public  void callFunction(String function,
    List params,
    Redirector redirector) throws Exception 
{
        if (!initialized)
            initialize();
        Method method = (Method) methods.get(function);
        if (method == null) {
            throw new ProcessingException("No method '" + function + "' found. " + methods);
        }
        if (getLogger().isDebugEnabled()) 
            getLogger().debug("calling method \"" + method + "\"");
        Request request = ContextHelper.getRequest(this.avalonContext);
        Session session = request.getSession(true);
        HashMap userScopes = (HashMap) session.getAttribute(USER_GLOBAL_SCOPE);
        if (userScopes == null)
            userScopes = new HashMap();
        Continuable flow = (Continuable) userScopes.get(method.getDeclaringClass());
        ContinuationContext context = new ContinuationContext();
        context.setObject(flow);
        context.setMethod(method);
        context.setAvalonContext(avalonContext);
        context.setLogger(getLogger());
        context.setServiceManager(manager);
        context.setRedirector(redirector);
        Parameters parameters = new Parameters();
        for(Iterator i=params.iterator(); i.hasNext();) {
            Argument argument = (Argument)i.next();
            parameters.setParameter(argument.name, argument.value);
        }
        context.setParameters(parameters);
        Continuation continuation = new Continuation(context);
        WebContinuation wk = continuationsMgr.createWebContinuation(
                continuation, null, timeToLive, getInterpreterID(), null);
        FlowHelper.setWebContinuation(ContextHelper.getObjectModel(this.avalonContext), wk);
        continuation.registerThread();
        try {
            if (flow == null) {
                if (getLogger().isDebugEnabled())
                    getLogger().debug("create new instance of \""+method.getDeclaringClass()+"\"");
                flow = (Continuable) method.getDeclaringClass().newInstance();
                context.setObject(flow);
            }
            method.invoke(flow, new Object[0]);
        } catch (InvocationTargetException ite) {
            if (ite.getTargetException() != null) {
                if (ite.getTargetException() instanceof Exception) 
                    throw (Exception) ite.getTargetException();
                else if (ite.getTargetException() instanceof Error)
                    throw new ProcessingException("An internal error occured", ite.getTargetException());
                else if (ite.getTargetException() instanceof RuntimeException)
                    throw (RuntimeException) ite.getTargetException();
                else
                    throw ite;
            } else {
                throw ite;
            }
        } finally {
            // remove last object reference, which is not needed to
            // reconstruct the invocation path
            if (continuation.isCapturing())
                continuation.getStack().popReference();
            continuation.deregisterThread();
        }
        userScopes.put(method.getDeclaringClass(), flow);
        session.setAttribute(USER_GLOBAL_SCOPE, userScopes);
}

Calls a Java function, passing params as its arguments. In addition to this, it makes available the parameters through the cocoon.parameters Java array (indexed by the parameter names).

 public  void configure(Configuration config) throws ConfigurationException 
{
     
        JXPathIntrospector.registerDynamicClass(VarMap.class, VarMapHandler.class);
        super.configure(config);
}

 public  void handleContinuation(String id,
    List params,
    Redirector redirector) throws Exception 
{
        if (!initialized)
            initialize();
        WebContinuation parentwk = continuationsMgr.lookupWebContinuation(id, getInterpreterID());
        if (parentwk == null) {
            /*
             * Throw an InvalidContinuationException to be handled inside the
             * < map:handle-errors > sitemap element.
             */
            throw new InvalidContinuationException("The continuation ID " + id + " is invalid.");
        }
        Continuation parentContinuation = (Continuation) parentwk.getContinuation();
        ContinuationContext parentContext = (ContinuationContext) parentContinuation.getContext();
        ContinuationContext context = new ContinuationContext();
        context.setObject(parentContext.getObject());
        context.setMethod(parentContext.getMethod());
        context.setAvalonContext(avalonContext);
        context.setLogger(getLogger());
        context.setServiceManager(manager);
        context.setRedirector(redirector);
        Parameters parameters = new Parameters();
        for(Iterator i=params.iterator(); i.hasNext();) {
            Argument argument = (Argument)i.next();
            parameters.setParameter(argument.name, argument.value);
        }
        context.setParameters(parameters);
        Continuation continuation = new Continuation(parentContinuation, context);
        Request request = ContextHelper.getRequest(this.avalonContext);
        Session session = request.getSession(true);
        HashMap userScopes = (HashMap) session.getAttribute(USER_GLOBAL_SCOPE);
        Continuable flow = (Continuable) context.getObject();
        Method method = context.getMethod();
        WebContinuation wk = continuationsMgr.createWebContinuation(
                continuation, parentwk, timeToLive, getInterpreterID(), null);
        FlowHelper.setWebContinuation(ContextHelper.getObjectModel(this.avalonContext), wk);
        continuation.registerThread();
        try {
            method.invoke(flow, new Object[0]);
        } catch (InvocationTargetException ite) {
            if (ite.getTargetException() != null) {
                if (ite.getTargetException() instanceof Exception)
                    throw (Exception) ite.getTargetException();
                else if (ite.getTargetException() instanceof Error)
                    throw new ProcessingException("An internal error occured", ite.getTargetException());
                else if (ite.getTargetException() instanceof RuntimeException)
                    throw (RuntimeException) ite.getTargetException();
                else
                    throw ite;
            } else {
                throw ite;
            }
        } finally {
            // remove last object reference, which is not needed to reconstruct
            // the invocation path
            if (continuation.isCapturing())
              continuation.getStack().popReference();
            continuation.deregisterThread();
        }
        userScopes.put(method.getDeclaringClass(), flow);
        session.setAttribute(USER_GLOBAL_SCOPE, userScopes);
}

 public synchronized  void initialize() throws Exception 
{
        if (initialized) {
            return;
        }
        try {
            if (getLogger().isDebugEnabled())
                getLogger().debug("initialize java flow interpreter");
            classloader = new ContinuationClassLoader(Thread.currentThread().getContextClassLoader());
            for (Iterator scripts = needResolve.iterator(); scripts.hasNext();) {
                String classname = (String) scripts.next();
                if (getLogger().isDebugEnabled())
                    getLogger().debug("registered java class \"" + classname + "\" for flow");
                if (!Continuable.class.isAssignableFrom(Class.forName(classname))) {
                    getLogger().error("java class \"" + classname + "\" doesn't implement Continuable");
                    continue;
                }
                Class clazz = classloader.loadClass(classname);
                final Map m = ReflectionUtils.discoverMethods(clazz);
                methods.putAll(m);
                //Only initialize if everything so far hasn't thrown any exceptions.
                initialized = true;
            }
        } catch (final Exception e) {
            throw new ConfigurationException("Cannot initialize JavaInterpreter", e);
        }
}