RE: [tag-comment] Re: [tag] coments on Section 3.7.2 "COmposition of Assertions" (V0.995)

["Durand, Jacques R." <JDurand@us.fujitsu.com>]

David:

 

>I see a problem when a prerequisite requires testing in order to determine eligibility.

>One can then build a dependency chain of the tests: e.g., you can't apply tests derived from TA 76345 until

>you have an outcome on any of a family of tests (list them here) that will show that the prerequisite of 76345 has been satisfied.

>Some of those tests may have their own prerequisites and hence dependencies, etc.

Yes but that is precisely the behavior expected by some TA users:

 

- in many cases eligibility requires anyway some "testing" i.e. when the prerequisite is itself a predicate expression.

 

- in some of these cases, eligibility refers to another TA(s) - meaning to the outcome of the predicate of these TAs. It is more informative to "reuse" another TA in the prerequiiste Instead of just replicating the predicate expression: this indicates to test suite writers a way to avoid redundant testing.

It also indicates what is the impact of failing a TA on the outcome of other TAs (so that users can make the difference between a "naturally unqualified" target and a target that is not qualified because it failed a previous TA where it should have passed it.

 

Yes that introduces some partial order among TAs (dependencies) but again thats what some users need (e.g. WS-I).

You do not have to use it :-)

 

Jacques

---

From: david_marston@us.ibm.com [mailto:david_marston@us.ibm.com]
Sent: Wednesday, October 22, 2008 12:05 PM
To: tag-comment@lists.oasis-open.org
Cc: Durand, Jacques R.; stephen.green@documentengineeringservices.com; Kevin Looney
Subject: [tag-comment] Re: [tag] coments on Section 3.7.2 "COmposition of Assertions" (V0.995)

I see a problem when a prerequisite 
requires testing in order to determine eligibility. One can then build a 
dependency chain of the tests: e.g., you can't apply tests derived from TA 76345 
until you have an outcome on any of a family of tests (list them here) that will 
show that the prerequisite of 76345 has been satisfied. Some of those tests may 
have their own prerequisites and hence dependencies, etc. 

Prerequisite: [the widget] is conformant to 
Mini-Widget Small Box Specification 1.2 
Predicate: [the widget] is conformant to WidgetSpec 1.0 
  

<SG> the main 
assertion is that such a small widget is also a widget in that it conforms to 
the WidgetSpec 1.0 
 the way this TA reads, the normative Source must be aligned with the 
Predicate: it should be "Conformance clause to 
WidgetSpec 1.0" (exactly like in widget-TA109-1) 
I think it reads that you must already 
determine that the target is a Small Box 1.2 Mini-Widget before you can even ask 
about whether it is a 1.0 Widget. Circular dependency? 


<SG> Surely this is just another way of saying the same 
thing: 
"conformant to WidgetSpec 1.0" == "conforms to 
the conformance clause of WidgetSpec 1.0" 
That equivalence is true if WidgetSpec 1.0 only has one class 
of product. Otherwise, it must say something like "is a conformant [class] as 
defined by WidgetSpec 1.0". 

  
The presence of the prerequisite means that the TA only 
applies to widgets already known as confirming to Mini-Widget Small Box spec: 

<SG> I agree 
The problem is the "already known" part. I think this drives 
the debate about whether prerequisites can be based on either (1) declarations 
from the product provider and (2) measurable/testable properties of the 
implementation. A "type 2" prerequisite, if as broad as "is a conformant widget" 
could still exist in a formal structure of measured facts (predicates, as it 
were) as long as the TAs for widgets include a final "summary" TA for overall 
conformance. 

I think you 
can see why I wish this example used an orthogonal spec. The example I suggested 
is power sources for portable devices. Specify that some but not all widgets are 
portable, and certain portable ones must conform to the specs about power 
sources. 
.................David 
Marston 
IBM Research