Processors
As the name indicates, a RIDDL processor definition specifies the
inputs and outputs of some processor of data. The inputs to the processor
are declared with inlet statements and the outputs from the processor are
declared with outlet statements.
An inlet statement in the definition of a processor provides the name and
data type for an input to the processor. There can be multiple inlets to the
processor but each one must have a separate inlet statement. A processor
with no inlets defined is called a source since it originates data and only has an outlet.
An outlet statement in the definition of a processor provides the name and data type for an output
of the processor. There can be multiple outlets to the processor but each noe must have a
separate outlet statement. A processor with no outlets is called a sink since it terminates data
and only has an inlet.
RIDDL supports six kinds of processors that are used as the keyword to introduce the processor. The kind of processor depends solely on the number of inlet sand outlets that are defined. The keyword used ensures RIDDL knows how to validate the intention for the number of inlets and outlets.
| # Inlets | # Outlets | Kind | Description |
|---|---|---|---|
| 0 | 1 | Source | Originates data, and puts it to an outlet. Repositories can be a source |
| 1 | 0 | Sink | Terminate data, and consume it from its inlet. Repositories can be a sink |
| 1 | 1 | Flow | Transforms data from an inlet to an outlet |
| 1 | any | Split | Splits or broadcasts from one inoet to multiple outlets |
| any | 1 | Merge | Merges data from multiple inlets to a single outlet |
| any | any | Router | Routes messages, without transformation, from its inlets to its outlets |
| any | any | Multi | Any other combination is a many-to-many flow, usually with transformation |
source GetWeatherForecast is {
outlet Weather is type Forecast
} explained as "This is a source for Forecast data"
flow GetCurrentTemperature is {
inlet Weather is type Forecast
outlet CurrentTemp is type Temperature
} explained as "This is a Flow for the current temperature, when it changes"
sink AttenuateSensor is {
inlet CurrentTemp is type Temperature
} explained as "This is a Sink for making sensor adjustments based on temperature"
The above example shows the definition of three processors of different types.
GetWeatherForecast is a source of data that generates weather forecast
data as type Forecast. Presumably, that data could be used as the input to
the flow named GetCurrentTemperature which takes the forecast and
puts out temperate changes as indicated by the latest Forecast received.
Finally, the AttenuateSenso processor is a sink of data that makes
adjustments to a sensor’s attenuation based on the temperature.