RE: JDBC Data Source -- JAVA400-L

Richard

Bare with me.  I don't know if I know enough to ask
the right questions.

According to the javadocs: javax.sql.DataSource is

"a factory for Connection objects. An object that
implements the DataSource interface will
typically be registered with a JNDI service provider.
A JDBC driver that is accessed via the DataSource API
does not automatically register itself with the DriverManager."

So when you say "DataSource classes are specific to
the driver they work with." I get confused.

In Websphere there is a "Default DataSource" configured
which I use to get DB connections in all my servlets.

My question is how do I configure a DataSource to
use 1 pool of connections across all of my servlets
in Tomcat?

I've tested the ConnectionPool example from the book
"SERVLETS  and  JAVASERVER  PAGESTM by Marty Hall" but
it is a pool per servlet.  He talks a little about
a pool across the application server but doesn't give a
complete example.

Thanx, PLA

-----Original Message-----
From: owner-java400-l@midrange.com
[mailto:owner-java400-l@midrange.com]On Behalf Of Richard Dettinger
Sent: Wednesday, June 27, 2001 10:16 AM
To: JAVA400-L@midrange.com
Subject: RE: JDBC Data Source



Note:  when throughout this note, when I talk about there being a
DataSource class (like DB2DataSource), I really mean to suggest that there
is a complete suite of DataSources classes around that same base name (like
DB2ConnectionPoolDataSource and all the other stuff).

Which JDBC driver are you going to use?  DataSource classes are specific to
the driver they work with.  The native JDBC driver has a DB2DataSource and
DB2StdDataSource class which can be used to create connections (you would
want to use DB2StdDataSource as the DB2DataSource is a non-standard variety
from before there was a complete standard).  I think there is a prototype
of a connection pool implementation that uses them shipped with the driver,
but I would suggest you build your own pool if you are going to use these
(its not very hard).  That is what websphere does (which is why I never
wrote the complete pooling module in the first place).

The Toolbox JDBC driver has an AS400JDBCDataSource class which does the
same thing with toolbox connections.  They also have a class called
AS400ConnectionPool which is an implementation of a pool (I think).  I will
leave it up to someone else to explain it in more detail or you to read the
javadoc for it or ask more specific questions about it.  Here is something
interesting though... you could probably specify the Toolbox connection
property of driver=native and use the AS400JDBCDataSource class to
implement a native JDBC connection pool.  I don't know that it would work,
but I can't see an immediate reason why it wouldn't/shouldn't.

As far as running a naming service, in stand alone applications, I have
always used JNDI and the fscontext support (I think that is still a
seperately availble jar file).  The fs stands for file system and it allows
you to run JNDI over the file system.  So I persist my datasource to some
common IFS directory and load it from there to create the pool.

Finally:  I wrote a new set of data source classes for the Native JDBC
driver in v5r1 which I will be discussing in an article in the September
issue of News/400.  They are UDBDataSource, UDBConnectionPoolDataSource,
etc.  They are designed to support connection and statement pooling
completely transparently to the running applications that use them (read
the JDBC 3.0 spec available from Sun's website if you want to learn about
statement pooling and how it works).  This new feature does have all the
pooling support available (the pool gets created internally based on the
DataSource properties).  There is no XA support in this new feature yet,
but that will likely be in our next release.  If people are interested in
seeing some of the source code for the article that creates/uses the new
support, send me an e-mail and I will forward some examples to you (as I
get them written, that is).  There is some thought of allowing this new
DataSource feature work with both Native and Toolbox JDBC drivers, but I
have not done any work in that area just yet.

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


"Patrick L Archibald" <Patrick.Archibald@HOMETELCO.COM>@midrange.com on
06/27/2001 06:56:52 AM

Please respond to JAVA400-L@midrange.com

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


To:   <JAVA400-L@midrange.com>
cc:
Subject:  RE: JDBC Data Source




Along the same  lines as Giles,� I'd like to know how  to set up a
DataSource connection pool in Tomcat on the AS/400.

Thanx,  PLA
-----Original Message-----
From: owner-java400-l@midrange.com  [mailto:owner-java400-l@midrange.com]On
Behalf Of DUCRET Gilles  (GVA)
Sent: Wednesday, June 27, 2001 3:25 AM
To:  'JAVA400-L@midrange.com'
Subject: JDBC Data  Source



Hi all,

has anyone of you ever used the Jdbc 2 datasource  feature on the as400?

In this cas, how do you run/manage the naming  service on the AS400 without
using  Websphere.

With Websphere it is really easy, since you can  declare this datasource.

In this case i can't use websphere.

Any example?

Many thanks

Gilles Ducret
Wealth Management Division
IT  Architect
Lloyds TSB Bank
Tel: + 41 22 307 31 50
Mob: +41 79 217 21 41


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