In the GAE/J documentation under "How-To | Handling Scheduled
Maintenance Periods", it states:
"During this period, all datastore writes and transactions will throw
an exception. Your application can detect these errors and indicate to
the user that the application is in read-only, recommending that they
try again later."
An example is then given to catch the relevant exception during
PersistenceManager#makePersistent(...), but I cannot find an example
for datastore updates of already-existing entities.
Does anyone know at what point an update to a persistent entity (not
using PersistenceManager#makePersistent(...)) will result in the
CapabilityDisabledException exception being thrown? For example, where
in the following code extract could I expect this exception?
// Non-GAE method to return the singleton instance
PersistenceManagerFactory pmf =
DataExchange.getPersistenceManagerFactory();
PersistenceManager pm = pmf.getPersistenceManager();
Transaction tx = pm.currentTransaction();
try
{
tx.begin();
// Non GAE method to get a detatched instance by its ID
(within the current tx)
Item itemEdit = findItemByID(tx, pidData.loID,
loLoggedOnUserID);
// Non GAE method to amend the itemEdit instance
itemEdit = updateItemWithPageItemData(tx, itemEdit, pidData,
ipmMode);
tx.commit();
}
finally
{
try
{
if (tx.isActive()) // Because of an exception, say
{
tx.rollback();
}
}
finally
{
pm.close();
}
}
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