The main components of the workflow model are variables and actions. Use variables to specify input files and parameters for your processing services. Variables for output files must not have a value. The names of output files will be generated by Steep during workflow execution.
A variable holds a value for inputs and outputs of processing services. It can be defined (inputs) or undefined (outputs). Defined values are immutable. Undefined variables will be assigned a value by Steep during workflow execution.
Variables are also used to link two services together and to define the data flow in the workflow graph. For example, if the output parameter of a service A refers to a variable V, and the input parameter of service B refers to the same variable, Steep will first execute A to determine the value of V and then execute B.
An execute action instructs Steep to execute a certain service with given inputs and outputs.
A for-each action has an input, a list of sub-actions, and an output. It clones the sub-actions as many times as there are items in its input, executes the actions, and then collects the results in the output.
Although the action is called ‘for-each’, the execution order of the sub-actions is undefined (i.e. the execution is non-sequential and non-deterministic). Instead, Steep always tries to execute as many sub-actions as possible in parallel.
For-each actions may contain execute actions but also nested for-each actions.
Include actions can be used to include the actions of a macro at a certain point in a workflow. They can also be used in macros to include other macros.
Note that include actions are evaluated in a static pre-processing step during workflow parsing. The pre-processor replaces each include action with the list of actions it specifies and takes care of assigning parameter values as well as renaming IDs and variables to avoid naming collisions.
value must be given but not both!
Output parameters of execute actions have additional properties compared to inputs.
Include output parameters
This data model describes output parameters of include actions.
Retry policy defaults
A default retry policy that should be used within a workflow unless a more specific retry policy is defined elsewhere.