registry.md

Registry

Firebolt uses an internal registry to create instances of the nodes used in your application.

All custom types must be registered before the configuration file is loaded. Firebolt will validate your configuration file, checking that:

• all source/node types are registered
• each node returns the same datatype expected by it's children

Built in sources (kafkaconsumer) and nodes (kafkaproducer, elasticsearch) are registered by Firebolt itself and do not need to be registered by your application.

When registering custom types, you must provide:

• the name of the type, this will be the name: you use in the config file
• a factory function that creates instances of your type
• the reflect.Type that it expects to receive in Process()'s firebolt.Event.Payload
• the reflect.Type that it expects to return from Process() in firebolt.Event.Payload, or nil for a sink that does not return data

Registering a Node

This example registers a node type that expects event payloads of type []byte and returns string:

    node.GetRegistry().RegisterNodeType("filternode", func() node.Node {
        return &FilterNode{}
    }, reflect.TypeOf(([]byte)(nil)), reflect.TypeOf(""))

Registering a Source

This example registers a source that emits event payloads of type &RawMsg

    node.GetRegistry().RegisterSourceType("tcpreceiver", func() node.Source {
        return &TCPReceiver{}
    }, reflect.TypeOf(&RawMsg{}))