UnionMemo

Description

Similarly to Union, UnionMemo node merges branches into one branch. Events are emitted on every incoming event and event time is inherited from the incoming event.

There are however important differences in the way UnionMemo works:

• events from the incoming branches are merged together based on a common key value
• data that arrived from any of the incoming branches will be memoized by the UnionMemo node for time duration defined in stateTimeout. If new event arrives before stateTimeout, the stateTimeout timer is reset
• #input variable is no longer available downstream the UnionMemo node

Parameters and configuration

Name	Description
key	Expression, which is used to match events from the incoming branches. The key can be of any type, but all branches must use the same key type.
value	The result of this expression will be put in the a field of the output variable. The name of the field will be the same as branch id
stateTimeout	Defines for how long events are memoized. Must be a positive duration.
Output variable name	This variable will hold result of the UnionMemo node

The output variable will contain the following json object.

{
  "key": "value of key expression for given event",
  "branch1-name": "value of output expression if memoized, otherwise null",
  "branch2-name": "value of output expression if memoized, otherwise null",
  "branchN-name": "value of output expression if memoized, otherwise null"
}