This class provides an implementation of the start batched transaction
extended request. It may be used to begin a transaction that allows multiple
write operations to be processed as a single atomic unit. The
StartBatchedTransactionExtendedResult
that is returned will include a
a transaction ID. For each operation that is performed as part of the
transaction, this transaction ID should be included in the corresponding
request through the
BatchedTransactionSpecificationRequestControl
.
Finally, after all requests for the transaction have been submitted to the
server, the
EndBatchedTransactionExtendedRequest
should be used to
commit that transaction, or it may also be used to abort the transaction if
it is decided that it is no longer needed.
NOTE: This class, and other classes within the
com.unboundid.ldap.sdk.unboundidds
package structure, are only
supported for use against Ping Identity, UnboundID, and
Nokia/Alcatel-Lucent 8661 server products. These classes provide support
for proprietary functionality or for external specifications that are not
considered stable or mature enough to be guaranteed to work in an
interoperable way with other types of LDAP servers.
Transactions processed using this mechanism are called "batched transactions"
because the associated requests are collected in the server and are only
processed once the
EndBatchedTransactionExtendedRequest
has been
received to indicate that the transaction should be committed. As a result,
it is only possible to include write operations (in particular, add, delete,
modify, modify DN, and password modify operations) in a batched transaction.
Read operations (like search, bind, and compare) cannot be included in a
batched transaction. However, it is possible to use some controls within the
transaction and they may prove to be sufficient in many cases. The controls
that can be included in operations that are part of a batched transaction
include:
In particular, the assertion control may be used to ensure that an operation
is only performed if the target entry matches a given filter (which allows
for an atomic compare-and-swap operation), and the pre-read and post-read
controls may be used to retrieve a copy of an entry immediately before or
immediately after the operation was performed.
Note that even though the operations which are part of this transaction
aren't actually processed until the end batched transaction request is
received, the directory server will send back a response for each operation
that is to be performed as part of the transaction. If the result of this
response is
ResultCode.SUCCESS
, then it means that the server has
accepted the operation and it will be processed when the end batched
transaction request is received indicating that the transaction should be
committed. However, if it has some other result then it indicates that the
request may have been malformed or did not meet the requirements for the
transaction (e.g., it included a control that is not allowed for a
transaction). Note that even if the server returns a non-success response
for an operation prior to the end batched transaction request, the
transaction will still be active in the server and other operations may still
be included in the transaction if desired. If it is no longer desirable to
process the transaction, then the end batched transaction request should be
used to abort the transaction.
Example
The following example demonstrates the process for using batched
transactions. It will modify two different entries as a single atomic
unit.
// Use the start transaction extended operation to begin a transaction.
StartBatchedTransactionExtendedResult startTxnResult;
try
{
startTxnResult = (StartBatchedTransactionExtendedResult)
connection.processExtendedOperation(
new StartBatchedTransactionExtendedRequest());
// This doesn't necessarily mean that the operation was successful, since
// some kinds of extended operations return non-success results under
// normal conditions.
}
catch (LDAPException le)
{
// For an extended operation, this generally means that a problem was
// encountered while trying to send the request or read the result.
startTxnResult = new StartBatchedTransactionExtendedResult(
new ExtendedResult(le));
}
LDAPTestUtils.assertResultCodeEquals(startTxnResult, ResultCode.SUCCESS);
ASN1OctetString txnID = startTxnResult.getTransactionID();
// At this point, we have a transaction available for use. If any problem
// arises, we want to ensure that the transaction is aborted, so create a
// try block to process the operations and a finally block to commit or
// abort the transaction.
boolean commit = false;
try
{
// Create and process a modify operation to update a first entry as part
// of the transaction. Make sure to include the transaction specification
// control in the request to indicate that it should be part of the
// transaction.
ModifyRequest firstModifyRequest = new ModifyRequest(
"cn=first,dc=example,dc=com",
new Modification(ModificationType.REPLACE, "description", "first"));
firstModifyRequest.addControl(
new BatchedTransactionSpecificationRequestControl(txnID));
LDAPResult firstModifyResult;
try
{
firstModifyResult = connection.modify(firstModifyRequest);
}
catch (LDAPException le)
{
firstModifyResult = le.toLDAPResult();
}
LDAPTestUtils.assertResultCodeEquals(firstModifyResult,
ResultCode.SUCCESS);
// Perform a second modify operation as part of the transaction.
ModifyRequest secondModifyRequest = new ModifyRequest(
"cn=second,dc=example,dc=com",
new Modification(ModificationType.REPLACE, "description", "second"));
secondModifyRequest.addControl(
new BatchedTransactionSpecificationRequestControl(txnID));
LDAPResult secondModifyResult;
try
{
secondModifyResult = connection.modify(secondModifyRequest);
}
catch (LDAPException le)
{
secondModifyResult = le.toLDAPResult();
}
LDAPTestUtils.assertResultCodeEquals(secondModifyResult,
ResultCode.SUCCESS);
// If we've gotten here, then all writes have been processed successfully
// and we can indicate that the transaction should be committed rather
// than aborted.
commit = true;
}
finally
{
// Commit or abort the transaction.
EndBatchedTransactionExtendedResult endTxnResult;
try
{
endTxnResult = (EndBatchedTransactionExtendedResult)
connection.processExtendedOperation(
new EndBatchedTransactionExtendedRequest(txnID, commit));
}
catch (LDAPException le)
{
endTxnResult = new EndBatchedTransactionExtendedResult(
new ExtendedResult(le));
}
LDAPTestUtils.assertResultCodeEquals(endTxnResult, ResultCode.SUCCESS);
}