ID Generators

In addition to standard settings, writeable state managers can also utilize id generators for assigning globally unique ids to each input event

Id generator class is defined with "id.generator" setting and can be one of the following classes.

All id generators can use the following parameters:

Parameter	Definition	Example	Default
id.prefix	Prefix to add to generated ids	ID-	-
id.suffix	Suffix to add to generated ids	-val	-
id.digits	Minimum number of digits for an id	10	-
id.filler	Character to repeat as prefix if id is shorter than minimum number of digits	X	0

RandomIDGenerator

Generates a random globally unique ID each time. This generator has no settings.

JmesPathIDGenerator

Generates an ID using JmesPath expression with event payload used as the input. Uses the following state parameters:

Parameter	Definition	Example	Default
id.pattern	JmesPath pattern to apply	join('' ['id-', data.id])	-

NumberIDGenerator

Uses instance of a number generator to generate unique numerical ids. Uses the following state parameters:

Parameter	Definition	Example	Default
id.numberGenerator	Class name of number generator to use	com.rierino.handler.util.generator.ConstantNumberGenerator	-
id.label	Label to use for numbers generated if number generator is shared between different types of data	product	-
id.checksum	Whether to calculate a checksum digit for generated number	true	false
id.checkReverse	Whether the checksum digit should be subtracted from 10	true	false
id.checkOddMultiplier	Number to multiply each odd digit with for checksum calculation	3	1
id.checkEvenMultiplier	Number to multiply each even digit with for checksum calculation	1	1

ConstantNumberGenerator

Produces a constant number only, using "id.value" setting, assigning same id to all records, only used for testing purposes.

EpochNumberGenerator

Produces number based on epoch time in milliseconds, which does not guarantee uniqueness especially for a distributed deployment.

MongoNumberGenerator

Through "id.system" and "id.collection" settings, uses a MongoDB collection for creating and tracking globally unique ids.

MongoNumberGenerator is a buffered number generator, where "id.buffer" can be set to define maximum increments allowed for "reserving" ids on each request.

Buffering happens in exponential iterations (e.g. reserving 1, 2, 4, 8, ... until max is reached) so that continuous system restarts do not result in unnecessary reservations.

OffsetPartitionedIDGenerator

Uses source partition, key and offset of the event for generating unique ids. This generator has no settings.

PartitionedIDGenerator

Uses instances of another id generator class, with each instance dedicated to a specific partition. Partition is suffixed to the id generated by used instances, ensuring global uniqueness across partitions. Uses the following state parameters:

Parameter	Definition	Example	Default
id.partitioned.class	Class name of inner generator to use	com.rierino.handler.util.generator.NumberIDGenerator	com.rierino.handler.util.generator.RandomIDGenerator

Dependent ID Generators

These id generators generate ids for children of an existing entity (e.g. variants of a product), in a [prefix][delimiter][newid] type format. The following settings are shared among these generators:

Parameter	Definition	Example	Default
id.digits	Number of digits to generate children id with (prefixing shorted ids with 0)	4	-
id.suffixParent	Whether parent id should be a prefix or a suffix	true	false
id.delimiter	Delimiter between parent and child ids	-
id.parentPath	Json path of the data element keeping parent id for a child record	data.parent	data.parentId

DependentEventIDGenerator

Uses and increments an ID provided in event payload to generate a new ID. Typically used within a saga where a previous step calculates max child id so far.

Parameter	Definition	Example	Default
id.maxChildPath	Json path of the max ID so far in event payload	prevId	maxId

DependentQueryIDGenerator

Uses and increments the max ID stored in a database to generate a new ID. Typically used with a query getting maximum child ID directly from a database table / collection.

Parameter	Definition	Example	Default
id.eventParent	...	true	false
id.query.state	State manager keeping query details	query_local	query
id.query.id	Id of the query for selecting max child id for a given parent	product_maxid	[state]_maxid
id.query.manager	Query manager which should run the query for selecting max child id	product_master	master

This generator injects "%%parentid%%" variable in executed query and expects the query to return maximum child id so far as "maxId" field.