Embedded State Machines and State Machine Extension

[pasetti]

The rules for embedded state machines and state machine extension are not very clear in the FW Profile Definition Document and need to be clarified. I propose to do it as described below.

Let S be a state of state machine SM_A and let SM_B be a state machine derived from SM_A. The rules for adding embedded state machines to SM_B are as follows:

• If state S is "empty" in SM_A (i.e. it does not have any embedded state machine), then it is allowed to add any embedded state machine in state S of SM_B
• If state machine SM_E is embedded in state S in SM_A, then, in state S of SM_B, it is allowed to replace SM_E with a state machine derived from SM_E

The basic idea is that, during the state machine extension process, you are allowed either to add new embedded state machine or to replace existing embedded state machines with their children (i..e when you extend a state machine, you can also extend its embedded state machines - see figure below).

smembeddingandderivation

NB: Marcel points out to me that the current implementation of the FW Profile does not allow an embedded state machine in a base state machine to be overridden.

NB#2 This issue was initially and mistakenly submitted in the cordetfw project.