User`s guide

SLTALink Manager on this PC receives the callback just like any other normal
dial-out call and launches the application contained in the link. At this point
there may be two copies of the application open. Depending on sharing
configuration, the second application may fail because appropriate LNS database
in already opened.
To prevent these failures, Echelon recommends that the initial call should either be a
manual connection from within the SLTALink Manager or the initial call should
originate from a “dummy” application that terminates itself without opening the LNS
databases.
Call Termination
The four scenarios for call termination include: termination of the host application,
application controlled hang-up, a manual disconnect in the SLTALink Manager, and
time-out. In all of these cases, the important system-level issues involve making sure
that the termination strategy is compatible with the call initiation strategy.
The behavior of an application at termination is not always known. By default,
applications based on the Object Server of LNS 1.5 and higher should exhibit two
types of behavior. First, if the interface adapter is an SLTA-10 Adapter in NSI
modem using modems and there are explicitly bound network variables to the host
application, then at the LNS application’s termination the host network variables
and their connections should not be removed from the LNS database. This behavior
facilitates the use of the first case described under Dial-Out to the Remote PC Only
where a network variable update addressed to the SLTA-10 Adapter’s NSI mode
results in a call being initiated. Second, if the interface adapter is not an SLTA-10
Adapter in NSI modem using modems or there are no explicitly-bound network
variables to the host application, then at the LNS application’s termination, any host
network variables and their connections are removed from the LNS database and the
other nodes in the network.
In addition, if the interface does not host the LNS
database, upon termination of the LNS application the interface is deconfigured.
The second behavior described would be desirable in the event that multiple remote
host PCs needed to be able to dial-in to the same network. As long as no explicitly-
bound network variables were left when the host applications terminated, then
several remote PCs could share one SLTA-10 Adapter. Note: this assumes that the
LNS Server exists somewhere on the network and is not located on one of the remote
PCs sharing the single SLTA-10 Adapter.
Both an application controlled hang-up (using the SLTALINK . EXE programmatic
interface) and a manual disconnect in the SLTALink Manager will terminate the
phone call; however, neither results in the termination of the host application.
In
these scenarios the host application remains running as the call can be re-established
by the host application itself, by a manual connect in the SLTALink Manager, or a
dial-out initiated on the network. The disadvantage of these system solutions is that
they do not scale well to monitoring multiple networks on one PC. The result is
many applications continually and concurrently running on the same PC. Also, one
possible system failure to avoid is that the SLTALink Manager settings may result in
multiple copies of the host applications.
By default, the SLTA-10 NSI mode will terminate a phone call after three minutes
with no traffic going across the modems. As with the application-controlled hang-up
SLTA-10 Adapter User’s Guide
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