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From "Jimmy Wan" <j...@21technologies.com>
Subject RE: Usage of TranQL
Date Wed, 12 Dec 2007 01:29:09 GMT
David, thanks for the response.
 
In our particular scenario, we have a handful of statically defined data
sources (configured/viewable via Geronimo), but we also have a
potentially large number of dynamic data sources that we're trying to
create on the fly. It is the configuration of these dynamic data sources
that is proving somewhat tricky. Up till now, we've been using some
combination of custom code, TranQL connectors, and vendor provided XA
DataSources. From the initial conversations on this list (years ago
now), the consensus seemed to be that the creation of dynamic data
sources would not really be possible without writing a GBean and jumping
through some hoops. Having created a similar system in the past where we
just created/bound the data sources directly into JNDI, that seemed like
a lot of work for minimal benefit.
 
Original Code:
We had been using JTA everywhere via BMT until we started running into
an issue with DDL apparently screwing up DML. So I decided to try and
separate out the usage of DDL/DML to separate data sources. Most of the
transactions are "pretty small". Everything is close to a
transaction-per-request or smaller. We have no "long-running"
transactions.
 
First Change:
I tried to move all DDL operations to separate XA data sources. This
didn't seem like the best idea and it didn't work.
 
Second Change:
JTA in code with BMT for DML. DDL will be handled in separate local JDBC
data sources that should have no transaction management. This is not
working yet, but it seems like this would be the best way to avoid
complications arising from the execution of DDL. As an aside, it is
possible to interact with the DDL and DML databases. The DDL/DML do not
need to be kept within a single transaction boundary.
 
In all cases, we are using custom JCA code. Originally, we couldn't find
the Geronimo JCA implementation. Now that I've seen it, it looks as
though it would be hard to programmatically add/remove data sources. The
Geronimo JCA implementation looks too heavyweight for what I'd like to
do. (just provide some connection info and be done).
 
________________________________

From: David Jencks [mailto:david_jencks@yahoo.com] 
Sent: Tuesday, December 11, 2007 15:10
To: user@geronimo.apache.org
Subject: Re: Usage of TranQL


The tranql lists are not exactly dead but there is very little
development going on.  Since you want to know how to use the connectors
inside geronimo this seems like a better list.

You  have left out a lot of details about what you are trying to do,
especially about transactions and how you are controlling them (JTA,
local, etc) and how much work you want to get into each transaction. 

Generally DDL doesn't mix well with transactions.  I suggest you use a
no-tx datasource such as the one we provide in geronimo 2.x for the DDL.
If you are not using JTA but rather local transactions then it would be
appropriate to use this datasource for the DML as well.  If you are
using JTA transactions then something like the system-datasource would
be more appropriate.

hope this helps
david jencks

On Dec 11, 2007, at 10:34 AM, Jimmy Wan wrote:


	Does anyone know if there is a new TranQL mailing list? The one
on codehaus appears to be dead, form the archives I found. It seems like
Tranql development was adopted by the Geronimo team, so I'll fire away
here.
	 
	I'm having some trouble with my application which needs to
perform plain SQL as well as execute some DDL. Right now, we are
incorrectly mixing the SQL/DDL which inadvertently commits things and
changes the autocommit values in ways that we don't want. I'd like to
completely separate my DDL statements by putting them into their own
entirely separate datasource but I'm unsure how to do this.
	 
	As I understand it, Tranql lets you do things such as have
non-XA resources participate in XA transactions. However, what if I have
things that need to happen outside the boundary of an XA transaction
(such as DDL)?
	 
	Using Derby as an example:
	There are two managed connection factories as part of the
tranql-connector-derby package: ClientLocalMCF backed by a non-XA driver
and ClientXAMCF backed by an XA driver.
	 
	Do I need to create a local data source backed by a
ClientLocalMCF as well as an XA data source backed by ClientXAMCF?
	
	Would it be OK to create two data source that are both backed by
the XA driver using ClientXAMCF as long as I keep my DDL operations
separate from the other SQL statements?
	Will executing DDL on my "DDL Datasource" cause problems if it
is backed by an XA DataSource?



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