Toll Terminal

The example model describes a toll terminal (a system which collect fees for providing access to using a facility, e.g. a subway). The toll terminal is designed to grant access into a controlled zone only after a special token is dropped into a token-receiver. The toll terminal has a color access indicator. The red color means that access is forbidden. The green color means that access is granted. The terminal has also a sensor to detect whether the passenger has started to go through.

The toll terminal is the system under development in this MSC specification. The name of the system is 'Terminal'. A passenger going through the toll terminal is represented on MSC diagrams by an instance named 'Passenger'. The single scenario named 'Pass' describes a passage of the passenger through the terminal. There are one normal and two abnormal variants in this scenario:

1. The passenger drops a token and successfully passes through the toll terminal after it indicates that access is granted. This is a normal variant, that is describes sequential composition of MSCs Pass_Token and Pass_Enter.
2. The passenger drops a token but fails to enter through the toll terminal. If nobody goes through during a 60-second time interval the terminal rings and returns to its initial state. This means that the passage becomes again forbidden and the next token is expected. This is described by sequential composition of MSCs Pass_Token and Pass_Timeout.
3. The passenger tries to pass through the terminal without dropping a token. In this case the terminal blocks the passage. This is described by MSC Pass_Blocked.

MSC Pass_Token is the common part of scenarios 1 and 2. It ends with global condition 'wait'. MSCs Pass_Enter and Pass_Timeout start with the same global condition. MSC Pass_Token may be therefore composed with any of MSCs Pass_Enter and Pass_Timeout depending on which of scenarios 1 and 2 takes place. The behavior specified by this model is represented by HMSC 'Terminal'.

All source files in MSC PR format and Telelogic Tau diagrams and synthesized SDL executable model can be found in MSC to SDL installation directory in doc/examples/Terminal.