com.google.walkaround.wave.server.rpc.ChannelHandler.java Source code

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Here is the source code for com.google.walkaround.wave.server.rpc.ChannelHandler.java

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/*
 * Copyright 2011 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.walkaround.wave.server.rpc;

import com.google.inject.Inject;
import com.google.walkaround.slob.server.AccessDeniedException;
import com.google.walkaround.slob.server.SlobStoreSelector;
import com.google.walkaround.slob.server.SlobNotFoundException;
import com.google.walkaround.slob.server.SlobStore;
import com.google.walkaround.slob.server.SlobStore.ConnectResult;
import com.google.walkaround.slob.server.SlobStore.HistoryResult;
import com.google.walkaround.util.server.servlet.AbstractHandler;
import com.google.walkaround.util.server.servlet.BadRequestException;
import com.google.walkaround.wave.server.ObjectSession;
import com.google.walkaround.wave.server.servlet.ServletUtil;
import com.google.walkaround.wave.shared.SharedConstants.Params;

import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;
import java.util.logging.Logger;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Used by the client to notify the server of connection to an object at a
 * specific revision, or to refresh a channel.
 *
 * @author danilatos@google.com (Daniel Danilatos)
 */
public class ChannelHandler extends AbstractHandler {

    @SuppressWarnings("unused")
    private static final Logger log = Logger.getLogger(ChannelHandler.class.getName());

    @Inject
    SlobStoreSelector storeSelector;
    @Inject
    ObjectSession session;

    @Override
    public void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        try {
            inner(req, resp);
        } catch (JSONException e) {
            throw new Error(e);
        }
    }

    private void inner(HttpServletRequest req, HttpServletResponse resp) throws IOException, JSONException {
        JSONObject result = new JSONObject();
        SlobStore store = storeSelector.get(session.getStoreType()).getSlobStore();
        try {
            int revision = Integer.parseInt(requireParameter(req, Params.REVISION));
            ConnectResult r = store.reconnect(session.getObjectId(), session.getClientId());
            if (r.getChannelToken() != null) {
                result.put("token", r.getChannelToken());
                HistoryResult history = store.loadHistory(session.getObjectId(), revision, null);
                result.put("history", HistoryHandler.serializeHistory(revision, history.getData()));
                result.put("head", r.getVersion());
            } else {
                // TODO(ohler): Figure out and document how the client-server protocol
                // works and what the different endpoints do.  It's not clear to me why
                // the above case returns history and head version (even though the
                // javadoc doesn't mention this) and this case doesn't (even though it
                // could).
                result.put("error", "Too many concurrent connections");
            }
        } catch (SlobNotFoundException e) {
            throw new BadRequestException("Object not found or access denied", e);
        } catch (AccessDeniedException e) {
            throw new BadRequestException("Object not found or access denied", e);
        } catch (NumberFormatException nfe) {
            throw new BadRequestException("Parse error", nfe);
        }

        resp.setContentType("application/json");
        ServletUtil.writeJsonResult(resp.getWriter(), result.toString());
    }

}