Flow / Unit types / Data / Memory
Memory
Description
This unit is a Processor unit type.
This unit can be used to store key(s)/value(s) in its memory. You can use several input fields as a multi key, and one input field as a value. This is a very flexible unit that can be used for many different purposes. You can configure an unlimited number of input/output ports with as many functionalities as required.
Data is stored in a multivalued table, 'mapping' each key-values list pair. Each mapping has a timestamp of the moment it was last used. The same applies for each individual value.
The unit is triggered upon receiving input events, or when a bound is fulfilled.
Input event handling starts with an action execution phase:
An input event comes through one of the configured input ports. Depending on the settings for that port, input events need to contain key(s) and value, just key(s), or nothing.
A sequence of actions is executed. Actions will either be successfully completed (e.g. delete existing key(s)) or will fail (e.g. attempt to delete key(s) that do not exist). Even when an action fails, the following actions are still executed, as actions are considered individually.
Actions to be performed on an input event are deconstructed into 'segments', each with a success/failure branch. This recursive structure defines a tree. With any input event, a path on this tree is traversed until a leave node is reached, executing actions it comes across along the way. For more information, see Decision Tree Learning.
Successful actions will be sent to the 'Success' branch.
Failed actions take the 'Failure' branch.
Then, successful events are generated. The path is traversed from end to beginning and, at each segment, output events for each action are sent to the specified out port.
Failed events are generated in the same way, this time with a 'reason' event sent to the specified destinations. A reason event is the input event enriched to indicate the first failed action on the segment.
Finally, the bounds are processed. Fulfilling a bound will trigger specified actions, and events are sent to given destinations.
The process is the same when triggered by a timeout bound.
Configuration
After dragging this unit into the Flow canvas, double-click it to access its configuration options. The following table describes the configuration options of this unit:
| Tab | Field | Description | |
|---|---|---|---|
| General | Name | Enter a name for the unit. It must start with a letter, and cannot contain spaces. Only letters, numbers, and underscores are allowed. | |
| Key field(s) | Enter the name of the input event fields containing key(s). The unit can be configured to either use a global port for all events or to create a new port for each key. | ||
| Value field | Enter the name of the input event field containing the value. The unit can be configured to either use a global port for all events or to create a new port for each value. | ||
| Allow duplicates | Whether to repeat the same (key(s), value) pair. The functionality of some actions depend on this. | ||
| Allow empty collections | Whether empty collections should emit a result or not (false by default). This only applies when a value is set in the 'Collect' setting of the output port. | ||
| Input ports | Input ports | Click the plus icon to add as many additional input ports as needed. | |
| Name | Enter a name for the input event port containing the key(s). | ||
| Key field(s) | Enter the name of the input event field containing key(s). This overrides the unit-level Key fields setting for this particular input port. | ||
| Value field | Enter the name of the input event field containing the value. This overrides the unit-level Value field setting for this particular input port. | ||
| Key index(es) | Select the position of the key field(s) with respect to the full key used in the stored action. The numbering is zero-based (0 is the first position). | ||
| Actions | A list of actions to execute. Describe actions to be taken using clear, concise patterns to facilitate the creation of custom functionality. For example, if you want to save an entry, you have to specify both 'store' and 'touch'. Some functionality will depend on whether you have set Allow duplicates to on or off. | ||
| Destinations | Select the output port to which events will be sent. | ||
| Success | The branch to be taken when all actions in this segment are successful. You can add as many success branches and actions as needed. | ||
| Failure | Branch to be taken when an action in this segment fails. All actions in the segment are executed, even if some of them fail. You can add as many failure branches and actions as needed. | ||
| Output ports | Output ports | Click the plus icon to add a list of output ports. | |
| Name | Enter a name for the output port. | ||
| Collect | Type of grouping applied to output events coming through this port. | ||
| Collect as first | Whether the collection type is Collection (true) or Array (false). | ||
| Key(s) field | Enter a name for the output event field containing key(s). | ||
| Value(s) field | Enter a name for the output event field containing value(s). | ||
| Count(s) field | Enter a name for the output event field containing counter(s). This is 1 when there's no grouping, and the number of grouped items otherwise. | ||
| Percent(s) field | Enter a name for the output event field containing percent(s). The percent is the value of the counter with respect to the total elements in memory (a number between 0 and 1). | ||
| Report field | The name of the output event field containing the report. The report is a map of two values:
| ||
| Time field | Enter a name for the output event field containing the timestamp. When groupings are present, the timestamp will be the oldest found. | ||
| Error field | Enter a name for the output event field containing the error. Error is the name of the first action that failed in a segment, with this port configured as one of the destinations of its 'reason'. | ||
| Bounds | Bounds | Bounds are a way of establishing limits that, when reached, will generate some reaction. Currently, you can set size (max number of items) and time (ttl, timeout) limits. Click the plus icon to add bounds. | |
| Actions | A list of actions to execute. This setting does not apply for size bounds, as the only possible action is remove. | ||
| Destinations | Select the output port to which events will be sent. | ||
| Seconds | Amount of time to wait (in seconds) before purging events from the memory. | ||
| Size | The maximum number of elements to store in the memory. | ||
| Purge size | The number of elements to purge from the memory when it is full (1 by default). This only applies when byValue is on. | ||
| Bound per Key | Whether previous bound settings refer to individual keys or whole memory. This setting only applies to size bounds. | ||
| By value | Whether previous bound settings refer to individual values or whole mappings. | ||
Input ports
Add as many input ports as you need. Names must be unique within the unit.
Output ports
Add as many input ports as you need. Names must be unique within the unit.