D2000 system provides object Event that is used to process scripts and implementation of various calculations and process algorithms.
Object of Event type is configured in process D2000 CNF. During configuration, the following is defined:
- own algorithm
- start conditions to execute the algorithm
- algorithm execution conditions
- parent object - D2000 Event Handler (its extension is .EVH)
The controller of all scripts is process
D2000 Event Handler - client process of D2000 system. Process
provides starting and execution of scripts. This process may be running in multiple instances - in various
LAN nodes. Each process D2000 Event Handler process handles its own set of scripts that is given by
the parent - child relation in the system configuration.
The OPENEVENT action allows to "enforce" the execution of Server event on another process as defined in the configuration of the event.
A script occurs in two various states - running and not running. If the request to run a script appears, while some of scripts is already running, then the scripts are processed simultaneously from this moment. It is possible to run one script in more instances. If the priority of two scripts is not the same (priority is defined in the script configuration), a script with higher priority will be processed first.
Script algorithm is defined using the ESL (Event Script Language). It is just a sequence of executable actions. Script termination, changing into the not running state occurs after the script termination (conditions and termination method are given by ESL properties). Script termination may be also caused by an error occurrence.
Script algorithm is, when the specified start conditions are met, activated (interpreted) by the particular process D2000 Event Handler (parent process).
Algorithm execution conditions
Algorithm execution conditions define mainly a priority assigned to the given script. Priority defines particular preference in the execution of algorithms of various scripts in case of their being processed simultaneously. There are 5 specified priority levels, where the priority of 1 determines the lowest one, and the priority of 5 is the highest one.