at.ac.univie.isc.asio.insight.EventResource.java Source code

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Here is the source code for at.ac.univie.isc.asio.insight.EventResource.java

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/*
 * #%L
 * asio server
 * %%
 * Copyright (C) 2013 - 2015 Research Group Scientific Computing, University of Vienna
 * %%
 * 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.
 * #L%
 */
package at.ac.univie.isc.asio.insight;

import at.ac.univie.isc.asio.Scope;
import at.ac.univie.isc.asio.platform.CurrentTime;
import com.google.common.eventbus.Subscribe;
import org.glassfish.jersey.media.sse.EventOutput;
import org.glassfish.jersey.media.sse.OutboundEvent;
import org.glassfish.jersey.media.sse.SseBroadcaster;
import org.glassfish.jersey.media.sse.SseFeature;
import org.slf4j.Logger;
import org.springframework.security.access.prepost.PreAuthorize;
import org.springframework.stereotype.Component;

import javax.annotation.PreDestroy;
import javax.ws.rs.DELETE;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.SecurityContext;
import java.io.IOException;
import java.util.UUID;

import static org.slf4j.LoggerFactory.getLogger;

/**
 * Publish events from the internal event bus as server-sent-event streams.
 */
@Component
@Path("/api/events")
public class EventResource implements AutoCloseable {
    private static final Logger log = getLogger(EventResource.class);

    private static final Correlation STREAM_CORRELATION = Correlation.valueOf(UUID.randomUUID().toString());

    /**
     * sent immediately on registration
     */
    static final OutboundEvent SUBSCRIBED = new OutboundEvent.Builder()
            .data(Event.class,
                    Event.simple("stream", "subscribed").init(STREAM_CORRELATION, CurrentTime.instance().read()))
            .mediaType(MediaType.APPLICATION_JSON_TYPE).build();

    private final SseBroadcaster broadcaster = new SseBroadcaster();

    @GET
    @Produces(SseFeature.SERVER_SENT_EVENTS)
    @PreAuthorize("hasAuthority('PERMISSION_ACCESS_INTERNALS')")
    public EventOutput subscribe(@Context final SecurityContext security) throws IOException {
        final EventOutput subscription = new EventOutput();
        subscription.write(SUBSCRIBED);
        broadcaster.add(subscription);
        log.debug(Scope.SYSTEM.marker(), "{} subscribed to event stream", security.getUserPrincipal());
        return subscription;
    }

    @Subscribe
    public void publish(final Event event) {
        final OutboundEvent sse = new OutboundEvent.Builder().data(Event.class, event)
                .mediaType(MediaType.APPLICATION_JSON_TYPE).build();
        broadcaster.broadcast(sse);
    }

    @DELETE
    @PreDestroy
    @PreAuthorize("hasAuthority('PERMISSION_ADMINISTRATE')")
    @Override
    public void close() throws Exception {
        log.info(Scope.SYSTEM.marker(), "closing all event streams");
        broadcaster.closeAll();
    }
}