RE: Asynchronous IO api

["Lim Hock-Chai" <Lim.Hock-Chai@xxxxxxxx>]

It is probably a overkill for what I need.  However, I thought I'll create a 
standard one that can stand the test of time.

I attended one of the John Kasperski's class in the COMMONS.  He provided an 
example in C.  We are RPG shop and C will probably not goes well in our 
environment.  I was going to try to translate the example to RPG but the multi 
thread thing seems to be making it impossible.

Chapter 8 in the red-book below talks about the benefit of using Async IO with 
socket programming
http://publib.boulder.ibm.com/html/as400/v5r1/ic2994/info/rzab6/rzab6mst.pdf


Thanks for everybody's respond.



-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx]On Behalf Of Bruce Vining
As usual it, of course, all depends.

send() and recv() are synchronous in nature.  You call the APIs and your
code basically waits for the send and/or receive APIs to copy your buffer
of data to/from internal buffers.

QsoStartSend() and QsoStartRecv() are asynchronous in nature.  You call the
APIs and control is returned to you almost immediately.  While your code
continues on its way to do other things the system is, in the background,
sending or receiving data into the buffer you specified on the Qso* call.
Your code should not do anything with the buffer until the background
operation has completed (or terrible things might happen) but could be
doing "other" processing if there is any.

For some applications this ability to have the IO performed asynchronously
while the application continues to process may be of little or no value.
For other applications it might provide significant performance
improvements.  I really can't say where your application may fall in this
range as the ability to productively use these features is very application
specific.

As you mentioned combining asynch IO APIs and sockets APIs (which I
interpret as meaning send() and recv()) I will point out that the Usage
Notes for the Qso* APIs recommend not using these two sets of APIs on the
same socket.

Bruce



                                                                           
             "Lim Hock-Chai"                                               
             <Lim.Hock-Chai@ar                                             
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I used Scott's socket tutorial to create a client side socket program a
while back.  It works wonderfully.
Currently, I'm researching on creating a server side socket program.
Combine Async IO and Socket APIs seem to be the most efficient way for
this.  However, as Scott mentioned, I did notice that Async IO apis are
multi threaded.  That is way I post the question to make sure that it can
be done in RPG before I try it.

Bruce:  Will I still get a lot of benefit out of it if I use Async IO with
single thread?


Thanks.


-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx]On Behalf Of Bruce Vining

Scott,

If by asynchronous IO you are refering to the Qso* socket APIs then
consider yourself gently corrected :)

While the Information Center examples refer to and use a multi-threaded
server environment you can also use asynchronout IO from a single threaded
environment and still obtain the benefits that the APIs provide.

Bruce

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