Abstract: Method and arrangement for dispatching messages between instance specific dispatch tables of objects, when a particular object does not have resident the method called for execution in response to a message directed toward it. When a message is sent to a first object and the method called for execution is not resident or associated with the first object, the first object may expressly reference another object of the same class which may contain the required method. The message is according dispatched to another instance specific dispatch table associated with an object which may be able to execute the method called for by the message initially transmitted. Upward chaining between instance, class, and superclass level dispatch tables, and method supercalls canceling the effect of method overriding by instance level methods are included in the method and arrangement.
Abstract: A database management system is provided for security of database objects. These objects may be passive elements such as tables, rows, views, the databases themselves, etc., or they may be executable items such as stored procedures or triggers. A mechanism is provided for "certifying" that certain types of objects such as stored procedures, triggers, and views can be safely used to access other, sensitive objects in the database. Certification indicates that (1) a security officer has evaluated and certified the object, and (2) the now certified object has not undergone a defined security-relevant change since certification. Certification is particularly important in the context of a "trusted" stored procedure or a "trusted" stored trigger. "Trusted" executable objects can be executed at sensitivity levels that exceed that of a user or subject. Thus, the subject may use a trusted stored procedure or trigger to access certain objects having higher sensitivity levels than his or her own.
Abstract: Method and system for distributing prefragmented data processing loads in a fault tolerant system linked in a ring topology of disk subsystems and data processing nodes. The data processing load of the node under fault is shifted in one direction along the ring, and adjacent nodes in the same direction along the ring successively shift their entire data processing loads to their immediately adjacent data processing nodes. The adjacent data processing nodes in the non-shifted direction absorb increased workloads by one net data fragment each until the entire data processing load of the data processing node under fault is absorbed.
Abstract: A method for ensuring reliable interactions between principals within a database or between databases. The method involves the creation of database contracts which are, in essence, binding constraints on the behavior of entities within a database system that can be enforced by the system. A database contract is formed when two or more principals agree on the terms and conditions of the contract, and a monitor puts in to place the constraints necessary to enforce the agreed-upon terms and conditions after determining that each of the principals has the requisite authority and ability to carry out the contract.
Abstract: Method and system for dispatching a message to an alternate object upon its failure to find a required method at the object to which originally sent. The method and system employ the technique of using alternate dispatch variables which can be provided with values naming the alternate objects to which the messages are to be dispatched upon failure of execution at the local object. The alternate object toward which the message is dispatched may contain a method required for execution by a message sent to a first object, but which is unfulfilled by absence of the desired method in the first object. The class of the first object establishes alternate dispatch variables which can be set at run-time by a user making entries in a graphical user interface (GUI) effective to cause redispatch of the message to the alternate object.
Abstract: A data backup system implements coordination between a Database Server and a Backup Server to produce a recoverable database dump. By utilizing a technique referred to as stripe affinity, a mechanism is disclosed for ensuring the integrity of a database backup made to multiple archive devices simultaneously. In addition, by utilizing stripe affinity, archived data may be reloaded from fewer archive devices than were used to make the original backup. A task scheduler mechanism allocates processor time among the tasks that comprise the backup system. In this way the I/O service tasks can process their event queues while the current set of allocation pages are also being processed.