Abstract: Application-level replication, the synchronization of data updates within a cluster of application servers, may be provided by having application servers themselves synchronize all updates to multiple redundant databases, precluding the need for database-level replication. This may be accomplished by first sending a set of database modifications requested by the transaction to a first database. Then a message may be placed in one or more message queues, the message indicating the objects inserted, updated, or deleted in the transaction. Then a commit command may be sent to the first database. The set of database modifications and a commit command may then be sent to second database. This allows for transparent synchronization of the database and quick recovery from a database failure, while imposing little performance or network overhead.

Abstract: A Web page cache that stores Web pages such that servers will be able to retrieve valid dynamic pages without going to a dynamic content server or origin Web server for the page every time a user requests that dynamic page. The dynamic content cache receives information that defines data upon which each dynamic page is dependent, such that when the value of any dependency data item changes, the associated dynamic page is marked as invalid or deleted. The dynamic page cache stores dependency data, receives change event information, and indicates when pages in the cache are invalidated or need to be refreshed.