Re: AS/400 Program Call

["Fred Kulack" <kulack@xxxxxxxxxx>]

On 05/10/2001 at 02:29:26 PM, owner-java400-l@midrange.com wrote:
     I have a program, that resides on a server and is called by serveral
clients. Further one thread of this program calls programs on an AS/400
that create a file, do some work, and returns to the java thread. My
problem is this: I need to use the same file for all instances of the
program calls on the AS/400 and I can not have more than 1 client
calling the AS/400 programs at once as the file can not be overwritten
by client 2 while client 1 is running the AS/400 programs. I have
syncronized the method of the thread but do not feel like this is
sufficient. Does anyone have a suggestion. Thanks in advance.

--- end of excerpt ---

You never really said if or when that file was modified anywhere else
in the application or on the system.

If the file is ONLY touched by the program that you call and you
ONLY call that program from Java, then simply using sychronized
around the java code that calls the program, would be sufficient.

However, you've probably got some other issues regarding just simple
thread safety that you need to be concerned about any time you
call out to native methods.

You need to be sure the program is thread safe in general
as a seperate question from the 'serialize access to the file
due to application requirements'.
http://www.as400.ibm.com/developer/threads

Since I do JDBC, I might think about calling the program
via JDBC using the SQL CALL statement. Then, you could create
1 JDBC connection for each client, have the program use
QTEMP, and handle as many clients as you want at the same
time.
Each client gets a JDBC connection. When the client is finished,
the JDBC connection is saved for a subsequent client.



"The stuff we call "software" is not like anything that human society
  is used to thinking about. Software is something like a machine, and
  something like mathematics, and something like language, and
  something like thought, and art, and information...
  but software is not in fact any of those other things."
Bruce Sterling - The Hacker Crackdown

Fred A. Kulack  -  AS/400e  Java and Java DB2 access, Jdbc, JTA, etc...
IBM in Rochester, MN  (Phone: 507.253.5982   T/L 553-5982)
mailto:kulack@us.ibm.com   Personal: mailto:kulack@bresnanlink.net
AOL Instant Messenger: Home:FKulack  Work:FKulackWrk

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