Queue Timers

• Queue timer records are defined to post a queue-based message after a specified time delay. The moments in time that a timer will fire are defined using UNIX CRON-like definitions.

• For those unfamiliar with CRON, this means being able to create a firing schedule such as:
  • At 8 a.m., every Monday through Friday; or

  • At 1:30 a.m., every last Friday of the month.

• CRON expressions are comprised of six required fields and one optional field separated by white space. The fields respectively are described as follows:

  Field Name	Allowed Values	Allowed Special Characters
  Seconds	0-59	, - * /
  Minutes	0-59	, - * /
  Hours	0-23	, - * /
  Day-of-Month	1-31	, - * ? / L W C
  Month	1-12 or JAN-DEC	, - * /
  Day-of-Week	1-7 or SUN-SAT	, - * ? / L #
  Year (Optional)	empty, 1970-2099	, - * /

  • The * character is used to specify all values. For example, an asterisk (*) in the minute field means every minute.

  • The ? character is allowed for the day-of-month and day-of-week fields. It is used to specify no specific value. This is useful when you need to specify something in one of the two fields, but not the other.

  • The - character is used to specify ranges. For example, 10-12 in the hour field means the hours 10, 11 and 12.

  • The , character is used to specify additional values. For example, MON,WED,FRI in the day-of-week field means the days Monday, Wednesday, and Friday.

  • The / character is used to specify increments. For example, 0/15 in the seconds field means the seconds 0, 15, 30, and 45, and 5/15 in the seconds field means the seconds 5, 20, 35, and 50. Specifying * before the / is equivalent to specifying that 0 is the value with which to start. Essentially, for each field in the expression, there is a set of numbers that can be turned on or off. For seconds and minutes, the numbers range from 0 to 59. For hours 0 to 23, for days of the month 0 to 31, and for months 1 to 12. The slash (/) character simply helps you turn on every nth value in the given set. Thus 7/6 in the month field only turns on month 7, it does not mean every 6th month; please note that subtlety.

  • The L character is allowed for the day-of-month and day-of-week fields. This character is short-hand for last, but it has different a meaning in each of the two fields. For example, the value L in the day-of-month field means the last day of the month—day 31 for January, day 28 for February on non-leap years. If used in the day-of-week field by itself, it simply means 7 or SAT. But if used in the day-of-week field after another value, it means the last xxx day of the month—for example 6L means the last Friday of the month. When using the L option, it is important not to specify lists, or ranges of values, as you will get confusing results.

  • The W character is allowed for the day-of-month field. This character is used to specify the weekday (Monday-Friday) nearest the given day. As an example, if you were to specify 15W as the value for the day-of-month field, the meaning is the nearest weekday to the 15th of the month. So if the 15th is a Saturday, the trigger will fire on Friday the 14th. If the 15th is a Sunday, the trigger will fire on Monday the 16th. If the 15th is a Tuesday, then it will fire on Tuesday the 15th. However, if you specify 1W as the value for day-of-month, and the 1st is a Saturday, the trigger will fire on Monday the 3rd, as it will not jump over the boundary of a month's days. The W character can only be specified when the day-of-month is a single day, not a range or list of days.

  • The L and W characters can also be combined for the day-of-month expression to yield LW, which translates to last weekday of the month.

  • The # character is allowed for the day-of-week field. This character is used to specify the nth XXX day of the month. For example, the value of 6#3 in the day-of-week field means the third Friday of the month (day 6 equals Friday and #3 equals the 3rd one in the month). Other examples: 2#1 equals the first Monday of the month and 4#5 equals the fifth Wednesday of the month. Note that if you specify #5 and there is not 5 of the given day-of-week in the month, then no firing will occur that month.

  • The legal characters and the names of months and days of the week are not case-sensitive.

  • Support for specifying both a day-of-week and a day-of-month value is not complete (you will need to use the ? character in one of these fields).

  Note: Be careful when setting fire times between midnight and 1:00 a.m. Daylight savings can cause a skip or a repeat depending on whether the time moves back or jumps forward. Here are some examples:

  Expression	Meaning
  0 0 12 * * ?	Fire at 12 p.m. (noon) every day.
  0 15 10 ? * *	Fire at 10:15 a.m. every day.
  0 15 10 * * ?	Fire at 10:15 a.m. every day.
  0 15 10 * * ? *	Fire at 10:15 a.m. every day.
  0 15 10 * * ? 2005	Fire at 10:15 a.m. every day during the year 2005.
  0 * 14 * * ?	Fire every minute starting at 2 p.m. and ending at 2:59 p.m., every day.
  0 0/5 14 * * ?	Fire every 5 minutes starting at 2 p.m. and ending at 2:55 p.m., every day.
  0 0/5 14,18 * * ?	Fire every 5 minutes starting at 2 p.m. and ending at 2:55 p.m., AND fire every 5 minutes starting at 6 p.m. and ending at 6:55 p.m., every day.
  0 0-5 14 * * ?	Fire every minute starting at 2 p.m. and ending at 2:05 p.m., every day.
  0 10,44 14 ? 3 WED	Fire at 2:10 p.m. and at 2:44 p.m. every Wednesday in the month of March.
  0 15 10 ? * MON-FRI	Fire at 10:15 a.m. every Monday, Tuesday, Wednesday, Thursday and Friday.
  0 15 10 15 * ?	Fire at 10:15 a.m. on the 15th day of every month.
  0 15 10 L * ?	Fire at 10:15 a.m. on the last day of every month.
  0 15 10 ? * 6L	Fire at 10:15 a.m. on the last Friday of every month.
  0 15 10 ? * 6L	Fire at 10:15 a.m. on the last Friday of every month.
  0 15 10 ? * 6L 2002-2005	Fire at 10:15 a.m. on every last Friday of every month during the years 2002, 2003, 2004 and 2005.
  0 15 10 ? * 6#3	Fire at 10:15 a.m. on the third Friday of every month.

Note: While deploying the system, the Copy Timer action should be executed against all of the generic timers (i.e. timer records for which the instance name is tecsys_default). Refer to the Application Server Instances topic for more details.

As a general rule, once you have changed a queue timer record, you must launch the Service Monitor resource and select either the Start hyperlink to start (or restart) the application or the Refresh hyperlink. This ensures that your changes take effect.

The following special actions exist for this resource:

• The Execute Now action is used to fire a timed service immediately.

• The Copy Timer action is applicable to the Queue Timers view only. Use this action to copy timer records to specific instances. For more details, refer to the Application Server Instances help topic.

The following list defines every field available in the queue timer (md_timer) resource in alphabetical order:

• Allow Concurrent Execution - indicates if a message will be posted if there remains an unconsumed posted message from the last time the timer event fired. The following options are available: Yes and No (default).

• Created By - displays the name of the user who created the record you are viewing or maintaining. May not be overridden.

• Created On - displays the date on which the record that you are creating or maintaining was created. May not be overridden. May also represent the creation date of the records you are attempting to retrieve.

• Day of Month in CRON Format - the day of month portion of the CRON expression.

• Day of Week in CRON Format - the day of week portion of the CRON expression.

• Ending Date and Time - the time at which the timer will quit repeating. Leave this field to indicate that the timer does not quit repeating.

• Execute as Job - indicates whether or not the timer is executed as a job. The following options are available: Yes and No (default).
  • A value of No indicates that the timer is not executed as a job.

  • A value of Yes indicates that the timer is executed as a job.

  Note: This flag can only be set to Yes if the Allow Concurrent Execution flag is set to No.

• Extra Attributes - a CLOB-type field used to store additional JSON information.

• Hour in CRON Format - the hour portion of the CRON expression.

• Instance Name - the name of the instance to which the timer is restricted, when the meta database is shared by multiple EliteSeries Web Component (ESWC) environments. May be left blank.

• Is Active - indicates whether or not this timer record is active. The following options are available: Yes (default) and No.

• Last Execution Date and Time - this field is not maintainable. The date and time of execution of the last posting from this timer.

• Last Message - this field is not maintainable. An expression column that allows you to link directly to the actual message in its queueing table.

• Minute in CRON Format - the minutes portion of the CRON expression.

• Misfire Policy - the timer's misfire policy. A misfire will occur if the application server was down while the timer event was scheduled to occur. The following options are available:
  • Do Not Refire (default)

  • Refire Once - indicates that the timer event will refire immediately upon starting up the application server. It will refire once only regardless of the number of misfires.

• Modification Counter - this field is not maintainable. The date and time a given record was last modified.

• Modified By - this field is not maintainable. The user or system process that last modified the record.

• Modified On - this field is not maintainable. The date on which the record was last modified.

• Month in CRON Format - the month portion of the CRON expression.

• Next Execution Date and Time - this field is not maintainable. The next date and time that this timer event is to occur.
  • Note: The value of this field should always be reset whenever a message is posted by the timer. This can happen whenever the event fires through the Quartz scheduler or through the use of the Execute Now action. Reset the next execution date and time by using the Start or Refresh hyperlinks in the Service Monitor resource.

• Queue Message Body - the queue message body content that will be posted when the timer event occurs.

• Queue Message Header - the queue message header content that will be posted when the timer event occurs.

• Queue Message ID - the unique queue message identifier of the last posting from this timer. May not be modified.

• Queue Name - the queue to which the message will be posted when the timer event occurs.

• Queue Timer Description - the description for the timer record.

• Run as User - the user name that will be used for the process that consumes the message.

• Schedule - the timer's frequency schedule.

• Schedule Description - this field is not maintainable. The timer's frequency schedule description.

• Second in CRON Format - the seconds portion of the CRON expression.

• Starting Date and Time - the date and time at which the timer will start. Leave this field blank to indicate that it should start immediately.

• Timer Name - the unique identifier for the timer record.

• Year in CRON Format - the year portion of the CRON expression.

For the functionality of each action (i.e. button) available on this view, refer to the About the Actions topic.