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Task Contract — Stream Processor Tasks

Task is the abstraction of stream processor tasks.

Table 1. Task Contract
Method	Description
`applicationId`	`String applicationId()` Application ID of the Kafka Streams application the task belongs to
`changelogPartitions`	`Collection<TopicPartition> changelogPartitions()` Changelog partitions associated with the task Used when: `AssignedStreamsTasks` is requested to updateRestored and addToRestoring `AssignedTasks` is requested to mark a task as ready for execution and processing records `StreamTask` is requested to initialize state stores
`close`	`void close( boolean clean, boolean isZombie)` Closes the task Used when: `AssignedTasks` is requested to closeNonRunningTasks, suspendTasks, closeZombieTask, close, and closeUnclean `StandbyTask` is requested to closeSuspended
`closeSuspended`	`void closeSuspended( boolean clean, boolean isZombie, RuntimeException e)` Used when: `AssignedTasks` is requested to closeNonAssignedSuspendedTasks `StreamTask` is requested to close
`commit`	`void commit()` Commits the task Used when: `AssignedStreamsTasks` is requested to maybeCommitPerUserRequested `AssignedTasks` is requested to commit `StandbyTask` is requested to close
`commitNeeded`	`boolean commitNeeded()` Used when: `AssignedStreamsTasks` is requested to maybeCommitPerUserRequested `AssignedTasks` is requested to commit
`context`	`ProcessorContext context()` ProcessorContext of the task
`getStore`	`StateStore getStore(String name)` Looks up the state store by name Used exclusively when `StreamThreadStateStoreProvider` is requested for the stores
`hasStateStores`	`boolean hasStateStores()`
`id`	`TaskId id()` TaskId of the task
`initializeStateStores`	`boolean initializeStateStores()` Initializes state stores (of the ProcessorTopology) Enabled (`true`) if the task has no state stores that need restoring. `StandbyTask` always returns true Used exclusively when `AssignedTasks` is requested to initialize new tasks
`initializeTopology`	`void initializeTopology()` Initializes the topology of processor nodes Used exclusively when `AssignedTasks` is requested to mark the specified task as ready for execution and processing records
`partitions`	`Set<TopicPartition> partitions()` Used when: `AssignedStreamsTasks` is requested to addToRestoring `AssignedTasks` is requested to maybeResumeSuspendedTask, transitionToRunning, and closeNonAssignedSuspendedTasks `StreamThread` is requested to updateThreadMetadata
`resume`	`void resume()` Resumes the task Used exclusively when `AssignedTasks` is requested to attempt to resume suspended task (when the task has actually been suspended)
`suspend`	`void suspend()` Suspends the task Used exclusively when `AssignedTasks` is requested to suspend tasks.
`topology`	`ProcessorTopology topology()` ProcessorTopology of the task
`toString`	`String toString(String indent)` Describes the task (textual representation)

Note	AbstractTask is the base implementation of the Task Contract in Kafka Streams (with StandbyTask and StreamTask as the only concrete implementations).

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