Experimental Physics and
Industrial Control System

"Kasemir, Kay via Core-talk" <[email protected]> · Fri, 27 Sep 2019 13:15:23 +0000

> Anyway, the point that I wanted to make in the explanations is that the structure information is exchanged only at connection time. 

Absopositively. The protocol, https://github.com/epics-base/pvAccessCPP/wiki/protocol, exchanges the structure information at the start of a get/put/monitor....:
When the data is then exchanged, it's based on bitfields to indicate which piece of the structure follows, then just the raw data.

Even the initial structure exchange is optimized.
Like "timeStamp" is only described once as
 structure #47 = timeStamp { long seconds, int nano, ..}

Later, the server would just send "type 47" over the existing TCP connection, since the client remembers that type 47 = { long seconds, ...}.

-Kay

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System