event-graph

Make an application by composing nodes in a graph. Uses events behind the scenes.

npm install --save event-graph

Note: this is currently a work in progress

Example

This graph will set up two nodes:

• helloworld is a Value node which gets configured to emit a value after the graph has been initialized. Value nodes are the only ones that can be configured via the graph definition. All other types of nodes must use inputs for their configuration.
• console is a ConsoleNode which is a type defined in the core of event-graph. Among other inputs, ConsoleNodes have a data input which takes arbitrary data and logs it to the console.

The graph also defines one edge which hooks up the value output of the helloworld node to the data input of the console node. The source and target attributes specify the ids of the nodes to connect. And the output and input attributes are used to specify which input from the source node is connected to which output from the target node.

graph.json

{
    "graph": {
        "type": "ExampleGraph",
        "nodes": [{
            "id": "helloworld",
            "type": "Value",
            "metadata": {
                "value": "Hello World"
            }
        }, {
            "id": "console",
            "type": "event-graph/core/ConsoleNode"
        }],
        "edges": [{
            "source": "helloworld",
            "target": "console",
            "metadata": {
                "output": "value",
                "input": "data"
            }
        }]
    }
}

example.js:

var EventGraph = require("event-graph");

var graphConfig = require("./graph.json");

var graph = EventGraph(graphConfig);
var events = graph.events;

// graph.events is an instance of mqtt-emitter
events.on("#", function (data, params, path) {
    console.log("Event:", path, ":", data);
});

// graph.dispose(); will clean up resources