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Task

A Task is an executable unit which executes the statements within sequentially. The name of the Task should be a lowercase string.

The Production Task

A Task with the name productionTask serves as the starting point of the production order. Every PFDL program has to define this Task. This is comparable to a main method in conventional programming languages. The examples below show the use of such a Task.

Call a Task

Tasks can be called within other Tasks just like Service calls. In the example below the productionTask calls the Task paintingTask which executes the Service Painting. 

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Task productionTask
    paintingTask
End

Task paintingTask
    Painting
        In
            Color 
            {
                "name": "green",
                "rgb": [0, 255, 0]
            }
        Out
            pr: PaintingResult
End

Input and Output of Tasks

When Tasks are called they can receive input parameters and return an output too (just like Services). This can be used to transfer variables from one Task to another. Variables are always bound to a Service so with this functionality it is possible to use a variable from one Task in other Tasks.

The input must be defined at the start of a Task definition with the keyword In. Afer the In keyword one can insert an arbitrary amount of variable definitions, consisting of the variable name that is used within the Task and its type.

The output must be defined at the end of a Task definition with the keyword Out. Only variable names known in the Tasks can be used here per line as output of the Task.

In the following example the Task paintingTask defines an input and an output. The input variable paint_color must be of type Color. After the Service Painting is finished we receive a variable pr of type PaintingResult. This variable is defined as the output of the Task. The productionTask calls the Task paintingTask and instantiates a Color variable which serves as the input. The output is defined in the variable pr of type PaintingResult.

Note: Variable pr has the same name and the same value as in paintingTask but technically they are two different variables. 

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Task productionTask
    paintingTask
        In
            Color 
            {
                "name": "green",
                "rgb": [0, 255, 0]
            }
        Out
            pr: PaintingResult
End

Task paintingTask
    In
        paint_color: Color
    Painting
        In
            paint_color
        Out
            pr: PaintingResult
    Out
        pr
End