Peers and Ties

Table of contents

1. Peer Definition
2. Multiple Connections per Peer
3. Optional Connections

Peer Definition

Using the Peer type, a programmer can specify the different peers needed for the program. The relation between them is specified using the Tie type. An example for this is a typical client-server relationship (where one server is connected to multiple clients), which can be defined like this:

@peer type Peer
@peer type Server <: Peer {
  type Tie <: Multiple[Client]
}
@peer type Client <: Peer {
  type Tie <: Single[Server]    
}

Multiple Connections per Peer

Additional connections can be specified by adding them with the with keyword:

type Tie <: Multiple[Client] with Single[Registry]

Optional Connections

If a tie might not be needed during the complete runtime of a program (e.g. if an introducer is used), it can be specified using an Optional tie:

type Tie <: Multiple[Client] with Optional[Registry]

In this case the connection to the Registry might not be available, which has to be handled by the programmer.