org.apache.pulsar.functions.api.Function Maven / Gradle / Ivy
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* 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.pulsar.functions.api;
import org.apache.pulsar.common.classification.InterfaceAudience;
import org.apache.pulsar.common.classification.InterfaceStability;
/**
* This is the core interface of the function api. The process is called
* for every message of the input topic of the function. The incoming input bytes
* are converted to the input type I for simple Java types(String, Integer, Boolean,
* Map, and List types) and for org.Json type. If this serialization approach does not
* meet your needs, you can use the byte stream handler defined in RawRequestHandler.
*/
@InterfaceAudience.Public
@InterfaceStability.Stable
@FunctionalInterface
public interface Function {
/**
* Process the input.
*
* @return the output
*/
T process(X input, Context context) throws Exception;
/**
* Called once to initialize resources when function instance is started.
*
* @param context The Function context
*
* @throws Exception if an error occurs
*/
default void initialize(Context context) throws Exception {}
/**
* Called once to properly close resources when function instance is stopped.
*
* @throws Exception if an error occurs
*/
default void close() throws Exception {}
}