Port

A port is a small square on a component’s boundary, with its name beside it. It is a named interaction point.

component Modem {
  port serial
  port radio
}

Ports with interfaces

A port usually provides or requires one interface, which makes it a simple port. Two simple ports matched by name form a ball-and-socket. A port listing more than one interface is complex: its connector is drawn plain and named after the interface. See Interface.

component Radio { port rx provides IPackets }
component Stack { port input requires IPackets }

An unconnected port interface draws as a stub on the port.

component Controller {
  port ctl provides IControl
  port bus requires ICan
}

Choosing a side

drumlin chooses a side from a port’s connections. To override it, write left, right, top or bottom.

component Board {
  port power top
  port ground bottom
  port uart left
  port spi right
}

Delegation

A connector from a composite’s port to an inner part delegates the interaction, and is drawn solid. Refer to a port by its bare name when it is unique, or as component.port.

component Client { requires IApi }

component Service as svc {
  port api provides IApi
  port store requires IStore

  component Router
  component Worker

  api --> Router
  Router --> Worker
  Worker --> store
}

component Database { provides IStore }

Syntax

port <name> [left | right | top | bottom] [provides <i> | requires <i>]...

Specification

UML 2.5.1, 11.3.4 (p. 191): a small square with the name near it, placed on or inside the boundary. Delegation connector: 11.3.3 (p. 191) and Figure 11.47 (p. 214). Port type labels and multiple interfaces on one lollipop are optional UML notation that drumlin does not draw.

Used in

Hexagonal service, Vehicle gateway, Storage engine.