Echelon OpenLNS - Manual (Page 887)

OpenLNS Programmer's Reference 850
CancelTransaction
Summary Cancels an active transaction.
When a transaction is canceled, either explicitly because of a
reset, all network and database updates made since the call
to the StartTransaction method are reversed.
Once a transaction has been committed, it can no longer be
cancelled.
If you use the CancelTransaction method to end a transaction
that was initiated as part of a new application program
download and the download has already started, the device
receiving the program download will be left in an
applicationless state. However, this is not true if the
transaction was canceled before the transaction actually
started the download process.
The CancelTransaction method may return an "update type
error" indicating that the cancel has successfully reversed the
modifications to the database, but has been unable to update
one or more application devices. This will be an error in the
NS error range, but will be without the
lcaErrRangeNsStart (1000) value. To compare the update
error types returned by the CancelTransaction method to the
constant error values used in other OpenLNS operations, you
will need to add the lcaErrRangeNsStart (1000) value to
the returned error value.
For example, consider a case where the CancelTransaction
method returns error 63. To compare the returned exception
to the constant error values for the NS error range, you
would need to add lcaErrRangeNsStart (1000) to the
returned value. In this case, the returned error maps to the
lcaErrNsNothingToCancel exception.
Unlike most other methods, the CancelTransaction method
may be called in an OnSystemNssIdleSystem event callback,
which allows you to cancel the current method or property,
and the transaction explicitly or implicitly containing it.
Availability Local, full, and lightweight clients.
Syntax returnCode = systemObject.CancelTransaction
Element Description
returnCode An Integer value which is assigned
the return status code.
systemObject The System object whose
transaction will be canceled.
Added to API Prior to LNS Release 3.0.
Close
Summary Closes the system, ends events, shuts down the NSS, and
detaches the NSI from the network (if not opened in