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funk

A web-based GUI for visual function composition.

screenshot

Overview

Funk was developed as a GUI for another - currently unreleased - application, called Dataflow Engine. It is, however, sufficiently flexible and configurable to be used for many different use-cases.

The user of funk creates and manipulates a DAG on a canvas, adding and configuring nodes of different types and connecting them with edges.

Each node-type defines the node's inputs and outputs, in particular their types. These are color coded: edges and connectors (the point into which edges can be plugged) are displayed in the appropriate color. Edge-types impose a constraint on the connection between nodes, since an edge may only exist between connectors of matching type.

A node-type can also define additional properties of a node. This allows nodes to receive further static configuration, accessible through a property page.

The collection of available node- and edge-types is freely configurable.

Usage by the Dataflow Engine

The Dataflow Engine is a cross-protocol, semantics-aware broker application. It receives data through one or more inputs, modifies it (split, merge, filter, interpret, ...) and sends the result through one or more outputs. Funk is used to create the configuration that drives this behaviour.

When used this way, nodes represent operations on data and edges represent the flow between them. Consequently, the list of available node-types reflects all operations of the dataflow engine and edge-types reflect the available data types like integer, string, etc.

Usage

(Tested on Linux)

Installation

  1. Clone the repository
  2. cd into the project folder
  3. Activate the virtual environment: source venv/bin/activate (see: https://packaging.python.org/tutorials/installing-packages/#creating-virtual-environments)
  4. Install dependencies: pip install -r requirements.txt

Execution

  1. If necessary cd into the project folder
  2. If necessary activate the virtual environment: source venv/bin/activate
  3. Run application: ./funk.py
  4. Open browser to: http://localhost:5000

CLI Options

usage: funk.py [-h] [-e EXPORT]

optional arguments:
  -h, --help                    show this help message and exit
  -e EXPORT, --export EXPORT    a folder to which flows are exported upon saving

Configuring funk

The edge- and node-types that the user may create are configured in funk/static/nodetypes.json. This file contains a Json object with two members: datatypes and nodetypes. (Edge-types being called datatypes is due to the application's origin as a GUI for the dataflow engine.) Both contain a list of objects.

Example of an element of datatypes:

{
  "id": "integer",
  "name": "Integer",
  "color": "#153D61"
}

Each edge-type (datatype) contains a unique id, a human-meaningful name and a color for display in the GUI.

Example of an element of nodetypes:

{
  "type": "mean_over_time",
  "name": "Mean over Time",
  "color": "#94d1cc",
  "categories": [
    "Float"
  ],
  "connector_l": [
    {
      "id": "in",
      "name": "In",
      "type": "float",
      "direction": "in",
      "maxConnections": 1
    }
  ],
  "connector_r": [
    {
      "id": "out",
      "name": "Out",
      "type": "float",
      "direction": "out",
      "maxConnections": -1
    },
    {
      "id": "nr_of_values",
      "name": "Nr of Values",
      "type": "integer",
      "direction": "out",
      "maxConnections": -1
    }
  ],
  "props": [
    {
      "propid": "seconds",
      "name": "Seconds",
      "type": "float",
      "value": 10.0
    }
  ]
}

Like the edge-type, the node-type has id, name and color. In addition, it has a list of categories which allow for easier browsing of node-types in the GUI.

Next, the inputs and outputs are defined. They consist of:

  • an id that must be unique in the scope of the node-type
  • a human-meaningful name that is displayed on the node
  • a type that must reference the id of one of the previously defined edge-types.
  • a direction that must be either in or out; the GUI allows only edges between different directions; this is a legacy from the context of the dataflow engine and might be changed in the future.
  • the number of maxConnections defining the maximum number of edges that may connect to this input or output; a value of -1 means an unlimited number.

Finally, the static properties are defined. They consist of:

  • a propid that must be unique in the scope of the node-type
  • a human-meaningful name that is displayed on the node
  • a type that must be one of string, boolean, integer or float
  • a value that defined the default value of the prop and must be of the appropriate type

See the current nodetypes.json for the configuration that is used for the dataflow engine.