path: root/src/com/vaadin/terminal/gwt/server/AbstractCommunicationManager.java

/*
@VaadinApache2LicenseForJavaFiles@
 */

package com.vaadin.terminal.gwt.server;

import java.io.BufferedWriter;
import java.io.ByteArrayOutputStream;
import java.io.CharArrayWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.Serializable;
import java.io.StringWriter;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.security.GeneralSecurityException;
import java.text.CharacterIterator;
import java.text.DateFormat;
import java.text.DateFormatSymbols;
import java.text.SimpleDateFormat;
import java.text.StringCharacterIterator;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.GregorianCalendar;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Set;
import java.util.UUID;
import java.util.logging.Level;
import java.util.logging.Logger;

import com.vaadin.Application;
import com.vaadin.Application.SystemMessages;
import com.vaadin.RootRequiresMoreInformationException;
import com.vaadin.external.json.JSONArray;
import com.vaadin.external.json.JSONException;
import com.vaadin.external.json.JSONObject;
import com.vaadin.terminal.CombinedRequest;
import com.vaadin.terminal.LegacyPaint;
import com.vaadin.terminal.PaintException;
import com.vaadin.terminal.PaintTarget;
import com.vaadin.terminal.RequestHandler;
import com.vaadin.terminal.StreamVariable;
import com.vaadin.terminal.StreamVariable.StreamingEndEvent;
import com.vaadin.terminal.StreamVariable.StreamingErrorEvent;
import com.vaadin.terminal.Terminal.ErrorEvent;
import com.vaadin.terminal.Terminal.ErrorListener;
import com.vaadin.terminal.Vaadin6Component;
import com.vaadin.terminal.VariableOwner;
import com.vaadin.terminal.WrappedRequest;
import com.vaadin.terminal.WrappedResponse;
import com.vaadin.terminal.gwt.client.ApplicationConnection;
import com.vaadin.terminal.gwt.client.Connector;
import com.vaadin.terminal.gwt.client.communication.MethodInvocation;
import com.vaadin.terminal.gwt.client.communication.SharedState;
import com.vaadin.terminal.gwt.server.BootstrapHandler.BootstrapContext;
import com.vaadin.terminal.gwt.server.ComponentSizeValidator.InvalidLayout;
import com.vaadin.ui.AbstractComponent;
import com.vaadin.ui.AbstractField;
import com.vaadin.ui.Component;
import com.vaadin.ui.DirtyConnectorTracker;
import com.vaadin.ui.HasComponents;
import com.vaadin.ui.Panel;
import com.vaadin.ui.Root;
import com.vaadin.ui.Window;

/**
 * This is a common base class for the server-side implementations of the
 * communication system between the client code (compiled with GWT into
 * JavaScript) and the server side components. Its client side counterpart is
 * {@link ApplicationConnection}.
 * 
 * TODO Document better!
 */
@SuppressWarnings("serial")
public abstract class AbstractCommunicationManager implements Serializable {

    private static final String DASHDASH = "--";

    private static final Logger logger = Logger
            .getLogger(AbstractCommunicationManager.class.getName());

    private static final RequestHandler APP_RESOURCE_HANDLER = new ApplicationResourceHandler();

    private static final RequestHandler UNSUPPORTED_BROWSER_HANDLER = new UnsupportedBrowserHandler();

    /**
     * TODO Document me!
     * 
     * @author peholmst
     */
    public interface Callback extends Serializable {

        public void criticalNotification(WrappedRequest request,
                WrappedResponse response, String cap, String msg,
                String details, String outOfSyncURL) throws IOException;
    }

    static class UploadInterruptedException extends Exception {
        public UploadInterruptedException() {
            super("Upload interrupted by other thread");
        }
    }

    private static String GET_PARAM_REPAINT_ALL = "repaintAll";

    // flag used in the request to indicate that the security token should be
    // written to the response
    private static final String WRITE_SECURITY_TOKEN_FLAG = "writeSecurityToken";

    /* Variable records indexes */
    public static final char VAR_BURST_SEPARATOR = '\u001d';

    public static final char VAR_ESCAPE_CHARACTER = '\u001b';

    private final HashMap<Integer, ClientCache> rootToClientCache = new HashMap<Integer, ClientCache>();

    private static final int MAX_BUFFER_SIZE = 64 * 1024;

    /* Same as in apache commons file upload library that was previously used. */
    private static final int MAX_UPLOAD_BUFFER_SIZE = 4 * 1024;

    private static final String GET_PARAM_ANALYZE_LAYOUTS = "analyzeLayouts";

    private final Application application;

    private List<String> locales;

    private int pendingLocalesIndex;

    private int timeoutInterval = -1;

    private DragAndDropService dragAndDropService;

    private String requestThemeName;

    private int maxInactiveInterval;

    private Connector highlightedConnector;

    /**
     * TODO New constructor - document me!
     * 
     * @param application
     */
    public AbstractCommunicationManager(Application application) {
        this.application = application;
        application.addRequestHandler(getBootstrapHandler());
        application.addRequestHandler(APP_RESOURCE_HANDLER);
        application.addRequestHandler(UNSUPPORTED_BROWSER_HANDLER);
        requireLocale(application.getLocale().toString());
    }

    protected Application getApplication() {
        return application;
    }

    private static final int LF = "\n".getBytes()[0];

    private static final String CRLF = "\r\n";

    private static final String UTF8 = "UTF8";

    private static final String GET_PARAM_HIGHLIGHT_COMPONENT = "highlightComponent";

    private static String readLine(InputStream stream) throws IOException {
        ByteArrayOutputStream bout = new ByteArrayOutputStream();
        int readByte = stream.read();
        while (readByte != LF) {
            bout.write(readByte);
            readByte = stream.read();
        }
        byte[] bytes = bout.toByteArray();
        return new String(bytes, 0, bytes.length - 1, UTF8);
    }

    /**
     * Method used to stream content from a multipart request (either from
     * servlet or portlet request) to given StreamVariable
     * 
     * 
     * @param request
     * @param response
     * @param streamVariable
     * @param owner
     * @param boundary
     * @throws IOException
     */
    protected void doHandleSimpleMultipartFileUpload(WrappedRequest request,
            WrappedResponse response, StreamVariable streamVariable,
            String variableName, Connector owner, String boundary)
            throws IOException {
        // multipart parsing, supports only one file for request, but that is
        // fine for our current terminal

        final InputStream inputStream = request.getInputStream();

        int contentLength = request.getContentLength();

        boolean atStart = false;
        boolean firstFileFieldFound = false;

        String rawfilename = "unknown";
        String rawMimeType = "application/octet-stream";

        /*
         * Read the stream until the actual file starts (empty line). Read
         * filename and content type from multipart headers.
         */
        while (!atStart) {
            String readLine = readLine(inputStream);
            contentLength -= (readLine.length() + 2);
            if (readLine.startsWith("Content-Disposition:")
                    && readLine.indexOf("filename=") > 0) {
                rawfilename = readLine.replaceAll(".*filename=", "");
                String parenthesis = rawfilename.substring(0, 1);
                rawfilename = rawfilename.substring(1);
                rawfilename = rawfilename.substring(0,
                        rawfilename.indexOf(parenthesis));
                firstFileFieldFound = true;
            } else if (firstFileFieldFound && readLine.equals("")) {
                atStart = true;
            } else if (readLine.startsWith("Content-Type")) {
                rawMimeType = readLine.split(": ")[1];
            }
        }

        contentLength -= (boundary.length() + CRLF.length() + 2
                * DASHDASH.length() + 2); // 2 == CRLF

        /*
         * Reads bytes from the underlying stream. Compares the read bytes to
         * the boundary string and returns -1 if met.
         * 
         * The matching happens so that if the read byte equals to the first
         * char of boundary string, the stream goes to "buffering mode". In
         * buffering mode bytes are read until the character does not match the
         * corresponding from boundary string or the full boundary string is
         * found.
         * 
         * Note, if this is someday needed elsewhere, don't shoot yourself to
         * foot and split to a top level helper class.
         */
        InputStream simpleMultiPartReader = new SimpleMultiPartInputStream(
                inputStream, boundary);

        /*
         * Should report only the filename even if the browser sends the path
         */
        final String filename = removePath(rawfilename);
        final String mimeType = rawMimeType;

        try {
            /*
             * safe cast as in GWT terminal all variable owners are expected to
             * be components.
             */
            Component component = (Component) owner;
            if (component.isReadOnly()) {
                throw new UploadException(
                        "Warning: file upload ignored because the componente was read-only");
            }
            boolean forgetVariable = streamToReceiver(simpleMultiPartReader,
                    streamVariable, filename, mimeType, contentLength);
            if (forgetVariable) {
                cleanStreamVariable(owner, variableName);
            }
        } catch (Exception e) {
            synchronized (application) {
                handleChangeVariablesError(application, (Component) owner, e,
                        new HashMap<String, Object>());
            }
        }
        sendUploadResponse(request, response);

    }

    /**
     * Used to stream plain file post (aka XHR2.post(File))
     * 
     * @param request
     * @param response
     * @param streamVariable
     * @param owner
     * @param contentLength
     * @throws IOException
     */
    protected void doHandleXhrFilePost(WrappedRequest request,
            WrappedResponse response, StreamVariable streamVariable,
            String variableName, Connector owner, int contentLength)
            throws IOException {

        // These are unknown in filexhr ATM, maybe add to Accept header that
        // is accessible in portlets
        final String filename = "unknown";
        final String mimeType = filename;
        final InputStream stream = request.getInputStream();
        try {
            /*
             * safe cast as in GWT terminal all variable owners are expected to
             * be components.
             */
            Component component = (Component) owner;
            if (component.isReadOnly()) {
                throw new UploadException(
                        "Warning: file upload ignored because the component was read-only");
            }
            boolean forgetVariable = streamToReceiver(stream, streamVariable,
                    filename, mimeType, contentLength);
            if (forgetVariable) {
                cleanStreamVariable(owner, variableName);
            }
        } catch (Exception e) {
            synchronized (application) {
                handleChangeVariablesError(application, (Component) owner, e,
                        new HashMap<String, Object>());
            }
        }
        sendUploadResponse(request, response);
    }

    /**
     * @param in
     * @param streamVariable
     * @param filename
     * @param type
     * @param contentLength
     * @return true if the streamvariable has informed that the terminal can
     *         forget this variable
     * @throws UploadException
     */
    protected final boolean streamToReceiver(final InputStream in,
            StreamVariable streamVariable, String filename, String type,
            int contentLength) throws UploadException {
        if (streamVariable == null) {
            throw new IllegalStateException(
                    "StreamVariable for the post not found");
        }

        final Application application = getApplication();

        OutputStream out = null;
        int totalBytes = 0;
        StreamingStartEventImpl startedEvent = new StreamingStartEventImpl(
                filename, type, contentLength);
        try {
            boolean listenProgress;
            synchronized (application) {
                streamVariable.streamingStarted(startedEvent);
                out = streamVariable.getOutputStream();
                listenProgress = streamVariable.listenProgress();
            }

            // Gets the output target stream
            if (out == null) {
                throw new NoOutputStreamException();
            }

            if (null == in) {
                // No file, for instance non-existent filename in html upload
                throw new NoInputStreamException();
            }

            final byte buffer[] = new byte[MAX_UPLOAD_BUFFER_SIZE];
            int bytesReadToBuffer = 0;
            while ((bytesReadToBuffer = in.read(buffer)) > 0) {
                out.write(buffer, 0, bytesReadToBuffer);
                totalBytes += bytesReadToBuffer;
                if (listenProgress) {
                    // update progress if listener set and contentLength
                    // received
                    synchronized (application) {
                        StreamingProgressEventImpl progressEvent = new StreamingProgressEventImpl(
                                filename, type, contentLength, totalBytes);
                        streamVariable.onProgress(progressEvent);
                    }
                }
                if (streamVariable.isInterrupted()) {
                    throw new UploadInterruptedException();
                }
            }

            // upload successful
            out.close();
            StreamingEndEvent event = new StreamingEndEventImpl(filename, type,
                    totalBytes);
            synchronized (application) {
                streamVariable.streamingFinished(event);
            }

        } catch (UploadInterruptedException e) {
            // Download interrupted by application code
            tryToCloseStream(out);
            StreamingErrorEvent event = new StreamingErrorEventImpl(filename,
                    type, contentLength, totalBytes, e);
            synchronized (application) {
                streamVariable.streamingFailed(event);
            }
            // Note, we are not throwing interrupted exception forward as it is
            // not a terminal level error like all other exception.
        } catch (final Exception e) {
            tryToCloseStream(out);
            synchronized (application) {
                StreamingErrorEvent event = new StreamingErrorEventImpl(
                        filename, type, contentLength, totalBytes, e);
                synchronized (application) {
                    streamVariable.streamingFailed(event);
                }
                // throw exception for terminal to be handled (to be passed to
                // terminalErrorHandler)
                throw new UploadException(e);
            }
        }
        return startedEvent.isDisposed();
    }

    static void tryToCloseStream(OutputStream out) {
        try {
            // try to close output stream (e.g. file handle)
            if (out != null) {
                out.close();
            }
        } catch (IOException e1) {
            // NOP
        }
    }

    /**
     * Removes any possible path information from the filename and returns the
     * filename. Separators / and \\ are used.
     * 
     * @param name
     * @return
     */
    private static String removePath(String filename) {
        if (filename != null) {
            filename = filename.replaceAll("^.*[/\\\\]", "");
        }

        return filename;
    }

    /**
     * TODO document
     * 
     * @param request
     * @param response
     * @throws IOException
     */
    protected void sendUploadResponse(WrappedRequest request,
            WrappedResponse response) throws IOException {
        response.setContentType("text/html");
        final OutputStream out = response.getOutputStream();
        final PrintWriter outWriter = new PrintWriter(new BufferedWriter(
                new OutputStreamWriter(out, "UTF-8")));
        outWriter.print("<html><body>download handled</body></html>");
        outWriter.flush();
        out.close();
    }

    /**
     * Internally process a UIDL request from the client.
     * 
     * This method calls
     * {@link #handleVariables(WrappedRequest, WrappedResponse, Callback, Application, Root)}
     * to process any changes to variables by the client and then repaints
     * affected components using {@link #paintAfterVariableChanges()}.
     * 
     * Also, some cleanup is done when a request arrives for an application that
     * has already been closed.
     * 
     * The method handleUidlRequest(...) in subclasses should call this method.
     * 
     * TODO better documentation
     * 
     * @param request
     * @param response
     * @param callback
     * @param root
     *            target window for the UIDL request, can be null if target not
     *            found
     * @throws IOException
     * @throws InvalidUIDLSecurityKeyException
     */
    public void handleUidlRequest(WrappedRequest request,
            WrappedResponse response, Callback callback, Root root)
            throws IOException, InvalidUIDLSecurityKeyException {

        requestThemeName = request.getParameter("theme");
        maxInactiveInterval = request.getSessionMaxInactiveInterval();
        // repaint requested or session has timed out and new one is created
        boolean repaintAll;
        final OutputStream out;

        repaintAll = (request.getParameter(GET_PARAM_REPAINT_ALL) != null);
        // || (request.getSession().isNew()); FIXME What the h*ll is this??
        out = response.getOutputStream();

        boolean analyzeLayouts = false;
        if (repaintAll) {
            // analyzing can be done only with repaintAll
            analyzeLayouts = (request.getParameter(GET_PARAM_ANALYZE_LAYOUTS) != null);

            if (request.getParameter(GET_PARAM_HIGHLIGHT_COMPONENT) != null) {
                String pid = request
                        .getParameter(GET_PARAM_HIGHLIGHT_COMPONENT);
                highlightedConnector = root.getApplication().getConnector(pid);
                highlightConnector(highlightedConnector);
            }
        }

        final PrintWriter outWriter = new PrintWriter(new BufferedWriter(
                new OutputStreamWriter(out, "UTF-8")));

        // The rest of the process is synchronized with the application
        // in order to guarantee that no parallel variable handling is
        // made
        synchronized (application) {

            // Finds the window within the application
            if (application.isRunning()) {
                // Returns if no window found
                if (root == null) {
                    // This should not happen, no windows exists but
                    // application is still open.
                    logger.warning("Could not get root for application");
                    return;
                }
            } else {
                // application has been closed
                endApplication(request, response, application);
                return;
            }

            // Change all variables based on request parameters
            if (!handleVariables(request, response, callback, application, root)) {

                // var inconsistency; the client is probably out-of-sync
                SystemMessages ci = null;
                try {
                    Method m = application.getClass().getMethod(
                            "getSystemMessages", (Class[]) null);
                    ci = (Application.SystemMessages) m.invoke(null,
                            (Object[]) null);
                } catch (Exception e2) {
                    // FIXME: Handle exception
                    // Not critical, but something is still wrong; print
                    // stacktrace
                    logger.log(Level.WARNING,
                            "getSystemMessages() failed - continuing", e2);
                }
                if (ci != null) {
                    String msg = ci.getOutOfSyncMessage();
                    String cap = ci.getOutOfSyncCaption();
                    if (msg != null || cap != null) {
                        callback.criticalNotification(request, response, cap,
                                msg, null, ci.getOutOfSyncURL());
                        // will reload page after this
                        return;
                    }
                }
                // No message to show, let's just repaint all.
                repaintAll = true;
            }

            paintAfterVariableChanges(request, response, callback, repaintAll,
                    outWriter, root, analyzeLayouts);
            postPaint(root);
        }

        outWriter.close();
        requestThemeName = null;
    }

    /**
     * Method called after the paint phase while still being synchronized on the
     * application
     * 
     * @param root
     * 
     */
    protected void postPaint(Root root) {
        // Remove connectors that have been detached from the application during
        // handling of the request
        root.getApplication().cleanConnectorMap();
    }

    protected void highlightConnector(Connector highlightedConnector) {
        StringBuilder sb = new StringBuilder();
        sb.append("*** Debug details of a component:  *** \n");
        sb.append("Type: ");
        sb.append(highlightedConnector.getClass().getName());
        if (highlightedConnector instanceof AbstractComponent) {
            AbstractComponent component = (AbstractComponent) highlightedConnector;
            sb.append("\nId:");
            sb.append(highlightedConnector.getConnectorId());
            if (component.getCaption() != null) {
                sb.append("\nCaption:");
                sb.append(component.getCaption());
            }

            printHighlightedComponentHierarchy(sb, component);
        }
        logger.info(sb.toString());
    }

    protected void printHighlightedComponentHierarchy(StringBuilder sb,
            AbstractComponent component) {
        LinkedList<Component> h = new LinkedList<Component>();
        h.add(component);
        Component parent = component.getParent();
        while (parent != null) {
            h.addFirst(parent);
            parent = parent.getParent();
        }

        sb.append("\nComponent hierarchy:\n");
        Application application2 = component.getApplication();
        sb.append(application2.getClass().getName());
        sb.append(".");
        sb.append(application2.getClass().getSimpleName());
        sb.append("(");
        sb.append(application2.getClass().getSimpleName());
        sb.append(".java");
        sb.append(":1)");
        int l = 1;
        for (Component component2 : h) {
            sb.append("\n");
            for (int i = 0; i < l; i++) {
                sb.append("  ");
            }
            l++;
            Class<? extends Component> componentClass = component2.getClass();
            Class<?> topClass = componentClass;
            while (topClass.getEnclosingClass() != null) {
                topClass = topClass.getEnclosingClass();
            }
            sb.append(componentClass.getName());
            sb.append(".");
            sb.append(componentClass.getSimpleName());
            sb.append("(");
            sb.append(topClass.getSimpleName());
            sb.append(".java:1)");
        }
    }

    /**
     * TODO document
     * 
     * @param request
     * @param response
     * @param callback
     * @param repaintAll
     * @param outWriter
     * @param window
     * @param analyzeLayouts
     * @throws PaintException
     * @throws IOException
     */
    private void paintAfterVariableChanges(WrappedRequest request,
            WrappedResponse response, Callback callback, boolean repaintAll,
            final PrintWriter outWriter, Root root, boolean analyzeLayouts)
            throws PaintException, IOException {

        // Removes application if it has stopped during variable changes
        if (!application.isRunning()) {
            endApplication(request, response, application);
            return;
        }

        openJsonMessage(outWriter, response);

        // security key
        Object writeSecurityTokenFlag = request
                .getAttribute(WRITE_SECURITY_TOKEN_FLAG);

        if (writeSecurityTokenFlag != null) {
            outWriter.print(getSecurityKeyUIDL(request));
        }

        writeUidlResponse(repaintAll, outWriter, root, analyzeLayouts);

        closeJsonMessage(outWriter);

        outWriter.close();

    }

    /**
     * Gets the security key (and generates one if needed) as UIDL.
     * 
     * @param request
     * @return the security key UIDL or "" if the feature is turned off
     */
    public String getSecurityKeyUIDL(WrappedRequest request) {
        final String seckey = getSecurityKey(request);
        if (seckey != null) {
            return "\"" + ApplicationConnection.UIDL_SECURITY_TOKEN_ID
                    + "\":\"" + seckey + "\",";
        } else {
            return "";
        }
    }

    /**
     * Gets the security key (and generates one if needed).
     * 
     * @param request
     * @return the security key
     */
    protected String getSecurityKey(WrappedRequest request) {
        String seckey = null;
        seckey = (String) request
                .getSessionAttribute(ApplicationConnection.UIDL_SECURITY_TOKEN_ID);
        if (seckey == null) {
            seckey = UUID.randomUUID().toString();
            request.setSessionAttribute(
                    ApplicationConnection.UIDL_SECURITY_TOKEN_ID, seckey);
        }

        return seckey;
    }

    @SuppressWarnings("unchecked")
    public void writeUidlResponse(boolean repaintAll,
            final PrintWriter outWriter, Root root, boolean analyzeLayouts)
            throws PaintException {
        ArrayList<ClientConnector> dirtyVisibleConnectors = new ArrayList<ClientConnector>();
        Application application = root.getApplication();
        // Paints components
        DirtyConnectorTracker rootConnectorTracker = root
                .getDirtyConnectorTracker();
        logger.log(Level.FINE, "* Creating response to client");
        if (repaintAll) {
            getClientCache(root).clear();
            rootConnectorTracker.markAllComponentsDirty();

            // Reset sent locales
            locales = null;
            requireLocale(application.getLocale().toString());
        }

        dirtyVisibleConnectors
                .addAll(getDirtyVisibleComponents(rootConnectorTracker));

        logger.log(Level.FINE, "Found " + dirtyVisibleConnectors.size()
                + " dirty connectors to paint");
        for (ClientConnector connector : dirtyVisibleConnectors) {
            if (connector instanceof Component) {
                ((Component) connector).updateState();
            }
        }
        rootConnectorTracker.markAllComponentsClean();

        outWriter.print("\"changes\":[");

        List<InvalidLayout> invalidComponentRelativeSizes = null;

        JsonPaintTarget paintTarget = new JsonPaintTarget(this, outWriter,
                !repaintAll);
        legacyPaint(paintTarget, dirtyVisibleConnectors);

        if (analyzeLayouts) {
            invalidComponentRelativeSizes = ComponentSizeValidator
                    .validateComponentRelativeSizes(root.getContent(), null,
                            null);

            // Also check any existing subwindows
            if (root.getWindows() != null) {
                for (Window subWindow : root.getWindows()) {
                    invalidComponentRelativeSizes = ComponentSizeValidator
                            .validateComponentRelativeSizes(
                                    subWindow.getContent(),
                                    invalidComponentRelativeSizes, null);
                }
            }
        }

        paintTarget.close();
        outWriter.print("], "); // close changes

        // send shared state to client

        // for now, send the complete state of all modified and new
        // components

        // Ideally, all this would be sent before "changes", but that causes
        // complications with legacy components that create sub-components
        // in their paint phase. Nevertheless, this will be processed on the
        // client after component creation but before legacy UIDL
        // processing.
        JSONObject sharedStates = new JSONObject();
        for (Connector connector : dirtyVisibleConnectors) {
            SharedState state = connector.getState();
            if (null != state) {
                // encode and send shared state
                try {
                    JSONArray stateJsonArray = JsonCodec.encode(state,
                            application);
                    sharedStates
                            .put(connector.getConnectorId(), stateJsonArray);
                } catch (JSONException e) {
                    throw new PaintException(
                            "Failed to serialize shared state for connector "
                                    + connector.getClass().getName() + " ("
                                    + connector.getConnectorId() + "): "
                                    + e.getMessage());
                }
            }
        }
        outWriter.print("\"state\":");
        outWriter.append(sharedStates.toString());
        outWriter.print(", "); // close states

        // TODO This should be optimized. The type only needs to be
        // sent once for each connector id + on refresh. Use the same cache as
        // widget mapping

        JSONObject connectorTypes = new JSONObject();
        for (ClientConnector connector : dirtyVisibleConnectors) {
            String connectorType = paintTarget.getTag(connector);
            try {
                connectorTypes.put(connector.getConnectorId(), connectorType);
            } catch (JSONException e) {
                throw new PaintException(
                        "Failed to send connector type for connector "
                                + connector.getConnectorId() + ": "
                                + e.getMessage());
            }
        }
        outWriter.print("\"types\":");
        outWriter.append(connectorTypes.toString());
        outWriter.print(", "); // close states

        // Send update hierarchy information to the client.

        // This could be optimized aswell to send only info if hierarchy has
        // actually changed. Much like with the shared state. Note though
        // that an empty hierarchy is information aswell (e.g. change from 1
        // child to 0 children)

        outWriter.print("\"hierarchy\":");

        JSONObject hierarchyInfo = new JSONObject();
        for (Connector connector : dirtyVisibleConnectors) {
            if (connector instanceof HasComponents) {
                HasComponents parent = (HasComponents) connector;
                String parentConnectorId = parent.getConnectorId();
                JSONArray children = new JSONArray();

                for (Component child : getChildComponents(parent)) {
                    if (isVisible(child)) {
                        children.put(child.getConnectorId());
                    }
                }
                try {
                    hierarchyInfo.put(parentConnectorId, children);
                } catch (JSONException e) {
                    throw new PaintException(
                            "Failed to send hierarchy information about "
                                    + parentConnectorId + " to the client: "
                                    + e.getMessage());
                }
            }
        }
        outWriter.append(hierarchyInfo.toString());
        outWriter.print(", "); // close hierarchy

        // send server to client RPC calls for components in the root, in call
        // order

        // collect RPC calls from components in the root in the order in
        // which they were performed, remove the calls from components

        LinkedList<ClientConnector> rpcPendingQueue = new LinkedList<ClientConnector>(
                dirtyVisibleConnectors);
        List<ClientMethodInvocation> pendingInvocations = collectPendingRpcCalls(dirtyVisibleConnectors);

        JSONArray rpcCalls = new JSONArray();
        for (ClientMethodInvocation invocation : pendingInvocations) {
            // add invocation to rpcCalls
            try {
                JSONArray invocationJson = new JSONArray();
                invocationJson.put(invocation.getConnector().getConnectorId());
                invocationJson.put(invocation.getInterfaceName());
                invocationJson.put(invocation.getMethodName());
                JSONArray paramJson = new JSONArray();
                for (int i = 0; i < invocation.getParameters().length; ++i) {
                    paramJson.put(JsonCodec.encode(
                            invocation.getParameters()[i], application));
                }
                invocationJson.put(paramJson);
                rpcCalls.put(invocationJson);
            } catch (JSONException e) {
                throw new PaintException(
                        "Failed to serialize RPC method call parameters for connector "
                                + invocation.getConnector().getConnectorId()
                                + " method " + invocation.getInterfaceName()
                                + "." + invocation.getMethodName() + ": "
                                + e.getMessage());
            }

        }

        if (rpcCalls.length() > 0) {
            outWriter.print("\"rpc\" : ");
            outWriter.append(rpcCalls.toString());
            outWriter.print(", "); // close rpc
        }

        outWriter.print("\"meta\" : {");
        boolean metaOpen = false;

        if (repaintAll) {
            metaOpen = true;
            outWriter.write("\"repaintAll\":true");
            if (analyzeLayouts) {
                outWriter.write(", \"invalidLayouts\":");
                outWriter.write("[");
                if (invalidComponentRelativeSizes != null) {
                    boolean first = true;
                    for (InvalidLayout invalidLayout : invalidComponentRelativeSizes) {
                        if (!first) {
                            outWriter.write(",");
                        } else {
                            first = false;
                        }
                        invalidLayout.reportErrors(outWriter, this, System.err);
                    }
                }
                outWriter.write("]");
            }
            if (highlightedConnector != null) {
                outWriter.write(", \"hl\":\"");
                outWriter.write(highlightedConnector.getConnectorId());
                outWriter.write("\"");
                highlightedConnector = null;
            }
        }

        SystemMessages ci = null;
        try {
            Method m = application.getClass().getMethod("getSystemMessages",
                    (Class[]) null);
            ci = (Application.SystemMessages) m.invoke(null, (Object[]) null);
        } catch (NoSuchMethodException e) {
            logger.log(Level.WARNING,
                    "getSystemMessages() failed - continuing", e);
        } catch (IllegalArgumentException e) {
            logger.log(Level.WARNING,
                    "getSystemMessages() failed - continuing", e);
        } catch (IllegalAccessException e) {
            logger.log(Level.WARNING,
                    "getSystemMessages() failed - continuing", e);
        } catch (InvocationTargetException e) {
            logger.log(Level.WARNING,
                    "getSystemMessages() failed - continuing", e);
        }

        // meta instruction for client to enable auto-forward to
        // sessionExpiredURL after timer expires.
        if (ci != null && ci.getSessionExpiredMessage() == null
                && ci.getSessionExpiredCaption() == null
                && ci.isSessionExpiredNotificationEnabled()) {
            int newTimeoutInterval = getTimeoutInterval();
            if (repaintAll || (timeoutInterval != newTimeoutInterval)) {
                String escapedURL = ci.getSessionExpiredURL() == null ? "" : ci
                        .getSessionExpiredURL().replace("/", "\\/");
                if (metaOpen) {
                    outWriter.write(",");
                }
                outWriter.write("\"timedRedirect\":{\"interval\":"
                        + (newTimeoutInterval + 15) + ",\"url\":\""
                        + escapedURL + "\"}");
                metaOpen = true;
            }
            timeoutInterval = newTimeoutInterval;
        }

        outWriter.print("}, \"resources\" : {");

        // Precache custom layouts

        // TODO We should only precache the layouts that are not
        // cached already (plagiate from usedPaintableTypes)
        int resourceIndex = 0;
        for (final Iterator<Object> i = paintTarget.getUsedResources()
                .iterator(); i.hasNext();) {
            final String resource = (String) i.next();
            InputStream is = null;
            try {
                is = getThemeResourceAsStream(root, getTheme(root), resource);
            } catch (final Exception e) {
                // FIXME: Handle exception
                logger.log(Level.FINER, "Failed to get theme resource stream.",
                        e);
            }
            if (is != null) {

                outWriter.print((resourceIndex++ > 0 ? ", " : "") + "\""
                        + resource + "\" : ");
                final StringBuffer layout = new StringBuffer();

                try {
                    final InputStreamReader r = new InputStreamReader(is,
                            "UTF-8");
                    final char[] buffer = new char[20000];
                    int charsRead = 0;
                    while ((charsRead = r.read(buffer)) > 0) {
                        layout.append(buffer, 0, charsRead);
                    }
                    r.close();
                } catch (final java.io.IOException e) {
                    // FIXME: Handle exception
                    logger.log(Level.INFO, "Resource transfer failed", e);
                }
                outWriter.print("\""
                        + JsonPaintTarget.escapeJSON(layout.toString()) + "\"");
            } else {
                // FIXME: Handle exception
                logger.severe("CustomLayout not found: " + resource);
            }
        }
        outWriter.print("}");

        Collection<Class<? extends ClientConnector>> usedClientConnectors = paintTarget
                .getUsedClientConnectors();
        boolean typeMappingsOpen = false;
        ClientCache clientCache = getClientCache(root);

        for (Class<? extends ClientConnector> class1 : usedClientConnectors) {
            if (clientCache.cache(class1)) {
                // client does not know the mapping key for this type, send
                // mapping to client
                if (!typeMappingsOpen) {
                    typeMappingsOpen = true;
                    outWriter.print(", \"typeMappings\" : { ");
                } else {
                    outWriter.print(" , ");
                }
                String canonicalName = class1.getCanonicalName();
                outWriter.print("\"");
                outWriter.print(canonicalName);
                outWriter.print("\" : ");
                outWriter.print(getTagForType(class1));
            }
        }
        if (typeMappingsOpen) {
            outWriter.print(" }");
        }

        boolean typeInheritanceMapOpen = false;
        if (typeMappingsOpen) {
            // send the whole type inheritance map if any new mappings
            for (Class<? extends ClientConnector> class1 : usedClientConnectors) {
                if (!ClientConnector.class.isAssignableFrom(class1
                        .getSuperclass())) {
                    continue;
                }
                if (!typeInheritanceMapOpen) {
                    typeInheritanceMapOpen = true;
                    outWriter.print(", \"typeInheritanceMap\" : { ");
                } else {
                    outWriter.print(" , ");
                }
                outWriter.print("\"");
                outWriter.print(getTagForType(class1));
                outWriter.print("\" : ");
                outWriter
                        .print(getTagForType((Class<? extends ClientConnector>) class1
                                .getSuperclass()));
            }
            if (typeInheritanceMapOpen) {
                outWriter.print(" }");
            }
        }

        // add any pending locale definitions requested by the client
        printLocaleDeclarations(outWriter);

        if (dragAndDropService != null) {
            dragAndDropService.printJSONResponse(outWriter);
        }
    }

    private void legacyPaint(PaintTarget paintTarget,
            ArrayList<ClientConnector> dirtyVisibleConnectors)
            throws PaintException {
        List<Vaadin6Component> legacyComponents = new ArrayList<Vaadin6Component>();
        for (Connector connector : dirtyVisibleConnectors) {
            // All Components that want to use paintContent must implement
            // Vaadin6Component
            if (connector instanceof Vaadin6Component) {
                legacyComponents.add((Vaadin6Component) connector);
            }
        }
        sortByHierarchy((List) legacyComponents);
        for (Vaadin6Component c : legacyComponents) {
            logger.fine("Painting Vaadin6Component " + c.getClass().getName()
                    + "@" + Integer.toHexString(c.hashCode()));
            paintTarget.startTag("change");
            final String pid = c.getConnectorId();
            paintTarget.addAttribute("pid", pid);
            LegacyPaint.paint(c, paintTarget);
            paintTarget.endTag("change");
        }

    }

    private void sortByHierarchy(List<Component> paintables) {
        // Vaadin 6 requires parents to be painted before children as component
        // containers rely on that their updateFromUIDL method has been called
        // before children start calling e.g. updateCaption
        Collections.sort(paintables, new Comparator<Component>() {
            public int compare(Component c1, Component c2) {
                int depth1 = 0;
                while (c1.getParent() != null) {
                    depth1++;
                    c1 = c1.getParent();
                }
                int depth2 = 0;
                while (c2.getParent() != null) {
                    depth2++;
                    c2 = c2.getParent();
                }
                if (depth1 < depth2) {
                    return -1;
                }
                if (depth1 > depth2) {
                    return 1;
                }
                return 0;
            }
        });

    }

    private ClientCache getClientCache(Root root) {
        Integer rootId = Integer.valueOf(root.getRootId());
        ClientCache cache = rootToClientCache.get(rootId);
        if (cache == null) {
            cache = new ClientCache();
            rootToClientCache.put(rootId, cache);
        }
        return cache;
    }

    /**
     * Checks if the component is visible in context, i.e. returns false if the
     * child is hidden, the parent is hidden or the parent says the child should
     * not be rendered (using
     * {@link HasComponents#isComponentVisible(Component)}
     * 
     * @param child
     *            The child to check
     * @return true if the child is visible to the client, false otherwise
     */
    private boolean isVisible(Component child) {
        HasComponents parent = child.getParent();
        if (parent == null || !child.isVisible()) {
            return child.isVisible();
        }

        return parent.isComponentVisible(child) && isVisible(parent);
    }

    private static class NullIterator<E> implements Iterator<E> {

        public boolean hasNext() {
            return false;
        }

        public E next() {
            return null;
        }

        public void remove() {
        }

    }

    public static Iterable<Component> getChildComponents(HasComponents cc) {
        // TODO This must be moved to Root/Panel
        if (cc instanceof Root) {
            Root root = (Root) cc;
            List<Component> children = new ArrayList<Component>();
            if (root.getContent() != null) {
                children.add(root.getContent());
            }
            for (Window w : root.getWindows()) {
                children.add(w);
            }
            return children;
        } else if (cc instanceof Panel) {
            // This is so wrong.. (#2924)
            if (((Panel) cc).getContent() == null) {
                return Collections.emptyList();
            } else {
                return Collections.singleton((Component) ((Panel) cc)
                        .getContent());
            }
        }
        return cc;
    }

    /**
     * Collects all pending RPC calls from listed {@link ClientConnector}s and
     * clears their RPC queues.
     * 
     * @param rpcPendingQueue
     *            list of {@link ClientConnector} of interest
     * @return ordered list of pending RPC calls
     */
    private List<ClientMethodInvocation> collectPendingRpcCalls(
            List<ClientConnector> rpcPendingQueue) {
        List<ClientMethodInvocation> pendingInvocations = new ArrayList<ClientMethodInvocation>();
        for (ClientConnector connector : rpcPendingQueue) {
            List<ClientMethodInvocation> paintablePendingRpc = connector
                    .retrievePendingRpcCalls();
            if (null != paintablePendingRpc && !paintablePendingRpc.isEmpty()) {
                List<ClientMethodInvocation> oldPendingRpc = pendingInvocations;
                int totalCalls = pendingInvocations.size()
                        + paintablePendingRpc.size();
                pendingInvocations = new ArrayList<ClientMethodInvocation>(
                        totalCalls);

                // merge two ordered comparable lists
                for (int destIndex = 0, oldIndex = 0, paintableIndex = 0; destIndex < totalCalls; destIndex++) {
                    if (paintableIndex >= paintablePendingRpc.size()
                            || (oldIndex < oldPendingRpc.size() && ((Comparable<ClientMethodInvocation>) oldPendingRpc
                                    .get(oldIndex))
                                    .compareTo(paintablePendingRpc
                                            .get(paintableIndex)) <= 0)) {
                        pendingInvocations.add(oldPendingRpc.get(oldIndex++));
                    } else {
                        pendingInvocations.add(paintablePendingRpc
                                .get(paintableIndex++));
                    }
                }
            }
        }
        return pendingInvocations;
    }

    protected abstract InputStream getThemeResourceAsStream(Root root,
            String themeName, String resource);

    private int getTimeoutInterval() {
        return maxInactiveInterval;
    }

    private String getTheme(Root root) {
        String themeName = root.getApplication().getThemeForRoot(root);
        String requestThemeName = getRequestTheme();

        if (requestThemeName != null) {
            themeName = requestThemeName;
        }
        if (themeName == null) {
            themeName = AbstractApplicationServlet.getDefaultTheme();
        }
        return themeName;
    }

    private String getRequestTheme() {
        return requestThemeName;
    }

    /**
     * Returns false if the cross site request forgery protection is turned off.
     * 
     * @param application
     * @return false if the XSRF is turned off, true otherwise
     */
    public boolean isXSRFEnabled(Application application) {
        return !"true"
                .equals(application
                        .getProperty(AbstractApplicationServlet.SERVLET_PARAMETER_DISABLE_XSRF_PROTECTION));
    }

    /**
     * TODO document
     * 
     * If this method returns false, something was submitted that we did not
     * expect; this is probably due to the client being out-of-sync and sending
     * variable changes for non-existing pids
     * 
     * @return true if successful, false if there was an inconsistency
     */
    private boolean handleVariables(WrappedRequest request,
            WrappedResponse response, Callback callback,
            Application application2, Root root) throws IOException,
            InvalidUIDLSecurityKeyException {
        boolean success = true;

        String changes = getRequestPayload(request);
        if (changes != null) {

            // Manage bursts one by one
            final String[] bursts = changes.split(String
                    .valueOf(VAR_BURST_SEPARATOR));

            // Security: double cookie submission pattern unless disabled by
            // property
            if (isXSRFEnabled(application2)) {
                if (bursts.length == 1 && "init".equals(bursts[0])) {
                    // init request; don't handle any variables, key sent in
                    // response.
                    request.setAttribute(WRITE_SECURITY_TOKEN_FLAG, true);
                    return true;
                } else {
                    // ApplicationServlet has stored the security token in the
                    // session; check that it matched the one sent in the UIDL
                    String sessId = (String) request
                            .getSessionAttribute(ApplicationConnection.UIDL_SECURITY_TOKEN_ID);

                    if (sessId == null || !sessId.equals(bursts[0])) {
                        throw new InvalidUIDLSecurityKeyException(
                                "Security key mismatch");
                    }
                }

            }

            for (int bi = 1; bi < bursts.length; bi++) {
                // unescape any encoded separator characters in the burst
                final String burst = unescapeBurst(bursts[bi]);
                success &= handleBurst(request, application2, burst);

                // In case that there were multiple bursts, we know that this is
                // a special synchronous case for closing window. Thus we are
                // not interested in sending any UIDL changes back to client.
                // Still we must clear component tree between bursts to ensure
                // that no removed components are updated. The painting after
                // the last burst is handled normally by the calling method.
                if (bi < bursts.length - 1) {

                    // We will be discarding all changes
                    final PrintWriter outWriter = new PrintWriter(
                            new CharArrayWriter());

                    paintAfterVariableChanges(request, response, callback,
                            true, outWriter, root, false);

                }

            }
        }
        /*
         * Note that we ignore inconsistencies while handling unload request.
         * The client can't remove invalid variable changes from the burst, and
         * we don't have the required logic implemented on the server side. E.g.
         * a component is removed in a previous burst.
         */
        return success;
    }

    /**
     * Helper class for parsing variable change RPC calls.
     * 
     * Note that variable changes still only support the old data types and
     * partly use Vaadin 6 way of encoding of values. Other RPC method calls
     * support more data types.
     * 
     * @since 7.0
     */
    private class VariableChange {
        private final String name;
        private final Object value;

        public VariableChange(MethodInvocation invocation) throws JSONException {
            name = (String) invocation.getParameters()[0];
            value = invocation.getParameters()[1];
        }

        /**
         * Returns the variable name for the modification.
         * 
         * @return variable name
         */
        public String getName() {
            return name;
        }

        /**
         * Returns the (parsed and converted) value of the updated variable.
         * 
         * @return variable value
         */
        public Object getValue() {
            return value;
        }
    }

    /**
     * Processes a message burst received from the client.
     * 
     * A burst can contain any number of RPC calls, including legacy variable
     * change calls that are processed separately.
     * 
     * Consecutive changes to the value of the same variable are combined and
     * changeVariables() is only called once for them. This preserves the Vaadin
     * 6 semantics for components and add-ons that do not use Vaadin 7 RPC
     * directly.
     * 
     * @param source
     * @param app
     *            application receiving the burst
     * @param burst
     *            the content of the burst as a String to be parsed
     * @return true if the processing of the burst was successful and there were
     *         no messages to non-existent components
     */
    public boolean handleBurst(Object source, Application app,
            final String burst) {
        boolean success = true;
        try {
            List<MethodInvocation> invocations = parseInvocations(burst);

            // Perform the method invocations, grouping consecutive variable
            // changes for the same Paintable.

            // Combining of variable changes is currently needed to preserve the
            // old semantics for any component that relies on them. If the
            // support for legacy variable change events is removed, each call
            // can be performed separately and thelogic here simplified.

            for (int i = 0; i < invocations.size(); i++) {
                MethodInvocation invocation = invocations.get(i);

                MethodInvocation nextInvocation = null;
                if (i + 1 < invocations.size()) {
                    nextInvocation = invocations.get(i + 1);
                }

                final String interfaceName = invocation.getInterfaceName();

                if (!ApplicationConnection.UPDATE_VARIABLE_INTERFACE
                        .equals(interfaceName)) {
                    // handle other RPC calls than variable changes
                    applyInvocation(app, invocation);
                    continue;
                }
                final ClientConnector connector = getConnector(app,
                        invocation.getConnectorId());
                final VariableOwner owner = (VariableOwner) connector;

                boolean connectorEnabled = (connector != null && connector
                        .isConnectorEnabled());

                if (owner != null && connectorEnabled) {
                    VariableChange change = new VariableChange(invocation);

                    // TODO could optimize with a single value map if only one
                    // change for a paintable

                    Map<String, Object> m = new HashMap<String, Object>();
                    m.put(change.getName(), change.getValue());
                    while (nextInvocation != null
                            && invocation.getConnectorId().equals(
                                    nextInvocation.getConnectorId())
                            && ApplicationConnection.UPDATE_VARIABLE_METHOD
                                    .equals(nextInvocation.getMethodName())) {
                        i++;
                        invocation = nextInvocation;
                        change = new VariableChange(invocation);
                        m.put(change.getName(), change.getValue());
                        if (i + 1 < invocations.size()) {
                            nextInvocation = invocations.get(i + 1);
                        } else {
                            nextInvocation = null;
                        }
                    }

                    try {
                        changeVariables(source, owner, m);
                    } catch (Exception e) {
                        Component errorComponent = null;
                        if (owner instanceof Component) {
                            errorComponent = (Component) owner;
                        } else if (owner instanceof DragAndDropService) {
                            if (m.get("dhowner") instanceof Component) {
                                errorComponent = (Component) m.get("dhowner");
                            }
                        }
                        handleChangeVariablesError(app, errorComponent, e, m);
                    }
                } else {
                    // TODO convert window close to a separate RPC call and
                    // handle above - not a variable change

                    VariableChange change = new VariableChange(invocation);

                    // Handle special case where window-close is called
                    // after the window has been removed from the
                    // application or the application has closed
                    if ("close".equals(change.getName())
                            && Boolean.TRUE.equals(change.getValue())) {
                        // Silently ignore this
                        continue;
                    }

                    // Ignore variable change
                    String msg = "Warning: Ignoring RPC call for ";
                    if (owner != null) {
                        msg += "disabled component " + owner.getClass();
                        String caption = ((Component) owner).getCaption();
                        if (caption != null) {
                            msg += ", caption=" + caption;
                        }
                    } else {
                        msg += "non-existent component, VAR_PID="
                                + invocation.getConnectorId();
                        // TODO should this cause the message to be ignored?
                        success = false;
                    }
                    logger.warning(msg);
                    continue;
                }
            }

        } catch (JSONException e) {
            logger.warning("Unable to parse RPC call from the client: "
                    + e.getMessage());
            // TODO or return success = false?
            throw new RuntimeException(e);
        }

        return success;
    }

    /**
     * Execute an RPC call from the client by finding its target and letting the
     * RPC mechanism call the correct method for it.
     * 
     * @param app
     * 
     * @param invocation
     */
    protected void applyInvocation(Application app, MethodInvocation invocation) {
        Connector c = app.getConnector(invocation.getConnectorId());
        if (c instanceof RpcTarget) {
            ServerRpcManager.applyInvocation((RpcTarget) c, invocation);
        } else if (c == null) {
            logger.log(
                    Level.WARNING,
                    "RPC call " + invocation.getInterfaceName() + "."
                            + invocation.getMethodName()
                            + " received for connector id "
                            + invocation.getConnectorId()
                            + " but no such connector could be found");

        } else {
            logger.log(Level.WARNING, "RPC call received for connector "
                    + c.getClass().getName() + " (" + c.getConnectorId()
                    + ") but the connector is not a ServerRpcTarget");
        }
    }

    /**
     * Parse a message burst from the client into a list of MethodInvocation
     * instances.
     * 
     * @param burst
     *            message string (JSON)
     * @return list of MethodInvocation to perform
     * @throws JSONException
     */
    private List<MethodInvocation> parseInvocations(final String burst)
            throws JSONException {
        JSONArray invocationsJson = new JSONArray(burst);

        ArrayList<MethodInvocation> invocations = new ArrayList<MethodInvocation>();

        // parse JSON to MethodInvocations
        for (int i = 0; i < invocationsJson.length(); ++i) {
            JSONArray invocationJson = invocationsJson.getJSONArray(i);
            String connectorId = invocationJson.getString(0);
            String interfaceName = invocationJson.getString(1);
            String methodName = invocationJson.getString(2);
            JSONArray parametersJson = invocationJson.getJSONArray(3);
            Object[] parameters = new Object[parametersJson.length()];
            for (int j = 0; j < parametersJson.length(); ++j) {
                parameters[j] = JsonCodec.decode(
                        parametersJson.getJSONArray(j), application);
            }
            MethodInvocation invocation = new MethodInvocation(connectorId,
                    interfaceName, methodName, parameters);
            invocations.add(invocation);
        }
        return invocations;
    }

    protected void changeVariables(Object source, final VariableOwner owner,
            Map<String, Object> m) {
        owner.changeVariables(source, m);
    }

    protected ClientConnector getConnector(Application app, String connectorId) {
        ClientConnector c = app.getConnector(connectorId);
        if (c == null
                && connectorId.equals(getDragAndDropService().getConnectorId())) {
            return getDragAndDropService();
        }

        return c;
    }

    private DragAndDropService getDragAndDropService() {
        if (dragAndDropService == null) {
            dragAndDropService = new DragAndDropService(this);
        }
        return dragAndDropService;
    }

    /**
     * Reads the request data from the Request and returns it converted to an
     * UTF-8 string.
     * 
     * @param request
     * @return
     * @throws IOException
     */
    protected String getRequestPayload(WrappedRequest request)
            throws IOException {

        int requestLength = request.getContentLength();
        if (requestLength == 0) {
            return null;
        }

        ByteArrayOutputStream bout = requestLength <= 0 ? new ByteArrayOutputStream()
                : new ByteArrayOutputStream(requestLength);

        InputStream inputStream = request.getInputStream();
        byte[] buffer = new byte[MAX_BUFFER_SIZE];

        while (true) {
            int read = inputStream.read(buffer);
            if (read == -1) {
                break;
            }
            bout.write(buffer, 0, read);
        }
        String result = new String(bout.toByteArray(), "utf-8");

        return result;
    }

    public class ErrorHandlerErrorEvent implements ErrorEvent, Serializable {
        private final Throwable throwable;

        public ErrorHandlerErrorEvent(Throwable throwable) {
            this.throwable = throwable;
        }

        public Throwable getThrowable() {
            return throwable;
        }

    }

    /**
     * Handles an error (exception) that occurred when processing variable
     * changes from the client or a failure of a file upload.
     * 
     * For {@link AbstractField} components,
     * {@link AbstractField#handleError(com.vaadin.ui.AbstractComponent.ComponentErrorEvent)}
     * is called. In all other cases (or if the field does not handle the
     * error), {@link ErrorListener#terminalError(ErrorEvent)} for the
     * application error handler is called.
     * 
     * @param application
     * @param owner
     *            component that the error concerns
     * @param e
     *            exception that occurred
     * @param m
     *            map from variable names to values
     */
    private void handleChangeVariablesError(Application application,
            Component owner, Exception e, Map<String, Object> m) {
        boolean handled = false;
        ChangeVariablesErrorEvent errorEvent = new ChangeVariablesErrorEvent(
                owner, e, m);

        if (owner instanceof AbstractField) {
            try {
                handled = ((AbstractField<?>) owner).handleError(errorEvent);
            } catch (Exception handlerException) {
                /*
                 * If there is an error in the component error handler we pass
                 * the that error to the application error handler and continue
                 * processing the actual error
                 */
                application.getErrorHandler().terminalError(
                        new ErrorHandlerErrorEvent(handlerException));
                handled = false;
            }
        }

        if (!handled) {
            application.getErrorHandler().terminalError(errorEvent);
        }

    }

    /**
     * Unescape encoded burst separator characters in a burst received from the
     * client. This protects from separator injection attacks.
     * 
     * @param encodedValue
     *            to decode
     * @return decoded value
     */
    protected String unescapeBurst(String encodedValue) {
        final StringBuilder result = new StringBuilder();
        final StringCharacterIterator iterator = new StringCharacterIterator(
                encodedValue);
        char character = iterator.current();
        while (character != CharacterIterator.DONE) {
            if (VAR_ESCAPE_CHARACTER == character) {
                character = iterator.next();
                switch (character) {
                case VAR_ESCAPE_CHARACTER + 0x30:
                    // escaped escape character
                    result.append(VAR_ESCAPE_CHARACTER);
                    break;
                case VAR_BURST_SEPARATOR + 0x30:
                    // +0x30 makes these letters for easier reading
                    result.append((char) (character - 0x30));
                    break;
                case CharacterIterator.DONE:
                    // error
                    throw new RuntimeException(
                            "Communication error: Unexpected end of message");
                default:
                    // other escaped character - probably a client-server
                    // version mismatch
                    throw new RuntimeException(
                            "Invalid escaped character from the client - check that the widgetset and server versions match");
                }
            } else {
                // not a special character - add it to the result as is
                result.append(character);
            }
            character = iterator.next();
        }
        return result.toString();
    }

    /**
     * Prints the queued (pending) locale definitions to a {@link PrintWriter}
     * in a (UIDL) format that can be sent to the client and used there in
     * formatting dates, times etc.
     * 
     * @param outWriter
     */
    private void printLocaleDeclarations(PrintWriter outWriter) {
        /*
         * ----------------------------- Sending Locale sensitive date
         * -----------------------------
         */

        // Send locale informations to client
        outWriter.print(", \"locales\":[");
        for (; pendingLocalesIndex < locales.size(); pendingLocalesIndex++) {

            final Locale l = generateLocale(locales.get(pendingLocalesIndex));
            // Locale name
            outWriter.print("{\"name\":\"" + l.toString() + "\",");

            /*
             * Month names (both short and full)
             */
            final DateFormatSymbols dfs = new DateFormatSymbols(l);
            final String[] short_months = dfs.getShortMonths();
            final String[] months = dfs.getMonths();
            outWriter.print("\"smn\":[\""
                    + // ShortMonthNames
                    short_months[0] + "\",\"" + short_months[1] + "\",\""
                    + short_months[2] + "\",\"" + short_months[3] + "\",\""
                    + short_months[4] + "\",\"" + short_months[5] + "\",\""
                    + short_months[6] + "\",\"" + short_months[7] + "\",\""
                    + short_months[8] + "\",\"" + short_months[9] + "\",\""
                    + short_months[10] + "\",\"" + short_months[11] + "\""
                    + "],");
            outWriter.print("\"mn\":[\""
                    + // MonthNames
                    months[0] + "\",\"" + months[1] + "\",\"" + months[2]
                    + "\",\"" + months[3] + "\",\"" + months[4] + "\",\""
                    + months[5] + "\",\"" + months[6] + "\",\"" + months[7]
                    + "\",\"" + months[8] + "\",\"" + months[9] + "\",\""
                    + months[10] + "\",\"" + months[11] + "\"" + "],");

            /*
             * Weekday names (both short and full)
             */
            final String[] short_days = dfs.getShortWeekdays();
            final String[] days = dfs.getWeekdays();
            outWriter.print("\"sdn\":[\""
                    + // ShortDayNames
                    short_days[1] + "\",\"" + short_days[2] + "\",\""
                    + short_days[3] + "\",\"" + short_days[4] + "\",\""
                    + short_days[5] + "\",\"" + short_days[6] + "\",\""
                    + short_days[7] + "\"" + "],");
            outWriter.print("\"dn\":[\""
                    + // DayNames
                    days[1] + "\",\"" + days[2] + "\",\"" + days[3] + "\",\""
                    + days[4] + "\",\"" + days[5] + "\",\"" + days[6] + "\",\""
                    + days[7] + "\"" + "],");

            /*
             * First day of week (0 = sunday, 1 = monday)
             */
            final Calendar cal = new GregorianCalendar(l);
            outWriter.print("\"fdow\":" + (cal.getFirstDayOfWeek() - 1) + ",");

            /*
             * Date formatting (MM/DD/YYYY etc.)
             */

            DateFormat dateFormat = DateFormat.getDateTimeInstance(
                    DateFormat.SHORT, DateFormat.SHORT, l);
            if (!(dateFormat instanceof SimpleDateFormat)) {
                logger.warning("Unable to get default date pattern for locale "
                        + l.toString());
                dateFormat = new SimpleDateFormat();
            }
            final String df = ((SimpleDateFormat) dateFormat).toPattern();

            int timeStart = df.indexOf("H");
            if (timeStart < 0) {
                timeStart = df.indexOf("h");
            }
            final int ampm_first = df.indexOf("a");
            // E.g. in Korean locale AM/PM is before h:mm
            // TODO should take that into consideration on client-side as well,
            // now always h:mm a
            if (ampm_first > 0 && ampm_first < timeStart) {
                timeStart = ampm_first;
            }
            // Hebrew locale has time before the date
            final boolean timeFirst = timeStart == 0;
            String dateformat;
            if (timeFirst) {
                int dateStart = df.indexOf(' ');
                if (ampm_first > dateStart) {
                    dateStart = df.indexOf(' ', ampm_first);
                }
                dateformat = df.substring(dateStart + 1);
            } else {
                dateformat = df.substring(0, timeStart - 1);
            }

            outWriter.print("\"df\":\"" + dateformat.trim() + "\",");

            /*
             * Time formatting (24 or 12 hour clock and AM/PM suffixes)
             */
            final String timeformat = df.substring(timeStart, df.length());
            /*
             * Doesn't return second or milliseconds.
             * 
             * We use timeformat to determine 12/24-hour clock
             */
            final boolean twelve_hour_clock = timeformat.indexOf("a") > -1;
            // TODO there are other possibilities as well, like 'h' in french
            // (ignore them, too complicated)
            final String hour_min_delimiter = timeformat.indexOf(".") > -1 ? "."
                    : ":";
            // outWriter.print("\"tf\":\"" + timeformat + "\",");
            outWriter.print("\"thc\":" + twelve_hour_clock + ",");
            outWriter.print("\"hmd\":\"" + hour_min_delimiter + "\"");
            if (twelve_hour_clock) {
                final String[] ampm = dfs.getAmPmStrings();
                outWriter.print(",\"ampm\":[\"" + ampm[0] + "\",\"" + ampm[1]
                        + "\"]");
            }
            outWriter.print("}");
            if (pendingLocalesIndex < locales.size() - 1) {
                outWriter.print(",");
            }
        }
        outWriter.print("]"); // Close locales
    }

    /**
     * Ends the Application.
     * 
     * The browser is redirected to the Application logout URL set with
     * {@link Application#setLogoutURL(String)}, or to the application URL if no
     * logout URL is given.
     * 
     * @param request
     *            the request instance.
     * @param response
     *            the response to write to.
     * @param application
     *            the Application to end.
     * @throws IOException
     *             if the writing failed due to input/output error.
     */
    private void endApplication(WrappedRequest request,
            WrappedResponse response, Application application)
            throws IOException {

        String logoutUrl = application.getLogoutURL();
        if (logoutUrl == null) {
            logoutUrl = application.getURL().toString();
        }
        // clients JS app is still running, send a special json file to tell
        // client that application has quit and where to point browser now
        // Set the response type
        final OutputStream out = response.getOutputStream();
        final PrintWriter outWriter = new PrintWriter(new BufferedWriter(
                new OutputStreamWriter(out, "UTF-8")));
        openJsonMessage(outWriter, response);
        outWriter.print("\"redirect\":{");
        outWriter.write("\"url\":\"" + logoutUrl + "\"}");
        closeJsonMessage(outWriter);
        outWriter.flush();
        outWriter.close();
        out.flush();
    }

    protected void closeJsonMessage(PrintWriter outWriter) {
        outWriter.print("}]");
    }

    /**
     * Writes the opening of JSON message to be sent to client.
     * 
     * @param outWriter
     * @param response
     */
    protected void openJsonMessage(PrintWriter outWriter,
            WrappedResponse response) {
        // Sets the response type
        response.setContentType("application/json; charset=UTF-8");
        // some dirt to prevent cross site scripting
        outWriter.print("for(;;);[{");
    }

    /**
     * Returns dirty components which are in given window. Components in an
     * invisible subtrees are omitted.
     * 
     * @param w
     *            root window for which dirty components is to be fetched
     * @return
     */
    private ArrayList<Component> getDirtyVisibleComponents(
            DirtyConnectorTracker dirtyConnectorTracker) {
        ArrayList<Component> dirtyComponents = new ArrayList<Component>();
        for (Component c : dirtyConnectorTracker.getDirtyComponents()) {
            if (isVisible(c)) {
                dirtyComponents.add(c);
            }
        }

        return dirtyComponents;
    }

    /**
     * Queues a locale to be sent to the client (browser) for date and time
     * entry etc. All locale specific information is derived from server-side
     * {@link Locale} instances and sent to the client when needed, eliminating
     * the need to use the {@link Locale} class and all the framework behind it
     * on the client.
     * 
     * @see Locale#toString()
     * 
     * @param value
     */
    public void requireLocale(String value) {
        if (locales == null) {
            locales = new ArrayList<String>();
            locales.add(application.getLocale().toString());
            pendingLocalesIndex = 0;
        }
        if (!locales.contains(value)) {
            locales.add(value);
        }
    }

    /**
     * Constructs a {@link Locale} instance to be sent to the client based on a
     * short locale description string.
     * 
     * @see #requireLocale(String)
     * 
     * @param value
     * @return
     */
    private Locale generateLocale(String value) {
        final String[] temp = value.split("_");
        if (temp.length == 1) {
            return new Locale(temp[0]);
        } else if (temp.length == 2) {
            return new Locale(temp[0], temp[1]);
        } else {
            return new Locale(temp[0], temp[1], temp[2]);
        }
    }

    protected class InvalidUIDLSecurityKeyException extends
            GeneralSecurityException {

        InvalidUIDLSecurityKeyException(String message) {
            super(message);
        }

    }

    private final HashMap<Class<? extends ClientConnector>, Integer> typeToKey = new HashMap<Class<? extends ClientConnector>, Integer>();
    private int nextTypeKey = 0;

    private BootstrapHandler bootstrapHandler;

    String getTagForType(Class<? extends ClientConnector> class1) {
        Integer id = typeToKey.get(class1);
        if (id == null) {
            id = nextTypeKey++;
            typeToKey.put(class1, id);
            logger.log(Level.FINE, "Mapping " + class1.getName() + " to " + id);
        }
        return id.toString();
    }

    /**
     * Helper class for terminal to keep track of data that client is expected
     * to know.
     * 
     * TODO make customlayout templates (from theme) to be cached here.
     */
    class ClientCache implements Serializable {

        private final Set<Object> res = new HashSet<Object>();

        /**
         * 
         * @param paintable
         * @return true if the given class was added to cache
         */
        boolean cache(Object object) {
            return res.add(object);
        }

        public void clear() {
            res.clear();
        }

    }

    abstract String getStreamVariableTargetUrl(Connector owner, String name,
            StreamVariable value);

    abstract protected void cleanStreamVariable(Connector owner, String name);

    /**
     * Gets the bootstrap handler that should be used for generating the pages
     * bootstrapping applications for this communication manager.
     * 
     * @return the bootstrap handler to use
     */
    private BootstrapHandler getBootstrapHandler() {
        if (bootstrapHandler == null) {
            bootstrapHandler = createBootstrapHandler();
        }

        return bootstrapHandler;
    }

    protected abstract BootstrapHandler createBootstrapHandler();

    protected boolean handleApplicationRequest(WrappedRequest request,
            WrappedResponse response) throws IOException {
        return application.handleRequest(request, response);
    }

    public void handleBrowserDetailsRequest(WrappedRequest request,
            WrappedResponse response, Application application)
            throws IOException {

        // if we do not yet have a currentRoot, it should be initialized
        // shortly, and we should send the initial UIDL
        boolean sendUIDL = Root.getCurrentRoot() == null;

        try {
            CombinedRequest combinedRequest = new CombinedRequest(request);

            Root root = application.getRootForRequest(combinedRequest);
            response.setContentType("application/json; charset=UTF-8");

            // Use the same logic as for determined roots
            BootstrapHandler bootstrapHandler = getBootstrapHandler();
            BootstrapContext context = bootstrapHandler.createContext(
                    combinedRequest, response, application, root.getRootId());

            String widgetset = context.getWidgetsetName();
            String theme = context.getThemeName();
            String themeUri = bootstrapHandler.getThemeUri(context, theme);

            // TODO These are not required if it was only the init of the root
            // that was delayed
            JSONObject params = new JSONObject();
            params.put("widgetset", widgetset);
            params.put("themeUri", themeUri);
            // Root id might have changed based on e.g. window.name
            params.put(ApplicationConnection.ROOT_ID_PARAMETER,
                    root.getRootId());
            if (sendUIDL) {
                String initialUIDL = getInitialUIDL(combinedRequest, root);
                params.put("uidl", initialUIDL);
            }
            response.getWriter().write(params.toString());
        } catch (RootRequiresMoreInformationException e) {
            // Requiring more information at this point is not allowed
            // TODO handle in a better way
            throw new RuntimeException(e);
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    /**
     * Generates the initial UIDL message that can e.g. be included in a html
     * page to avoid a separate round trip just for getting the UIDL.
     * 
     * @param request
     *            the request that caused the initialization
     * @param root
     *            the root for which the UIDL should be generated
     * @return a string with the initial UIDL message
     * @throws PaintException
     *             if an exception occurs while painting
     */
    protected String getInitialUIDL(WrappedRequest request, Root root)
            throws PaintException {
        // TODO maybe unify writeUidlResponse()?
        StringWriter sWriter = new StringWriter();
        PrintWriter pWriter = new PrintWriter(sWriter);
        pWriter.print("{");
        if (isXSRFEnabled(root.getApplication())) {
            pWriter.print(getSecurityKeyUIDL(request));
        }
        writeUidlResponse(true, pWriter, root, false);
        pWriter.print("}");
        String initialUIDL = sWriter.toString();
        logger.log(Level.FINE, "Initial UIDL:" + initialUIDL);
        return initialUIDL;
    }

    /**
     * Stream that extracts content from another stream until the boundary
     * string is encountered.
     * 
     * Public only for unit tests, should be considered private for all other
     * purposes.
     */
    public static class SimpleMultiPartInputStream extends InputStream {

        /**
         * Counter of how many characters have been matched to boundary string
         * from the stream
         */
        int matchedCount = -1;

        /**
         * Used as pointer when returning bytes after partly matched boundary
         * string.
         */
        int curBoundaryIndex = 0;
        /**
         * The byte found after a "promising start for boundary"
         */
        private int bufferedByte = -1;
        private boolean atTheEnd = false;

        private final char[] boundary;

        private final InputStream realInputStream;

        public SimpleMultiPartInputStream(InputStream realInputStream,
                String boundaryString) {
            boundary = (CRLF + DASHDASH + boundaryString).toCharArray();
            this.realInputStream = realInputStream;
        }

        @Override
        public int read() throws IOException {
            if (atTheEnd) {
                // End boundary reached, nothing more to read
                return -1;
            } else if (bufferedByte >= 0) {
                /* Purge partially matched boundary if there was such */
                return getBuffered();
            } else if (matchedCount != -1) {
                /*
                 * Special case where last "failed" matching ended with first
                 * character from boundary string
                 */
                return matchForBoundary();
            } else {
                int fromActualStream = realInputStream.read();
                if (fromActualStream == -1) {
                    // unexpected end of stream
                    throw new IOException(
                            "The multipart stream ended unexpectedly");
                }
                if (boundary[0] == fromActualStream) {
                    /*
                     * If matches the first character in boundary string, start
                     * checking if the boundary is fetched.
                     */
                    return matchForBoundary();
                }
                return fromActualStream;
            }
        }

        /**
         * Reads the input to expect a boundary string. Expects that the first
         * character has already been matched.
         * 
         * @return -1 if the boundary was matched, else returns the first byte
         *         from boundary
         * @throws IOException
         */
        private int matchForBoundary() throws IOException {
            matchedCount = 0;
            /*
             * Going to "buffered mode". Read until full boundary match or a
             * different character.
             */
            while (true) {
                matchedCount++;
                if (matchedCount == boundary.length) {
                    /*
                     * The whole boundary matched so we have reached the end of
                     * file
                     */
                    atTheEnd = true;
                    return -1;
                }
                int fromActualStream = realInputStream.read();
                if (fromActualStream != boundary[matchedCount]) {
                    /*
                     * Did not find full boundary, cache the mismatching byte
                     * and start returning the partially matched boundary.
                     */
                    bufferedByte = fromActualStream;
                    return getBuffered();
                }
            }
        }

        /**
         * Returns the partly matched boundary string and the byte following
         * that.
         * 
         * @return
         * @throws IOException
         */
        private int getBuffered() throws IOException {
            int b;
            if (matchedCount == 0) {
                // The boundary has been returned, return the buffered byte.
                b = bufferedByte;
                bufferedByte = -1;
                matchedCount = -1;
            } else {
                b = boundary[curBoundaryIndex++];
                if (curBoundaryIndex == matchedCount) {
                    // The full boundary has been returned, remaining is the
                    // char that did not match the boundary.

                    curBoundaryIndex = 0;
                    if (bufferedByte != boundary[0]) {
                        /*
                         * next call for getBuffered will return the
                         * bufferedByte that came after the partial boundary
                         * match
                         */
                        matchedCount = 0;
                    } else {
                        /*
                         * Special case where buffered byte again matches the
                         * boundaryString. This could be the start of the real
                         * end boundary.
                         */
                        matchedCount = 0;
                        bufferedByte = -1;
                    }
                }
            }
            if (b == -1) {
                throw new IOException("The multipart stream ended unexpectedly");
            }
            return b;
        }
    }

}