RDF System Management Manual

Process-Lockstep Operation
HP NonStop RDF System Management Manual—524388-003
14-3
Invoking DoLockStep by way of TAL
Invoking DoLockStep by way of TAL
The lockstep software provided with the RDF/IMPX and RDF/ZLT products includes a
TAL header file containing the DoLockstep procedure declaration and the
corresponding object file. You must modify your program to source in the header file
FDOLOCK. For example, include the following lines of code where you add procedure
declarations.
?LIST
?NOLIST, SOURCE EXTDECS
?LIST
?NOLIST, SOURCE FDOLOCK;
?LIST
After recompiling your program, you must then decide whether you want to bind the
object explicitly into your program or treat the object as a user library.
Typically you should explicitly bind the object into your program. The object file
(LSLIBTO) is very small, and there are no benefits to treating it as a user library.
To bind LSLIBTO into your program, issue the following statement:
Select Search <$vol.subvol>.LSLIBTO
where <$vol.subvol> is the location where you have placed the object file.
If you do not want to bind the object into your program and if you do not already use a
user library, then you can skip the bind step and treat LSLIBTO as a user library.
The TAL procedure call syntax is:
status := DoLockstep;
where status is an int.
DoLockStep Execution
DoLockstep communicates with an RDF gateway process that acts as the coordinator
of the lockstep operation. This gateway initiates a new lockstep transaction against a
special RDF lockstep file. The gateway passes information about the lockstep
transaction to the RDF extractor. When the RDF receiver has flushed all audit records
up to and including the lockstep audit into the image trail, it replies to the extractor that
the lockstep data is safe. When the extractor receives that information, it replies to the
gateway which, in turn, passes status back to the DoLockstep call, and the latter then
returns status to the application.
DoLockstep is a waited operation that waits until the RDF subsystem has safely stored
all audit data up to and including all audit data associated with the lockstep transaction
in the image trail. Therefore, if the communications line between the primary and
Note. The DoLockstep procedure can only be invoked from TAL and COBOL85 programs.
Non-native C and native mode languages (C, C++, native mode COBOL, and pTAL) are not
supported.