GlossaryΒΆ

group of values
value group

A set of values that have the same meaning, but which were possibly collected at different places (see group origin) and concern different monitored objects. Identified by group name.

Group of related values is collected at some origin at once, expires at once, and changes at once. If a list of value keys changes, the keys that were present but are missing should disappear from StateTip as soon as possible.

List of network interfaces of a server is a good example of a group of related values.

unrelated values

Values from a group of unrelated values don’t form a meaningful set, apart from telling the same thing about similar objects. Each value changes and expires independently of the others.

An example of such values is expiry time of X.509 certificates installed on a server. Unlike with network interfaces, a value for an old certificate doesn’t need to disappear immediately with next reading of certs’ statuses.

group name
Name of a value group.
group origin
value origin

Place (source) where some of the values in a value group were collected from. Value group can consist of values from many origins.

Hostname usually makes a good origin. Origin may also be null if there is no meaningful distinction where the value was collected from.

log file
state log file

Append-only binary file that records every value change or expiration. Log file is used to restore values after StateTip restart.

log compaction

Process of reading all log records, discarding the ones that were replaced by newer ones, and writing a new log file with only the newest records.

Part of this process is replaying the compacted log file.

log record
Block of binary data that describes a new state of value (its group name, origin, key, state, expiry time, etc.) or marks that the value expired or changed in some other way.
log replaying
Process of reading records from a log file and applying changes they describe to a data structure, so that the result reflects the state of all the values in StateTip at the time of writing the log file.
reader client
Program that extracts data out of StateTip through StateTip reader protocol.
sender client
Program that sends values to StateTip through StateTip sender protocol.
value

Last remembered state of some object that is being observed (monitored), usually collected for displaying on a dashboard or providing a listing what objects are monitored.

Consists of group name, origin, key, state, and some metadata.

key
“Name” of a value. Together with group name and origin identifies particular value.
state
Textual representation of the actual status of the monitored object, e.g. “up”/”down” for server’s availability. Can be null for values collected for the sake of keeping an inventory of objects.
severity
Conformity of the state with expectations. One of the three values: “expected”, “warning”, “error”.

These terms are only used in source code:

value group registry
Process that keeps track of value group keeper processes.
value group keeper
Process that remembers values of specific origin from a value group. Registered in value group registry process under a name built of group name and origin.
state logger
Process responsible for writing changes in values to a log file and for periodical compaction of the file.

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