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EvmEvent(5)							   EvmEvent(5)

       EvmEvent - The structure of an EVM Event

       An  EVM	event is a self-contained data structure, which can be manipu‐
       lated and accessed using EVM API functions.  Application code can: Cre‐
       ate,  duplicate	and  destroy  an  event Set and retrieve the values of
       standard data items contained within the event Add variable data	 items
       to  the	event, and set and retrieve their values Post the event to the
       EVM daemon for distribution to subscribers Read	events	from  an  open
       file descriptor Write events to an open file descriptor

       Command	line  utilities	 are provided that allow users access to these

   The Contents of an Event
       The event structure includes two types of  data	items:	Standard  data
       items,  with predefined names Variable data items, with names and types
       defined at the time they are added to the event

       When you create an event you can include as  many  data	items  as  you
       like.  When you post the event, the API functions automatically add the
       standard items which pertain to the current environment,	 such  as  the
       host name and timestamp.

   Standard Data Items
       Standard	 data items are those which are commonly required in an event,
       and which are understood and may be acted upon by EVM.	The  following
       table  is a list of the standard data items that may be contained in an
       event.  The identifier is the keyword used to post, display, or	format
       the item.

       Data item/Id	     Description
       Event Name
       NAME		     Names  the	 event. Must match a name
			     in the daemon's template database if
			     the event is to be posted.

       Time Posted
       TIMESTAMP	     UNIX  system  time	 when  the  first
			     occurrence of this event was  gener‐

       Repeat Count
       REPEAT_COUNT	     Number  of	 instances  of	the  same
			     event that have been combined into a
			     single   stored   event.	The  Time
			     Posted  and  Last	Timestamp   items
			     indicate  when  the  first	 and last
			     instances of the event were posted.

       Last Timestamp
       LAST_TIMESTAMP	     If Repeat Count is present and  non-
			     zero,  the system time when the lat‐
			     est occurrence  of	 this  event  was

       Event Identifier

       EVENT_ID		     Identifies	  the	event.	 See  the
			     description following this table.

       Host Name
       HOST_NAME	     Name of the posting node.

       Host IP Address
       HOST_IP		     IP address of the posting node.

       Cluster Event
       CLUSTER_EVENT	     In a cluster environment, a value of
			     EvmTRUE indicates that the event was
			     posted on behalf of the cluster, not
			     the  individual  node,  and  will be
			     distributed to  every  node  in  the

       Cluster Name
       CLUSTER_NAME	     In	 a  cluster environment, the name
			     of the posting cluster.

       Cluster IP Address
       CLUSTER_IP	     In a  cluster  environment,  the  IP
			     address of the posting cluster.

       Cluster Member ID
       MEMBER_ID	     In a cluster environment, the node's
			     cluster ID.

       Kernel Only
       KERNEL_ONLY	     If present and EvmTRUE for an  event
			     generated	in  the kernel, the event
			     will not be propagated from the ker‐
			     nel to user space.

       Process ID
       PID		     PID  of the process which posted the

       Parent Process ID
       PPID		     PID of the	 parent	 of  the  process
			     which posted the event.

       User name
       USER_NAME	     Name  of  the  owner  of the posting

       PRIORITY		     Indicates	the  importance	 of   the
			     event.  Does not affect the order of
			     event   distribution.     See    the
			     description following this table.

       I18N catalog
       I18N_CATALOG	     Name of I18N catalog file for inter‐
			     nationalized events.

       I18N message set id
       I18N_SET_ID	     Identifies the  message  set  within
			     the I18N message catalog.

       I18N message id
       I18N_MSG_ID	     I18N message id for the event.


       FORMAT		     Event    format   text.	See   the
			     EvmEventFormat(3) and evmtemplate(4)
			     reference pages for a description of
			     the format string.

       REF		     Reference to event explanation text.

   Event Name
       The event name is the primary means of identifying an event.   It  must
       be present for an event to be posted.  Although it can be any syntacti‐
       cally-valid string, the name  should  generally	identify  the  posting
       facility and indicate what happened.

       The event name is an ASCII character string, made up of a dot-separated
       series of components, with the left-most component representing the top
       of  a notational hierarchy. Component substrings may include any combi‐
       nation of letters, digits and underbar characters. There is no restric‐
       tion on the number of components that can be included in an event name.
       An event template must contain at least two components.	An event  must
       contain at least three components to be accepted for posting.

       The  naming  scheme provides an open-ended way to identify events, let‐
       ting you provide detail to any level.  Careful naming gives the	system
       administrator an intuitive and precise way to select events for viewing
       and monitoring and facilitates the identification of the system	compo‐
       nents  which  issue events and the recognition of patterns that warn of
       problems.  The more detail included in the event name, the more precise
       the specification criteria can be.

   Event Identifier
       The  event  identifier  data item is a numeric quantity, assigned to an
       event by the EVM daemon as the event is posted.	 In  combination  with
       the  host  and timestamp data items, the value can be used to produce a
       unique identity for an event.

       The daemon assigns identifiers according to the following  rules:  Each
       posted  event receives an unsigned integer event identification number,
       with a value greater by one than that  of  the  previous	 event	posted
       through	the  same EVM daemon.  The event identifier of the first event
       posted after the daemon is started or restarted	is  zero.   The	 event
       identifier  wraps  back to zero after it has reached its maximum value.
       If a daemon receives an event that already contains an  identifier,  it
       does  not  generate  a new identifier for the event. This may happen if
       the event is a cluster event posted in another node.  New event identi‐
       fiers  are  assigned  only  to  events  which  the daemon validates and
       accepts for distribution.  If an event is accepted and does not already
       contain an identifier, a new identifier is assigned to it even if there
       are no subscribers for the event.

   Event Priority
       EVM uses an event's priority value solely for  filtering,  sorting  and
       presentation  purposes - it does not use it to prioritize the distribu‐
       tion sequence. The priority is an integer value	in  the	 range	0-700,
       with  zero  being the least significant priority.  This table indicates
       the event priority, the default action taken by evmlogger for that pri‐
       ority, and a description of the priority.

       EVM Priority/Name   Notification	       Description

       Emergency	   Log, mail to root   A  dangerous  situation
					       has been	 detected  and
					       immediate action either
					       is required or has been
       600 - 699

       Alert		   Log, mail to root   A  dangerous  situation
					       is imminent and immedi‐
					       ate  action  either  is
					       required	 or  has  been
       500 - 599

       Critical		   Log, mail to root   A   failure   has  been
					       detected	 that  renders
					       some part of the system
       400 - 499

       Error		   Log		       A non-critical  failure
					       has been detected in or
					       by  some	 component  of
					       the  system or applica‐
       300 - 399

       Warning		   Log		       Some aspect of the sys‐
					       tem    or   application
					       requires attention.
       200 - 299

       Notice		   Log		       Notification   of    an
					       expected	   operational
					       event that  the	compo‐
					       nent   is  designed  to
					       deal with.
       100 - 199

       Information	   None		       A  normal   operational
					       event - for example, an
					       application has started
					       or terminated normally.
					       Events  in  this	 range
					       typically  will	not be
					       saved in the system EVM
					       log file.
       1 - 99

       Debug		   None		       Program	debug informa‐
					       tion.  Events  in  this
					       range  may be monitored
					       for informational  pur‐
					       poses,	but  typically
					       will not	 be  saved  in
					       the   system   EVM  log

       None		   Application	       Priority	 0  should  be
					       used  for  events  that
					       are	  specifically
					       intended	  to  be  sub‐
					       scribed to by programs,
					       and are not expected to
					       be    interesting    to

   Catalog Name and Message Set Id
       If you plan to internationalize your events, you will need to supply an
       I18N catalog file containing the format strings for all of the  events,
       and  include  the name of the file in the event. You also can break the
       file into multiple message sets, and give the message  set  id  in  the
       event  -	 but  note  that all messages pertaining to a particular event
       must belong to the same set. If all events described in a  single  tem‐
       plate  file  use messages from the same catalog or message set or both,
       you will probably want to supply these items as global values, so  that
       you need only to specify them once.

   Cluster event
       You  should set the cluster event data item only if your application is
       cluster-aware, and is posting the  event	 on  behalf  of	 the  cluster,
       rather  than an individual node.	 Cluster events are distributed to all
       nodes in the cluster.

   Formatting an Event for Display
       Although an event is an opaque binary structure, it  can	 be  formatted
       into  a	human-readable	string	by  using the evmshow(1) command or by
       calling the EvmEventFormat(3) function.	Formatting  is	essential  for
       human-oriented output, but may not be necessary for an application pro‐
       gram that will simply extract any variable data the event contains, and
       take the necessary action.

       The  starting point for formatting an event is the format data item.  A
       format is a text string that may contain a simple piece	of  text,  the
       names  of  standard  data items, or the names of variables whose values
       are to be substituted into the text, or any combination of these.

       You include variable names for substitution by preceding them with a  $
       character - for example $temp.  You include standard data items by pre‐
       ceding their names with @ - for example, @timestamp.

       The EvmEventFormat(3) routine  automatically  converts  data  items  or
       variables into displayable form, regardless of their types.

       You can escape the special meaning of a $ or @ characters in the format
       text by preceding it with a backslash (\). To include a	literal	 back‐
       slash in the text, use a double backslash.

       If  an  event  does  not include a format data item, formatting it will
       result in a default text string that includes the event	name  and  any
       variables the event may contain.

       If  the	event  includes	 a  repeat  count,  then  the  repeat count is
       prepended to the output in the form [repeat_counttimes].

   Variable Data Items
       You can use variable data items in your events to provide data that may
       be different each time the event is posted.

       You can give the variable any name you like - the name is a string that
       is carried with the event, and can be used by a subscriber  to  extract
       the  data  in its original form.	 A variable name can be made up of any
       combination of upper or lower  case  alphanumeric  characters  and  the
       underscore  character.	By  convention, names beginning with an under‐
       score are reserved for system use.

       EVM's variable data items have these properties: A name A type A	 value
       A  size	(implicit for most types) An I18N message id (for string vari‐
       ables only)

       The following table shows the variable types that EVM supports:

       Type Identification   Remarks
       EvmTYPE_BOOLEAN	     8-bit integer
       EvmTYPE_CHAR	     8-bit character
       EvmTYPE_INT16	     16-bit signed integer
       EvmTYPE_INT32	     32-bit signed integer
       EvmTYPE_INT64	     64-bit signed integer
       EvmTYPE_UINT8	     8-bit unsigned integer

       EvmTYPE_UINT16	     16-bit unsigned integer
       EvmTYPE_UINT32	     32-bit unsigned integer
       EvmTYPE_UINT64	     64-bit unsigned integer
       EvmTYPE_FLOAT	     32-bit floating point value
       EvmTYPE_DOUBLE	     64-bit floating point value
       EvmTYPE_STRING	     Null-terminated character string
       EvmTYPE_OPAQUE	     Binary data - cannot be  interpreted
			     directly. The size must be specified

       Data types EvmTYPE_FLOAT and EvmTYPE_DOUBLE cannot be used  for	events
       posted within the kernel.

       Commands: evmshow(1)

       Routines: EvmEventFormat(3)

       Files: evmtemplate(4)

       Event Management: EVM(5)


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