Concepts

Concepts

This page is an overview of Senfi.

Measurement, Metric, Tag

Measurement

Senfi deals with data in a time series. Each sample or record in this time series consists of:

• a timestamp indicating when the data was sampled
• a set of tags
• a set of metrics

A measurement is composed of multiple samples.

Metric

A metric is a discrete reading or unit of data. It can be produced/measured by sensors, equipment, or complex systems. An example of a metric is temperature (eg. 37). A metric may or may not have units associated (eg. degrees Celsius).

Tag

A tag is an attribute of the sample. It is usually used as a way to identify where is the metrics are taken from (eg. device ID). It is also useful for filtering (eg. select all samples from this region).

Sensor

Unlike applications like Prometheus or InfluxDB which deals purely with temporal data in a time series, Senfi associates such data with physical objects in the real world.

A sensor in Senfi represents a physical object/system of interest. A sensor may produce one or more measurements, or it may not produce any measurements. There are 3 types of sensors in Senfi:

Managed sensors

Sensors that produces at least one measurement

Specialized sensors

Sensors with special behaviour, eg. lift controller

Unmanaged sensors

Sensors that does not produce measurement