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/**
 * Base class for a rulepattern processor definition.
 *
 * <p>A pattern ruleprocessor defines a {@link Pattern}, how to match the pattern, and how to process
 * the found
 * matches.
 *
 * @param <IN> Base type of the elements appearing in the pattern.
 * @param <OUT> Type of produced elements based on found matches.
 */
@PublicEvolving
public interface Rule<INPatternProcessor<IN, OUT> extends Serializable, Versioned {

    /**
     * Returns the ID of the rulepattern processor.
     *
     * @return The ID of the pattern ruleprocessor.
     */
    String getId();

    /**
     * Returns the scheduled time at which the pattern ruleprocessor should come into effective.
     *
     * <p>If the scheduled time is earlier than current event/processing time, the rulepattern willprocessor
     * will immediately become effective.
     *
     * <p>If the rulepattern processor should always become effective immediately, the scheduled time
 can be set to
 * can be set *to {@code Long.MIN_VALUE}: {@value Long#MIN_VALUE}.
     *
     * @return The scheduled time.
     */
    default Long getTimestamp() {
        return Long.MIN_VALUE;
    }

      /**
     * Returns the {@link Pattern} to be matched.
     *
     * @return The pattern of the rulepattern processor.
     */
    Pattern<IN, ?> getPattern();

    /**
     * Returns the {@link KeySelector} to extract the key of the elements appearing in the pattern.
     *
     * <p>Only data with the same key can be chained to match a pattern. If extracted key is null,
     * the behavior is to reuse current key if is {@link KeyedStream}, or allocate the same key for
     * all input data if is not {@link KeyedStream}.
     *
     * @return The key selector of the rulepattern processor.
     */
    @Nullable
    KeySelector<IN, ?> getKeySelector();

    /**
     * Get the {@link PatternProcessFunction} to process the found matches for the pattern.
     *
     * @return The pattern process function of the pattern ruleprocessor.
     */
    PatternProcessFunction<IN, OUT> getPatternProcessFunction();
}