content: /*
   * 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.beam.sdk.util.construction;
  
  import java.util.List;
  import java.util.Optional;
  import org.apache.beam.model.pipeline.v1.RunnerApi;
  
  /**
   * An interface for artifact resolvers. Artifact resolvers transform {@link
   * RunnerApi.ArtifactInformation} from one type to another typically from remote or deferred
   * artifacts to locally accessible file artifacts.
   */
  public interface ArtifactResolver {
  
    /**
     * Register {@link ResolutionFn}. When multiple {@link ResolutionFn}s are capable of resolving the
     * same {@link RunnerApi.ArtifactInformation}, the application order is up to the implementing
     * class of this interface.
     *
     * @param fn a resolution function to be registered
     */
    void register(ResolutionFn fn);
  
    /** Updating pipeline proto by applying registered {@link ResolutionFn}s. */
    RunnerApi.Pipeline resolveArtifacts(RunnerApi.Pipeline pipeline);
  
    /** Resolves a list of artifacts by applying registered {@link ResolutionFn}s. */
    List<RunnerApi.ArtifactInformation> resolveArtifacts(
        List<RunnerApi.ArtifactInformation> artifacts);
  
    /**
     * A lazy transformer for resolving {@link RunnerApi.ArtifactInformation}. Note that {@link
     * ResolutionFn} postpones any side-effect until {@link
     * ArtifactResolver#resolveArtifacts(RunnerApi.Pipeline)} is called.
     */
    interface ResolutionFn {
      Optional<List<RunnerApi.ArtifactInformation>> resolve(RunnerApi.ArtifactInformation info);
    }
  }
  