software.amazon.kinesis.checkpoint

Class SequenceNumberValidator

java.lang.Object

software.amazon.kinesis.checkpoint.SequenceNumberValidator

public class SequenceNumberValidator
extends Object

This supports extracting the shardId from a sequence number.

Warning

Sequence numbers are an opaque value used by Kinesis, and maybe changed at any time. Should validation stop working you may need to update your version of the KCL

Constructor Summary

Constructors

Constructor and Description
SequenceNumberValidator()

Method Summary

Modifier and Type	Method and Description
Optional<String>	shardIdFor(String sequenceNumber) Attempts to retrieve the shardId from a sequence number.
Optional<Boolean>	validateSequenceNumberForShard(String sequenceNumber, String shardId) Validates that the sequence number provided contains the given shardId.
Optional<Integer>	versionFor(String sequenceNumber) Attempts to retrieve the version for a sequence number.

Methods inherited from class java.lang.Object

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

Constructor Detail

SequenceNumberValidator

public SequenceNumberValidator()

Method Detail

versionFor

public Optional<Integer> versionFor(String sequenceNumber)

Attempts to retrieve the version for a sequence number. If no reader can be found for the sequence number this will return an empty Optional.

This will return an empty Optional if the it's unable to extract the version number. This can occur for multiple reasons including:

• Kinesis has started using a new version of sequence numbers
• The provided sequence number isn't a valid Kinesis sequence number.

Parameters:

sequenceNumber - the sequence number to extract the version from

Returns:

an Optional containing the version if a compatible sequence number reader can be found, an empty Optional otherwise.

shardIdFor

public Optional<String> shardIdFor(String sequenceNumber)

Attempts to retrieve the shardId from a sequence number. If the version of the sequence number is unsupported this will return an empty optional. This will return an empty Optional if the sequence number isn't recognized. This can occur for multiple reasons including:

• Kinesis has started using a new version of sequence numbers
• The provided sequence number isn't a valid Kinesis sequence number.

This should always return a value if versionFor(String) returns a value

Parameters:

sequenceNumber - the sequence number to extract the shardId from

Returns:

an Optional containing the shardId if the version is supported, an empty Optional otherwise.

validateSequenceNumberForShard

public Optional<Boolean> validateSequenceNumberForShard(String sequenceNumber,
                                                        String shardId)

Validates that the sequence number provided contains the given shardId. If the sequence number is unsupported this will return an empty Optional.

Validation of a sequence number will only occur if the sequence number can be parsed. It's possible to use versionFor(String) to verify that the given sequence number is supported by this class. There are 3 possible validation states:

Some(True)

The sequence number can be parsed, and the shardId matches the one in the sequence number

Some(False)

THe sequence number can be parsed, and the shardId doesn't match the one in the sequence number

None

It wasn't possible to parse the sequence number so the validity of the sequence number is unknown

Handling unknown validation causes is application specific, and not specific handling is provided.

Parameters:

sequenceNumber - the sequence number to verify the shardId

shardId - the shardId that the sequence is expected to contain

Returns:

true if the sequence number contains the shardId, false if it doesn't. If the sequence number version is unsupported this will return an empty Optional