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Evaluator - basics

Dynamic rules

This feature enables you to raise alarms on certain conditions or to react on specific states. Dynamic rules respond to changes in database tables. For instance, if a figure goes above a certain threshold, the rule could trigger a warning email to be sent out.

Defining a dynamic rule

To define a rule, you need to insert a row into the DYNAMIC_RULE table. This table is defined as follows:

Field Name	Usage
NAME	Name of the Rule
DESCRIPTION	Simple description of the function of the rule
USER_NAME	The User Name that will be used to perform the operation / null implies system
RULE_TABLE	The table to listen to for changes, e.g.
RULE_STATUS	This is either "ENABLED" or "DISABLED" and respectively enables or disables the rule
RULE_EXPRESSION	This is a groovy expression, which is evaluated when there is a table change on RULE_TABLE, if this evaluates to true, then the RESULT_EXPRESSION logic is activated e.g. `(QUANTITY > 500)`
PROCESS_NAME	Process Name to send the event e.g. POSITION_APP_EVENT_HANDLER
MESSAGE_TYPE	The Message Type that will be defined
RESULT_EXPRESSION	This is a groovy expression, which should set on the MESSAGE Object that is defined in MESSAGE_TYPE e.g. `(POSITION_ID = POSITION_ID)`

note

Groovy expressions need to be surrounded by brackets.

MESSAGE_TYPE fields define the Java/Kotlin class that is instantiated and set by the RESULT_EXPRESSION. The MESSAGE_TYPE is defined as SNAKE_CASE, but the class is defined as regular Camel case (for example, POSITION_CANCEL maps to PositionCancel).

Fields that are set in the expression but which are not on the class are ignored. The instantiated class is sent to the Event Handler implementation defined in the process identified by PROCESS_NAME.

To set up a MESSAGE_TYPE for the Event Handlers, simply create an appropriate data class: for example, position_app-server\position_app-messages\src\main\java\global\genesis\position_app\message\event\PositionCancel.kt.

Rules can be loaded into the database by creating a csv file containing the rules in the above format. The following is an example of a csv file, which can be loaded into the database by saving as DYNAMIC_RULE.csv and running sendIt:

NAME,DESCRIPTION,RULE_TABLE,RULE_STATUS,RULE_EXPRESSION,USER_NAME,PROCESS_NAME,MESSAGE_TYPE,RESULT_EXPRESSION
MY_RULE,It’s a rule,POSITION,ENABLED,(QUANTITY > 500),JaneDee,ALPHA_EVENT_HANDLER,EVENT_POSITION_CANCEL,((QUANTITY = 0) && (POSITION_ID = POSITION_ID))

To set up a MESSAGE_TYPE for the Event Handlers, simply create an appropriate data class: for example, application-name-server\application-name-messages\src\main\java\global\genesis\application-name\message\event\PositionCancel.kt.

package global.genesis.position_app.message.event

data class PositionCancel(
    val positionId: String,
)

So if the RULE_TABLE is set to POSITION, and the RULE_EXPRESSION is set to (POSITION_ID = POSITION_ID), then this will take the POSITION_ID from the POSITION table and set it on the PositionClass object that gets instantiated and ultimately sent to the Event Handler.

For example, if you have an Event Handler that inserts a Notify email message, you could set up the Event Handler in this way in the application-script-config\src\main\resources\scripts\application-eventhandler.kts file:

{
eventHandler<PositionCancel> {
        onCommit { event ->
            val positionId = event.details.positionId

            entityDb.insert(
                Notify {
                    topic = "PositionAlert"
                    header = "Position Alert for $positionId"
                    body = mapOf<String, Any?>(
                        "emailDistribution" to mapOf(
                            "to" to listOf("peter.kievits@genesis.global"),
                            "cc" to emptyList(),
                            "bcc" to emptyList(),
                        ),
                        "content" to "Position $positionId breached the limit"
                    ).toJsonString(true)
                }
            )
            ack()
        }
    }
}

For the example above to work, you need to set up a Notify process together with inserting a GATEWAY and a NOTIFY_ROUTE in the database and add the details of the connection for the SMTP server to the genesis-system-definition.kts file. You can see an example of a dynamic rule using Notify email messages being set up in our tutorial.

Static rules

Static rules are used to create scheduled activities. For instance to schedule the production of EOD reports, or to run a batch report on the hour.

Defining a static rule

To define a scheduled event, you need to insert a row into the CRON_RULE table. This row must specify the CRON schedule that triggers the event. The table is defined as follows:

Field Name	Usage
NAME	Name of the rule
CRON_EXPRESSION	Quartz Cron Expressions.
DESCRIPTION	Simple description of the function of the rule
TIME_ZONE	eg Europe/London
RULE_STATUS	This is either "ENABLED" or "DISABLED", respectively enables or disables the rule
USER_NAME	The User Name that will be used to perform the operation / null implies system
PROCESS_NAME	Process Name to send the Event e.g. POSITION_APP_EVENT_HANDLER
MESSAGE_TYPE	The message type that will be defined
RESULT_EXPRESSION	This is a groovy expression which should set on the MESSAGE Object that is defined in MESSAGE_TYPE

Load the static (Cron) rule

To load a static (Cron) rule into the database, create a csv file with the rule in the above format. Call the file CRON_RULE.csv.

CRON_EXPRESSION,DESCRIPTION,TIME_ZONE,RULE_STATUS,NAME,USER_NAME,PROCESS_NAME,MESSAGE_TYPE
"* 15 7 ? * MON-FRI *","Week days at 7.15","Europe/London","ENABLED","A rule","JaneDee","ALPHA_EVENT_HANDLER","EVENT_POSITION_REPORT"

Load the cron rule CRON_RULE.csv file into the CRON_RULE table.

Run SendIt

You can see an example of a static rule being configured in our tutorial.

Custom Log messages

Genesis provides a class called LOG that can be used to insert custom log messages. This class provides you with 5 methods to be used accordingly: info, warn, error,trade,debug. To use these methods, you need to provide, as an input, a string that will be inserted into the Logs.

Here is an example where you can insert an info message into the log file:

LOG.info("This is an info message")

The LOG instance is a Logger from SLF4J.

note

In order to see these messages, you must set the logging level accordingly. You can do this using the logLevel command.

Dynamic rules​

Defining a dynamic rule​

Static rules​

Defining a static rule​

Load the static (Cron) rule​

Custom Log messages​