Caches a release signal identifier in the distributed cache, optionally along with the FlowFile's attributes. Any flow files held at a corresponding Wait processor will be released once this signal in the cache is discovered.
map, cache, notify, distributed, signal, release
In the list below, the names of required properties appear in bold. Any other properties (not in bold) are considered optional. The table also indicates any default values, and whether a property supports the NiFi Expression Language.
| Display Name | API Name | Default Value | Allowable Values | Description |
|---|---|---|---|---|
| Release Signal Identifier | release-signal-id | A value, or the results of an Attribute Expression Language statement, which will be evaluated against a FlowFile in order to determine the release signal cache key Supports Expression Language: true (will be evaluated using flow file attributes and variable registry) | ||
| Signal Counter Name | signal-counter-name | default | A value, or the results of an Attribute Expression Language statement, which will be evaluated against a FlowFile in order to determine the signal counter name. Signal counter name is useful when a corresponding Wait processor needs to know the number of occurrences of different types of events, such as success or failure, or destination data source names, etc. Supports Expression Language: true (will be evaluated using flow file attributes and variable registry) | |
| Signal Counter Delta | signal-counter-delta | 1 | A value, or the results of an Attribute Expression Language statement, which will be evaluated against a FlowFile in order to determine the signal counter delta. Specify how much the counter should increase. For example, if multiple signal events are processed at upstream flow in batch oriented way, the number of events processed can be notified with this property at once. Zero (0) has a special meaning, it clears target count back to 0, which is especially useful when used with Wait Releasable FlowFile Count = Zero (0) mode, to provide 'open-close-gate' type of flow control. One (1) can open a corresponding Wait processor, and Zero (0) can negate it as if closing a gate. Supports Expression Language: true (will be evaluated using flow file attributes and variable registry) | |
| Signal Buffer Count | signal-buffer-count | 1 | Specify the maximum number of incoming flow files that can be buffered until signals are notified to cache service. The more buffer can provide the better performance, as it reduces the number of interactions with cache service by grouping signals by signal identifier when multiple incoming flow files share the same signal identifier. | |
| Distributed Cache Service | distributed-cache-service | Controller Service API: AtomicDistributedMapCacheClient Implementations: CouchbaseMapCacheClient HBase_2_ClientMapCacheService DistributedMapCacheClientService RedisDistributedMapCacheClientService HazelcastMapCacheClient | The Controller Service that is used to cache release signals in order to release files queued at a corresponding Wait processor | |
| Attribute Cache Regex | attribute-cache-regex | Any attributes whose names match this regex will be stored in the distributed cache to be copied to any FlowFiles released from a corresponding Wait processor. Note that the uuid attribute will not be cached regardless of this value. If blank, no attributes will be cached. |
| Name | Description |
|---|---|
| success | All FlowFiles where the release signal has been successfully entered in the cache will be routed to this relationship |
| failure | When the cache cannot be reached, or if the Release Signal Identifier evaluates to null or empty, FlowFiles will be routed to this relationship |
| Name | Description |
|---|---|
| notified | All FlowFiles will have an attribute 'notified'. The value of this attribute is true, is the FlowFile is notified, otherwise false. |
DistributedMapCacheClientService, DistributedMapCacheServer, Wait