Echelon OpenLDV - Manual (Page 142)

134 Extending xDriver
these fields should only be updated from the UpdateLookup function. The
database configuration interface that you create must update these fields in a
guaranteed, safe manner. For more information about how the lookup extension
component handles authentication key changes, see Authentication Key Handling
on page 111.
After the SCO has been filled in and the UpdateLookup() method has been
called (if necessary), the OpenLDV application that launched the lookup
extension component can open the network, and perform whatever network
operations are desired.
The destructor, Finalize function, is called last. It is used to close the database
connection if it is still open. If an instance has not been defined, the destructor is
called following DownlinkLookup function. If an instance has been defined,
the destructor is called when the last object using the instance closes.
xDriver Profiles
After you finish programming your custom lookup extension component, you can
create an xDriver profile to use it. An xDriver profile represents a set of
configuration parameters that determines how xDriver manages sessions,
including:
• The port that xDriver uses to listen for uplink connection requests
• The port that xDriver uses to initiate downlink connections
• The lookup extension to use to look up RNIs
• A flag to enable xDriver automatic reconnection
If you enable automatic reconnection, xDriver attempts to reconnect any uplink
or downlink session that is broken as a result of some unexpected connection
failure. With automatic reconnection enabled, you can configure xDriver to
attempt reconnection as soon as it detects a failed session. xDriver attempts
reconnection until the session has been successfully reestablished or until a time
period that you define has expired.
The profile to be used for each session is determined on a session-by-session
basis. For a downlink session, the profile to use is specified in the network
interface name of the RNI. The network interface name for an RNI using
xDriver must use the following naming convention:
X.[Profile Name].[Downlink Lookup Key]
where [Profile Name] represents the name of the profile to use for the session and
[Downlink Lookup Key] represents the downlink lookup key that was assigned to
the RNI when it was added to the xDriver database. For sample programs that
use this naming convention, see Downlink Sample Applications on page 138.
For an uplink session, the request for connection arrives on a specific TCP port.
The xDriver profile using that port as its listener port handles the uplink session.
You can set the listener port that a profile should use with the OpenLDV xDriver
Profile Editor.
There are two ways to install profiles when you distribute your application:
• Install the profiles with permanent Registry entries that will never be
uninstalled or overwritten. This method has the disadvantage that re-