Abstract: In an object-based computer system, each object is contained in, and each task executes in, a protection domain. Domains exist at several hierarchical domain levels, some levels having multiple discrete domains, while others have one common domain. A task may access an object if the domain in which the task is executing is the same as the domain containing the object, or if the domain in which it is executing occupies a higher hierarchical domain level than the domain containing the object. Each object includes a domain attribute, which is a numerical value defining the domain in which it is contained. The domain attribute of the currently executing task is stored in a domain register. When an attempt is made to access data within an object, the domain attribute of the object is compared with the domain attribute stored in the domain register. If the access conditions are met, access is permitted.

Abstract: Each panel or display screen of data, is defined by a title and the tagged description of the objects, such as instruction lines, data entry lines, menu areas and command lines. Each of these objects may include other objects, described in the same syntax. Panel definitions are joined in a source file to form a panel group. Objects can be shared by all panels.

Abstract: A quick recovery of logical files which provide alternate views of databases is provided. Unchanged logical file pages are journaled before being changed. Transactions affecting databases covered by the logical files are also journaled. To recover a logical file, the journaled unchanged pages of the logical file that correspond to the changed pages are inserted back into the logical file, and the transactions that were journaled are processed to provide the changes to the logical file and to the database. This brings the logical file and the underlying database up to date, and in synchronization with each other.

Abstract: A storage management mechanism distributes parity blocks corresponding to multiple data blocks substantially equally among a set of storage devices. N storage units in a set are divided into a multiple of equally sized address blocks, each containing a plurality of records. Blocks from each storage unit having the same address ranges form a stripe of blocks. Each stripe has a block on one storage device containing parity for the remaining blocks of the stripe. Further stripes also have parity blocks, which are distributed on different storage units. Parity updating activity associated with every change to a data record is therefore distributed over the different storage units, enhancing access characteristics of the set of storage devices. The parity updating activity also includes the use of an independent version number stored with each data record and corresponding version numbers stored with the parity record.