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ADF - Configure MDS and Its Customization

In this tutorial, you will learn how to configure MDS and its customization. MDS customization can be performed using the ADF properties and MDS customization can be done using the file adf-config.xml.

Configuring MDS

After deployment, one can tune specific aspects of MDS via Fusion Middleware Control or WLST commands and MBeans.

To update this configuration via Enterprise Manager, the first step is to launch the MBean browser by navigating to the target domain and application and then starting the ADF | Configure ADF menu. In the MBean browser, the ADFConfig folder exposes the child MBeans, and one of these child MBeans is MDSAppConfig.

The table lists some of the MDS configuration properties that can be accessed and set at the application level via these MBeans.

ADF Related MDS Configuration Properties

AttributeDescription
DeployTargetsReposThe metadata repository where the application's metadata (in the MAR) is deployed to. This same repository typically also contains any user personalizations create via the application runtime. This field is read-only.
AppMetadataRepositoryInfoThe MDS partition in the deploy target repository where the metadata of the application is deployed. This field is read-only.
AutoPurgeTimeToLiveUseful to purge the unwanted versions of metadata in the repository. If the auto-purge functionality is configured in the adf-config.xml, MDS automatically purges versions of metadata documents older than the given time interval specified in seconds, if those versions do not correspond to a saved label.
ExternalChangeDetectionThe value of this attribute is either true or false. If true, this enables the application to detect appropriate metadata changes (for example, personalization or customization is done via a different application node.
ExternalChangeDetectionIntervalThe maximum time interval, in seconds, with which the application will detect external metadata changes. The default is 30 seconds.
MaximumCacheSizeThe maximum size of the metadata cache in kilobytes. If the value is 0, caching is disabled. The metadata services layer caches the metadata in this cache. The default is 10 megabytes.
ReadOnlyModeThe value of this attribute is either true or false. If true, this makes the application read-only with respect to the target repository. Therefore, no metadata updates can be made to this repository from this application.
RetryConnectionEnables the application to retry to connect to the metadata repository after connection failure to the same. This is typically used for high-availability configuration.
SharedMetadataRepositoryInfoThis property refers to the shared metadata partitions referenced by the application. This field is read-only.

All of these property changes affect all instances of the application running in the cluster. Some of these properties will take effect immediately, such as the external changes detection interval, and some others will apply after the application is restarted.

In the Operations tab of the same UI, the operation RestoreToOriginalConfiguration is exposed. Invoking this operation resets the ADF configuration to the values at the deployment time. Other runtime operations on metadata are exposed as runtime MBeans within the MBeans browser. Some actions that can be performed here are described in the table.

Configuring MDS Customizations

The configuration of an application to use customizations defined in the applications adf-config.xml file. It is a development activity, not an administration activity, to configure an application for customizations. Hence, there are no MBeans to change this configuration in a running application.

This includes defining the customization layers and configuring an application to use them via the adf-config.xml file. Similarly, setting an application to persist implicit user personalization is also a development-time activity.

If an application is configured for customizations and implicit personalizations, then an administrator can turn on or off the personalizations on specific components in a page. This is stored as customization of the page. This change needs to be done from WebCenter Page Composer.

MDS MBean Operations

AttributeDescription
clearCacheClears the MDS metadata cache. Can be used to diagnose if a stale copy of metadata is in the cache and not invalidated.
createMetadataLabelMetadata in MDS repository is versioned, and creating a label will mark a consistent site of metadata so that a subsequent recovery or reset can make use of this label.
deleteMetadataLabelIt is good practice to delete labels that are not needed because unlabeled metadata will be purged as needed via the auto-pured tool.
exportMetadataUsed to export the metadata in the MDS repository. This operation can be used to migrate metadata from a test instance to a production instance.
importMetadataUsed to import metadata into the MDS repository.
deleteMetadataUsed to delete metadata from the MDs repository

Implicit personalization does have some performance impact due to the additional, although optimized, cost of loading, and applying customizations. Therefore, it is good practice to configure them only on pages where this functionality is needed, rather than turning them on for the entire application UI.

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