New post
AllAccepted answers
Robert Cemper · Aug 23, 2017

to work down a collection of varying number of elements I'd use this kind of loop
in this case it's a double loop

For res=1:1:callresponse.result.Count() {
  Continue:'$IsObject(callresponse.result.GetAt(res)
  For err=1:1:callresponse.result.GetAt(res).Count() {
    Continue:'$IsObject(callresponse.result.GetAt(res).errors.GetAt(err)
    Set context.ErrorMessage= callresponse.result.GetAt(res).errors.GetAt(err).message
    - - - -
    }
 }

This is the paranoic version!
If you trust ENSEMBLE you may skip the check for $IsObject()

HTH

Robert Cemper · Aug 21, 2017

Alexey,

with $ZF(-1,command)  you are at OS level.
Nothing  prevents you from extending command to a script that  writes its pid in a file.
using $JOB_".pid" or similar as file name should be enough to  identify it.
So after a moderate HANG your pid should be available.

I prefer this to using pipes or other sophisticated solutions (e.g. listening on a TCP/IP or UDP port, ...)
as you get  an embedded trace for free  

HTH

Robert Cemper · Aug 21, 2017

online docs don't give a direct hint.

so my shot from the hip: 
selection expression - $select(), $case()  where you get a value based  on a condition
data expression - anything that sets, modifies, composes data.

this is  a quite academic view since  data expressions may contain selection expressions
and selection expressions may contain data expressions.
both variants and any mix of it  are quite common in COS 

HTH

Robert Cemper · Aug 17, 2017

Similar using  Class %System.License. ...  you may reduce the number of allowed connections by USER
This might  be interesting in SaaS situation.

classmethod SetUserLimit(MaxLU As %Integer) as %Integer

$SYSTEM.License.SetUserLimit establishes the maximum number of license units that this Cache instance will consume. This permits a system manager to prevent a Cache instance from consuming all the license units in a MultiServer key shared among multiple Cache instances. The Method returns the former maximum value. In the absence of a call to $SYSTEM.License.SetUserLimit(max) a Cache instance may consume all available license units. 

Requires access to the %Admin Manage resource.
Robert Cemper · Aug 17, 2017

Using  Class %System.License. ...  you may reduce the number of allowed connections by instance

• classmethod SetConnectionLimit(MaxCon As %Integer) as %Integer

$SYSTEM.License.SetConnectionLimit establishes the maximum number of connections permitted per user on this instance. This enables a system administrator to prevent a user from making so many connections to a Cache instance that they consume all available license units. Calling $SYSTEM.License.SetConnectionLimit($SYSTEM.License.MaxConnections()) permits a user to make the maximum connections permitted but prevent transitioning to the license unit per connection state, insuring the user will consume no more than one license unit. A zero argument removes the limit. The failure to obtain a license will be indicated in the normal way. For example, a call to $system.License.Login() will return zero (0) while a failure to log in to a new terminal connection will receive a error. However, these license failures will not be reported in the console log. The method returns the former maximum value. 

The limit applies only to the local instance. If a Cache MultiServer license is shared among several instances it is still possible to exceed $SYSTEM.License.MaxConnections() over all instances. This can be avoided by setting the limit low enough on each instance that the combined connections to all instances will be unlikely to exceed $SYSTEM.License.MaxConnections(). 

$SYSTEM.License.SetConnectionLimit reqires access to the %Admin Manage resource. It is suggested that customers call this API from SYSTEM^%ZSTART.