Event processing

Owned by Leeza Gavronsky (Unlicensed)
Last updated: Jun 29, 2023 by Mariia Golubeva (Unlicensed)
5 min read

Overview

This section describes the configuration of Event Groovy rules.

The eventRule method helps to build a rule for event processing. It requires a few components for its instantiation.

eventRule(String description, Class<AppEvent> eventType, Predicate<AppEvent> ruleCondition, Consumer<AppEvent> ruleAction)
  • description - string with a free text description of the rule.
  • event type - type or subtype of the event for which the rule is applied.
  • rule condition - dynamic filter, which at the same time can check the appliance of this rule depending on the event content and source attributes. The context filter can be NULL if you’d like to ignore it.

  • rule action - describes the main goal of the rule.

EventType

The event type is the type of event for which the rule is applied. Subtype or general type can be specified.

The table below specifies the available list of types and their methods.

Event CategoryClass of eventMethodsDescription
General



BasicAppEvent


The basic class of all events that can be used for handling all the events the system throws.
Application



ServerStateEvent

getSource(): STARTED

Notifies about changes in the state of the FIX server.
Session



FIXSessionStateEvent

getSessionState(): CONNECTING, WAITING_FOR_LOGON, CONNECTED, WAITING_FOR_LOGOFF, DISCONNECTED, LOGON_RECEIVED, DEAD, DISCONNECTED_ABNORMALLY, RECONNECTING, WAITING_FOR_FORCED_LOGOFF, WAITING_FOR_FORCED_DISCONNECT

getSessionId(): String

Notifies about changes in the state of FIX sessions.

NewSessionEvent

SessionParameters getSessionParameters()

reject(String reason)

reject(String reason, boolean quiet)

The event is intended for accepting or rejecting a new incoming session. The session will be rejected if the reject method is called. Otherwise, the session will be accepted.

NOTE: If the reject method is called, the next rule for the event will not be processed.

Scheduler





SchedulerEvent

getId(): StringThe event that is created by the Scheduler when the trigger executes.

SnF





SnFEvent

getSource(): MESSAGE_WAS_QUEUED, MESSAGE_WAS_SKIPPED
Rule events



RuleErrorEvent

getException(): Exception

getMessage(): FIXFieldList

getRuleDescription(): String

Notifies that there is an exception in some of the rules processed.

UnprocessedMessageEvent

getMessage(): FIXFieldListNotifies that there are no acceptable rules defined for the specified message.

 If the BasicAppEvent is specified in the eventRule method as an event type parameter, all the events above will trigger the rule.

Examples

import com.epam.fej.server.fix.event.ServerStateEvent
import com.epam.fej.server.fix.event.SessionStateEvent
import com.epam.fej.scheduling.event.SchedulerEvent

[
        eventRule("Catching session events", SessionStateEvent.class, {
                appEvent ->
                    return true//do nothing but there can be additional logic
            },
            {
                sessionStateEvent ->
                    def sessionName = sessionStateEvent.getSessionId()
                    logger.info("I'm rule for session events, I was called because session '{}' has been started.", sessionName)
            }
        ),
        eventRule("Catching server events", ServerStateEvent.class, {
                appEvent -> return true//do nothing but there can be additional logic
            },
            {
                serverStateEvent ->
                    String state = String.valueOf(serverStateEvent.getSource())
                    logger.info("I'm rule for server events, I was called because server has {}.", state)
            }
        ),
        eventRule("Catching scheduler events", SchedulerEvent.class, {
                appEvent -> return true//do nothing but there can be additional logic
            },
            {
                schedulerEvent ->
                    logger.info("I'm rule for schedule events, id - {}.", schedulerEvent.getId())
            }
        ),
		eventRule("Custom accepting of FIX sessions", NewSessionEvent.class, null,
                {
                    newSessionEvent ->
                        boolean accepted = true
                        def sessionParameters = newSessionEvent.getSessionParameters()
                        if (sessionParameters.getIncomingUserName() != "User1" || sessionParameters.getIncomingPassword() != "Password1") {
                            newSessionEvent.reject("Wrong username or/and password")
                            accepted = false
                        }
                        logger.info("Session {} is {}", sessionParameters.getSessionID(), accepted ? "accepted" : "declined")
                }
        )
]

The example of the Scheduler settings: the SchedulerEvent event will be published every 10 seconds.

<schedule id="every10Seconds">
        <task name="event" timeZone="Europe/Samara">
            <event cron="*/10 * * ? * *"/>
        </task>
</schedule>