[Nsi-wg] A Message Transport Layer description for NSI
Jerry Sobieski
jerry at nordu.net
Tue Feb 5 21:20:51 EST 2013
Hi Jeroen-
I don't think we need to define the MTL Interface in a particular
language (C, or C++, Java, Python, etc.) But for the _/NSI Standard
Specification/_, we should define the functional interface between the
NSI layer and the MTL in order to bound what NSI protocols (in the
standards documents) can safely assume will always be available to
them...regardless of particualr transport protocol bindings.
This means that the NSI layer will know -for instance- that an NSA ID is
always sufficient to deliver a message to another NSA. Or, all NSI
protocols know that they can request notification of a successful send
as well as notification when a send fails, or that they can set a finite
time for a send to be completed, or that all messages between two
specific NSAs will always be sent in FIFO order, etc. If a capability
or feature is not described as part of the MTL Interface, then the NSI
protocol specification cannot depend upon it being available, and thus
cannot use it. Likewise, if a feature is described in the MTL
interface (say for instance a timeout value and a timeout callback) then
a conformant MTL must [somehow] provide that capability and the NSI
layer specification is allowed to reference that feature.
It seems the easiest way to describe this functional interface between
the NSI layer and an MTL would be to define a small set of specific
primitives with parameters and how those parameters are supposed to
function. I.e a psuedocode form of a set of interface routines.
Admitedly, these psuedocode fucntions need not be implemented as
described, but they nevertheless still offer a concise and bounded set
of functionality for the NSI _/standards/_ to use to describe how the
NSI protocol should behave. (We use state machines similarly to
describe how the protocol should function *in the standard*, but an
implementation is not required to implement state machines per se ...as
long as the protocol implementation behaves as described in the standard
by the state machine model, then the actual internal implementation
method is left to the coder. )
So we should define
a) the MTL Interface primitives in a psuedocode fashion,
b) the common behaviour of the MTL in terms of message delivery, and
c) the transport protocol specifics for each binding.
Hope this sheds more light...
Jerry
On 2/5/13 9:44 AM, Jeroen van der Ham wrote:
> Hi,
>
> I understand that we need to say something about the message transport between NSI.
> What I don't see in this slide pack is why it has to be different from the simple statement "The MTL must be a reliable transport layer". Possibly with the addition of "with delivery notification".
>
> It is all going to be outside of the scope of NSI anyway.
>
> Jeroen.
>
> On 4 Feb 2013, at 15:19, Jerry Sobieski <jerry at nordu.net> wrote:
>
>> HEre is some slides to present my ideas for separation of message transport from NSI protocols...
>>
>> JErry
>> <NSI Message Transport Layer.pptx>_______________________________________________
>> nsi-wg mailing list
>> nsi-wg at ogf.org
>> https://www.ogf.org/mailman/listinfo/nsi-wg
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