/*
 * Copyright 2022 Google LLC
 *
 * Licensed 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.
 */

syntax = "proto3";

package fcp.aggregation;

import "tensorflow/core/framework/tensor.proto";
import "tensorflow/core/protobuf/struct.proto";

option java_package = "fcp.aggregation";
option java_multiple_files = true;

// Configuration describing the kind of aggregation to perform.
message Configuration {
  // Represents a single aggregation operation, combining one or more input
  // tensors from a collection of clients into one or more output tensors on the
  // server.
  // TODO(team): Remove usage of TensorFlow from this message.
  message ServerAggregationConfig {
    // The uri of the aggregation intrinsic (e.g. 'federated_sum').
    string intrinsic_uri = 1;

    // Describes an argument to the aggregation operation.
    message IntrinsicArg {
      oneof arg {
        // Input tensor provided by each client.
        tensorflow.TensorSpecProto input_tensor = 2;

        // Constant parameter that is independent of client data (e.g. a modulus
        // for a federated modular sum operation).
        tensorflow.TensorProto parameter = 3;
      }
    }

    // List of arguments for the aggregation operation. The arguments can be
    // dependent on client data (in which case they must be retrieved from
    // clients) or they can be independent of client data (in which case they
    // can be configured server-side). For now we assume all client-independent
    // arguments are constants. The arguments must be in the order expected by
    // the server.
    repeated IntrinsicArg intrinsic_args = 4;

    // List of server-side outputs produced by the aggregation operation.
    repeated tensorflow.TensorSpecProto output_tensors = 5;

    // List of inner aggregation intrinsics. This can be used to delegate parts
    // of the aggregation logic (e.g. a groupby intrinsic may want to delegate
    // a sum operation to a sum intrinsic).
    repeated ServerAggregationConfig inner_aggregations = 6;
  }

  // A list of client-to-server aggregations to perform.
  repeated ServerAggregationConfig aggregation_configs = 1;
}