1487   sboTimeout = 0 in SBO mode

Created: 06 Apr 2016

Status: Not Applicable

Part: Part 7-2 (2010; Edition 2)

Links:

Page: 161 and 164

Clause: Clause 20

Paragraph:

Category: Issue for edition 2 of this part

Issue

If control mode is SBO (2 or 4) and attribute "sboTimeout" is configured with value zero (0) for a control, does it mean inmediate deselection once selected (in figure 42 will be inmediate transition from Ready state to EndSelection state)?

Another second option could be consider sboTimeout=0 as illegal value and therefore consider a default value internally (for example 10 seconds).

Another third option could be consider sboTimeout=0 as "eternal" selection. In figure 42, Ready state does not start timer (as time equals to 0) so [sboTimeout] situation never occurs. Of course [Cancel_req] or [Association lost] situations will lead the control to EndSelection state.

Proposal

If first option is the proper option (I guess), it could be good to add a note in 7-3 (page 71), indicating that zero value means inmediate deselection.

Discussion Created Status
Note also that some set of small values (1,2,3...) will be functionally equivalent to zero depending on the performance of the system.

"Correct" values is out of scope of the standard. 		07 Apr 16 Not Applicable
2010 Edition 2 page 162, clause 20.2.2. and 20.3.3. below a)
"....– If the Select operation is valid, the control object shall issue a positive response to the requesting client, shall change the state to ready and starts a deselect timer for either the interval defined by the sboTimeout attribute or, if unimplemented, some locally determined duration."
=>
This also implies, that if sboTimeout is present with a value of zero the select will timeout immediately.
If sboTimeout is unimplemented, some locally determined duration. 		07 Apr 16 Not Applicable
I agree with Joel. A value of 0 is a not good configuration and should timeout immediately. A following control will terminate negative with an AddCause Object-not-selected if available.
It may make sense to add a note in part 7-3, clause 8, at the definition of sboTimeout: "A value of 0 will immediately unselect the object." 		07 Apr 16 Triage
The standard gives no special meaning to the value zero.

In order to protect a resource from permanent blocking, an "eternal" value is no good.

If a value is given in the configuration it must be respected, not overridden.

Therefore, if sboTimeout is present with a value of zero the select will timeout immediately. 		06 Apr 16 Triage

 

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