| Description | A client machine may have multiple addresses during a period
of monitoring. The apmNameTable assigns a long-lived
identifier to a client and records what addresses were
assigned to that client for periods of time. Various
implementation techniques exist for tracking this mapping but
if an agent is unable to track client address mappings, it may
map client identifiers to client addresses rather than to
distinct client machines.
A particular apmNameClientID should be a constant attribute of
a particular client. When available, the agent may also record
the machine name and/or user name which may be valuable for
displaying to humans. The apmNameMachineName and
apmNameUserName are relatively constant, changing only if
these attributes actually change on the client.
The agent will store a historical log of these entries, aging
out old entries as the log becomes too large. Since this table
contains information vital to the interpretation of other
tables (e.g., the apmReportTable), the agent should ensure that
the log doesn't age out entries that would be referenced by
data in those tables.
Note that an entry for a clientID is active from its
StartTime until the StartTime of another entry (for the same
clientID) that supersedes it, or 'now' if none supersede
it. Therefore, if a clientID only has a single entry, it is by
definition very new and should never be aged out. No entry for
a clientID should be aged out unless it has been updated by a
new entry for the client (i.e., with an updated address) and
only if the new entry is 'old' enough.
To determine how old is old enough, compute the maximum value
of Interval * (NumReports + 1) of all entries in the
apmReportControlTable (the '+ 1' is to allow a reasonable
period of time for the report to be downloaded). Then take the
larger of this value and the age in seconds of the oldest
entry in the current transaction table. If an entry for a
clientID is superseded by another entry whose StartTime is
more than this many seconds ago, then the older entry may be
deleted. |