Migration to Broadcast only

[Michael Sweet]

angelb at bugarin.us wrote:
>>> b. The servers Broadcast function follow the same rule as the
>>> client's polling function. That is, it uses Broadcast interval to
>>> send out updates to the network. Setting the interval to a low
>>> setting, say very five minutes, will have an effect on CPU use on the
>>> client. Setting it to a higher setting, say every 60 minutes, will
>>> mean that changes will not be available to the clients until the
>>> update starts again.
> 
>> Correct, however in CUPS 1.2 we actually save the remote printers
>> between runs.  A user that reboots their system will immediately have
>> the full list of printers available (no waiting after the initial
>> discovery)
> 
> I'm sorry I don't think I understand this correctly.
> 
> When you "save the remote printers between runs" I presume you mean
> the printers list on the client during an update(polling/broadcast)?
> 
> Is that mean that only new addition or printer changes(attributes,
> status, etc) are sent back to the client for each cycle and NOT the
> entire printers list?

No, it still makes sure that every printer is broadcast at least
once per BrowseInterval, however since the information is saved on
the client you can use much larger BrowseInterval and BrowseTimeout
values.

In addition, the server can now broadcast "delete" messages to
remove the printers from the clients (no more waiting for the
timeout to expire) and send the "timeout" values to use for a
particular printer, so changes to the server's BrowseInterval and
timeout do not need to be mirrored on the clients.

(there are some safety mechanisms in place to protect against
denial-of-service attacks...)

> If that's the case, CPU load per update on the client will be a lot
> lower than how it is today.

I think the changes we've made for CUPS 1.2 will dramatically improve
performance and memory usage on clients; the browsing updates are
only a small part of that... :)

-- 
______________________________________________________________________
Michael Sweet, Easy Software Products           mike at easysw dot com
Internet Printing and Document Software          http://www.easysw.com