Transaction service settings

Specifies the name of a directory for this server where the transaction service stores log files for recovery. Optionally, you can specify the size of transaction log files. For the z/OS® platform, specifies the location of the JTA Partner Log.

If you do not specify this directory during server configuration, the transaction service uses a default directory that is based on the installation directory: app_server_root/ tranlog/cell_ name/node_ name/server_ name.

When an application that runs on the application server accesses more than one resource, the application server stores transaction information in the product 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 application server 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 your application server 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 application server stops in the middle of a run and must be restarted
• The disk that the application server is running on shows higher use

There are the following recommendations for a storage system for the log files:

• 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, ensure that 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 application server 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 you can specify is 64K. If you 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

For more information about transaction log sizes, see Managing transaction logging for optimum server availability.

Information	Value
Data type	String
Default	Directory name: app_server_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 than 5%, consider adding more physical disks to decrease the value.

On z/OS, this log is used for recovery of XA resources. When the application that runs on the WebSphere® product accesses XA resources, the WebSphere product stores information about the resource to enable XA transaction recovery. Use the following syntax:

[location type URL tag] location_specification

• location type URL tag specifies the optional location type for the JTA Partner Log:
  • The default is dir://, which specifies that the JTA Partner Log location is in a fully qualified HFS directory specified by location_specification.
• location specification specifies the location name for the JTA Partner Log:
  • To specify a logstream, use the syntax logstream://HLQ
    If your application server installation followed the convention of configuring logstreams to the coupling facility (CF), the logstream is named according to the syntax HLQ.server.X, where HLQ is a user-defined value between 1-8 characters specified in the installation dialog. Use this HLQ value to specify the JTA Partner Log location.

    Note: Set AUTODELETE(NO) for any logstreams.
  • If the location type URL tag is dir://, use a fully qualified HFS directory for the location specification. The complete name of the directory must be unique in the WebSphere node.

The default is dir://app_server_root/tranlog/server name.

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 you can specify is 64K. If you 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.

dir://directory_name/directory_name;file_sizeK

/directory_name/directory_name;file_sizeK

;file_sizeK   <!-- This keeps the default directory -->

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.

After the timeout occurs, transactions are allowed to continue running for a grace period of approximately four minutes. If the transaction is committed or rolled back during the grace period, the outcome of the transaction is always rolled back. If the transaction does not complete after the grace period, the controller abnormally ends the servant region in which the application component is running, with ABEND EC3 RSN=04130002 or 04130005.

Note: Only the total transaction lifetime timeout and the maximum transaction timeout have grace periods. You can disable the grace periods by using the DISABLE_TRANSACTION_TIMEOUT_GRACE_PERIOD custom property.

The upper limit of this timeout is constrained by the maximum transaction timeout. For example, if you 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 you set this timeout to 0, the timeout does not apply and the value of the maximum transaction timeout is used instead.

Information	Value
Data type	Integer
Units	Seconds
Default	120
Range	0 to 2 147 483 647
Range	0 to 2 147 040

Specifies the 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.

Specifies the 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 application server.

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

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 total transaction lifetime timeout and greater than or equal to the application component timeout. If the maximum transaction timeout is set to a value less than either the total transaction lifetime timeout or the application component timeout, application component transactions that may require more time will timeout when the maximum transaction timeout is reached.

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

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

To determine the occurrence of a timeout quickly, and to prevent further resource locking, the application server 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.

Information	Value
Data type	Integer
Units	Seconds
Default	300
Range	0 to 2 147 483 647
Range	0 to 2 147 040

Specifies the number of times that the application server 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 application server 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 application server 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 JavaBeans (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.

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

Specifies whether the application server 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 application server 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.

Specifies the direction that is used to complete a transaction that has a heuristic outcome; either the application server commits or rolls back the transaction, or depends on manual completion by the administrator.

This property applies only to transactions that are in the situations just described.

Specifies 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, you must configure applications individually to accept the heuristic hazard. You can configure applications either when they are assembled, or following deployment by using the Last participant support extension pane.

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

Specifies whether the secure exchange of transaction service protocol messages is enabled.

When transaction coordination authorization is enabled, the transaction service verifies the caller is permitted to the administrator role before handling the transaction.

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

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

You can choose from WS-Transaction 1.0, WS-Transaction 1.1 or WS-Transaction 1.2. For details of these specifications, see the topics about WS-AT support or WS-BA support in the application server.

The default WS-Transaction specification level is used if a level cannot be determined from the provider policy (the WS-Transaction WS-Policy assertion). This could be, for example, if 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 if the policy assertion is available but more than one specification level is applicable.

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

• If you 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 you want to configure WS-Transaction EndpointReferences to be published with non-default protocol,host or port values in their URLs. For example, when configuring inbound WS-Transaction protocol requests to flow into the application server via a forward proxy, such as the WebSphere Proxy Server, use this field to specify an SSL channel chain when global security is not enabled, or to specify a non-SSL channel when global security is enabled.

If either a specified custom prefix or a selected prefix is configured, that prefix is used. If a specified custom or selected prefix is not set, then, by default, if security is enabled, one of the application server's SSL enabled web container channel chains is automatically selected. Otherwise, a non-SSL enabled web container channel chain is automatically selected.

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

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

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

http://host_name:port

https://host_name:port

Specifies the number of transactions that await manual completion by an administrator.

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

Specifies the number of transactions with some resources being retried.

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

Specifies the number of transactions that have completed heuristically.

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

Specifies the 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, you can click the Review link to display a list of those transactions on the Transactions imported and prepared panel.

Under Additional Properties you can click the Custom properties link to display or change custom properties for your WebSphere Application Server transaction service.

You use Custom properties to specify whether or not information messages are displayed on the administrative console and written to the SystemOut.log file upon transaction service recovery.

To find out more about WebSphere Application Server transaction service custom properties, see the related link.