Echelon OpenLDV - Manual (Page 114)

106 Extending xDriver
on page 142.
You can also use the xDriver Profile Editor to specify a command to run
each time that the listener port for that profile receives an uplink session.
If you use an LNS Server as the OpenLDV application, the LNS Server
provides an enhanced interface for LNS applications.
7. If you are using an LNS Server, after the connection is established, the
LNS application can open the remote network interface that requested
the connection, enable the monitor set and monitor points for the
network, receive the monitor point update event that caused the uplink
session request, and handle the event. The monitor set and monitor
points can then be closed, followed by closing the network itself.
The LNS API provides a method to allow the withholding of monitor
point update events while an uplink session is started. This method
ensures that monitor point update events sent after a network requests
an uplink session, but before the network and its monitor set are opened
by an LNS application, are not lost, so that the user will receive the
monitor point update event that caused the uplink session. For more
information about this method, see ReleasePendingUpdates on page 158.
This feature is only supported by LNS listener applications; it is not
supported by command-line initiated uplink event handlers.
A network interface can reset after receiving and acknowledging (at OSI
Layer 2) an alarm event, but before the event has been propagated to the
LNS Server, which causes the event to be lost. To prevent this loss, your
LNS applications must send monitor point update alarm events for your
RNIs to the LNS Server to resend each monitor point update event
persistently to the LNS Server until receipt of those events is confirmed.
This technique results in reliable performance, and ensures that no
monitor point update events are lost before they are processed by the
LNS application.
You must program your LNS application to process uplink request
messages, and provide suitable responses to the L ON W ORKS network, in a
timely fashion. Timely responses are particularly critical when you are
using a SmartServer and the uplink is delivered over PPP, and the PPP
profile (connection) is exclusively set up for your SmartServer. Other
SmartServer applications cannot use the PPP link until the LNS
application terminates the xDriver. During this time, SmartServer Web
connections and alarm notifications that are configured to use a different
PPP profile (connection) fail.
Figure 17 on page 107 shows the flow of events that occur during an uplink
session within the LNS application that receives the uplink session request and
the lookup extension component.