Component Interface or Ports

Ports make up the interface of a component. They are the only point of interaction a component has with its environment.

Ports are declared within the bodies of the components to which they belong. It is possible to define multiple ports within one statement. One can also split the declaration over multiple statements. This allows the textual grouping of conceptually related ports.

The definition of a port contains the following concepts:

• The port's timing: Either event based or sync, where event is the default.
• The port's direction: Either it is incoming or outgoing.
  • Through incoming ports, a component receives data from its environment.
  • Through outgoing ports, a component sends data to its environment.
• The port's type.
  • The kind of information that flows through this port. See Type system for more information about types.
• The port's name that is later used to refer to the port and the information flowing through it.

For example, the following component has 5 ports.

component MyComp {
  port sync in int inPort1,
            in int inPort2,
       sync out int outPort1,
            out int outPort2;

  port out boolean outPortInSeparateDeclaration;
}

Where each port has the following properties:

Name	Timing	Direction	Type
inPort1	sync	incoming	int
inPort2	event	incoming	int
outPort1	sync	outgoing	int
outPort2	event	outgoing	int
outPortInSeparateDeclaration	event	outgoing	boolean

If multiple ports share the same properties, but only the names differ, there is an even shorter notation:

component MyComp {
  port in int inPort1, inPort2;
}

Complete syntax

port (sync)? <direction> <type> <name> ;