Xref: utzoo comp.lang.rexx:450 comp.sys.amiga.programmer:2512
Newsgroups: comp.lang.rexx,comp.sys.amiga.programmer
Path: utzoo!utgpu!cunews!bnrgate!bcrka451!cadnews
From: vansickl@bcrka340.bnr.ca (Greg VanSickle 1561848)
Subject: anomalous AREXX behaviour
Message-ID: <1991Apr9.151344.21097@bnr.ca>
Originator: vansickl@bcrka340
Sender: vansickl@bcrka340
Organization: Bell-Northern Research, Ottawa, Canada
Distribution: na
Date: Tue, 9 Apr 91 15:13:44 GMT

While showing rexx to a freind I typed in the simple programme given
in AC's Tech Amiga article on Interprocess Communication.
It didn't work! The source for the two programmes are given below -
note the two trace statements marked as T1 and T2, the symptoms
depended heavily on them. Simple1 runs simple2, sends it 25 messages,
then quits. Simple2 opens a port, waits for 25 messages, displays them,
closes the port and quits:


/* simple1.rexx */
                
trace r                                       <---- T1
address command
call addlib("rexxsupport.library",0, -30, 0)
run rx simple2
call delay(300)
address PORT
do i = 1 to 50 by 2
   i i i
end
exit



/* simple2.rexx */

trace r                                       <---- T2
call openport(PORT)
call delay(500)
do i = 1 to 50 by 2
   call waitpkt(PORT)
   pkt = getpkt(PORT)
   say getarg(pkt)
   call reply(pkt)
end
call closeport(PORT)
exit


If T1 isn't included, and T2 is, then the program runs to
completion as expected. However, if T2 is not included then
I get the following sent to the consol:

      1 1 1
      3 3 3
      5 5 5
      7 7 7

      Error 18 in line 8: Invalid argument to funtion
      +++ command returned 10

      Command returned 10/18: Invalid argument to function
      +++ Error 13 in line 9: Host Environment not found

      bin:rexx/rx faiiled (return code 10)


If T1 is included and T2 is not then I get a similar result
but it fails on the first message, not the 5th.

Question 1:  'address PORT'  ... 'i i i' must build a packet and send
             it to the port PORT. Does the programme continue past
             the statement  'i i i' before the reply message is received?

Question 2:  I noticed that it's difficult to keep consol output separate
             when two rexx programmes are running. Does anyone know an easy
             way to keep the output from simple1 and simple2 separate ?

Question 3:  I make the following (but shakey) conclusion, is it correct?

             Between waitpkt and getpck in simple2, simple1 terminates,
             which means the reply port disappears, hence PORT is no
             longer a valid argument for getpkt. This implies the answer
             to question 1 is 'yes', ie. all 25 messages are sent regardless
             of the status of replies to any of them. If this is the case,
             the programme is fundamentally flawed.

Question 4:  How do you make this work?


Thanks in advance.
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Geg VanSickle                                Silicon Support
                                                
Bell Northern Research                       phone: 613-763-5160                            
PO Box 3500                                  ESN: 393-5160
Nepean, Ontario, Canada                      
K2H 8V4                                      cocos: Greg Van Sickle
                                             email: vansickl@bnr.ca
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