..."/ >
            CategoryNode resources
                    = CategoryNodeBuilder.getCategoryNode(treeBuilder, "resources");
            if (resources == null)
                throw new ConfigurationException("This sitemap contains no resources. Cannot call at " + node.getLocation());
            ((CallNode)this.node).setResource(resources, this.resourceName);
        }
        else {
            // We have a < map:call > with either "function" or
            // "continuation", or both specified
            // Check to see if a flow has been defined in this sitemap
            FlowNode flow = (FlowNode)treeBuilder.getRegisteredNode("flow");
            if (flow == null)
                throw new ConfigurationException("This sitemap contains no control flows defined, cannot call at " + node.getLocation() + ". Define a control flow using < map:flow >, with embedded < map:script > elements.");
            // Get the Interpreter instance and set it up in the
            // CallFunctionNode function
            Interpreter interpreter = flow.getInterpreter();
            ((CallFunctionNode)node).setInterpreter(interpreter);
        }
}