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package org.glassfish.grizzly.comet;

import java.io.IOException;

import org.glassfish.grizzly.http.server.Response;

/**
 * This interface represents a suspended connection (or response). Passing an instance of this class to
 * {@link CometContext#addCometHandler(CometHandler)} automatically tells Grizzly Comet to suspend the underlying connection and to avoid
 * committing the response. Since the response is not committed, the connection is considered as suspended and can be
 * resumed later when an event happens by invoking {@link CometContext#resumeCometHandler(CometHandler)}, from {@link
 * CometHandler#onEvent}.  {@link CometContext#resumeCometHandler(CometHandler)}, resume the connection by committing the
 * response. As an example, a browser icons will spins when a connection is suspended, as the complete response hasn't
 * been sent back.
 * 
 * Components that implement this interface will be notified {@link org.glassfish.grizzly.comet.CometContext#notify()} is invoked
 * or when the {@link CometContext#getExpirationDelay()} expires.
 */
public interface CometHandler {
    /**
     * @return the response associated with the handler.
     */
    Response getResponse();

    void setResponse(Response response);

    CometContext getCometContext();

    void setCometContext(CometContext context);

    /**
     * Receive {@link CometEvent} notification. This method will be invoked every time a {@link CometContext#notify} is
     * invoked. The {@link CometEvent} will contains the message that can be pushed back to the remote client, cached or
     * ignored. This method can also be used to resume a connection once a notified by invoking {@link
     * CometContext#resumeCometHandler}.
 its not optimal to flush outputstream in this method for long polling,
     * flush is performed in each CometContext.resume call.
 flushing multiple times can fragment the data into
     * several tcp packets, that leads to extra IO and overhead in general due to client ack for each packet etc.
     */
    void onEvent(CometEvent event) throws IOException;

    /**
     * Receive {@link CometEvent} notification when Grizzly is about to suspend the connection. This method is always
     * invoked during the processing of {@link CometContext#addCometHandler} operations.
     */
    void onInitialize(CometEvent event) throws IOException;

    /**
     * Receive {@link CometEvent} notification when the response is resumed by a {@link CometHandler} or by the {@link
     * CometContext}
     */
    void onTerminate(CometEvent event) throws IOException;

    /**
     * Receive {@link CometEvent} notification when the underlying tcp communication is resumed by Grizzly. This happens
     * when the {@link CometContext#setExpirationDelay} expires or when the remote client close the connection.
     */
    void onInterrupt(CometEvent event) throws IOException;
}