protocol

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Protocol Template

In the this directory, you will find the implementation of a toy protocol where nodes work together to count how many instances of the protocol there are. It demonstrates how to send messages and how to handle incoming messages.

To implement a new protocol, you must create the NewProtocol function and register it.

func init() {
	_, err := onet.GlobalProtocolRegister(Name, NewProtocol)
	if err != nil {
		panic(err)
	}
}

Writing NewProtocol - the protocol constructor

Inside NewProtocol you must register the channels that are used for receiving messages, e.g., announceChan chan announceWrapper. Any state that is needed by the protocol (for example, the ChildCount channel) should be initialized here too.

The messages are defined in the file struct.go. For each message, you need to define the message itself (e.g., Announce), and the message as it will arrive to you from the cothority server (e.g., announceWrapper).

Writing the protocol logic

After registering, define a struct that implements the onet.ProtocolInstance interface:

type TemplateProtocol struct {
  *onet.TreeNodeInstance
  ...
}

// Check that *TemplateProtocol implements onet.ProtocolInstance
var _ onet.ProtocolInstance = (*TemplateProtocol)(nil)

Usually, an implementation for Start and Dispatch is needed, the others are optional and the default implementation will be used if they are not implemented. Dispatch is where the main protocol logic is implemented and it is called automatically by onet when the protocol is initiated. Start is the entry-point of the protocol, it needs to be called manually, typically by the root node.