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Time Series

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Johannes Heucher edited this page Jun 13, 2022 · 2 revisions

Xyna Time Series is a Function Group of the Factory Warehouse that stores data points indexed by time. A typical example is the storage of traffic data to monitor bandwidth usage of a remote device.

Time Series can be managed with the services provided by the Application named "timeseries".

Table of Contents

Concept/Architecture

Each Time Series conceptually consists of a definition, one or more types of stored data and meta data. For example it is possible to store the same data in different resolutions by configuring several storage type instances.

A Time Series is defined by:

  • A data source
    • Name
    • Type of the data (GAUGE/COUNTER)
    • Validation data (minimum, maximum)
  • One or more types of storage with corresponding configuration
Supported storage types are Meta data consists of statistics aggregated over the whole data/time range:
  • Date of first data
  • Date of last data

Storage Types

RRD

RRD specifies several key configuration parameters that are different from the ones used in the API in Xyna. This section explains the mapping to the RRD parameters (official RRD documentation).

  • step (corresponding to one primary data point): greatest common divisor of the precisions of all RRD storage definitions of the Time Series
  • steps (corresponding to one consolidated data point): precision
  • heartbeat: step times Xyna Property value (stepsizefactor, see below)
  • rows: calculated from the ring buffer length parameter
The RRD Archive files are stored (per default, see Xyna Property below) in the directory storage/timeseries/rrd4j.

Usage

XMOM

The Service Group xnwh.timeseries.TimeSeriesManagement contains the following operations:

  • Create Time Series
    • Choosing of alternatives is always done by using the appropriate sub types
      • StorageDefinition has sub type StorageDefinitionRRD
      • DataAggregationType has sub types Average, Minimum, Maximum, First and Last
      • TimeSeriesDataType has sub types Counter and Gauge
      • Interval has sub types IntervalStartDuration and IntervalStartEnd
  • Add Data
  • Fetch Data (The returned data contains information about interval and precision because it may differ from the requested specification)
  • Get Meta Data
  • Get Definition
  • Delete Time Series
Please note: The user is expected to keep track of all created Time Series. There is no query operation to discover existing time series.

CLI

The CLI contains the commands listtimeseries and deletetimeseries.

Configuration

The following Xyna Properties are used by the storage type RRD:

  • xnwh.timeseries.storage.rrd4j.directory.base: Path where RRD Archive files are stored (Default: storage/timeseries/rrd4j)
  • xnwh.timeseries.storage.rrd4j.heartbeat.stepsizefactor: This stepsizefactor * minimum step size. (cf. Official RRD Documentation to understand what the heartbeat is for) (Default: 5)
  • xnwh.timeseries.storage.rrd4j.cache.expiration: How long unused RrdDb entries are kept in memory (Default: 5 Min)
  • xnwh.timeseries.storage.rrd4j.cache.sync.interval: How often cached RrdDb entries are persisted to file (Default: 5 Min)
  • xnwh.timeseries.storage.rrd4j.cache.size: Maximum number of entries in cache (each entry corresponds to one open file descriptor) (Default: 1000)
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