Skip to main content

Ports

Description​

Ports are the only interfaces of actors. A port has always a protocol assigned. Service Access Points (SAP) and Service Provision Points (SPP) are specialized ports that are used to define layering.

Motivation​

  • Ports decouple interface definition (protocols) from interface usage

  • Ports decouple the logical interface from the transport

Notation​

Class Ports​

Ports that define an external interface of the actor class, are defined in the Interface. Ports that define an internal interface are defined in the Structure (e.g. internal ports).

  • External end ports are defined in the Interface and in the Structure

  • Internal end ports are only defined in the Structure

  • Relay ports are only defined in the Interface

  • End ports are always connected to the internal behavior of the ActorClass

  • Replicated ports can be defined with a fixed replication factor, e.g.
    Port port18 [5]: ProtocolClass1
    or a variable replication factor, e.g.
    Port port18[*]: ProtocolClass1

  • The graphical symbols of Interface ports are drawn on the border of the actor class. The graphical symbols of Structure ports are drawn inside the border of an actor class.

  • Ports have two types of connection preferences: optional and mandatory. By default, all ports are optional. If a port is defined with the mandatory keyword, it will be checked that the each port instance is connected through a binding. If it is not connected, a warning will be shown at the corresponding ActorClass definition. Below is an example of how to define a mandatory port. This keyword needs to be specified at the beginning of the port definition. Ports may also explicitly be marked to have an optional binding using the optional keyword. We strongly encourage explicitly marking all ports as optional or mandatory.

ActorClass AnActor {
	Interface {
		optional Port relayPort: ProtocolClass
	}
	Structure {
		mandatory conjugated Port internalPort: ProtocolClass
	}
}

An example warning has shown for mandatory Internal Port connection:

The table below shows all kinds of class ports with textual and graphical notation:

ElementGraphical NotationTextual Notation
Class End Port

External Class End Port:

ActorClass ActorClass6 {
	Interface {
		Port port12: ProtocolClass1
	}
	Structure {
		external Port port12
	}
}

Internal Class End Port:

ActorClass ActorClass6 {
	Interface { }
	Structure {
		Port port20
	}
}
Conjugated Class End Port

External Conjugated Class End Port:

ActorClass ActorClass6 {
	Interface {
		conjugated Port port13: ProtocolClass1
	}
	Structure {
		external Port port13
	}
}

Internal Conjugated Class End Port:

ActorClass ActorClass6 {
	Interface {}
	Structure {
		conjugated Port port21: ProtocolClass1
	}
}
Class Relay Port 

ActorClass ActorClass6 {
	Interface {
		Port port10: ProtocolClass1
	}
	Structure { }
}
Conjugated Class Relay Port 

ActorClass ActorClass6 {
	Interface {
		conjugated Port port10: ProtocolClass1
	}
	Structure {}
}
Replicated Class End Port

External Replicated Class End Port:

ActorClass ActorClass6 {
	Interface {
		Port port16[3]: ProtocolClass1
	}
	Structure {
		external Port port16
	}
}

Internal Replicated Class End Port:

ActorClass ActorClass6 {
	Interface {}
	Structure {
		Port port16[3]: ProtocolClass1
	}
}
Conjugated Replicated Class End Port

External Conjugated Replicated Class End Port:

ActorClass ActorClass6 {
	Interface {
		conjugated Port port17[3]: ProtocolClass1
	}
	Structure {
		external Port port17
	}
}

Internal Conjugated Replicated Class End Port:

ActorClass ActorClass6 {
	Interface { }
	Structure {
		conjugated Port port23[3]: ProtocolClass1
	}
}
Replicated Class Relay Port 

ActorClass ActorClass6 {
	Interface {
		Port port18[3]: ProtocolClass1
	}
	Structure { }
}
Conjugated Replicated Class Relay Port 

ActorClass ActorClass6 {
	Interface {
		conjugated Port port19[3]: ProtocolClass1
	}
	Structure { }
}

Reference Ports​

These symbols can only appear on the border of an actor class reference. Since the type of port is defined in the respective actor class, no textual notation for the Reference Ports exists.

The table below shows all kinds of reference ports with textual and graphical notation:

ElementGraphical NotationTextual Notation
Reference Portimageimplicit
Conjugated Reference Portimageimplicit
Replicated Reference Portimageimplicit
Conjugated Replicated Reference Portimageimplicit