Abstract: A system and method for EJB classloading. By changing the EJB classloading scheme so that the EJB impl class is loaded in a child ClassLoader, the system allows the old EJB impl class to be replaced with a new one without disturbing the rest of the deployment. The key to doing this is to remove all direct references to the EJB impl class from classes loaded in the parent ClassLoaders. Removing this dependency allows the old EJB impl class to be replaced at any time with a new impl class.

Abstract: A system for determining when an EJB compiler needs to be executed, comprising: a server, including an EJB or plurality of EJBs and an EJB compiler operating thereon; and, a logic that determines a first snapshot of the EJB at a particular moment in time or for a particular server version, and a second snapshot of said EJB at a later moment in time or a subsequent server version, and compares the first and second snapshots to determine whether the EJB should be recompiled.

Abstract: The performance of a database system can be improved by tracking the way in which data is accessed. By tracking such information, it is possible to load frequently-accessed fields of an entity bean, as well as related beans that are frequently accessed, by optimizing a field group for that entity bean. It is also possible to use the tracking information to prevent infrequently accessed fields from being automatically loaded. Information to be monitored can include how often each field is accessed, how many times a particular entity or application accesses a field, and how often a field is accessed for a given transaction context. By using this information to periodically optimize field groups, the fields and associated entity beans that are most often accessed, such as by the entity and/or transaction causing the entity bean to be loaded, can be automatically loaded when an entity bean is loaded into a container.

Abstract: A cursored collection can be used to allow a user to view subsets of a data result set, thereby conserving system resources. A persistence manager can execute SQL statements on a database, receive a result set from the database, and populate a set of EJBs with the result set. This can be a full result set, or a subset of the full result set. A bean manager can allow the user to access all the EJBs or a subset of the EJBs. The bean manager can also provide the user with a list of EJBs and let the client select the EJBs to access. The client can then iterate through the result set, either by viewing different subsets or selecting different EJBs from the list. This iterative process can continue until all the results have been viewed or the client does not wish to access any more results from the set.

Abstract: Transactions are granted concurrent access to a data item through the use of an optimistic concurrency algorithm. Each transaction gets its own instance of the data item, such as in a cache or in an entity bean, such that it is not necessary to lock the data. The instances can come from the data or from other instances. When a transaction updates the data item, the optimistic concurrency algorithm ensures that the other instances are notified that the data item has been changed and that it is necessary to read a new instance, from the database or from an updated instance.

Abstract: The performance of a database system can be improved by tracking the way in which data is accessed. By tracking such information, it is possible to load frequently-accessed fields of an entity bean, as well as related beans that are frequently accessed, by optimizing a field group for that entity bean. It is also possible to use the tracking information to prevent infrequently accessed fields from being automatically loaded. Information to be monitored can include how often each field is accessed, how many times a particular entity or application accesses a field, and how often a field is accessed for a given transaction context. By using this information to periodically optimize field groups, the fields and associated entity beans that are most often accessed, such as by the entity and/or transaction causing the entity bean to be loaded, can be automatically loaded when an entity bean is loaded into a container.

Abstract: A system and method for increasing entity bean performance in an application server environment. The system reduces the need for multiple or unnecessary queries by formulating a join query for the related beans and applying this query to the database. When a request is made to a database to read or retrieve a set of EJB beans, related beans are simultaneously retrieved and stored in a cache. In this manner, when the client sends a request for any of these related beans, they can be supplied from the cache rather than making another call to the database.

Abstract: The caching of heterogeneous bean sets has been improved from requiring each bean to have its own cache instance to caching the beans in a single cache. The beans can be identified by generating a unique identifier that is a combination of the bean's primary key and a self-reference identifier of the bean manager associated with that bean. The average size of a bean set associated with a bean manager can be specified such that the cache allocates memory for that set based on the average size. A callback interface can also be used to shift knowledge of a bean life cycle back to the bean manager.

Abstract: Separate instances of a data item can be allocated for each transaction in a system. Each instance can be held by an entity bean capable of updating by either reading a copy of the data item from the database or by reading a copy from another entity bean. When the data item in the database is changed, the system can notify each entity bean that it should read an updated copy of the data item before the next transaction.

Abstract: A user can generate queries dynamically at runtime without having to redeploy the appropriate EJB or hard-code the query into the user application. A properties object can be generated to accept the query settings from the user. These settings can be extracted at runtime when the appropriate finder method is invoked, such that the desired query statement, such as a SQL statement, can be generated and executed against the database.

Abstract: The invention provides a set of enhancements to the EJB Query Language (“EJB QL”) for providing ResultSets using EJB QL and to efficiently access databases using ejbSelect methods within Enterprise Java Beans. Particularly, these EJBQL language extensions allow for the selection and retrieval of ResultSets. Since the use of the invention is expressed in terms of object relational constructs defined in an EJB deployment, it allows for the efficient retrieval of data from a Database expressed in terms of the relationships defined in that EJB deployment.

Abstract: Servers in a network cluster can each store a copy of a data item in local cache, providing read access to these copies through read-only entity beans. The original data item in the database can be updated through a read/write entity bean one of the cluster servers. That cluster server has access to an invalidation target, which contains identification information relating to copies of the data item stored on servers in the cluster. Once the read/write bean updates the data item in the database, an invalidate request can be sent or multicast to all cluster members, or to any read-only bean or server contained in the invalidation target. Each server or read-only bean receiving the request knows to drop any copy of the data item in local cache, and can request a current copy of the data item from the database.

Abstract: In an account transaction such as an ATM transaction, a server in communication with an ATM stores a copy of the account balance. Before processing the transaction, the server reads the balance from memory and determines whether the account contains sufficient funds for the transaction. In order to prevent overdrawing of the account, the server makes any balance update predicated on the fact that the current balance in the account database is the same as the balance of the local copy of the account. If the account balance stored in the database is not the same, the server rolls back the request and updates the account balance stored in the local copy. This process continues until either the account balance is updated or the transaction is aborted.

Abstract: Concurrency can be maintained in cluster caching when processing an update request on network server that is storing a local copy of a data item. The request can be processed using the local copy of the data item. A predicated update request can be sent to a network database storing the data item, wherein the database can commit the update if the local copy is current with the data item. If the local copy is not current, the network server can request a new copy, process the request using the current copy, and try another predicated request. The process can continue until the update is committed to the database or aborted. Once committed, any other servers in the cluster can be notified that the data item has been updated. Those other servers can drop any local copy of the data item and can request an updated copy of the data item.