Computed facts are used when you want to run JDL to generate the value for a fact. Although computed facts are not jobs, they use the same JDL syntax.
To create a new computed fact, you subclass the ComputedFact class with the .cfact extension. An implementation uses the ComputedFactContext to get the evaluation context. For more information, see the job structure from the following examples in the PlateSpin Orchestrate 2.0 Developer Guide and Reference:
After the new computed fact is created, you deploy it using the same procedures required for jobs (using either the zosadmin command line tool or the PlateSpin Orchestrate Development Client).
The following example shows a computed fact that returns the number of active job instances for a specific job for the current job instance.This fact can be used in an accept or start constraint to limit how many jobs a user can run in the system.The constraint is added to the job policy in which to have the limit.In this example, the start constraint uses this fact to limit the number of active jobs for a user to one:
"""
<constraint type="start" >
<lt fact="cfact.activejobs"
value="1"
reason="You are only allowed to have 1 job running at a time" />
</constraint>
Change JOB_TO_CHECK to define which job is to be limited.
"""
JOB_TO_CHECK="quickie"
class activejobs(ComputedFact):
def compute(self):
j = self.getContext()
if j == None:
# This means computed Fact is executed in a non running
# job context. e.g., the ZOC fact browser
print "no job instance"
return 0
else:
# Computed fact is executing in a job context
user = j.getFact("user.id")
activejobs = self.getMatrix().getActiveJobs()
count = 0
for j in activejobs:
jobname = j.getFact("job.id")
# Don't include queued in count !
state = j.getFact("jobinstance.state.string")
if jobname == JOB_TO_CHECK \
and j.getFact("user.id") == user \
and (state == "Running" or state == "Starting"):
count+=1
jobid = j.getFact("jobinstance.id")
print "jobid=%s count=%d" % (jobid,count)
return count
For another computed fact example, see activejobs.cfact (located in the examples/activejobs.cfact directory).
For more information about policies, see Policy Elements
in the PlateSpin Orchestrate 2.0 Developer Guide and Reference.