Transaction service settings

Transcription

1 Transaction service settings Use this page to specify settings for the transaction service. The transaction service is a server runtime component that can coordinate updates to multiple resource managers to ensure atomic updates of data. Transactions are started and ended by applications or the container in which the applications are deployed. To view this administrative console page, click Servers > Server Types > WebSphere application servers > server_name > [Container Settings] Container Services > Transaction Service. Transaction log directory 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. Set this property to change the transaction log file directory for an application server only if the applications use distributed resources or XA transactions; for example, multiple databases and resources are accessed in a single transaction. 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 --> 1 of 9 18/12/ :18

2 2 of 9 18/12/ :18 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. String 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 then 5%, consider adding more physical disks to lower the value. 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 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. Units Seconds 120 Range 0 to Asynchronous response timeout 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. Units Seconds 30 Client inactivity timeout 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.

3 3 of 9 18/12/ :18 If you set this value to 0, there is no timeout limit. Units Seconds 60 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. Specifies the maximum time to complete, in seconds, 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. Table 1. Transaction timeout settings. The table shows how the different timeout settings apply to transactions running in the server. Timeout setting Transactions affected Maximum transaction timeout Total transaction lifetime timeout Application component 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. 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. Transactions that are specific to an application component. You cannot set this transaction timeout using the administrative console. If the component is a container-managed bean, set this timeout in the deployment descriptor for the component. For example, you can use an assembly tool, such as the Rational Application Developer. If the component is a bean-managed bean, set this timeout programmatically by using the UserTransaction.setTransactionTimeout method. 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. For example, consider the following timeout values: Table 2. Example timeout values. The table lists different timeout settings and their values. Timeout setting 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 you then change the application component timeout to 500, application component transactions time out after 360 seconds, the value of the maximum transaction timeout. If you set the maximum transaction timeout to 0, application component transactions time out after 500 seconds. If you remove the application component timeout, application component transactions time out after 240 seconds.

4 4 of 9 18/12/ :18 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. Units Seconds 300 Heuristic retry limit 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. 0 A value of 0 (the default) means try again indefinitely. Heuristic retry wait 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. 0 A value of 0 means that the application server determines the retry wait; the server doubles the retry wait after every 10 failed retries. Enable logging for heuristic reporting 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.

5 5 of 9 18/12/ :18 Range Check box Cleared Cleared The application server 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 application server 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 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. The heuristic completion direction property specifies how a transaction is completed in the following situations: The transaction manager reports a heuristic outcome for a last participant support (LPS) resource. 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. This property applies only to transactions that are in the situations just described. Range Drop-down list ROLLBACK COMMIT The application server heuristically commits the transaction. ROLLBACK The application server heuristically rolls back the transaction. MANUAL The application server depends on an administrator to manually complete or roll back transactions with heuristic outcomes. Accept heuristic hazard 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. Range Check box Cleared Selected All applications deployed on the server accept the increased risk of an heuristic outcome.

6 6 of 9 18/12/ :18 Cleared Applications must be individually configured to accept the increased risk of an heuristic outcome. Enable file locking Specifies whether the use of file locks is enabled when opening the transaction service recovery log. If you 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 WebSphere Application Server deployment, only one application server can access a particular transaction service recovery log at any one time. This setting has no effect in a standard deployment where you have not configured high availability support. Attention: This setting requires a compatible network file system, such as Network File System (NFS) version 4, to operate correctly. Check box Selected Enable transaction coordination authorization 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. Check box Selected WS-Transaction specification level 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. Drop-down list 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 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

7 7 of 9 18/12/ :18 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. Avoid trouble: The setting of the transaction coordination authorization does not have an effect upon whether SSL/non-SSL is selected. For more information about the relationship between transaction coordination authorization and the WS-Transactions, see the topic Configuring Web Services Transaction support in a secure environment. If the intermediary node is not a Proxy Server, the prefix must be unique for each server. 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. Drop-down list 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. String None Manual transactions 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. 0 Retry transactions 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. 0

8 8 of 9 18/12/ :18 Heuristic transactions 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. 0 Imported prepared transactions 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. 0 Additional Properties 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. Related concepts Web services transactions, high availability, firewalls and intermediary nodes Web Services Atomic Transaction support in the application server Web Services Business Activity support in the application server Related tasks Managing transaction logging for optimum server availability Configuring a server to use business activity support Interoperating transactionally between application servers Enabling WebSphere Application Server to use an intermediary node for web services transactions Configuring Web Services Transaction support in a secure environment Using 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 Configuring transaction properties for an application server Storing transaction and compensation logs in a relational database for high availability Related reference Transaction service custom properties Related information Transactions needing manual completion Transactions retrying resources Transactions with heuristic outcome Transactions imported and prepared Transaction resources Last participant support extension settings Reference topic

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