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From Brandon Goodin <brandon.goo...@gmail.com>
Subject Re: Combined DAO manager with a SqlMap client. Wrong?
Date Fri, 10 Feb 2006 23:01:11 GMT
"In JPetStore, if I remember right, commands are executed through a
daomanager.update() versus a sqlmap.update().  Am I correct? "

This is not correct. The DaoManager is used to retrieve an instance of
the Dao. One of the fuctions of the DaoManager is to be a Dao Factory.
In the dao.xml DAO interfaces are mapped to DAO implementations. The
DaoManager passes back the implementation of the DAO interface.

Another function of the DaoManager is transaciton management. When
using the DaoManager in conjunction with SqlMaps it retrieves an
intance of the Dao and also passes itself into the Dao implemenations
constructor. That is why classes that use the DaoManager in
conjunction with SqlMaps extend the SqlMapDaoTemplate.

In a standard web architecture you may see something like:

Application --> Service --> Data Access

Application is where Struts/JSP or whatever lives.
Service is where the Dao Manager exists.
The Data Access layer is where the SqlMaps exists.

The service layer is where you would make more course grained calls
that are made up of fine grained calls to the Data Access layer. Since
the service layer is responsible for grouping together calls to the
Data Access layer (or DAO classes) you would want to manage
transactions on the service layer. If you have mulitple calls to
multiple DAO classes in a method on your service class you would want
to wrap them in a transaction in the service class method. You would
do this with daoManager.startTransaction() etc...

In your Dao that extends SqlMapDaoTemplate you would simple calls the
queryFor.., insert,update, delete methods. These methods are calling
the SqlMapClient/SqlMapClientImpl as you normally would if you never
used the DaoManager. The only difference is that the calls are being
passed through the SqlMapDaoTemplate class and the transactions are
being managed by the DaoManager.

Hope that helps,

On 2/10/06, Albert L. Sapp <asapp@uiuc.edu> wrote:
> Brandon Goodin wrote:
> >Actually JPetstore does use the SqlMapDaoTemplate. All of the DAO
> >class extend BaseSqlMapDao which extends SqlMapDaoTemplate.
> >
> >In your case I am not completely clear on what you are doing. Perhaps
> >you can provide code from your application that shows us how you are
> >using iBatis. Code coupled with you explanation can go a long way.
> >
> >Brandon
> >
> >public class BaseSqlMapDao extends SqlMapDaoTemplate {
> >
> >On 2/10/06, Albert L. Sapp <asapp@uiuc.edu> wrote:
> >
> >
> >>Ok, we think we have found why our application transaction handling is
> >>not working right, but want to verify it.
> >>
> >>We downloaded and setup JPetStore to run against our Oracle database.
> >>No changes where made to the configuration of the database.  We modified
> >>the order placing function to force it to violate a primary key
> >>constraint on one (create order) of the multiple sql commands it does
> >>within the transaction.  This caused all the commands to rollback as we
> >>would expect.  No update of the quantity on hand of the item occured.
> >>
> >>In our application we define a DaoManager, but never reference the
> >>SqlMapDaoTemplate.  Instead, in our persistance layer, we define using
> >>the SqlMapClientBuilder a SqlMapClient.  All operations use this
> >>SqlMapClient (sqlmapclient.queryForList...).  Calls to start a
> >>transaction execute daomgr.startTransaction.  Extra layers of
> >>inheritance where implemented in the application by the then project
> >>head.  Don't ask me why.  Anyway, when we do a transaction all the sql
> >>commands up to the command that fails commit, when they should all
> >>rollback.  Same database with same configuration on it.
> >>
> >>It appears that JPetStore uses the DaoManager to execute the
> >>queryForList and such with no actual build of a SqlMapClient.  Am I
> >>correct?  Is that why our transactions don't rollback correctly?
> >>Otherwise, I am at a loss for why JPetStore rolls back correctly and our
> >>application does not.  We are having to use stored procedures right now
> >>to get the proper rollback, but one of the requirements is that the
> >>application not be database dependant.  In other words, no having to
> >>convert stored procedures on one database to another.
> >>
> >>Any help or comments would be greatly appreciated.
> >>
> >>Al
> >>
> >>
> >>
> >>
> >
> >
> >
> Brandon,
> I will try this again and leave out as much of the exception handling as
> I can.  I will try to trace through what I think is happening though I
> have never fully understood the explaination I was given.
> 1.  Say we want to create a inventory item.  We have collected all the
> information in our web page and created a transfer object bean in our
> action.  The action calls the appropriate manager.  In this case, it
> calls the StoreroomManager, which is implemented in the
> StoreroomManagerImpl and extends the BaseManager.
> 2.  We execute "startTransaction();", which executes
> "daoManager.startTransaction();" in the BaseManager.  BaseManager is
> where the DaoManager is defined and configured.
> 3.  Then, we execute "inventoryItemDAO.create(newInventoryItem);".
> inventoryItemDAO was defined "inventoryItemDAO =
> (InventoryItemDAO)getDao(InventoryItemDAO.class);" using the getDao
> defined in BaseManager.
> 4.  We go to SqlMapInventoryItemDAO which extends BaseDAO.
> 5.  The BaseDAO executes these commands:
>     a,  "reader = Resources.getResourceAsReader(sqlMapConf);"
>     b.  "sqlMap = SqlMapClientBuilder.buildSqlMapClient(reader);"
>     c.  create() contains "executeUpdate(getEntityName() + "Insert",to""
> which translates as "executeUpdate("InventoryItemInsert", inventoryItem)"
>     d.  executeUpdate contains "return
> sqlMap.update(InventoryItemInsert, inventoryItem);"
> 6.  This executes the statement in the inventoryItem.xml file called
> "InventoryItemInsert".
> 7.  If no exceptions are thrown, we execute "commitTransaction();",
> which executes "daoManager.commitTransaction();" in the BaseManager.
> I can send you the files themselves if you need to see them.  For single
> sql commands in a transaction, it either commits or rollback as we would
> expect.  With something like:
> startTransaction();
> invoiceDAO.createInvoice(new Invoice);
> for (int i = 0; i < invoiceItem.size(); i++)
> {
>     invoiceItem = (InvoiceItem) invoiceItems.get(i);
>     invoiceItemDAO.createInvoiceItem(invoiceItem);
> }
> inventoryItem.updateInventoryItem(inventoryItem);
> for (int z = 0; z < transactions.size(); z++)
> {
>     transaction = (Transaction) transactions.get(z);
>     transactionDAO.createTransaction(transaction);
> }
> stopTransaction();
> Everything is commited prior to an exception being encountered with only
> the current sql command, that caused the exception, being rolled back.
> Since this is contained in try blocks to trap exceptions, we always call
> endTransaction().
> In JPetStore, if I remember right, commands are executed through a
> daomanager.update() versus a sqlmap.update().  Am I correct?  Am I miss
> reading JPetStore code execution?  By executing the SqlMapClientBuilder
> instead of letting the daomanager use the SqlMapDaoTemplate taking
> control away from the daomanager transaction control?
> If you need the files, let me know.  In the meantime, I have begun
> rewriting the application in the pattern that JPetstore uses, since I
> know that it does the rollback correctly.
> Thanks,
> Al

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