Experiment Control

It is experiment control's responsibility to collect history data. One part of its configuration defines subscription parameters. The end user can define variables from which samples are collected during experiment. Subscription is a group, subscription item is a configuration for a single variable.

SubscriptionItem = {
    // Name of the subscription item
    name: String,
    // Source data file
    src: Variant,
    // Interval in seconds (optional)
    interval: Optional( Double( unit="s" )),
    // Deadband
    deadband : Optional( Double )
}

The collected data is stored in experiment's work area, each subscription item as a file. Experiment Work Area is a directory that contains experiment result files: timeseries and milestones.

Time series is databoard binary file (.dbb), and its databoard type is

 TimeSeries = {
     // Value source, typically a String
     source : Variant,
     // All labels
     labels : LocalizedTexts,
     // Subscription params
     params : SubscriptionItem,
     // Time series
     data : Map( <time type>, <value type> )
 }

File name corresponds to the subscription item name with the following encoding:

   S<string>.dbb   String types
                   control characters " : < > | ? * \ / % [0..31] [128..] are escaped with %<hex><hex>
   I<integer>.dbb  Integer types
   L<long>.dbb     Long types
   B<base64>.dbb   All other cases. The value is binary encoded and presented as single line Base64 string.
                   Base64 encoding has Url and filename safe encoding flags enabled.

Samples are captured at real-time from data source, eg. simulation or measuring device, and written to a SampleCollection. SamplingConfiguration is an input to the SampleCollector. It describes how to do sampling. There is a Record for each subscribed variable. Subscription is a describes how and when samples are recorded from a variable.

Samples may be collected:

• on every step

• on change

• on change that exceeds change tolerance dead band

• at intervals

  type SamplingConfiguration = {
         // Capture events, if true events are captured
         captureEvents : Boolean,
 
         // Subscribed Variables
         subscriptions : SubscriptionParameters[]
       }
  
  type SubscriptionParameters = {
         variableId : Variant,
         deadband : Optional( Double ),
         interval : Optional( Variant ),
         sampleEveryStep : Boolean
       }

If interval is omitted, the variable is sampled at every step (this applies to step wise data sources).

There can be multiple subscriptions for one variable, though they are both written to one record. If sampling from multiple subscriptions create a sample at the same timecode, only one sample is written to the record.