Collectives (and HA-SDK)

Discussion created by RJKSolutions on Dec 10, 2008
Latest reply on Dec 14, 2008 by bryan@osisoft.com

Would like to get some clarification on Collectives.


BN = Business Network, CN = Control Network, FW=Firewall


In a collective consisting of 2 PI Systems on BN and 2 PI systems on CN with a FW between BN & CN, where the Primary server is on one box of the CN.  The 2 BN PI systems have a route through the FW but all other clients on the BN do not have a route through the FW thus cannot see the Primary server on CN.

So taking the currently available solutions from OSI, clients on the BN cannot write data to the Primary server on CN so any connections from HA-SDK mean they will connect to a Secondary server on BN.  Now there are limitations when using HA-SDK on a Secondary server in a Collective, most notable is SDK cannot write values by default.  I see this can be overriden Replication_EnableSDKWriteValues, so SDK can now write to the secondary server.  Appreciate this set up is probably not advised but it is still likely to happen.  If this occurs, the secondary server starts to get data that the primary server does not know about.  As OSI does not have server side buffering yet, how should this be handled?  Data will already be coming from the Primary server to the Secondary server via PItoPI.


Any other comments on this and collectives?