shaoxuan-wang commented on a change in pull request #8402: [FLINK-12473][ml] Add the interface of ML pipeline and ML lib URL: https://github.com/apache/flink/pull/8402#discussion_r286831070
########## File path: flink-ml/flink-ml-api/src/main/java/org/apache/flink/ml/api/core/PipelineStage.java ########## @@ -0,0 +1,70 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you 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. + */ + +package org.apache.flink.ml.api.core; + +import org.apache.flink.ml.api.misc.param.ParamInfo; +import org.apache.flink.ml.api.misc.param.WithParams; +import org.apache.flink.ml.api.misc.persist.Persistable; +import org.apache.flink.ml.util.param.ExtractParamInfosUtil; +import org.apache.flink.ml.util.persist.MLStageFactory; + +import com.google.gson.Gson; +import com.google.gson.JsonObject; + +import java.io.Serializable; +import java.util.HashMap; +import java.util.List; +import java.util.Map; + +/** + * Base class for a stage in a pipeline. The interface is only a concept, and does not have any + * actual functionality. Its subclasses must be either Estimator or Transformer. No other classes + * should inherit this interface directly. + * + * <p>Each pipeline stage is with parameters and meanwhile persistable. + * + * @param <T> The class type of the PipelineStage implementation itself, used by {@link + * org.apache.flink.ml.api.misc.param.WithParams} + * @see WithParams + */ +interface PipelineStage<T extends PipelineStage<T>> extends WithParams<T>, Serializable, + Persistable { + + default String toJson() { Review comment: Yes @walterddr. "toJson" interface makes it easier to read/edit a persisted pipeline. We can continue to discuss/work on the design of model export/load in the next PR. And it will make the discussion much easier when there is a PR for model export ready for review. I can understand why the persistable interface introduces a lot confusions here. I talked with @c4emmmm offline again, and here are our decisions: 1. delete persistable interface (it is a common interface, but currently only intend for the persistence of pipelineStage, which does not quite make sense), and leave the implementation of `toJson` and `loadJson` just in PipelineStage. 2. delete the PipelineStageFactory interface as well as the `stageMap` in `toJson` and `loadJson`, as this contract is not ensured from interface. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services
