Network Router User Manual

GINA V4.0 System Administrator Guide – September 2000 205
Glossary
Druck vom 24. 01.2001 17:01.05 fachwort
data link point
A data link point is an →end of a transaction using commit. Transaction-monitored
changes become visible and permanent outside the transaction at a data link point (see
ACID property of →transactions).
data reference
A data reference DREF(P) is a special →global reference. It cannot be dereferenced.
A data reference can however be used as an object, a data member, an argument or a
result.
distributed transaction
Distributed processing is when a →transaction covers a number of processes, generally
on a number of machines. In this case, a number of →local transactions from different
→resource managers are grouped together by a →transaction monitor to form a
→global transaction.
end of transaction
At the end of a transaction, the entire operation must either be confirmed (commit) or
reversed (rollback). A (local) end of transaction occurs at the end of a transaction-
monitored call or at an →action point, which is a →data link point.
In →distributed transaction processing, all the local end of transactions only come into
effect when a global end of transaction occurs. Since the →server process is automat-
ically released under T-ORB when an end of transaction occurs, the end of transaction
is not only a →data link point for the database, but also a →restart point for the
operation.
exception handling
In addition to indicating processing errors using special return codes in the case of
method calls, exception situations in GINA are indicated by initiating exceptions. This
procedure is used in particular when resource bottlenecks occur.
external interface
A method in the external interface of a →server is called using a remote request/call.
The external interface method decodes the parameters, calls the technical operation
and encodes the results which are sent back to the →client. In DCE we call this a server
stub, in CORBA we talk about a skeleton.
framework
A framework refers to a general framework in which the application constructor adds
application-specific code as modules.