page_title: Real-Time Object-Oriented Modeling
section_title: Structure
hierarchical_section_title: Real-Time Object-Oriented Modeling / Concepts and Key Notions of ROOM / Structure
caption_attribution_description: example of a ROOM structure diagram
context_page_description: Real-Time Object-Oriented Modeling is a domain specific language.
  ROOM was developed in the early 1990s for modeling Real-time systems. The initial focus was on telecommunications, even though ROOM can be applied to any event-driven real-time system.
  ROOM was supported by ObjecTime Developer and is now implemented by the official Eclipse project eTrice
  When UML2 was defined, many elements of ROOM were taken over.
context_section_description: The structural view in ROOM is composed of actors or capsules. Actors can communicate with each other using ports. Those ports are connected by bindings. Actors do exchange messages asynchronously via ports and bindings. To each port a unique protocol is assigned. A protocol in ROOM defines a set of outgoing and a set of incoming messages. Ports can be connected with a binding if they belong to the same protocol and are conjugate to each other. That means that one port is sending the outgoing messages of the protocol and receiving the incoming ones. This port is called the regular port. Its peer port, the conjugated port, receives the outgoing messages and sends the incoming ones of the protocol. In other words, a port is the combination of a required and a provided interface in a role (since one and the same protocol can be used by several ports of an actor).
  An actor can contain other actors (as a composition). In ROOM these are called actor references or actor refs for short. This allows to create structural hierarchies of arbitrary depth.
  The actor's ports can be part of its interface (visible from the exterior) or part of its structure (used by itself) or both. Ports that are part of the interface only are called relay ports. They are directly connected to a port of a sub actor (they are delegating to the sub actor). Ports that are part of the structure only are called internal end ports. Ports that belong to both, structure and interface, are called external end ports.
caption: Example of a structure diagram
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