evmtemplate(4)

NAME

evmtemplate — Event Manager template file

SYNOPSIS

event { 
name          event_name
format        format_specifier
priority      priority
i18n_catalog  i18n_cat
i18n_set_id   i18n_set
i18n_msg_id   i18n_msg
reference     reference_string
var {
      name    variable_name
      type    variable_type
      value   variable_value
      i18n_msg_id   variable_value
      } 
} 

DESCRIPTION

A template event is a description of an event that is held centrally by EVM. The template is used for the following purposes:

To register the event with the EVM daemon, so that it will allow the event to be posted.
To centralize event information. This makes it easy to review and maintain details such as the associated message text and the event priority, and minimizes the amount of information that must be hard-coded into an application.

File Format

On startup, and each time the evmreload -d command is run, the EVM daemon reads all valid event template files stored in the template directory tree rooted at /usr/share/evm/templates, or in any directory tree linked to that directory, including the local template tree rooted at /var/evm/adm/templates. There is no limit to the number of template files that can be installed in the tree, or to the number of templates that can be included in each file.

Template file names must end with the suffix .evt, and the files must be owned by root or bin, and must have permissions of 0400, 0600, 0440, or 0640 to be recognized. If template files are added, deleted or modified while the daemon is running, the evmreload -d command should be used to instruct the daemon to reconfigure itself. Refer to the evmreload(1M) manpage for more information.

Every template event must contain a name data item with at least two components. A template typically also contains constant items such as the event priority and the message format string.

When a client posts an event, it must include in the posted event a name with at least three components. The posted event also typically contains any applicable variable data along with environmental items such as a timestamp and the name of the posting system.

When the EVM daemon receives a posted event, it searches its template database for the template event whose name best matches the name in the posted event. If it cannot find a matching template, the daemon rejects the posting attempt. Otherwise, the daemon merges the data items held in the two versions of the event, yielding a merged event which it distributes to subscribers.

A template event name does not have to be identical to the name of a posted event to be considered a match. If it has fewer name components than the posted event, a template event is still considered a match if all components in the template name exactly match their equivalent components in the posted name. If the template name is longer than the name of the posted event however, it cannot be a match. In determining the template that best matches the name of the posted event, the daemon selects the matching template with the most components.

The following table shows some examples of event name matching. In the final example, the template does not match the posted event because the template has too many components.

Posted Name	Template Name	Match?
`myco.myprod.env`	`myco.myprod.env`	`Yes`
`myco.myprod.env.temp.high.70`	`myco.myprod.env`	`Yes`
`myco.myotherprod`	`myco.myprod`	`No`
`myco.myotherprod`	`myco.myotherprod.start`	`No`

The syntax of an event template file is identical to the syntax of a file given as input to the evmpost command. The following keywords may be specified in a template file:

event

This keyword introduces an event group. The body of the group is delimited by braces.

name event_name

Names the template event. The name must be made up of two or more components containing only alphanumeric and underscore (_) characters, and separated by dot (.) characters.

format format_specifier

Event format text. The format_specifier is a string that will be used to produce a formatted message for display if the event is passed through the evmshow command, or the EvmEventFormat() library function. See the evmshow(1) and EvmEventFormat(3) manpages.

If a format_specifier contains no special characters, it is displayed unchanged as the event's message text. For example, if evmshow encounters an event containing the following simple format_specifier, it displays the string exactly as specified:

EVM logger: Logger started

If the format_specifier contains variable-specifier in the form $variable_name and either the posted event or the template event contains a variable with that name, the variable_value will be included in the formatted output in place of the variable-specifier. If no such variable is present, the variable-specifier is included in the output. For example, if an event contains a variable called logname and the format_specifier:

EVM logger: Started eventlog $logname

then evmshow might display the event as:

EVM logger: Started eventlog /var/evm/evmlog/evmlog.20000228

If the format_specifier contains a data-item-specifier in the form @item_name, the data-item-specifier is replaced with the value of the corresponding data item from the event. For example, if an event contains a variable called message and the format_specifier is:

EVM user msg (@user_name): $message

then evmshow might display the event as:

EVM user msg (steve): Engineering group is off-site today

If the data item is not present in the event, a hyphen character (-) is output in its place. An @ character that is not associated with a valid item name is unchanged in the output.

Any characters in the format_specifier that are not part of a variable_name or data-item-specifier are output unchanged.

If no format_specifier is supplied in either the template file or the posted event, a default event message is used when the event is formatted for display.

priority priority

Indicates the importance of the event, but does not affect the order of event distribution. The priority must be an integer value in the range 0 (lowest) to 700. See the EvmEvent(5) manpage for the meanings of specific priority values.

i18n_catalog i18n_cat

The name of an I18N catalog file holding text strings to be displayed in place of the strings contained in the event. This item is used for internationalizing events. If it is omitted, the strings contained in the event will be used when the event is formatted for display. Refer to the EVM Programmer's Guide for more information.

i18n_set_id i18n_set

Identifies the message set within the i18n_cat to be used for translation of all internationalized strings in the event. This item is ignored if no i18n_cat is supplied.

i18n_msg_id i18n_msg

Identifies the I18N catalog message to be used in place of the format data item when the event is formatted for display. This item is ignored if no i18n_cat is supplied. If an i18n_set has been specified, the i18n_msg must refer to a message identifier within the given set. If the catalog is missing, or if the i18n_set or i18n_msg values do not refer to a message in the catalog, the event's format data item is used.

reference reference_string

This text string is intended to be used by an event channel's explanation function to retrieve explanation text for the event. The format of the string is defined by the event channel.

var

This keyword introduces a variable group, with the body of the group being delimited by braces. An event may include any number of variable groups.

Although actual variable values are most likely to be included in the posted version of an event, and will override the values specified in the template version, it is usually helpful to include the variables in the template event as well, specifying dummy values such as zero, to provide documentation of the expected contents. For example, the template version will be seen if the results of an evmwatch -i command are piped into evmshow -d.

The following keywords are recognized in a variable group:

name variable_name: The name must be made up of alphanumeric and underscore characters.
type variable_type: The type of the variable item. See the EvmEvent(5) manpage for a list of types. All EVM variable types may be specified except for OPAQUE. If this keyword is omitted a type of STRING is assumed.
value variable_value: Value for the variable. A value must be specified in the template, but usually should be overridden by the value in the posted version of the event. Values supplied in the template should be default or nonnormal values that will be recognized as incomplete when the event is interpreted.
i18n_msg_id i18n_msg: For STRING variables, the i18n_msg identifies the I18N catalog message to be used in place of the variable_value when the event is formatted for display. This item is ignored if no i18n_cat is supplied for the event. If an i18n_set has been specified, the i18n_msg must refer to a message identifier within the given set. If the catalog is missing, or if the i18n_set or i18n_msg values do not refer to a message in the catalog, the variable_value is used.

Any items specified outside an event group are global items, which will be included in each following template that does not include them explicitly.

Notes

If you are concerned with allowing your file to be used on other systems that support EVM in the future, you should use the built-in macro @SYS_VP@ in place of the first two components (sys.unix) of the name of any system event. This will make it unnecessary to change the file if the other system uses a different event name prefix.

EXAMPLES

The following file is an example of an event template file.

# My example event file 
priority       200 

event { 
    name       myco.myapp.env.humid 
    format     "myapp: Humidity is $humidity" 
    var        { name humidity    type INT16    value 0 } 
} 

event { 
    name       myco.myapp.env.temp.normal 
    format     "myapp: Temperature is normal ($temp)" 
    var        { name temp        type FLOAT    value 0.0 } 
} 

event { 
    name       myco.myapp.env.temp.high 
    priority   500 
    format     "myapp: Temperature exceeds 80F ($temp)" 
    var        { name temp        type FLOAT    value 0.0 } 
} 

event { 
    name       myco.myapp.env.app_terminated 
    priority   300 
    format     "myapp: Production monitoring terminated - code $exit_code" 
    var        { name exit_code   type INT16    value 0 } 
} 

FILES

/usr/share/evm/templates: The root of the directory tree containing system event template files.
/var/evm/adm/templates: The root of the directory tree containing local event template files. This directory is accessed from the system template directory through a symbolic link.

evmtemplate(4)

Technical documentation

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NAME

SYNOPSIS

DESCRIPTION

File Format

Notes

EXAMPLES

FILES

SEE ALSO

Commands

Routines

Files

Event Management

EVM Events