org.apache.flink.api.common.io

Interface OutputFormat<IT>

Type Parameters:

IT - The type of the consumed records.

All Superinterfaces:

Serializable

All Known Implementing Classes:

BinaryOutputFormat, FileOutputFormat, RichOutputFormat, SerializedOutputFormat

@Public
public interface OutputFormat<IT>
extends Serializable

The base interface for outputs that consumes records. The output format describes how to store the final records, for example in a file.

The life cycle of an output format is the following:

1. configure() is invoked a single time. The method can be used to implement initialization from the parameters (configuration) that may be attached upon instantiation.
2. Each parallel output task creates an instance, configures it and opens it.
3. All records of its parallel instance are handed to the output format.
4. The output format is closed

Method Summary

Modifier and Type	Method and Description
void	close() Method that marks the end of the life-cycle of parallel output instance.
void	configure(Configuration parameters) Configures this output format.
void	open(int taskNumber, int numTasks) Opens a parallel instance of the output format to store the result of its parallel instance.
void	writeRecord(IT record) Adds a record to the output.

Method Detail

configure

void configure(Configuration parameters)

Configures this output format. Since output formats are instantiated generically and hence parameterless, this method is the place where the output formats set their basic fields based on configuration values.

This method is always called first on a newly instantiated output format.

Parameters:

parameters - The configuration with all parameters.

open

void open(int taskNumber,
          int numTasks)
   throws IOException

Opens a parallel instance of the output format to store the result of its parallel instance.

When this method is called, the output format it guaranteed to be configured.

Parameters:

taskNumber - The number of the parallel instance.

numTasks - The number of parallel tasks.

Throws:

IOException - Thrown, if the output could not be opened due to an I/O problem.

writeRecord

void writeRecord(IT record)
          throws IOException

Adds a record to the output.

When this method is called, the output format it guaranteed to be opened.

Parameters:

record - The records to add to the output.

Throws:

IOException - Thrown, if the records could not be added to to an I/O problem.

close

void close()
    throws IOException

Method that marks the end of the life-cycle of parallel output instance. Should be used to close channels and streams and release resources. After this method returns without an error, the output is assumed to be correct.

When this method is called, the output format it guaranteed to be opened.

Throws:

IOException - Thrown, if the input could not be closed properly.