Automation Engine Priority
The AE priority influences the processing of tasks. It can be used for clients and tasks, although with very different impacts.
The UC_CLIENT_SETTINGS variable contains entries for both priority types in which the administrator can specify default values:
| 
                         AE priority  | 
                    
                         Setting  | 
                
|---|---|
| 
                         Client priority  | 
                    
                         Key: CLIENT_PRIORITY Priority of the client  | 
                
| 
                         Task priority  | 
                    
                         Key: TASK_PRIORITY Default priority for all the objects of a client You can also specify a priority in the AE Priority property on the Attributes Page of an object. The priority applies to that particular object only and overrules the entry made in TASK_PRIORITY. The default here is 0, which means that the priority defined in the TASK_PRIORITY key applies.  | 
                
An Automation Engine system consists of the system client 0000 and up to 9999 user-defined clients.
The Automation Engine processes all messages sent by those clients, with the client priority determining the order in which they are processed. Clients of a higher priority are always given priority to clients of a lower priority, regardless of the order in which the messages were originally sent. The First-In-First-Out principle applies when there are two clients with the same priority. The message arriving first is processed first.
- Highest priority: 200
 - Lowest priority: 255
 - Default value: 200
 
Objects are processed in queues based on their priority. A Client variable that can be set by administrator users defines the default priority for tasks within in a Client (TASK_PRIORITY key of the UC_CLIENT_SETTINGS variable). 
Here you specify the priority you assign to this object, which overrides the default set by your administrator in the Client variable.
- 
                    
Allowed values: 0 to 255
 - 1 = highest priority
 - 255 = lowest priotiy
 - 0 = the value specified in the 
TASK_PRIORITYkey of theUC_CLIENT_SETTINGSvariable applies 
If no default priority is specified, or if the variable is not available in the Client, the priority is 200.
See also Automation Engine Priority and UC_CLIENT_SETTINGS - Various Client Settings.
For tasks of the same priority, the "First in/first out" principle applies.