Start Event - Timer

Timer events can be added to the process flow by themselves, as triggers on the start event, or they can be added within an Appian Smart Service to trigger an Exception Flow or an Escalation. This topic describes how to configure a timer on the Start Event.

  • Start event timers only delay the execution of the process flow, unless they are set to a recurring schedule.
  • Recurring schedules continue executing once you've launched the process model once.
  • To disable a recurring start event trigger, republish the process model without the recurring schedule.
    Only the most recently published process model will trigger new processes to start.


To add a Timer trigger to a Start Event:

  • Right click on a Start Event in the designer canvas and select Triggers. — or —
    Double-click the Start Event.
  • The Configure Start Event dialog box is displayed.
  • The Triggers tab allows you to add different triggering events.
    • To add a Timer event, click Timer. This creates a new entry beneath the Start Event Triggers section. To configure the timer event, click the Configure link. The Edit Timer Event dialog box is displayed.


General

On the General tab, you can edit the name and description of the event.

Setup

The start of a process can be delayed for a configurable time period, or it may be delayed until a particular date has been reached. In either case, the time period for which the flow is delayed is relative to the time at which the underlying process model was published.

To delay the process flow for a specific time period, select the radio button that corresponds to Delay for …

Once this option is selected, specify a numeric value through the provided text field. The text field can be populated by entering a value, or by using the expression editor to come up with an expression that returns a numeric value. After specifying a value, select one of the following units; Minute(s), Hour(s), Day(s), and Month(s). By default, the Minute(s) option is selected.

Apart from delaying the start of a process for a specified time period, you can also delay it until a specific date. Select Delay until the date specified by this expression:

  • This option requires a date, which can be defined by an expression, or typed into the text-field.

Recurrence

A timer trigger can also be configured to execute periodically. This option can be enabled by selecting the check box that corresponds to Timer Recurrence. Once this option is selected, select a radio button that corresponds to one of the options shown below:


  • Daily: Allows you to start a process either on a daily basis or periodically at a certain time (in a certain timezone)

  • Weekly: Allows you to start a process either on a weekly basis or periodically at a certain time (in a certain timezone)

  • Monthly: Allows you to start a process either on a monthly basis or periodically at a certain time (in a certain timezone)

  • Yearly: Allows you to start a process either on a yearly basis or periodically at a certain time (in a certain timezone)

  • At an interval: Allows you to start a process after a specified time period that can either be specified in minutes or hours. Only integer values must be supplied in the text fields.

The time zone used in a recurring event can be configured in the process model properties, and is indicated by the timezone process property (pp!timezone).

Timer Conditions

Conditions that govern the execution of the event may be added, by clicking the New Condition or New Expression buttons. Creating a new condition allows you to evaluate a process variable against another value that can either be populated through the expression editor, or by entering a value in the provided text area. Creating a new expression, on the other hand, allows you to create to create a complex expression using the expression editor that should always evaluate to true or false.

In order for an event to execute, all conditions created under this section should evaluate to true. Therefore, once a process model has been published, all conditions specified within a trigger are continually evaluated until all conditions evaluate to true, upon which the trigger is activated. For example, if a timer trigger is used within a start event to delay the start of process flow by 10 minutes, the 10 minutes only begins when all conditions specified beneath this section evaluate to true.

Creating a New Condition

To create a new condition, click New Condition. This creates a new row that consists of three different drop-down menus.


Using the first drop-down menu, select from the list of process variables that appear. Next, you will be required to choose an operator that is used to evaluate the condition. The table below lists the different operators that are made available for selection:

Choosing... means ...
= equals to
<> no equal to
< less than
> greater than
<= less than or equal to
>= greater than or equal to

Once an operator has been selected, specify the value used to evaluate against the selected process variable. This value can be specified by entering a value in the designated text field, or by using the Expression Editor. The expression editor opens in a new window.

Creating a New Expression

To create a new expression, click New Expression.


This creates a new row, from which the expression editor can be accessed. All expressions that are created as a rule should always evaluate to true or false. See Expressions for additional information.

Creating expressions to determine the conditions under which an event executes can result in reduced application performance. We recommend creating conditions instead of expressions when configuring Event Conditions.

See also: Messaging Best Practices

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