ecFlow's documentation is now on readthedocs!

This defines a dependency for a task or family. There can be only one trigger dependency per node, but that can be a complex boolean expression of the status of several nodes. Triggers should be avoided on suites.
A node with a trigger can only be activated when its trigger has expired. A trigger holds the node as long as the trigger's expression evaluation returns false. There are a few additional keywords and some names may point to other nodes with their value acting as the status of those nodes. Trigger mathematics are computed, using double arithmetic (with no string comparisons). There should not be any need to use numerical expressions, instead logical functions (and, or, not, eq, ne) with node names should be used.

The keywords in trigger mathematics are: unknown, suspended, complete, queued, submitted, active and aborted for task and family status; and clear and set for event status. These keywords are treated as numbers starting from 0 (unknown) to 6 (aborted). There is no need to be aware of the numerical values as long as you do not use a trigger in the form:
trigger plain_name # WARNING! DO NOT USE!

This is true only as long as the status of plain_name is unknown. It is not advisable to use mathematical function names for node names.
The full name or relative name of a node can also be used as an operand. A full name starts from the super-node. A relative name can include "../" to indicate the parent node level. A relative name can also include "./' to indicate the same level, this is needed if the task name is numeric (otherwise its numeric value would be used in the expression.)

family foo
  task bar
  task foobar
family second
  task 00z
     trigger ../foo/foobar==complete # task from previous family
  task another
     trigger ./00z == complete # the previous task

For events it is convenient to use a plain name, since an event can only have values clear or set, numerically 0 or 1. So triggers of the form:

trigger taskname:event
trigger taskname:event == set

Will hold as long as the event is not set. The second line shows a clearer alternative equivalent way to write the same trigger.
Meters can be used in triggers the same as events, except that their value should be compared against numerical expression. It is important to remember to use greater or equal instead of equals. In the following example foobar will not be submitted if, let's say, suite is suspended while foo sets it meter to first 120 and then to 130. bar will still be submitted once the suite is resumed.

task foo
 meter hour 0 240
 task bar
 trigger foo:hour >= 120
 task foobar
 trigger foo:hour == 120 # dangerous !!!

There is no automatic checking for deadlocks,
 which can be difficult to detect. However, if your suite is known to  complete (i.e. it does not run forever), then simulation can be used to check for deadlocks.

The following example is a simple case:

 task a ; trigger ./b == complete
 task b ; trigger ./a == complete # DEADLOCKS tasks a & b

There is no automatic simplification of the mathematics. ecFlow will read the whole of a suite definition into memory, but with comment lines removed and possibly different indentation.
Mathematical expressions must be given in a single logical line. Use continuation lines for long expressions. For example:

trigger /suite/family1/task1==complete and ( /suite/family2 \
        eq complete or /suite/family3 eq complete )

There cannot be any characters after the line continuation character `\'; any keyword can appear in an expression but they must be used in a way that makes sense. For example, a task can never be set or clear and, likewise, an event can only be set or clear.
See section on externs for details on using triggers external to the suite.