org.apache.flink.streaming.util.serialization.PulsarDeserializationSchema Maven / Gradle / Ivy
/*
* 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.
*/
package org.apache.flink.streaming.util.serialization;
import org.apache.flink.annotation.PublicEvolving;
import org.apache.flink.api.common.serialization.DeserializationSchema;
import org.apache.flink.api.common.typeinfo.TypeInformation;
import org.apache.flink.util.Collector;
import org.apache.pulsar.client.api.Message;
import org.apache.pulsar.client.api.Schema;
import java.io.IOException;
import java.io.Serializable;
/**
* The deserialization schema describes how to turn the pulsar messages
* into data types (Java/Scala objects) that are processed by Flink.
*
* @param The type created by the keyed deserialization schema.
*/
@PublicEvolving
public interface PulsarDeserializationSchema extends PulsarContextAware, Serializable {
@Deprecated
static PulsarDeserializationSchemaBuilder builder() {
return new PulsarDeserializationSchemaBuilder<>();
}
/**
* Wraps a Flink {@link DeserializationSchema} to a {@link PulsarDeserializationSchema}.
*
* @param valueDeserializer the deserializer class used to deserialize the value.
* @param the value type.
* @return A {@link PulsarDeserializationSchema} that deserialize the value with the given deserializer.
*/
static PulsarDeserializationSchema valueOnly(DeserializationSchema valueDeserializer) {
return new PulsarDeserializationSchema() {
@Override
public Schema getSchema() {
return new FlinkSchema<>(Schema.BYTES.getSchemaInfo(), null, valueDeserializer);
}
@Override
public V deserialize(Message message) throws IOException {
return message.getValue();
}
@Override
public boolean isEndOfStream(V nextElement) {
return valueDeserializer.isEndOfStream(nextElement);
}
@Override
public TypeInformation getProducedType() {
return valueDeserializer.getProducedType();
}
};
}
default void open(DeserializationSchema.InitializationContext context) throws Exception {
}
/**
* Method to decide whether the element signals the end of the stream. If
* true is returned the element won't be emitted.
*
* @param nextElement The element to test for the end-of-stream signal.
*
* @return True, if the element signals end of stream, false otherwise.
*/
boolean isEndOfStream(T nextElement);
/**
* Deserializes the Pulsar message.
*
* Can output multiple records through the {@link Collector}. Note that number and size of the
* produced records should be relatively small. Depending on the source implementation records
* can be buffered in memory or collecting records might delay emitting checkpoint barrier.
*
* @param message The message, as a byte array.
*/
T deserialize(Message message) throws IOException;
/**
* Deserializes the Pulsar message.
*
* Can output multiple records through the {@link Collector}. Note that number and size of the
* produced records should be relatively small. Depending on the source implementation records
* can be buffered in memory or collecting records might delay emitting checkpoint barrier.
*
* @param message The message, as a byte array.
* @param out The collector to put the resulting messages.
*/
default void deserialize(Message message, Collector out) throws IOException {
out.collect(deserialize(message));
}
}