Extract message from queue
receive( extracts an input
or local message from its receiving queue. If a valid message exists,
true. If a valid message
does not exist but there is a message in the queue, the chart removes the message
from the queue and
true. If a
valid message does not exist and there are no messages in the queue,
Check the queue for message
M and increment the value
x if both of these conditions are true:
A message is present in the queue.
The data value of the message is equal to 3.
If a message is not present or if the data value is not equal
to 3, then the value of
x does not change. If a message
is present, remove it from the queue regardless of the data value.