/*
 * 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.api.common.serialization;

import org.apache.flink.annotation.Public;

import java.io.Serializable;

/**
 * The serialization schema describes how to turn a data object into a different serialized
 * representation. Most data sinks (for example Apache Kafka) require the data to be handed
 * to them in a specific format (for example as byte strings).
 *
 * @param <T> The type to be serialized.
 */
@Public
public interface SerializationSchema<T> extends Serializable {

	/**
	 * Serializes the incoming element to a specified type.
	 *
	 * @param element
	 *            The incoming element to be serialized
	 * @return The serialized element.
	 */
	byte[] serialize(T element);
}

/*
 * 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.api.common.serialization;

import org.apache.flink.annotation.Public;
import org.apache.flink.annotation.PublicEvolving;
import org.apache.flink.metrics.MetricGroup;

import java.io.Serializable;

/**
 * The serialization schema describes how to turn a data object into a different serialized
 * representation. Most data sinks (for example Apache Kafka) require the data to be handed
 * to them in a specific format (for example as byte strings).
 *
 * @param <T> The type to be serialized.
 */
@Public
public interface SerializationSchema<T> extends Serializable {
	/**
	 * Initialization method for the schema. It is called before the actual working methods
	 * {@link #serialize(Object)} and thus suitable for one time setup work.
	 *
	 * <p>The provided {@link InitializationContext} can be used to access additional features such as e.g.
	 * registering user metrics.
	 *
	 * @param context Contextual information that can be used during initialization.
	 */
	@PublicEvolving
	default void open(InitializationContext context) throws Exception {
	}

	/**
	 * Serializes the incoming element to a specified type.
	 *
	 * @param element
	 *            The incoming element to be serialized
	 * @return The serialized element.
	 */
	byte[] serialize(T element);

	/**
	 * A contextual information provided for {@link #open(InitializationContext)} method. It can be used to:
	 * <ul>
	 *     <li>Register user metrics via {@link InitializationContext#getMetricGroup()}</li>
	 * </ul>
	 */
	@PublicEvolving
	interface InitializationContext {
		/**
		 * Returns the metric group for the parallel subtask of the source that runs
		 * this {@link DeserializationSchema}.
		 *
		 * <p>Instances of this class can be used to register new metrics with Flink and to create a nested
		 * hierarchy based on the group names. See {@link MetricGroup} for more information for the metrics
		 * system.
		 *
		 * @see MetricGroup
		 */
		MetricGroup getMetricGroup();
	}
}

Add open to SerializationSchema