[glue-wg] Speedy information [WAS: Comparison with CIM]

[Paul Millar]

Hi Stephen,

Discussion about ACLs aside, I was a bit confused by:

On Wednesday 07 May 2008 15:18:57 Burke, S (Stephen) wrote:
> [...] and in any case GLUE is designed for dynamic data, at least down to a
> timescale of a few minutes. 

This runs somewhat counter to what I understood for GLUE: that is should be  
independent of how the information propagates.  Since the propagation might  
be "slow", GLUE should have mostly static (or slowly changing) information.

Does GLUE require an information system to respond quickly?  If so, on what  
time-scale?

For comparison, here's an estimate of the liveliness of EGEE's information 
system.  I'm hoping Laurence will correct me here, but I believe the picture 
is roughly:
	o  Underlying system --> GIP plugin (takes ~10s, for all plugins),
	o  GIP-plugin --> GIP (results are cached for 60s),
	o  GIP --> resource BDII (maximum age of data is 60s, by default),
	o  resource BDII makes new data "live" (~1s?),
	o  resource BDII --> site BDII (max. age is 60s?),
        o  site BDII makes new data "live" (~10s?),
	o  site BDII --> top-level BDII (max age of data 60s?).
	o  top-level BDII makes new data "live" (~30s?)

So, worse-case delay is the simple sum of these: 291s or the best part of five 
minutes.  Although, I'm guessing this is slightly wrong as (my impression from 
talking to others is) it can take a bit longer for information to propagate.

HTH,

Paul.