4.3 A Camera Example

The Camera example introduces the system component (See Systems). The system diagram (See Invoking dzn graph) looks like this:

This is what the Camera system looks like in Dezyne:

component Camera
{
  provides IControl control;

  system
  {
    Driver driver;
    Acquisition acquisition;
    Optics optics;

    control <=> driver.control;
    driver.acquisition <=> acquisition.port;
    driver.optics <=> optics.port;
  }
}

It introduces the following concepts:

provides IControl control;

Similar to a regular component, it defines ports,

system

The system specification defines instances of components and their bindings,

Driver driver;

A component instance named driver of type Driver,

Acquisition acquisition;

A component instance named acquisition of type Acquisition, which is a system component itself,

Optics optics;

An instance of another system component,

control <=> driver.control;

A binding of the Camera’s port control to the port named control of the driver instance.

driver.acquisition <=> acquisition.port;

A binding between pairs of ports on component instances.

The light blue components in the system view, such as lens are foreign components (See Components); their definition looks like this:

component Lens
{
  provides ILens port;
}

A foreign component does not specify any implementation: neither a behavior nor a system; its behavior is said to be implementation elsewhere, and in a foreign language (in this case C++).

The full example is contained in the source tree at test/all/Camera/Camera.dzn or Camera.dzn.

The simplified⁵ state diagram: