HP (Hewlett-Packard) HP OpenView Vantagepoint – Operation Manual for UNIX User Manual

Using the VPO Application Programming Interfaces

The VPO management server’s message-stream interface provides
access to the internal message stream of the VPO management server.
Processes may connect to the message-stream interface on VPO’s
management server either in parallel or in series. Multiple connections
to the MSI are organized by means of order numbers. Assigning an order
number to each MSI connection allows VPO’s message manager to
determine at which point in the serial chain those external applications
which are connected to the MSI receive the messages passing through.
For example, an external application connected to the MSI can choose
either to receive messages in parallel with other connections or after the
messages have been processed by other applications in the serial chain,
such as an event-correlation (EC) engine, and passed back to the MSI.

Ideally, all messages should pass through the event-correlation engine
first: not only does this reduces the overall number of messages in the
MSI after the EC instance, it also means that subsequent MSI instances
receive more useful messages. A Trouble Ticket service should be
connected at the end of the serial chain so that it gets only those
messages which are not suppressed by other MSI connections.

The routine to open an instance of the VPO interface first requires a
parameter that specifies the type of interface to be accessed (server MSI,
legacy-link interface, etc.) followed by a user-defined instance name and
an order number. This information is stored in the configuration file
/etc/opt/OV/share/conf/OpC/mgmt_sv/msiconf

, which is described

in more detail in “VPO’s Serial MSI Configuration File” on page  175.
Entries in the MSI configuration file use the following format:

<MSI instance name> <order no.>

<MSI instance name> <order no.>

The term “user-defined” implies a potential naming conflict if different
applications specify the same instance string. This problem is similar to
the possible file naming conflicts known for operating systems. As the
instance name is related to the file names used for the interface message
queues, and VPO supports short file name OS versions, the length of the
string is restricted to 12 ASCII characters (two characters are required
for internal handling). The interface ID returned by the open routine is
then used in subsequent calls to the other API functions.