multiple loading of the same table

[Ivan Zolotukhin]

Hello,

I've encountered a bit frustrating behavior of SAMP clients when
loading single table several times in a sequence. If I emit a SAMP
message like this

samp.mtype: table.load.votable
  samp.params: {
     name: SAI OCL Catalog
     table-id: MyVOTable
     url: http://ocl.sai.msu.ru/catalog/votable/ }

multiple times, Aladin, TOPCAT and ds9 load the same table (note that
table-id and url are static) again and again disregarding the fact
that it is already loaded. While one may say that this behavior is
uncommon use case of manual table broadcasting (which is probably
true), the emerging SAMP plugins for browsers bring this problem up as
pressing.

Imagine I want to load automatically the VOTable counterpart of the
displayed HTML table upon web page load. If user hits reload button in
his browser or if he simply returns back after visiting some other web
pages, he gets multiple tables loaded in his VO clients. At the same
time, it is likely to be incorrect to keep track of broadcasted tables
on a side of transmitting client (browser SAMP plugin in this
example), since e.g. one may restart this client and loose its
previous state easily or e.g. one may restart connected TOPCAT without
restarting connected Aladin and we won't erroneously broadcast the
table when we really should. Adding clients polling to the protocol to
get the list of loaded tables in my mind is not an option either.

What do you think about tracking repetitive objects loading in
receiving clients?

--
With best regards,
Ivan Zolotukhin