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Appendix A. Object Store Implementations
A.1. The ObjectStore Copiar enlaceEnlace copiado en el portapapeles!
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This chapter covers the various JBoss Transaction Service object store implementations and provides guidelines for creating new implementations and using them in an application.
JBoss Transaction Service includes several different implementations of a basic object store. Each implementation is optimized for a particular purpose. All of the implementations are derived from the ObjectStore interface, which defines the minimum operations which is needed for an object store implementation to be used by JBoss Transaction Service. You can override the default object store implementation at runtime by setting the com.arjuna.ats.arjuna.objectstore.objectStoreType property to one of the types described below in Example A.1, “Object Store Type”.
Example A.1. Object Store Type
You do not usually need to interact with any of the object store implementations directly, except for creating them if you are not using the default store type. All stores manipulate instances of the class
ObjectState
, which are named using a type derived via the object's type()
operation, and a Uid. Object states in the store are usually in one of two distinct states OS_COMMITTED
or OS_UNCOMMITTED
. An object state starts in the OS_COMMITTED
state, but when modified under the control of an atomic action, a new second object state may be written that is in the OS_UNCOMMITTED
state. If the action commits, this second object state replaces the original and becomes OS_COMMITTED
. If the action aborts, this second object state is discarded. All of the implementations provided with this release use shadow copies to handle these state transitions. However, you are allowed to implement them in a different way. Object states may become hidden and inaccessible under the control of the crash recovery system.
The
allTypes
and allObjUids
methods provide the ability to browse the contents of a store. The allTypes
method returns an InputObjectState containing all of the type names of all objects in a store, terminated by a null name. The allObjUids
method returns an InputObjectState that contains all of the Uids of all objects of a given type terminated by the special Uid.nullUid()
type.