HP Reliable Transaction Router User Manual
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RTR Server Types
Callout server
The callout server enables message authentication on
transaction requests made in a given facility, and could be
used, for example, to provide audit trail logging. A callout server
can run on either backend or router nodes. A callout server
receives a copy of all messages in a facility. Because the callout
server votes on the outcome of each transaction it receives, it can
veto any transaction that does not pass its checks.
A callout server is facility-based, not partition-based; any
message arriving at the facility is routed to both the server
and the callout. A callout server is enabled when the facility is
defined. Figure 1–17 illustrates the use of a callout server that
authenticates every transaction in a facility.
Figure 1–17 A Callout Server
TR
BE
User Accounts Facility
Server
application
Callout
Server
VM-0836A-AI
Transaction
To
Partition A
To authenticate any part of a transaction, the callout server must
vote on the transaction, but does not write to the database. RTR
does not replay a transaction that is only authenticated.
1–22 Introduction