[NEW ISSUE] Suggestion to address suspected default/unqualified intentambiguity

["Rich.Levinson" <rich.levinson@oracle.com>]

Note: this can either be a new issue or it can be considered part of either or both of issues 90 and 95. Discussion so far of issues 90 and 95 has pretty much convinced me that something is insufficiently specified about unqualified vs qualified intents in conjunction with specifications for defaults.

TARGET:
SCA Policy FW cd02 rev1 (doc)
http://www.oasis-open.org/committees/document.php?document_id=31980&wg_abbrev=sca-policy

SUMMARY:
Specifically, it appears to be unclear whether specifying an unqualified version of an intent that has qualifiers defined for it means that one should use the unqualified intent to mean that ANY of the qualifiers is acceptable, or whether it means that the default qualifier should be applied to the unqualified version.

DETAILS:
The definition of default says (305-308):

@default (0..1) - a boolean value with a default value of "false". If @default="true" the particular qualifier is the default qualifier for the intent.  If an intent has more than one qualifier, one and only one MUST be declared as the default qualifier.

First, let me point out what appears to me to be a minor ambiguity in this defn: The highlighted text applies when there is MORE THAN ONE qualifier defined, and it says that ONE MUST be declared as the default. The "minor" ambiguity is that if there is ONLY ONE qualifier DEFINED, then is this by defn the default? or not? i.e. can an intent have only a single qualifier defined and at the same time have its "default" attribute have its default value of false? In my proposal below, this issue goes away, but I thought it worth mentioning.

What I consider to be the "major" ambiguity is what is described in the SUMMARY above, namely that if we go by the definition of "default" and have more than one qualifier defined, then one of those qualifiers must be defined as the default value. Therefore, one MUST assume (I would think) that if an unqualified intent was specified then when this intent was processed, that one MUST apply the default qualifier to it. Why? Because, otherwise the definition of "default" is rendered meaningless, because the default only is used when the intent is unqualified, and if we apply the default then the intent is now qualified. However, on the other hand, if we were say that the intent should remain unqualified, then this means there is no point to defining a default, since there are no circumstances when it would be used!

Based on the discussion of issue 95, and based on my original understanding of what was intended, and based on the proposed resolution to issue 95, which I believe is to allow the following lines about SOAP to remain accurate (2306-2310, esp. last sentence):

SOAP – The SOAP intent specifies that the SOAP messaging model is used for delivering messages. It does not require the use of any specific transport technology for delivering the messages, so for example, this intent can be supported by a binding that sends SOAP messages over HTTP, bare TCP or even JMS. If the intent is attached in an unqualified form then any version of SOAP is acceptable.

i.e. based on all the above I am suggesting the following proposal:

PROPOSAL:
In words, the proposal is:

1. Allow unqualified intents that have qualifiers defined, to indicate that ANY of the qualifiers is an acceptable means of satisfying the intent.
2. Change the meaning of "default" as follows:
1. Leave specification of the default to be optional (0:1) for each qualifier.
2. Do NOT require any qualifier to be the default. i.e. REMOVE the sentence that says "...one MUST be declared as the default qualifier"
3. But do say: "If one qualifier IS DEFINED with default="true", then if the intent is specified as unqualified, then the default value applies."
4. However, also say: "If one or more qualifiers is defined for the intent, and NONE of the qualifiers has a default="true" attribute THEN if the intent is specified as unqualified, then ANY one of the qualifiers may be used to satisfy the intent.

As indicated in the "minor" problem above, that problem goes away because we no longer require any qualifier to have the default attribute true and so there is no need to force the unqualified intent to assume a default qualifier.