The simple-data-flow library provides basic building blocks for creating and executing simple workflows. It not only contains abstract superclasses that can be used to implement new actors (= operators), but also a set of useful actors for controlling the flow of data and simple I/O.

Inspired by the ADAMS workflow system, there are no explicit connections between the actors. Instead, the nesting and use of control actors determines how the data flows and how the flow is being executed. The actors themselves can be input consumers and/or output producers. Data itself is wrapped in a Token wrapper. Multiple outputs a managed by outputting container objects, from which individual values can be retrieved with the ContainerValuePicker control actor. Objects can be parked and retrieved from internal storage using special actors, allowing the use of the same object in multiple locations.

Control actors control either the flow of data or the execution of the flow:

• simflow.control.Flow - the outermost actor that manages a complete workflow
• simflow.control.Branch - forwards the same input to all its branches and executes them one after the other
• simflow.control.ContainerValuePicker - obtains an object from a special Container object via its name
• simflow.control.Sequence - combines multiple operators into a sequence of steps; only takes input, does not generate output
• simflow.control.Stop - stops the flow execution when reached
• simflow.control.Tee - forks off the incoming data to a sub-flow before forwarding the data
• simflow.control.Trigger - executes the specified sub-flow whenever an input token arrives, but does not forward the input to the sub-flow

Source actors only generate data:

• simflow.source.CombineStorage - expands the storage item expression and forwards the generated string
• simflow.source.FileSupplier - forwards the specified files one by one
• simflow.source.ForLoop - outputs the value of loop variable
• simflow.source.GetStorageValue - outputs the named object from the internal storage
• simflow.source.ListFiles - lists the files/dirs in the specified directory
• simflow.source.Start - forwards a dummy token to trigger actor execution
• simflow.source.StringConstants - outputs the specified strings one by one

Transformers receive input data and generate output from it:

• simflow.transformer.Convert - applies the specified conversion object to the incoming data and forwards the generated output
• simflow.transformer.DeleteFile - deletes the incoming files (if they match the regexp)
• simflow.transformer.DeleteStorageValue - deletes the specified object from the internal storage
• simflow.transformer.InitStorageValue - initializes the specified storage value with an initial value
• simflow.transformer.MathExpression - evaluates a mathematical expression using the input value in its expression
• simflow.transformer.PassThrough - dummy actor that just forwards the input data
• simflow.transformer.SetStorageValue - stores the incoming data in internal storage under the specified name
• simflow.transformer.UpdateStorageValue - updates the specified internal storage item using the provided expression

Sinks only receive data:

• simflow.sink.Console - simply outputs the incoming data on stdout
• simflow.sink.DumpFile - stores the string representation of the incoming data in a file (can be appended)
• simflow.sink.Null - consumes the incoming data without doing anything

• output_actor_help.py - generates and outputs help for an actor
• for_loop.py - how to use the ForLoop actor
• init_storage_value.py - how to use the InitStorageValue actor
• list_files.py - lists files in the temp directory
• math_expression.py - applies a mathematical expression to the input data
• stop_flow.py - stops the execution when a certain condition is satisfied
• update_storage_value.py - updates an object in storage using a mathematical expression