Re: DB2 JDBC native driver

["Richard Dettinger" <cujo@xxxxxxxxxx>]

1) Is it impossible to use a DB2 JDBC driver if you have DB2 installed on
the
NT PC on which you're running VAJ?

You could use the JDBC driver shipped with DB2 on the NT PC and it would
talk to either the local DB2 database or I assume it could talk to the real
AS/400 database via DRDA.  I don't suggest you do this.  You can't use the
Native JDBC driver shipped with the 400/iSeries from NT (that I know of -
and I wrote it so it seems unlikely.  Perhaps VAJ remote support for
debugging... perhaps there is something there).  The suggestion I have is
to plan to develop/test with the Toolbox JDBC driver in VAJ and move to the
Native JDBC driver for performance on the host.

2) so there's potentially incompatibility between the development (NT) &
test/live (AS/400) JDBC drivers.

True, but we are trying very hard to eliminate these.  If incompatibilities
between the drivers are brough to our attention (this group would be a fine
place to do so - or e-mail me), we try to resolve them right away where
possible.  You might not always like the resolution, we might decide that
the driver that you were coding to is the one that needs to change for
specification compliance, performance or other reasons.  But we are trying
to get them to be very similar in functionality.  We use a common test
bucket for the two drivers that has about 7,000 tests of the various
interfaces and we work closely on new features (like JDBC 3.0 support).
The drivers are not identical.  They probably never will be.  But by
comparison, we do relatively little comparison testing with the JDBC
drivers shipped for other platforms (UDB on NT for example).  There are
many more subtle differences that can creep in when you go that route.

3) You also, although it may seem a trivial point, don't have to mess about
with the classpath.

This is a good time to be able to point out that the native JDBC driver is
in the classpath automatically only when you are running on JDK 1.1.X.
With JDK 1.2 and beyond, the Native JDBC driver is a JVM extension.  Its
still shipped with the system and ready for use, but there is a one time
setup that is needed to 'register' the driver in the extensions directory.
Here is a new entry that will be added to our faq in the short term future.
(The faq is at http://www.as400.ibm.com/developer/jdbc/Faqs/JDBCFAQ.html).
If there are things that are not in the faq that should be, please e-mail
them to me.  I have a list of a couple new items that I am maintaining for
when I have a rainy day - which almost never happens in Rochester. :)

B19. How do I get the native JDBC driver to be found in JDK 1.2 and beyond?


In JDK 1.2, functions like JDBC, SSL, and JNDI are JDK extensions. To use a
JDK extension, first find the ".jar" file in the
'/QIBM/ProdData/Java400/ext/' directory. Then, a symbolic link needs to be
established once to make the files a part of the
'/QIBM/UserData/Java400/ext/' directory. This is so that the class loader
can find them. For example, to establish the symbolic link for JDBC, use
the following command:
Pre-V5R1:
ADDLNK OBJ('/QIBM/ProdData/Java400/ext/db2_classes.jar') NEWLNK
('/QIBM/UserData/Java400/ext/db2_classes.jar')
V5R1 and Later:
ADDLNK OBJ('/QIBM/ProdData/OS400/Java400/ext/db2_classes.jar') NEWLNK
('/QIBM/UserData/Java400/ext/db2_classes.jar')



Note: WebSphere 3.6 will create this link automatically if it does not
exist, otherwise it will have to be done by hand.



If you need to use JDBC 2 Optional Package features in your application
(like DataSources), add this link:
ADDLNK OBJ('/QIBM/ProdData/Java400/ext/jdbc2_0-stdext.jar') NEWLNK
('/QIBM/UserData/Java400/ext/jdbc2_0-stdext.jar')



If you need to use JTA (Java Transaction API) features in your application,
add this link:
ADDLNK OBJ('/QIBM/ProdData/Java400/ext/jta-spec1_0_1.jar') NEWLNK
('/QIBM/UserData/Java400/ext/jta-spec1_0_1.jar')


Regards,

Richard D. Dettinger
AS/400 Java Data Access Team

"Biologists have a special word for stability -- dead"

                Larry Wall
                Open Source Developers Journal
                Issue 1, Jan  2000


mandy.shaw@uk.catalyst-solutions.com@midrange.com on 02/13/2001 05:30:24 PM

Please respond to JAVA400-L@midrange.com

Sent by:  owner-java400-l@midrange.com


To:   JAVA400-L@midrange.com
cc:
Subject:  Re: DB2 JDBC native driver



Is it impossible to use a DB2 JDBC driver if you have DB2 installed on the
NT PC on which you're running VAJ?

One of my customers is thinking of giving this a whirl. I have encouraged
him to use the Toolbox instead.  He is using the native DB2 driver on
AS/400 for the live app, so there's potentially incompatibility between the
development (NT) & test/live (AS/400) JDBC drivers. I have pointed out that
there'll probably be incompatibility between NT & AS/400 versions of the
DB2 driver anyway, & that testing the particular aspects of JDBC used
(basically, stored procedures with various combinations of in, out, inout
parameters and/or result sets) against both drivers with a special test
harness is probably the answer. (I have encountered large numbers of
incompatibilities in the past between OS/400 releases and PTF levels,
before you even worry about whether it's DB2 or Toolbox.)

Perhaps other people who are in this situation of having to use different
JDBC drivers for dev & live could comment on what they've encountered, as
well?

Incidentally I originally advised him to use of the DB2 driver in the live
environment, fundamentally because it's running over SNA for security and
the Toolbox doesn't support SNA, but also because our experience indicates
much better performance than with the Toolbox, even when the latter is
optimised to level 40. You also, although it may seem a trivial point,
don't have to mess about with the classpath.

Mandy





cujo@us.ibm.com on 12/02/2001 14:53:36

Please respond to JAVA400-L@midrange.com

To:   JAVA400-L@midrange.com
cc:    (bcc: Mandy Shaw/Pacific/UK)
Subject:  Re: DB2 JDBC native driver






You wrote:  "Basically I want to develop and debug my code inside IDE
(VisualAge) by using DB2 native JDBC driver. "

You can't (to the best of my knowledge).  Perhaps there is remote debug
support to some degree that you really can do this, but I am not wise
enough in the VAJ world to know it.  If someone knows how to make this
work, please assist.

Now, unless someone says that VAJ can do this, here is why.  The native
JDBC driver in its primary static initializer (you can't even create an
object before this happens), starts talking directly to the CLI on which
its built.  There is no network, the APIs talk directly to each other.  You
can get from one AS/400 to another system by a lower level network layer
(DRDA).  Today, you just can't escape the fact that the "client" system
*must* be an AS/400.  Even if you found a way to piece the parts together
so it would work on a different CLI/ODBC implementation, you would run into
all kinds of problems because ODBC/CLI is not nearly as portable as JDBC
drivers are.

What you probably want to do, in light of this is build your application
around the Toolbox JDBC driver.  Then simply plug the Native JDBC driver in
when you move your application. This solution is perhaps not the best, and
it might require a bit more isolated testing after primary development is
done, but the approach works pretty seamlessly for most people.  If there
are differences in the way the JDBC API works between the two drivers, they
should be posted to us here and we will investigate them.  That doesn't
mean we can work all of them out, but they should appear pretty identical
to application code.

Regards,

Richard D. Dettinger
AS/400 Java Data Access Team

"Biologists have a special word for stability -- dead"

                Larry Wall
                Open Source Developers Journal
                Issue 1, Jan  2000


"Xu, Weining" <Weining.Xu@AIG.com>@midrange.com on 02/12/2001 08:14:40 AM

Please respond to JAVA400-L@midrange.com

Sent by:  owner-java400-l@midrange.com


To:   "'JAVA400-L@midrange.com'" <JAVA400-L@midrange.com>
cc:
Subject:  DB2 JDBC native driver





You wrote:
        2) To the best of my knowledge, the native JDBC jar file is not in
        VisualAge anywhere.  You can always take the jar file noted above
and put
        it in VisualAge but for most purposes, this isn't really needed
because you
        would already be coding to the JDBC API interface.

I imported db2_classes.jar into a project called DB2 inside VisualAge
environment.  I have "import com.ibm.db2.jdbc.app.*;" for my class.  I
checked the classpath to DB2 project. But when I run the program, it seems
still cannot load "com.ibm.db2.jdbc.app.DB2Driver".

What could be wrong?

Basically I want to develop and debug my code inside IDE (VisualAge) by
using DB2 native JDBC driver. Then deploy them on AS/400, so the production
programs will be run on AS/400 machine.  I do not have problem on AS/400
yet.

Thanks,

Wayne

-----Original Message-----
From: Richard Dettinger [mailto:cujo@us.ibm.com]
Sent: Monday, February 05, 2001 11:40 AM
To: JAVA400-L@midrange.com
Subject: RE: Updating result set in Java


This should help:

1) The native JDBC driver is not in the classpath be default with JDK 1.2
and beyond.  The following CL command will put the Native JDBC driver in
your extensions classpath and then you won't have to worry about it again:

ADDLNK OBJ('/QIBM/ProdData/Java400/ext/db2_classes.jar') NEWLNK
('/QIBM/UserData/Java400/ext/db2_classes.jar')

Of course,  you can just add it to your classpath if you want.  That will
fix the no suitable driver messages.

2) To the best of my knowledge, the native JDBC jar file is not in
VisualAge anywhere.  You can always take the jar file noted above and put
it in VisualAge but for most purposes, this isn't really needed because you
would already be coding to the JDBC API interface.

3) You can't run the native JDBC driver from a system that is not a 400
(iSeries).  This is because it is tied directly into the database and the
JVM.  You can connect from one 400 to another 400 or from one 400 to a
different backend (such as a 390) over DRDA, but you can't have your
'client' not be an AS/400 or iSeries.


Regards,

Richard D. Dettinger
AS/400 Java Data Access Team

"Biologists have a special word for stability -- dead"

                Larry Wall
                Open Source Developers Journal
                Issue 1, Jan  2000

"Xu, Weining" <Weining.Xu@AIG.com>@midrange.com on 02/05/2001 10:08:19 AM

Please respond to JAVA400-L@midrange.com

Sent by:  owner-java400-l@midrange.com

To:   "'JAVA400-L@midrange.com'" <JAVA400-L@midrange.com>
cc:
Subject:  RE: Updating result set in Java




Thanks, Richard.

As you suggested, I am running the program on AS/400 by using DB2 native
JDBC driver.  Now I got other problems on AS/400. I have multiple JDKs on
the AS400. In order to use the JDBC 2.0 API, I have to use JDK 1.2.  But I
got "no suitable driver" message.  I have no problem to load the driver if
I run the program using JDK1.1.8, of course in this case all JDBC2.0 API
methods will not be recognized.  Does AS400 Developer Kit for Java only
support JDK1.1.8?  Do I miss something here?

By the way, I tried to run the db2 JDBC native driver inside VisualAge for
JAVA 3.5. But the program can not find the driver.  Do you know where is
the package "com.ibm.db2.jdbc.app" inside the IDE.  I have no problem to
use the native driver on AS400 (for JDK1.1.8).  What I understood is that
on AS400 I am using AS/400 Developer Kit for Java,  how about inside
VisualAge?

I do have write authority to the table.  In fact, I can use SQL statement
to update the ID field of the TEST table. The code looks like this:

        String myUpdate = "update TEST set ID = RRN(TEST)+30";
        stmt = con.createStatement();
        stmt.executeUpdate(myUpdate);

Thanks.

-----Original Message-----
From: Richard Dettinger [mailto:cujo@us.ibm.com]
Sent: Monday, February 05, 2001 9:11 AM
To: JAVA400-L@midrange.com
Subject: RE: Updating result set in Java

You don't have write authority to the table??? No, I don't have another
guess.

Export your program to the 400 and use the Native JDBC driver to see if the
problem is the same.
If the problem is the same, the issue is likely to be something about the
database (either setup
or a bug).  If it works that way, its likely to be a Toolbox JDBC driver
issue which should be investigated.

Regards,

Richard D. Dettinger
AS/400 Java Data Access Team

"Biologists have a special word for stability -- dead"

                Larry Wall
                Open Source Developers Journal
                Issue 1, Jan  2000

"Xu, Weining" <Weining.Xu@AIG.com>@midrange.com on 02/02/2001 03:52:00 PM

Please respond to JAVA400-L@midrange.com

Sent by:  owner-java400-l@midrange.com

To:   "'JAVA400-L@midrange.com'" <JAVA400-L@midrange.com>
cc:
Subject:  RE: Updating result set in Java



rs.next() did return true.  The code was simplified. I do use while
(rs.next()) in my real code.

any other thought??

-----Original Message-----
From: Richard Dettinger [mailto:cujo@us.ibm.com]
Sent: Friday, February 02, 2001 4:23 PM
To: JAVA400-L@midrange.com
Subject: Re: Updating result set in Java

Are you sure the call to rs.next() returned true?  If you don't test the
boolean return value, the resultset could have been empty.  That's my
first, best guess.

Of course, you can write code however you want, but I always make it a
practice to use while(rs.next())  if I am going to process all the rows and
if (rs.next()) if I want to process only one.  This ensures that there is
always data before I go off and try to do something to the ResultSet.

Regards,

Richard D. Dettinger
AS/400 Java Data Access Team

"Biologists have a special word for stability -- dead"

                Larry Wall
                Open Source Developers Journal
                Issue 1, Jan  2000

"Xu, Weining" <Weining.Xu@AIG.com>@midrange.com on 02/02/2001 02:29:04 PM

Please respond to JAVA400-L@midrange.com

Sent by:  owner-java400-l@midrange.com

To:   "'JAVA400-L@midrange.com'" <JAVA400-L@midrange.com>
cc:
Subject:  Updating result set in Java


I have problem to update the result set programmatically. I use VisualAge
for Java 3.5 Enterprise Edition. My database is DB2 in AS/400.  I am using
JDBC 2.0 API features to update the field in the result set.  I got error
message:

SQLException: Cursor state not valid.
SQLState:  24000

Here is my sample code:

import java.sql.*;
import com.ibm.as400.access.*;

class Test {

public static void main(java.lang.String[] args) {
        Connection con = null;
        Statement stmt = null;
        ResultSet rs = null;

                // Load Java JDBC driver.
        try {

                Class.forName("com.ibm.as400.access.AS400JDBCDriver");
        } catch(java.lang.ClassNotFoundException e) {
                System.err.print("ClassNotFoundException: "+e.getMessage
());
                }
        try {

                con = DriverManager.getConnection
("jdbc:as400://wilm620/agtcomp", "myID", "mypassword");
        } catch (SQLException e){
                   System.err.println("Connection Error Exception: "
+e.getMessage());
                        }

        try{
                stmt = con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,
ResultSet.CONCUR_UPDATABLE);
                rs = stmt.executeQuery("select ID from AGTCOMP.TEST");

                //move the cursor to the first row and update the ID field
(Integer) to 30.
                rs.next();
                rs.updateInt(1,30);

                stmt.close();
                con.close();
        }catch (SQLException e){
                System.err.println("SQLException: "+e.getMessage());
                System.err.println("SQLState:  "+e.getSQLState());
        }

        System.exit(0);
}
}

I have tried to scroll the result set up and down, there is no problem to
do that. But I just cannot update it. Of course I can not do rs.updateRow()
to update the row in the database either.

Any helps will be highly appreciated.

Weining (Wayne) Xu
Phone: +302.594.2846
Email:   weining.xu@aig.com

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      Regards,
      Mandy Shaw

      Catalyst Solutions plc
      Kingfisher House
      Frimley Business Park
      Camberley
      Surrey
      GU16 5SG
      UK

      http://www.catalyst-solutions.com
      Email: Mandy.Shaw@uk.catalyst-solutions.com

      Telephone: +44 (0)870 166 1000
      DDI: +44 870 166 1324
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