EMS Manual

Compiled Filters
EMS Manual—426909-005
5-29
Declarations
Filter Parameters
Filter parameters let you specify the value of certain tokens when you install the filter,
rather than when you compile the filter specification. The values of these parameter
tokens cannot be changed while the collector or distributor is examining a series of
event messages. Otherwise, filter parameters must be changed by object-oriented SPI
command messages like ADD, ALTER, DELETE, or REPLACE. For more information,
see Overview of Filter Operation on page 5-8.
Parameter tokens are known by name and cannot duplicate the names of tokens that
you refer to in the event message.
The syntax to declare each filter parameter follows. For the larger context in which this
declaration occurs, see FILTER Declaration
on page 5-27.
param
is a token name that is qualified by the subsystem ID of the user subsystem. For
details, see Qualified Tokens
on page 5-12.
If you omit both the REQUIRED and OPTIONAL keywords, the parameter token is
optional.
Parameter tokens are user-defined. When you declare parameters, you can but are not
required to qualify the parameter tokens with the subsystem ID of the user subsystem.
For details, see Qualified Tokens on page 5-12.
To refer to parameter tokens, use simple (unqualified) token names.
The EMF default subsystem ID has no effect on references to parameter tokens.
Considerations

If a REQUIRED parameter token is missing, the collector or distributor issues the
error ZEMS^ERR^REQ^PARAM: one or more filter parameter tokens are missing.

In a comparison, a reference to a missing OPTIONAL parameter token is treated
similarly to a reference to a missing event-message token. That is, the comparison
is always FALSE if the parameter token is missing.

You can include multiple instances of a token when you specify a set of parameter
tokens. Use an index to refer to each instance within the filter.
Example 1
Some typical parameter specifications:
[ REQUIRED ]
param
[ OPTIONAL ]