SessionServer.java

package com.tinkerpop.rexster.protocol.server;

import com.codahale.metrics.Gauge;
import com.codahale.metrics.MetricRegistry;
import com.tinkerpop.rexster.client.RexProException;
import com.tinkerpop.rexster.protocol.EngineController;
import com.tinkerpop.rexster.protocol.msg.ErrorResponseMessage;
import com.tinkerpop.rexster.protocol.msg.MessageUtil;
import com.tinkerpop.rexster.protocol.msg.RexProMessage;
import com.tinkerpop.rexster.protocol.msg.SessionRequestMessage;
import com.tinkerpop.rexster.protocol.msg.SessionResponseMessage;
import com.tinkerpop.rexster.protocol.session.RexProSession;
import com.tinkerpop.rexster.protocol.session.RexProSessions;
import com.tinkerpop.rexster.server.RexsterApplication;
import org.apache.log4j.Logger;

import java.io.IOException;
import java.util.List;

/**
 * @author Blake Eggleston (bdeggleston.github.com)
 */
public class SessionServer {

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

    private final RexsterApplication rexsterApplication;

    public SessionServer(final RexsterApplication rexsterApplication) {
        this.rexsterApplication = rexsterApplication;

        final String metricName = MetricRegistry.name("rexpro", "sessions");
        if (!this.rexsterApplication.getMetricRegistry().getGauges().containsKey(metricName)) {
            this.rexsterApplication.getMetricRegistry().register(metricName, new Gauge<Integer>() {
                @Override
                public Integer getValue() {
                    return RexProSessions.getSessionKeys().size();
                }
            });
        }
    }

    public void handleRequest(SessionRequestMessage message, RexProRequest request) throws IOException {
        try {
            message.validateMetaData();
        } catch (Exception e) {
            logger.error(e);
            request.writeResponseMessage(
                MessageUtil.createErrorResponse(
                    message.Request,
                    RexProMessage.EMPTY_SESSION_AS_BYTES,
                    ErrorResponseMessage.INVALID_MESSAGE_ERROR,
                    e.toString()
                )
            );
        }

        if (message.metaGetKillSession()) {
            //destroy the session
            RexProSessions.destroySession(message.sessionAsUUID().toString());
            request.writeResponseMessage(MessageUtil.createEmptySession(message.Request));

        } else {
            final EngineController engineController = EngineController.getInstance();
            final List<String> engineLanguages = engineController.getAvailableEngineLanguages();

            final SessionResponseMessage responseMessage = MessageUtil.createNewSession(
                    message.Request, engineLanguages);

            // construct a session with the right channel
            if(!RexProSessions.hasSessionKey(responseMessage.sessionAsUUID().toString())) {
                RexProSession session = RexProSessions.createSession(
                        responseMessage.sessionAsUUID().toString(),
                        this.rexsterApplication
                );

                //set on the request object
                request.setSession(session);

                //configure the graph object
                if (message.metaGetGraphName() != null) {
                    try {
                        session.setGraphObj(message.metaGetGraphName(), message.metaGetGraphObjName());
                    } catch (RexProException ex) {
                        //graph config problem
                        request.writeResponseMessage(
                                MessageUtil.createErrorResponse(
                                        message.Request, RexProMessage.EMPTY_SESSION_AS_BYTES,
                                        ErrorResponseMessage.GRAPH_CONFIG_ERROR,
                                        ex.toString()
                                )
                        );
                        return;
                    }
                }
            }
            request.writeResponseMessage(responseMessage);
        }
    }
}