Apparatus and method for maintaining cache memory integrity in a shared memory environment
Multiprocessing system including a shared cache
Software version management system
Data processing system
Personal computer attachment for host system display station
Method of inter-process communication in a distributed data processing system
Data base locking
Communication for version management in a distributed information service
System for merging virtual partitions of a distributed database
ApplicationNo. 685361 filed on 04/15/1991
US Classes:711/152, Memory access blocking709/201, DISTRIBUTED DATA PROCESSING709/205, Cooperative computer processing715/751Computer supported collaborative work between plural users
ExaminersPrimary: Lee, Thomas C.
Assistant: Pan, Daniel H.
International ClassesG06F 009/22
AbstractA multi-user collaborative system in which the contents as well as the current status of other user activity of a shared structured data object representing one or more related structured data objects in the form of data entries can be concurrently accessed by different users respectively at different workstations connected to a common link. The WYSIWIS user interface representation of the shared structured data object includes an ordered listing of such entries that are maintained by the structured data object and various attributes of each listed entry, inter alia, the type and class of entry; the revision number of the shared structured data object; the number of pages and revision number of each structured data object entry; the date of creation and last revision of each such entry; whether an entry can be accessed by a user and, if not, who has prevented such access; whether a local instance of an entry is present on a user's system; and a provision for miscellaneous notes or comments relative to each entry for view by other users. Means is provided for maintaining current information relative to the shared structured object and its entries on a user initiated demand updated basis invoked by a user operation, which operation requires updated information to properly implement the operation. Further, means is provided for locking up one or more data entries by an individual user and thereby prevent access of the locked entries by other users to prevent concurrent editing and other changes to the same entries by two or more users. In this connection, editing or modification cannot be performed by a user until the shared structured data object entry or entries have been locked up. Visual indication as to the locked state of entries and other information relative to the locking user and the time of lock is updated and displayed in the shared structured data object representation present at user workstations when a use invokes a user operation on the shared structured data object or its contents.