Abstract: A computer is programmed to accept queries over streams of, data structured as per a predetermined syntax (e.g. defined in XML). The computer is further programmed to execute such queries continually (or periodically) on data streams of tuples containing structured data that conform to the same predetermined syntax. In many embodiments, the computer includes an engine that exclusively processes only structured data, quickly and efficiently. The computer invokes the structured data engine in two different ways depending on the embodiment: (a) directly on encountering a structured data operator, or (b) indirectly by parsing operands within the structured data operator which contain path expressions, creating a new source to supply scalar data extracted from structured data, and generating additional trees of operators that are natively supported, followed by invoking the structured data engine only when the structured data operator in the query cannot be fully implemented by natively supported operators.

Abstract: One embodiment of the present invention provides a system that facilitates secure messaging. The system starts by creating a message at an origin. Next, the system computes a digest of the message. This digest is signed using an origin private encryption key. The message and the signed digest are forwarded to a queue for delivery to a recipient. Upon receiving the message and the signed digest at the queue, the system verifies that the digest was signed at the origin by using an origin public encryption key. If the signature is valid, the origin cannot deny creating the message. Valid messages and digests are placed on the queue and the recipient is notified that the message is available.

Abstract: One embodiment of the present invention provides a system that facilitates accessing communication queues using a public network. The system operates by first generating a message or messages at a client. The system then formats these messages in a publicly available format. Next, the system communicates the messages across the public network to a web server. The web server receives the messages and transforms the messages to a database specific format. The web server then passes the messages to a queue within a database server across a proprietary network. In one embodiment of the present invention, the system includes queue-to-queue propagation with exactly once guarantees and recovery from failures. In one embodiment of the present invention, the system includes transactional guarantees when a client accesses a queue.

Abstract: One embodiment of the present invention provides a system that facilitates accessing communication queues using a public network. The system operates by first generating a message or messages at a client. The system then formats these messages in a publicly available format. Next, the system communicates the messages across the public network to a web server. The web server receives the messages and transforms the messages to a database specific format. The web server then passes the messages to a queue within a database server across a proprietary network. In one embodiment of the present invention, the system includes queue-to-queue propagation with exactly once guarantees and recovery from failures. In one embodiment of the present invention, the system includes transactional guarantees when a client accesses a queue.

Abstract: A method for asynchronously notifying an application client of a system or data event of interest within a database includes steps of receiving a subscription to an event name from a logical agent, the event name corresponding to the event of interest, and receiving a registration from the application client, the registration including delivery information indicating at least where and how a notification concerning the event is to be delivered. The occurrence of the event is then detected within the database, whereupon the notification of the detected event is published to a data structure referenced by the event name. The delivery information is then retrieved and the published notification is formatted according to the retrieved delivery information. The formatted notification is then asynchronously delivered to the application client over a network, such as the Internet. The application client may specify a rule, the satisfaction of which is a precondition to the delivery of the notification.