org.lenskit.api.Recommender Maven / Gradle / Ivy
/*
* LensKit, an open source recommender systems toolkit.
* Copyright 2010-2014 LensKit Contributors. See CONTRIBUTORS.md.
* Work on LensKit has been funded by the National Science Foundation under
* grants IIS 05-34939, 08-08692, 08-12148, and 10-17697.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc., 51
* Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
package org.lenskit.api;
import javax.annotation.Nullable;
/**
* Main entry point for accessing recommender components. A recommender object
* is effectively a recommender session: it is a per-thread or per-request
* object, likely connected to a database connection or persistence session, that
* needs to be closed when the client code is finished with it.
*
* The various methods in this class return {@code null} if the corresponding
* operation is not supported by the underlying recommender configuration. This
* ensures that, if you can actually get an object implementing a particular interface,
* you are guaranteed to be able to use it.
*
* @compat Public
* @see RecommenderEngine
*/
public interface Recommender extends AutoCloseable {
/**
* Get the recommender's rating scorer.
*
* @return The rating predictor for this recommender configuration, or
* {@code null} if rating prediction is not supported.
*/
@Nullable
RatingPredictor getRatingPredictor();
/**
* Get the recommender's item recommender.
*
* @return The item recommender for this recommender configuration, or
* {@code null} if item recommendation is not supported.
*/
@Nullable
ItemRecommender getItemRecommender();
/**
* Get the recommender's item scorer.
* @return The item scorer for the configured recommender, or {@code null} if item scoring is not supported.
*/
@Nullable
ItemScorer getItemScorer();
/**
* Close the recommender. This closes underlying resources such as database collections. Components retrieved
* from the recommender must be used once the recommender is closed. Components capable of explicitly detecting
* use-after-close will indicate such invalid use by throwing {@link IllegalStateException}, although they may
* fail with other exceptions. The results of using a component after its recommender has been closed are formally
* undefined.
*/
@Override
void close();
}