Process Identification (PId) Each SDL process has a unique identifier, a value of data type PId. Special value NULL (no process) Predefined variables SELF: the process itself OFFSPRING: the most recent process created by SELF PARENT: SELF is OFFSPRING of PARENT SENDER: the process that sent the last signal received and processed by SELF 2007, rev. 08 SEG2101 Chapter 5

Use of PId Variables 2007, rev. 08 SEG2101 Chapter 5

Use of PId Variables (II) 2007, rev. 08 SEG2101 Chapter 5

5.5: Dynamic Generation of Process Instances In SDL, a process may create other processes. The creation is shown by a dashed line from PARENT to OFFSPRING. Blocks cannot be generated dynamically. 2007, rev. 08 SEG2101 Chapter 5

Creation of Processes 2007, rev. 08 SEG2101 Chapter 5

PROCESS CUControl Create Symbol 2007, rev. 08 SEG2101 Chapter 5

Process parameters 2007, rev. 08 SEG2101 Chapter 5

Stop Symbol Processes are created by their parent. A process terminates when it reaches a stop symbol. (Note: processes may not kill each other). 2007, rev. 08 SEG2101 Chapter 5