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NAME    [Toc]    [Back]

       EvmEvent - The structure of an EVM Event

DESCRIPTION    [Toc]    [Back]

       An EVM event is a self-contained data structure, which can
       be manipulated  and  accessed  using  EVM  API  functions.
       Application  code  can:  Create,  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

       Command  line  utilities  are  provided  that  allow users
       access to these capabilities.

   The Contents of an Event    [Toc]    [Back]
       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

   Standard Data Items    [Toc]    [Back]
       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 generated.

       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  nonzero,
  the system time when the latest
 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 kernel
 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 internationalized

       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    [Toc]    [Back]
       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  syntactically-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 combination of letters,
 digits and underbar characters. There is no restriction
  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,  letting 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  components
  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    [Toc]    [Back]
       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  identifiers  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    [Toc]    [Back]
       EVM  uses  an event's priority value solely for filtering,
       sorting and presentation purposes - it does not use it  to
       prioritize  the  distribution 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 priority, 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 immediate
  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 application.

       300 - 399

       Warning             Log                 Some aspect of the system
    or   application
                                               requires attention.
       200 - 299

       Notice              Log                 Notification   of    an
                                               expected    operational
                                               event that  the  component
   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 information.
  Events  in  this
                                               range  may be monitored
                                               for informational  purposes,
   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  subscribed
 to by programs,
                                               and are not expected to
                                               be    interesting    to

   Catalog Name and Message Set Id    [Toc]    [Back]
       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 template 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    [Toc]    [Back]
       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    [Toc]    [Back]
       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 program
       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 preceding 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 backslash in the text, use  a  double

       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

   Variable Data Items    [Toc]    [Back]
       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  underscore
 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 variables 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

RESTRICTIONS    [Toc]    [Back]

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

SEE ALSO    [Toc]    [Back]

       Commands: evmshow(1)

       Routines: EvmEventFormat(3)

       Files: evmtemplate(4)

       Event Management: EVM(5)

[ Back ]
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