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Subject: [NEW ISSUE] Wiring from a reference with no binding to a service with abinding
- From: Mike Edwards <mike_edwards@uk.ibm.com>
- To: "OASIS Assembly" <sca-assembly@lists.oasis-open.org>
- Date: Tue, 27 Nov 2007 15:42:56 +0000
<This issue is transferred from the
SCA Policy TC where it was dubbed POLICY-34>
RAISER Michael Rowley (original)
TARGET: SCA Assembly Specification
DESCRIPTION:
The algorithm in the policy spec says
that it is _not_ possible to wire from a reference that does not declare
a binding (i.e. uses binding.sca) to a service that declares one or more
bindings. However, I think this should be possible.
It is an unreasonable requirement to
say that a service with a binding can only be the target of a reference
that has that same binding. The default binding (binding.sca) should be
treated as the "I don't care" binding, and should work with any
binding available within the domain. Or, more precisely, any binding that
can satisfy the required intents.
Section 4.8.1 of the Policy frmework
spec states:
The wiring compatibility algorithm below
determines the compatibility of a wire by a pairwise choice of a binding
instance and the corresponding policySets on each side of the wire.
This should be changed to the following:
If either side of a wire does not specify
a binding (or explicitly specifies binding.sca) the wire is considered
to be valid for the purposes of policy processing. If both sides of the
wire use binding.sca then the policies will be determined by the union
of the required intents of both sides (policy sets aren't used with binding.sca).
Otherwise, the bindings and policies used for the wire will be determined
by adding the intents that are required by the binding.sca end of the wire
to the other end of the wire and then following the section 4.10 algorithm
in the Polcy Framework.
If neither side of the wire uses binding.sca,
then the wiring compatibilty algorithm below is used for determining compatibility.
Note that there may be many binding instances present at each side of the
wire. This algorithm determines the compatibility of a wire by a pairwise
choice of a binding instance and the corresponding policySets on each side
of the wire.
PROPOSAL:
The following should be added to the
Wires section of the Assembly specification:
If either end of a wire does not specify
a binding (or explicitly specifies binding.sca) the wire is regarded as
valid. In other words, binding.sca is regarded as being compatible
with
any other type of binding. Where
other types of binding are applied to each end of a wire, compatibility
of the two bindings is determined by the specifications for the two bindings
involved, allied to the intent and policies
attached at each end. In general, a wire which has two different
binding types at each end (non binding.sca) is likely not to be valid.
If both ends of the wire use binding.sca
then the policies will be determined by the union of the required intents
of both ends (policy sets aren't used with binding.sca).
Otherwise, where one end of the wire
uses binding.sca, the bindings and policies used for the wire will be determined
by adding the intents that are required by the binding.sca end of the wire
to the other end of the wire and then following the algorithm defined in
the Policy Framework specification section 4.10.
If neither end of the wire uses binding.sca,
then the wiring compatibilty algorithm described in section 4.10 of the
Policy Framework specification is used for determining compatibility. Note
that there may be many binding instances present at each side of the wire.
This algorithm determines the compatibility of a wire by a pairwise choice
of a binding instance and the corresponding policySets on each side of
the wire.
Yours, Mike.
Strategist - Emerging Technologies, SCA & SDO.
Co Chair OASIS SCA Assembly TC.
IBM Hursley Park, Mail Point 146, Winchester, SO21 2JN, Great Britain.
Phone & FAX: +44-1962-818014 Mobile: +44-7802-467431
Email: mike_edwards@uk.ibm.com
Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number
741598.
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6
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