pvxs/documentation/server.rst

Server API

sharedpv source

pvxs::server::Server represents a PVA protocol server.

#include <pvxs/server.h>
namespace pvxs { namespace server { ... } }

The basic recipe to run a server using configuration from the process environment is:

auto serv = server::Config::fromEnv()
            .build()
// calls to serv.addPV() or serv.addSource()
serv.run(); // run intil SIGINT or serv.interrupt()
// could also call serv.start() and later serv.stop()

A useful server will have one or more pvxs::server::Source instances added to it with addSource() method. Common usage will be with pvxs::server::StaticSource and one or more pvxs::server::SharedPV.

If more than one Source is added, then an order of precedence is established through the "order" argument of addSource(). In the event that more than one Source could provide/claim a given PV name, the Source with the lowest "order" will win.

Configuration

The recommended starting point when configuring a Server is pvxs::server::Config::fromEnv which will use the following environ when set.

Entries naming multiple environ will prefer the left most which is set. eg. EPICS_PVA_ADDR_LIST is only checked if EPICS_PVAS_BEACON_ADDR_LIST is unset.

EPICS_PVAS_INTF_ADDR_LIST

Space seperated list of local interface addresses to which the server will bind. Port numbers are parsed and ignore. Sets pvxs::server::Config::interfaces

EPICS_PVAS_BEACON_ADDR_LIST or EPICS_PVA_ADDR_LIST

Space seperated list of unicast or broadcast addresses. This list is supplimented all local broadcast addresses if auto-beacon is YES. Sets pvxs::server::Config::beaconDestinations

EPICS_PVAS_AUTO_BEACON_ADDR_LIST or EPICS_PVA_AUTO_ADDR_LIST

YES or NO. Sets pvxs::server::Config::auto_beacon

EPICS_PVAS_SERVER_PORT or EPICS_PVA_SERVER_PORT

Single integer. Prefered TCP port to bind. If already in use then a random port will be chosen. Sets pvxs::server::Config::tcp_port

EPICS_PVAS_BROADCAST_PORT or EPICS_PVA_BROADCAST_PORT

Single integer. UDP port to bind. If already in use, then an exception is thrown. Sets pvxs::server::Config::udp_port

EPICS_PVAS_IGNORE_ADDR_LIST

Space seperated list of addresses with optional port. Port zero is treated as a wildcard to match any port. UDP traffic from matched addresses will be ignored with no further processing.

EPICS_PVA_CONN_TMO

Inactivity timeout for TCP connections. For compatibility with pvAccessCPP a multiplier of 4/3 is applied. So a value of 30 results in a 40 second timeout.

0.3.0 All *_ADDR_LIST may contain IPv4 multicast, and IPv6 uni/multicast addresses.

0.2.0 Prior to 0.2.0 EPICS_PVA_CONN_TMO was ignored.

pvxs::server::Config

pvxs::server::Server