Sources/ApacheBeam/Core/Fn/SerializableFn.swift

/*
 * 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.
 */

import Foundation
import Logging

public struct SerializableFnBundleContext {
    let instruction: String
    let transform: String
    let payload: Data
    let log: Logging.Logger
}

/// SerialiableFn is a protocol for functions that should be parameterized for the pipeline. This is intended as a fairly low level class and users
/// should interact with the apply() functions defined in the transform section or implement the DoFn protocol which is then wrapped
public protocol SerializableFn {
    var urn: String { get }
    var payload: Data { get throws }
    func process(context: SerializableFnBundleContext, inputs: [AnyPCollectionStream], outputs: [AnyPCollectionStream]) async throws -> (String, String)
}

/// Provide some defaults where our function doesn't have any payload
public extension SerializableFn {
    var urn: String { .beamUrn("dofn", type: "swift:transform") }
    var payload: Data { Data() }
}