com.nabla.wapp.server.dispatch.DispatchService.java Source code

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Here is the source code for com.nabla.wapp.server.dispatch.DispatchService.java

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/**
* Copyright 2012 nabla
*
* 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.nabla.wapp.server.dispatch;

import java.sql.SQLException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import com.google.gwt.user.server.rpc.RemoteServiceServlet;
import com.google.inject.Inject;
import com.google.inject.Singleton;
import com.nabla.wapp.server.auth.IUserSessionContext;
import com.nabla.wapp.server.auth.IUserSessionContextProvider;
import com.nabla.wapp.server.general.UserSession;
import com.nabla.wapp.server.general.Util;
import com.nabla.wapp.shared.auth.IDispatchRemoteService;
import com.nabla.wapp.shared.auth.LoginRequiredException;
import com.nabla.wapp.shared.dispatch.DispatchException;
import com.nabla.wapp.shared.dispatch.IAction;
import com.nabla.wapp.shared.dispatch.IResult;
import com.nabla.wapp.shared.dispatch.InternalErrorException;
import com.nabla.wapp.shared.dispatch.UnsupportedActionException;

@Singleton
public class DispatchService extends RemoteServiceServlet implements IDispatchRemoteService {

    private static final long serialVersionUID = 1L;
    private static final Log log = LogFactory.getLog(DispatchService.class);

    private final ActionHandlerRegister handlers;
    private final IUserSessionContextProvider ctxFactory;

    @Inject
    public DispatchService(final ActionHandlerRegister handlers, final IUserSessionContextProvider ctxFactory) {
        this.handlers = handlers;
        this.ctxFactory = ctxFactory;
    }

    @Override
    public IResult execute(String sessionId, final IAction<?> action) throws DispatchException {
        final UserSession session = UserSession.load(this.getThreadLocalRequest());
        if (session == null || !session.getSessionId().equals(sessionId))
            throw new LoginRequiredException();
        return dispatch(action, session);
    }

    private <A extends IAction<R>, R extends IResult> R dispatch(A action, final UserSession session)
            throws DispatchException {
        if (log.isTraceEnabled())
            log.trace("handling command '" + action.getClass().getSimpleName() + "'");
        IActionHandler<A, R> handler = handlers.findHandler(action);
        if (handler == null)
            throw new UnsupportedActionException(action);
        try {
            final IUserSessionContext ctx = ctxFactory.get(session, handler.requireWriteContext());
            try {
                return handler.execute(action, ctx);
            } finally {
                ctx.close();
            }
        } catch (final SQLException e) {
            if (log.isErrorEnabled())
                log.error("SQL error " + e.getErrorCode() + "-" + e.getSQLState(), e);
            throw new InternalErrorException(Util.formatInternalErrorDescription(e));
        } catch (DispatchException e) {
            if (log.isErrorEnabled())
                log.error("internal error", e);
            throw e;
        } catch (Throwable e) {
            if (log.isErrorEnabled())
                log.error("internal error", e);
            throw new InternalErrorException(Util.formatInternalErrorDescription(e));
        }
    }

}