Re: version 1.3 of xAP documents

[Kevin Hawkins <yahoogroupskh@xxxxxxxxxxxxxx>]

Hi Steven,

There's a formal spec, plus a rewrite of the v1.2 spec imminent.
It's been delayed due to some aspects of the specification that haven't
been finalised and so will now be deferred to a future v1.4  (not
anytime soon).  The deferred aspects are not impacting typical usage but
are desireable for some more demanding applications  and include  long
messages, message continuations, sequencing, acknowledges,
re-transmissions, authentication, security, discovery and configuration
aspects.  These are essentially impemented using a higher protocol layer
sitting on top of the v1.3 protocol and so will be totally backward
compatible.   There are outline proposals for many of these allowing for
experimentation within xAP v1.3.

The aspects that have been finalised for v1.3 include various header
and body flexibility changes - which are backwards compatible with v1.2.
The v1.3 UID format change however is mostly compatible in that it is
transparent to nearly every existing xAP application except those using
the xAP BSC or TSC schema which might need updating.  Most affected
applications have already been updated .  A xAP v1.3 application must
support existing v1.2  messages and UID formats transparently so that
ensures forward compatibility.

Re the UID it has been changed from the v1.2 fixed length NNAAAASS
format to NN.AAAA:SS in v1.3.
ie a '.' and ':' delimiting the three segments has been added which
now allows any of these segments to be any (even) length of uppercase
hex digits.
The main reason for this was to allow expansion of the sub address
field SS from the v1.2 two hex digits to longer as many applications
required.
In all segments values of all 0's or all F's are reserved or have
special meaning.

NN -  network number - usually the special all F's representing the
local network
AA -  application/device ID (unique on the network)
SS - sub address (if the application or device implements multiple
endpoints) . All 0's represents the application itself rather than an
endpoint within it.

Having previously said that any even number of characters is now
permissable in any segment there are some recommended formats that
suffice for most needs.
NN usually always two characters
AAAA usually four, six or rarely eight characters
SS usually  two, four, six or eight characters - although some
implementations have used longer sub addresses..(eg 1-wire 64bit 16chars)
All leading 0's must be included to maintain consistent segment length
for the application

A v1.2 UID of FF1234A2 is directly equivalent to a v1.3 UID of FF.1234:A2

Examples of v1.3 UID's:

UID=FF.1234:00A6
UID=FF.AB34:67A203
UID=FF.000032:5C

There are ramifications to the xAPBSC v1.3 Basic Status and Control
schema (and xAPTSC)  but these are self evident I hope as you read the
specification.

Any questions .. ask away....

Cheers Kevin


Bauer, Steven J. wrote:
>
>
> Is there anyplace where a person can find (even the draft spec) of the
> version 1.3 xAP??  I would like to support the extended uid correctly
> in the programs that I am writing?
>
> Thanks!
>
> Steve Bauer
>
>
>



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