Subject: Re: [storm] iSER update request from Alex Nezhinsky on DatamoverInterface

From: <[email-masked]>
Date: Fri, 16 Oct 2009 20:39:57 -0400

WG chair hat off:
 
The Data Mover interface has always been an abstraction for
the purpose of clarity in explaining the architecture.  It's
not required in implementations.  If that's not sufficiently
clear, it could be made clearer ...

Thanks,
--David

________________________________

	From: [email-masked] [mailto:[email-masked]] On
Behalf Of Mike Ko
	Sent: Thursday, August 20, 2009 8:37 PM
	To: STORM
	Subject: [storm] iSER update request from Alex Nezhinsky on
DatamoverInterface

	Alex sent me the following iSER update request:
	 
	> The spec uses the Data-Mover abstraction. No existing
	> implementation adheres to this paradigm, opting for "on-wire"
	> compliance. Moreover, this interface was never envisioned as a
	> mandatory one, but the spec's language may be easily
interpreted as if
	> the Data-Mover interface is mandatory.
	> There is no disclaimer explicitly stating that the actual
	> implementation MAY choose NOT to implement Data-Mover
interface, on
	> the other hand, there are plenty clauses that
	> use MUST referencing various Data-Mover primitives.
	>
	> Suggested solution: to add an introductory clause clarifying
the
	> advisory status of Data-Mover interface.
	
	iSER is defined as a datamover in section 2.1.  As a datamover,
it operates in conjunction with the transport layers to move the control
and data information on the iSCSI connection.  It uses Operational
Primitives for the communication between the iSCSI layer and itself.  In
section 3, it was stated that "An Operational Primitive is an abstract
functional interface procedure ... that requests one layer to perform a
specific action on behalf of the other layer or notifies the other layer
of some event."  "The abstract model and the Operational Primitives
defined in this section facilitate the description of the iSER protocol.
In the rest of the iSER specification, the compliance statements related
to the use of these Operational Primitives are only for the purpose of
the required interactions between the iSCSI layer and the iSER layer.
Note that the compliance statements related to the Operational
Primitives in the rest of this specification only mandate functional
equivalence on implementations, but do not put any requirements on the
implementation specifics of the interface between the iSCSI layer and
the iSER layer."  It seems to me this text from section 3 as quoted
above adequately clarifies the advisory status of the datamover
interface.
	 
	Mike