Example 7-1 Committing the Current Transaction

In this example, commit() is a method that commits the current Transaction. In the example, dp is the DataProvider.

private void commit()
{
  try 
  {
    (dp.getTransactionProvider()).commitCurrentTransaction();
  } 
  catch (Exception ex) 
  {
    System.out.println("Could not commit the Transaction. " + ex);
  } 
}

Example 7-2 Rolling Back a Transaction

This example uses the TopBottomTemplate and SingleSelectionTemplate classes that are described in Creating Dynamic Queries. In creating the TopBottomTemplate and SingleSelectionTemplate objects, the example uses the same code that appears in Example 10-4. This example does not show that code. It sets the state of the TopBottomTemplate. It begins a child Transaction that sets a different state for the TopBottomTemplate and then rolls back the child Transaction. The println method displays text through a CursorPrintWriter object and the getContext method gets a Context11g object that has methods that create Cursor objects and display their values through the CursorPrintWriter. The CursorPrintWriter and Context11g classes are used by the example programs in this documentation.

// The current Transaction is a read Transaction, t1.
// Create a TopBottomTemplate using a hierarchy of the PRODUCT_AWJ dimension
// as the base and dp as the DataProvider.
TopBottomTemplate topNBottom = new TopBottomTemplate(prodHier, dp);

// Changing the state of a Template requires a write Transaction, so a
// write child Transaction, t2, is automatically started.
topNBottom.setTopBottomType(TopBottomTemplate.TOP_BOTTOM_TYPE_TOP);
topNBottom.setN(10);
topNBottom.setCriterion(singleSelections.getSource());

// Get the TransactionProvider and commit the Transaction t2.
TransactionProvider tp = dp.getTransactionProvider();
try
{
  tp.commitCurrentTransaction();           // t2 disappears
}
catch(Exception e)
{
  println("Cannot commit the Transaction. " + e);
}

// The current Transaction is now t1.
// Get the dynamic Source produced by the TopBottomTemplate.
Source result = topNBottom.getSource();

// Create a Cursor and display the results
println("\nThe current state of the TopBottomTemplate" +
        "\nproduces the following values:\n");
getContext().displayTopBottomResult(result);

// Start a child Transaction, t3. It is a read Transaction.
tp.beginSubtransaction();          // t3 is the current Transaction

// Change the state of topNBottom. Changing the state requires a 
// write Transaction so Transaction t4 starts automatically.
topNBottom.setTopBottomType(TopBottomTemplate.TOP_BOTTOM_TYPE_BOTTOM);
topNBottom.setN(15);

// Commit the Transaction.
try
{
  tp.commitCurrentTransaction();           // t4 disappears
}
catch(Exception e)
{
  println("Cannot commit the Transaction. " + e);
}

// Create a Cursor and display the results. // t3 is the current Transaction
println("\nIn the child Transaction, the state of the" +
        "\nTopBottomTemplate produces the following values:\n");
getContext().displayTopBottomResult(result);
// The displayTopBottomResult method closes the CursorManager for the
// Cursor created in t3.

// Undo t3, which discards the state of topNBottom that was set in t4.
tp.rollbackCurrentTransaction();        // t3 disappears

// Transaction t1 is now the current Transaction and the state of
// topNBottom is the one defined in t2.

// To show the current state of the TopNBottom template Source, commit
// the Transaction, create a Cursor, and display the Cursor values.
try
{
  tp.commitCurrentTransaction();
}
catch(Exception e)
{
  println("Cannot commit the Transaction. " + e);
}

println("\nAfter rolling back the child Transaction, the state of"
        + "\nthe TopBottomTemplate produces the following values:\n");
getContext().displayTopBottomResult(result);

The example produces the following output.

The current state of the TopBottomTemplate
produces the following values:
 
 1. PRODUCT_PRIMARY::TOTAL_PRODUCT::TOTAL
 2. PRODUCT_PRIMARY::CLASS::SFT
 3. PRODUCT_PRIMARY::FAMILY::ACC
 4. PRODUCT_PRIMARY::CLASS::HRD
 5. PRODUCT_PRIMARY::FAMILY::MOD
 6. PRODUCT_PRIMARY::FAMILY::OS
 7. PRODUCT_PRIMARY::FAMILY::DISK
 8. PRODUCT_PRIMARY::ITEM::MOUSE PAD
 9. PRODUCT_PRIMARY::ITEM::OS 1 USER
10. PRODUCT_PRIMARY::ITEM::DLX MOUSE
 
In the child Transaction, the state of the
TopBottomTemplate produces the following values:
 
 1. PRODUCT_PRIMARY::ITEM::EXT CD ROM
 2. PRODUCT_PRIMARY::ITEM::OS DOC ITA
 3. PRODUCT_PRIMARY::ITEM::OS DOC SPA
 4. PRODUCT_PRIMARY::ITEM::INT CD USB
 5. PRODUCT_PRIMARY::ITEM::ENVY EXT KBD
 6. PRODUCT_PRIMARY::ITEM::19 SVGA
 7. PRODUCT_PRIMARY::ITEM::OS DOC FRE
 8. PRODUCT_PRIMARY::ITEM::OS DOC GER
 9. PRODUCT_PRIMARY::ITEM::ENVY ABM
10. PRODUCT_PRIMARY::ITEM::INT CD ROM
11. PRODUCT_PRIMARY::ITEM::ENVY EXE
12. PRODUCT_PRIMARY::ITEM::OS DOC KAN
13. PRODUCT_PRIMARY::ITEM::ENVY STD
14. PRODUCT_PRIMARY::ITEM::1GB USB DRV
15. PRODUCT_PRIMARY::ITEM::SENT MM
 
After rolling back the child Transaction, the state of
the TopBottomTemplate produces the following values:
 
 1. PRODUCT_PRIMARY::TOTAL_PRODUCT::TOTAL
 2. PRODUCT_PRIMARY::CLASS::SFT
 3. PRODUCT_PRIMARY::FAMILY::ACC
 4. PRODUCT_PRIMARY::CLASS::HRD
 5. PRODUCT_PRIMARY::FAMILY::MOD
 6. PRODUCT_PRIMARY::FAMILY::OS
 7. PRODUCT_PRIMARY::FAMILY::DISK
 8. PRODUCT_PRIMARY::ITEM::MOUSE PAD
 9. PRODUCT_PRIMARY::ITEM::OS 1 USER
10. PRODUCT_PRIMARY::ITEM::DLX MOUSE