Re: Proposal for VSCP schema

[Kevin Hawkins <lists@xxxxxxxxxxxxxxxxx>]

YAP wrote:

>Kevin,
>
>thanks for your comments and suggestions. Pling was new to me and I
>will add it. How long can such a line be?
>
>
>
There is no formal length to a xAP packet but it is often restricted by
the transport - in the case of UDP a  message can be up to 1500 bytes
total (ie xAP header + bodies).  Again at some point in the future we
will add a formal mechansim for continuation packets and sequencing
information but no-one has really hit that yet.

You did make one comment about dividing your data into 'rows' with 32
bytes max per row.   This isn't easily accomplished in xAP as you can't
include the CHR(10) in a text based parameter value and in a ! value it
may be interpreted as data (might it ??).  You also shouldn't use
repeating parameter names within one block (as the order is not
significant and some apps/hubs even re-order parameters) - the spec
actually states you can but we are now discouraging this and probably
will be deprecating  it as it causes many parsing problems (recovering
the state parameter from a block when there are several for example) .
You can however index parameter names if you want to use the same type
of data several times   as in...

block.name
{
state=On
data.1=Hello
data.2=Goodbye
data.3=Hello again
}

.. this works because the values are now sequenced by the index as well

you can also include several identical blocks in one message using the
same approach (BSC uses this)


block.name.1
{
....
}
block.name.2
{
....
}


etc

Kevin