org.apache.beam.sdk.io.gcp.pubsub

Class PubsubSchemaIOProvider

java.lang.Object

org.apache.beam.sdk.io.gcp.pubsub.PubsubSchemaIOProvider

All Implemented Interfaces:

SchemaIOProvider

@Internal
 @AutoService(value=SchemaIOProvider.class)
public class PubsubSchemaIOProvider
extends java.lang.Object
implements SchemaIOProvider

An implementation of SchemaIOProvider for reading and writing JSON/AVRO payloads with PubsubIO.

Schema

The data schema passed to from(String, Row, Schema) must either be of the nested or flat style.

Nested style

If nested structure is used, the required fields included in the Pubsub message model are 'event_timestamp', 'attributes', and 'payload'.

Flat style

If flat structure is used, the required fields include just 'event_timestamp'. Every other field is assumed part of the payload. See PubsubMessageToRow for details.

Configuration

configurationSchema() consists of two attributes, timestampAttributeKey and deadLetterQueue.

timestampAttributeKey

An optional attribute key of the Pubsub message from which to extract the event timestamp. If not specified, the message publish time will be used as event timestamp.

This attribute has to conform to the same requirements as in PubsubIO.Read.withTimestampAttribute(String)

Short version: it has to be either millis since epoch or string in RFC 3339 format.

If the attribute is specified then event timestamps will be extracted from the specified attribute. If it is not specified then message publish timestamp will be used.

deadLetterQueue

deadLetterQueue is an optional topic path which will be used as a dead letter queue.

Messages that cannot be processed will be sent to this topic. If it is not specified then exception will be thrown for errors during processing causing the pipeline to crash.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	PubsubSchemaIOProvider.PayloadFormat

Field Summary

Fields

Modifier and Type	Field and Description
static Schema.FieldType	TIMESTAMP
static Schema.FieldType	VARCHAR

Constructor Summary

Constructors

Constructor and Description
PubsubSchemaIOProvider()

Method Summary

Modifier and Type	Method and Description
Schema	configurationSchema() Returns the expected schema of the configuration object.
org.apache.beam.sdk.io.gcp.pubsub.PubsubSchemaIOProvider.PubsubSchemaIO	from(java.lang.String location, Row configuration, Schema dataSchema) Produce a SchemaIO given a String representing the data's location, the schema of the data that resides there, and some IO-specific configuration object.
java.lang.String	identifier() Returns an id that uniquely represents this IO.
PCollection.IsBounded	isBounded()
boolean	requiresDataSchema() Indicates whether the dataSchema value is necessary.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

VARCHAR

public static final Schema.FieldType VARCHAR

TIMESTAMP

public static final Schema.FieldType TIMESTAMP

Constructor Detail

PubsubSchemaIOProvider

public PubsubSchemaIOProvider()

Method Detail

identifier

public java.lang.String identifier()

Returns an id that uniquely represents this IO.

Specified by:

identifier in interface SchemaIOProvider

configurationSchema

public Schema configurationSchema()

Returns the expected schema of the configuration object. Note this is distinct from the schema of the data source itself.

Specified by:

configurationSchema in interface SchemaIOProvider

from

public org.apache.beam.sdk.io.gcp.pubsub.PubsubSchemaIOProvider.PubsubSchemaIO from(java.lang.String location,
                                                                                    Row configuration,
                                                                                    Schema dataSchema)

Produce a SchemaIO given a String representing the data's location, the schema of the data that resides there, and some IO-specific configuration object.

Specified by:

from in interface SchemaIOProvider

requiresDataSchema

public boolean requiresDataSchema()

Description copied from interface: SchemaIOProvider

Indicates whether the dataSchema value is necessary.

Specified by:

requiresDataSchema in interface SchemaIOProvider

isBounded

public PCollection.IsBounded isBounded()

Specified by:

isBounded in interface SchemaIOProvider