Express (Distributed operating systems), v8.0 > Secure applications and their environment > Authenticate users > Select a registry or repository > Manage realms in a federated repository > Virtual member manager > Component overview
Transaction support
Virtual member manager provides limited transaction support when called by the WebSphere security or by an application.
If virtual member manager is called by WebSphere security , virtual member manager always uses a local transaction for its operations with an underlying repository.
If virtual member manager is called by an application through its Java SDO-based API or through its stateless session EJB after the caller global transaction has started, virtual member manager participates in the caller global transaction. Virtual member manager does not provide a method to prevent its participation caller global transaction in this situation. If the caller has not started a global transaction, virtual member manager starts its own global transaction.
This behavior is enabled because the transaction attribute is set to TX-Supports in the virtual member manager stateless session EJB. When the virtual member manager stateless session EJB is not used, virtual member manager uses the WAS transaction manager.
When designing a global transaction, if the caller starts a global transaction before calling virtual member manager, the caller needs to consider that virtual member manager does not provide any transactional support for non-transactional repositories. If a repository is not capable of supporting transactions, it does not participate in any transaction that is started by virtual member manager or the virtual member manager caller.
Virtual member manager treats LDAP servers as non-transactional repositories.
If virtual member manager is configured with a mixture of transactional and non-transactional repositories and if a transaction needs to be rolled back, only the transactional repositories are rolled back. Error messages are logged and administrator might need to manually clean up the non-transactional repositories. For example, virtual member manager is configured with an LDAP server and the property-extension repository (which is a database), and you are creating a person entry on the LDAP repository with some additional properties in the extension database. If the person entry is created successfully on the LDAP repository, but the creation of the additional properties in the database failed, the extension database is rolled back, but the person entry created on LDAP is not removed automatically. An error message is logged. The administrator must examine the log and remove the person entry from the LDAP repository.
zOS controller region restrictions
Because virtual member manager supports plug-ins and custom repository adapters, if you are writing custom code to be called by virtual member manager, your custom code may participate in virtual member manager transactions. You need to be aware of the following platform restrictions when designing your custom extensions to virtual member manager:
- Global transaction is not supported.
- Local Transaction Containment is not supported.
- Only type 4 JDBC driver can be used in the Controller region.
Parent topic: Component overview