EMS Manual

Introduction to EMS
EMS Manual—426909-005
1-6
Basic Capabilities
Event messages can be reported by subsystems for the NonStop server or
subsystems you write. They are subsystem specific, and hundreds of different event
messages are produced by subsystems for the NonStop server alone. Although this
wide range of messages provides the diversity and depth of information required to
manage systems and networks, it also creates the need for tools to manage the event
messages themselves.
Basic Capabilities
EMS supports many aspects of managing event messages, from generation of a
message in the subsystem environment to generation of text for display in the
operations environment. This list describes the basic EMS capabilities, in the
approximate order in which they would apply to a single event message:

Message building. EMS includes several library procedures that subsystems for
the NonStop server, and subsystems you write use to build event messages. One
procedure initializes a buffer, ensuring that a message has the correct format and
providing some of the standard information found in all event messages. The
subsystem then calls other procedures to add different kinds of information to the
event message.

Message collection, filtering, and logging. The EMS primary and alternate
collectors accept event messages from subsystems, use pre-log filtration (PLF) for
specific event messages, use burst detection and suppression (BDS) to suppress
specified types of event bursts, and write unfiltered events to log files. Pre-log
filtration makes use of compiled filters or filter tables to totally suppress the logging
of certain event types.

Message filtering and distribution. The EMS distributor processes provide:

Selection (or filtering) of event messages

Use of burst filters to implement BDS on specified types of event bursts

Distribution of event messages to their destination devices
As with collector filters, filtering in distributors is the process of evaluating event
messages and selecting only those in which a particular requester has expressed
interest. Distribution is the returning of a selected event message to a requester
through the appropriate interface. EMS can distribute event messages to
processes, files, collectors on other nodes, and display devices such as terminals
and printers.

Text formatting. EMS includes a procedure that returns text suitable for display to
an operator.
Key Features
EMS has many significant characteristics that help you manage your system or
network: