A component is the fundamental LISA+ construct that is used to describe components and systems.

Components can have subcomponents and form a hierarchy. The top level component of a system, meaning the component that does not have any parent component, is sometimes also referred to as a system. There is, however, nothing special about a system component or top level component and they are declared in the same way as any other component.

Systems that have external ports can be used as a component in a higher-level system. The term system is sometimes used to distinguish a collection of connected components that does not include any external ports.

Components definitions can contain the following sections:

A component declaration uses the component keyword and can contain any of the sections listed in any order.

Example 2.1 shows an example of a component declaration:

component MyComponent
{
     includes
     {      
          // ...
     }

     resources
     {
          // ...
     }

     internal port<MyProtocol> port0
     {
          // ...
     }

     behavior init
     {
          // ...
     }
}