Transaction service settings


 

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The transaction service coordinates updates to resource managers, ensuring atomic updates of data. Transactions can be opened and closed by apps or the container.

To specify settings for the transaction service.

Servers | Server Types | WebSphere application servers | server_name | [Container Settings] Container Services | Transaction Service

Transaction log directory

Directory where the transaction service stores log files for recovery. Optionally specify the size of transaction log files.

Change the transaction log file directory....

  • If the applications use distributed resources or XA transactions; for example, multiple databases and resources are accessed in a single transaction.

  • If we configure the system for high availability of transactions. In this situation, the transaction log directory must be unique for each server in the cluster, and all servers in the cluster must be able to access the transaction log directory.

    In a high availability (HA) environment, both the transaction log and the compensation log directory for each server in a cluster must be unique.

Default directory

APP_ROOT/tranlog/cell_name/node_name/server_name

When an application that runs on the appserver accesses more than one resource, the application server stores transaction information in WAS directory so that it can coordinate and manage the distributed transaction correctly. When there is a higher transaction load, storing persistent information in this way can slow the performance of the appserver because it depends on the operating system and the underlying storage systems. To achieve better performance, designate a new directory for the log files on a separate, physically larger, storage system. If the appserver demonstrates one or more of the following symptoms, change the transaction log directory:

  • CPU use remains low despite an increase in transactions
  • Transactions fail with several timeouts
  • Transaction rollbacks occur with the exception "Unable to enlist transaction"
  • The appserver stops in the middle of a run and must be restarted
  • The disk that the appserver is running on shows higher use

Log file storage recommendations:

  • Store log files on a redundant array of independent disks (RAID)

    In RAID configurations, the task of writing data to the physical media is shared across the multiple drives. This technique yields more concurrent access to storage for persisting transaction information, and faster access to that data from the logs. Depending on the design of the application and storage subsystem, performance gains can range from 10% to 100%, or more in some cases.

  • Do not store log files with the operation system I/O mode set to concurrent I/O (CIO)

    When you designate a transaction log directory, verify the file system uses only synchronous write-through and write serialization operations. Some operating systems, such as AIX JFS2, support an optional concurrent I/O (CIO) mode, where the file system does not enforce serialization of write operations. On these systems, do not use CIO mode for appserver transaction recovery log files.

To specify the size of transaction log files, include a file size setting. Use one of the following formats, where directory_name is the name of the transaction log directory and file_size is the new disk space allocation for the transaction log files, specified in KB (nK) or MB (nM). The minimum transaction log file size that we can specify is 64K. If we specify a value that is less than 64K, or you do not specify a value for the file size, the default value of 1M is used.

;file_size <!-- This format keeps the default directory -->
directory_name;file_size
dir: //directory_name/directory_name;file_size
/directory_name/directory_name;file_size

Data type String
Default Directory name: APP_ROOT/tranlog/cell_name/node_name/server_name

File size: 1MB

Recommended Create a file system with at least three to four disk drives raided together in a RAID-0 configuration. Then, create the transaction log on this file system with the default size. When the server is running under load, check the disk input and output. If disk input and output time is more then 5%, consider adding more physical disks to lower the value.

If we migrate a WAS Version 5 node to V6, the stored location of this configuration property is moved from the server level to the node (server index) level. If we specified a non-default log directory for a V 5 appserver, we are prompted to save the transaction service settings again, to confirm that you want the log directory saved to the node level.

Total transaction lifetime timeout

The default maximum time, in seconds, allowed for a transaction that is started on this server before the transaction service initiates timeout completion. Any transaction that does not begin completion processing before this timeout occurs is rolled back.

This timeout is used only if the application component does not set its own transaction timeout.

The upper limit of this timeout is constrained by the maximum transaction timeout. For example, if we set a value of 500 for the total transaction lifetime timeout, and a value of 300 for the maximum transaction timeout, transactions will time out after 300 seconds.

If we set this timeout to 0, the timeout does not apply and the value of the maximum transaction timeout is used instead.

Data type Integer
Units Seconds
Default 120
Range

0 to 2 147 483 647

Asynchronous response timeout

Amount of time, in seconds, that the server waits for an inbound Web Services Atomic Transaction (WS-AT) protocol response before resending the previous WS-AT protocol message.

Data type Integer
Units Seconds
Default 30
Range 0 to 2 147 483 647

Client inactivity timeout

Maximum duration, in seconds, between transactional requests from a remote client. Any period of client inactivity that exceeds this timeout results in the transaction being rolled back in this appserver.

If we set this value to 0, there is no timeout limit.

Data type Integer
Units Seconds
Default 60
Range 0 to 2 147 483 647

Maximum transaction timeout

Specifies, in seconds, the upper limit of the transaction timeout for transactions that run in this server. This value should be greater than or equal to the value specified for the total transaction timeout.

This timeout constrains the upper limit of all other transaction timeouts.

The following table shows how the different timeout settings apply to transactions running in the server.


Table 1. Transaction timeout settings.

Timeout setting Transactions affected
Maximum transaction timeout All transactions running in this server that are not affected by the total transaction lifetime timeout or an application component timeout. These transactions include transactions imported from outside this server, such as those imported from a client.
Total transaction lifetime timeout All transactions that originated in this server that are not affected by an application component timeout, in other words, the associated application component does not set its own timeout.
Application component timeout Transactions that are specific to an application component.

We cannot set this transaction timeout using the admin console.

If the component is a container-managed bean, set this timeout in the deployment descriptor for the component. For example, we can use an assembly tool, such as the Rational Application Developer.

If the component is a bean-managed bean, set this timeout programmatically using the UserTransaction.setTransactionTimeout method.

If we set a timeout to 0, that timeout does not apply, and is effectively disabled. If we set all timeouts to 0, transactions never time out.

For example, consider the following timeout values:


Table 2. Example timeout values

Timeout setting Value
Maximum transaction timeout 360
Total transaction lifetime timeout 240
Application component timeout 60

In this example, transactions that are specific to the application component time out after 60 seconds. Other local transactions time out after 240 seconds, and any transactions that are imported from outside this server time out after 360 seconds. If we then change the application component timeout to 500, application component transactions time out after 360 seconds, the value of the maximum transaction timeout. If we set the maximum transaction timeout to 0, application component transactions time out after 500 seconds. If we remove the application component timeout, application component transactions time out after 240 seconds.

To determine the occurrence of a timeout quickly, and to prevent further resource locking, the appserver prevents further transactional work on the transactional path where the timeout condition has taken place. This applies equally to attempting to undertake work under the current transaction context and to attempting to perform work under a different transactional context.

Data type Integer
Units Seconds
Default 300
Range 0 to 2 147 483 647

Heuristic retry limit

Number of times that the appserver retries a completion signal, such as commit or rollback. Retries occur after a transient exception from a resource manager or remote partner, or if the configured asynchronous response timeout expires before all Web Services Atomic Transaction (WS-AT) partners have responded.

If the appserver abandons the retries, the resource manager or remote partner is responsible for ensuring that the resource or partner branch of the transaction is completed appropriately. The appserver raises (on behalf of the resource or partner) an exception that indicates a heuristic hazard. If a commit request was made, the transaction originator receives an exception on the commit operation; if the transaction is container-initiated, the container returns a remote exception or Enterprise Java Beans™ (EJB) exception to the EJB client.

During recovery of a subordinate server in a distributed transaction, when the number of heuristic retries is exceeded, the heuristic completion direction property specifies how the transaction is completed.

Data type Integer
Default 0
Range 0 to 2 147 483 647

A value of 0 (the default) means try again indefinitely.

Heuristic retry wait

Number of seconds that the appserver waits before retrying a completion signal, such as commit or rollback, after a transient exception from a resource manager or remote partner.

Data type Integer
Default 0
Range 0 to 2 147 483 647

A value of 0 means that the appserver determines the retry wait; the server doubles the retry wait after every 10 failed retries.

Enable logging for heuristic reporting

Whether the appserver logs about-to-commit-one-phase-resource events from transactions that involve both a one-phase commit resource and two-phase commit resources.

This property enables logging for heuristic reporting. If applications are configured to allow one-phase commit resources to participate in two-phase commit transactions, reporting of heuristic outcomes that occur at appserver failure requires extra information to be written to the transaction log. If enabled, one additional log write is performed for any transaction that involves both one-phase and two-phase commit resources. No additional records are written for transactions that do not involve a one-phase commit resource.

Data type Check box
Default Cleared
Range

Cleared

The appserver does not log "about to commit one-phase resource" events from transactions that involve a one-phase commit resource and two-phase commit resources.

Selected

The appserver does log "about to commit one-phase resource" events from transactions that involve a one-phase commit resource and two-phase commit resources.

Heuristic completion direction

Direction used to complete a transaction that has a heuristic outcome; either the appserver commits or rolls back the transaction, or depends on manual completion by the administrator.

The heuristic completion direction property also specifies how a transaction is completed in the following situations:

  • The heuristic retry limit is exceeded during the recovery of a subordinate server in a distributed transaction.

  • The transaction is imported from a Java EE Connector Architecture (JCA) provider.

Data type Drop-down list
Default ROLLBACK
Range

COMMIT

The appserver heuristically commits the transaction.

ROLLBACK

The appserver heuristically rolls back the transaction.

MANUAL

The appserver depends on an administrator to manually complete or roll back transactions with heuristic outcomes.

Accept heuristic hazard

Whether all applications on this server accept the possibility of a heuristic hazard occurring in a two-phase transaction that contains a one-phase resource. This setting configures last participant support (LPS) for the server. Last participant support is an extension to the transaction service that enables a single one-phase resource to participate in a two-phase transaction with one or more two-phase resources.

If the Accept heuristic hazard option is not selected, configure applications individually to accept the heuristic hazard. Configure applications either when they are assembled, or following deployment by using the Last participant support extension pane.

Data type Check box
Default Cleared
Range

Selected

All applications deployed on the server accept the increased risk of an heuristic outcome.

Cleared

Applications must be individually configured to accept the increased risk of an heuristic outcome.

Enable file locking

Whether the use of file locks is enabled when opening the transaction service recovery log.

If we enable this setting, a file lock will be obtained before accessing the transaction service recovery log files. File locking is used to ensure that, in a highly available WAS deployment, only one appserver can access a particular transaction service recovery log at any one time. This setting has no effect in a standard deployment where we have not configured high availability support.

This setting requires a compatible network file system, such as Network File System (NFS) version 4, to operate correctly.

Data type Check box
Default Selected

Enable transaction coordination authorization

Whether the secure exchange of transaction service protocol messages is enabled.

This setting has no effect unless you enable WebSphere Application WAS security on the server.

Data type Check box
Default Selected

Default WS-Transaction spec level

Specifies the default WS-Transaction spec level to use for outbound requests that include a Web Services Atomic Transaction (WS-AT) or Web Services Business Activity (WS-BA) coordination context.

We can choose from WS-Transaction 1.1 or WS-Transaction 1.0. For details of these specifications, see the topics about WS-AT support or WS-BA support in the appserver.

The default WS-Transaction spec level is used if the specification level that the server requires cannot be determined from the provider policy (the WS-Transaction WS-Policy assertion). For example, the policy assertion is not available, either from the WSDL of the target Web service or from the WS-Transaction policy type of the client, or the policy assertion is available but both spec levels are applicable.

Data type Drop-down list
Default 1.0

External WS-Transaction HTTP(S) URL prefix

Select or specify the external WS-Transaction HTTP(S) URL prefix.

Select or specify one of these fields if we are using an intermediary node, such as an HTTP server or Proxy Server for WebSphere, to send requests that comply with the Web Services Atomic Transaction (WS-AT) or Web Services Business Activity (WS-BA) protocols.

If WAS security is enabled and transaction coordination authorization is enabled, the HTTPS prefix is used. Otherwise, the HTTP prefix is used.

If the intermediary node is not a Proxy Server, the prefix must be unique for each server.

For a Proxy Server, prefixes can be the same for each server in a cluster, because the Proxy Server determines dynamically which server to forward the request to.

Select prefix

Select this option to select the external endpoint URL information to use for WS-AT and WS-BA service endpoints from the list.

Data type Drop-down list
Default None

Specify custom prefix

Select this option to specify the external endpoint URL information to use for WS-AT and WS-BA service endpoints in the field.

Use one of the following formats for the prefix, where host_name and port represent the intermediary node that is an HTTP or HTTPS proxy for the server.

http://host_name:port

https:
//host_name:port

Data type String
Default None

Manual transactions

Number of transactions that await manual completion by an administrator.

If there are transactions awaiting manual completion, we can click the Review link to display a list of those transactions on the Transactions needing manual completion panel.

Data type Integer
Default 0

Retry transactions

Number of transactions with some resources being retried.

If there are transactions with resources being retried, we can click the Review link to display a list of those transactions on the Transactions retrying resources panel.

Data type Integer
Default 0

Heuristic transactions

Number of transactions that have completed heuristically.

If there are transactions that have completed heuristically, we can click the Review link to display a list of those transactions on the Transactions with heuristic outcome panel.

Data type Integer
Default 0

Imported prepared transactions

Number of transactions that are imported and prepared but not yet committed.

If there are transactions that have been imported and prepared but not yet committed, we can click the Review link to display a list of those transactions on the Transactions imported and prepared panel.

Data type Integer
Default 0





Subtopics

Transactions needing manual completion
Transactions retrying resources
Transactions with heuristic outcome
Transactions imported and prepared
Transaction resources

 

Related concepts

Web Services transactions, high availability, firewalls and intermediary nodes
Web Services Atomic Transaction support in the appserver
Web Services Business Activity support in the appserver

 

Related tasks


Manage transaction logging for optimum server availability
Set a server to use business activity support
Disable file locking
Interoperating transactionally between appservers
Enable WAS to use an intermediary node for Web services transactions
Set Web Services Transaction support in a secure environment
Use one-phase and two-phase commit resources in the same transaction
Assembling an application to use one-phase and two-phase commit resources in the same transaction
Set transaction properties for an appserver

 

Related information


Last participant support extension settings
Compensation service settings