MigratableTargetMBean

Overview

A target that is suitable for services that shall be active on at most one server of a cluster at a time.

Related MBeans

This section describes attributes that provide access to other MBeans.

AllCandidateServers

The list of servers that are candidates to host the migratable services deployed to this migratable target. If the constrainedCandidateServers list is empty, all servers in the cluster are returned. If the constrainedCandidateServers list is not empty, only those servers will be returned. The user-preferred server will be the first element in the list.

Cluster

Returns the cluster this singleton service is associated with.

ConstrainedCandidateServers

The (user-restricted) list of servers that can host the migratable services deployed to this migratable target. The migratable service will not be allowed to migrate to a server that is not in the returned list of servers.

For example, this feature may be used to configure two servers that have access to a dual-ported ported disk. All servers in this list must be part of the cluster that is associated with the migratable target.

HostingServer

Returns the name of the server that currently hosts the singleton service.

UserPreferredServer

Returns the server that the user prefers the singleton service to be active on.

Attributes

This section describes the following attributes:

AdditionalMigrationAttempts

A migratable service could fail to come up on every possible configured server. This attribute controls how many further attempts, after the service has failed on every server at least once, should be tried. Note that each attempt specified here indicates another full circuit of migrations amongst all the configured servers. So for a 3-server cluster, and a value of 2, a total of 4 additional migrations will be attempted. (the original server is never a valid destination)

CachingDisabled

Private property that disables caching in proxies.

DynamicallyCreated

Return whether the MBean was created dynamically or is persisted to config.xml

Id

Return the unique id of this MBean instance

MBeanInfo

Returns the MBean info for this MBean.

Deprecated.

MigrationPolicy

Defines the type of migration policy to use for the services hosted by this migratable target. Valid options are:

• Manual Service Migration Only

  Indicates that no automatic migration of services hosted by this migratable target will occur.

• Auto-Migrate Exactly-Once Services

  Indicates that if at least one Managed Server in the candidate server list is running, the services hosted by this migratable target will be active somewhere in the cluster if servers should fail or are administratively shut down (either gracefully or forcibly). For example, it is a recommended best practice to use this policy when a migratable target hosts a path service, so if its preferred server fails or is shut down, the path service will automatically migrate to another candidate server, and so will always be active in the cluster.

  Note This value can lead to target grouping on a server member. For example, if you have five exactly-once migratable targets and only one Managed Server is started in the cluster, then all five targets will be activated on that server.

• Auto-Migrate Failure-Recovery Services

  Indicates that the services hosted by this migratable target will only start if the migratable target's User Preferred Server (UPS) is started. If an administrator manually shuts down the UPS, either gracefully or forcibly, then a failure-recovery service will not migrate. However, if the UPS fails due to an internal error, then the service will be migrated to another candidate server. If such a candidate server is unavailable (due to either a manual shutdown or an internal failure), then the migration framework will first attempt to reactivate the service on its UPS server. If the UPS server is not available at that time, then the service will be migrated to another candidate server.

For more information, see:

• setUserPreferredServer

MillisToSleepBetweenAttempts

Controls how long of a pause there should be between the migration attempts described in getAdditionalMigrationAttempts(). Note that this delay only happens when the service has failed to come up on every server. It does not cause any sort of delay between attempts to migrate otherwise.

Name

The user-specified name of this MBean instance.

This name is included as one of the key properties in the MBean's javax.management.ObjectName:
Name=user-specified-name

NonLocalPostAllowed

Specifies whether or not the post-deactivation script is allowed to run on a different machine.

Normally, when auto migration occurs, the post-deactivation script will be run on the service's current location, and the pre-activation script on the service's new location. If the current location is unreachable for some reason, this value will be checked to see if it is safe to run it on the service's new machine.

This is useful if the post-deactivation script controls access to a networked resource and does not need any data from the current machine.

Notes

Optional information that you can include to describe this configuration.

WebLogic Server saves this note in the domain's configuration file (config.xml) as XML PCDATA. All left angle brackets (<) are converted to the XML entity <. Carriage returns/line feeds are preserved.

Note:

If you create or edit a note from the Administration Console, the Administration Console does not preserve carriage returns/line feeds.

NumberOfRestartAttempts

Specifies how many restart attempts to make before migrating the failed service.

Note that these are consecutive attempts. If the value is set to 6, and the service restart fails 5 times before succeeding, but then fails again later, it will not instantly migrate. Each failure gets its own count of restart attempts.

A value of 0 is identical to setting RestartOnFailure to false. A value of -1 indicates the service shouldnever be migrated; instead, it will be restarted until it either works or the server shuts down.

ObjectName

Returns the ObjectName under which this MBean is registered in the MBean server.

Deprecated.

Parent

Return the immediate parent for this MBean

PostScript

Specifies the path to the post-migration script to run after a migratable target is fully deactivated. The script must be in the MIDDLEWARE_HOME/user_projects/domains/mydomain/bin/service_migration directory.

After the migratable target is deactivated, if there is a script specified, and Node Manager is available, then the script will run. Specifying a script without an available Node Manager will result in an error upon migration.

PostScriptFailureFatal

Specifies whether or not a failure during execution of the post-deactivation script is fatal to the migration.

If it is fatal, the migratable target will not be automatically migrated until an administrator manually migrates it to a server, thus reactivating it.

Note: Enabling this value will result in weakening the exactly-once guarantee. It is provided to prevent more dangerous data corruption if the post-deactivation script fails. Also if this value is enabled, then the script may be called more than once by the migration framework after the Migratable Target is deactivated or the server or machine hosting the Migratable Target crashed or is network partitioned. The script is expected not to return different exit values when invoked multiple times in such scenarios.

PreScript

Specifies the path to the pre-migration script to run before a migratable target is actually activated. The script must be in the MIDDLEWARE_HOME/user_projects/domains/mydomain/bin/service_migration directory.

Before the migratable target is activated, if there is a script specified, and Node Manager is available, then the script will run. Specifying a script without an available Node Manager will result in an error upon migration.

If the script fails or cannot be found, migration will not proceed on the current server, and will be tried on the next suitable server. This could be the next server in the candidate server list, or in the cluster, if there is no candidate server list.

Registered

Returns false if the MBean represented by this object has been unregistered.

Deprecated.

RestartOnFailure

Specifies whether or not a failed service will first be deactivated and reactivated in place, instead of being migrated.

The number of restart attempts is controlled by NumberOfRestartAttempts . Once these restart attempts are exhausted, the service will migrate. A restarting migratable target will deactivate all services on it in order, then reactivate them all.

SecondsBetweenRestarts

Specifies how many seconds to wait in between attempts to restart the failed service.

Type

Returns the type of the MBean.

Operations

This section describes the following operations:

addConstrainedCandidateServer

freezeCurrentValue

If the specified attribute has not been set explicitly, and if the attribute has a default value, this operation forces the MBean to persist the default value.

Unless you use this operation, the default value is not saved and is subject to change if you update to a newer release of WebLogic Server. Invoking this operation isolates this MBean from the effects of such changes.

Note:

To insure that you are freezing the default value, invoke the restoreDefaultValue operation before you invoke this.

This operation has no effect if you invoke it on an attribute that does not provide a default value or on an attribute for which some other value has been set.

Deprecated. 9.0.0.0

getInheritedProperties

return all properties' names whose value is inherited from template mbean. this is a convenient method to get inheritance info on multiple properties in one jmx call.

isInherited

Check if the value of a property is inherited from template mbean or not.

isSet

Returns true if the specified attribute has been set explicitly in this MBean instance.

removeConstrainedCandidateServer

restoreDefaultValue

If the specified attribute has a default value, this operation removes any value that has been set explicitly and causes the attribute to use the default value.

Default values are subject to change if you update to a newer release of WebLogic Server. To prevent the value from changing if you update to a newer release, invoke the freezeCurrentValue operation.

This operation has no effect if you invoke it on an attribute that does not provide a default value or on an attribute that is already using the default.

Deprecated. 9.0.0.0

unSet

Restore the given property to its default value.