Process Identification (PId)

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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

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Use of PId Variables
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Use of PId Variables (II)
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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.

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Creation of Processes
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PROCESS CUControl
Create Symbol
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Process parameters
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Stop Symbol

• Processes are created by their parent.
• A process terminates when it reaches a stop
  symbol. (Note processes may not kill each
  other).