Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
1998-03-20
2001-06-12
Choules, Jack (Department: 2777)
Data processing: database and file management or data structures
Database design
Data structure types
C707S793000, C707S793000, C707S793000, C707S793000, C709S241000, C709S203000
Reexamination Certificate
active
06247026
ABSTRACT:
The following identified U.S. patent applications are relied upon and are incorporated by reference in this application.
Provisional U.S. Patent Application No. 60/076,048, entitled “Distributed Computing System,” filed on Feb. 26, 1998.
U.S. patent application Ser. No. 09/044,923, entitled “Method and System for Leasing Storage,” pending, and filed on the same date herewith.
U.S. patent application Ser. No. 09/044,834, entitled “Method, Apparatus and Product for Leasing of Group Membership in a Distributed System,” pending, and filed on the same date herewith.
U.S. patent application Ser. No. 09/044,916, entitled “Methods and Systems For Distributed Failure Detection and Recovery Using Leasing,” U.S. Pat. No. 6,016,500, and filed on the same date herewith.
U.S. patent application Ser. No. 09/044,933, entitled “Method for Transporting Behavior in Event Based System,” pending, and filed on the same date herewith.
U.S. patent application Ser. No. 09/044,919, entitled “Deferred Reconstruction of Objects and Remote Loading for Event Notification in a Distributed System,” pending, and filed on the same date herewith.
U.S. patent application Ser. No. 09/044,938, entitled “Methods and Apparatus for Remote Method Invocation,” pending, and filed on the same date herewith.
U.S. patent application Ser. No. 09/045,652, entitled “Method and System for Deterministic Hashes to Identify Remote Methods,” pending, and filed on the same date herewith.
U.S. patent application Ser. No. 09/044,790, entitled “Method and Apparatus for Determining Status of Remote Objects in a Distributed System,” pending, and filed on the same date herewith.
U.S. patent application Ser. No. 09/044,930, entitled “Downloadable Smart Proxies for Performing Processing Associated with a Remote Procedure Call in a Distributed System,” pending, and filed on the same date herewith.
U.S. patent application Ser. No. 09/044,917, entitled “Suspension and Continuation of Remote Methods,” pending, and filed on the same date herewith.
U.S. patent application Ser. No. 09/044,835, entitled “Method and System for Multi-Entry and Multi-Template Matching in a Database,” pending, and filed on the same date herewith.
U.S. patent application Ser. No. 09/044,839, entitled “Method and System for In-Place Modifications in a Database,” abandoned, and filed on the same date herewith.
U.S. patent application Ser. No. 09/044,945, entitled “Method and System for Typesafe Attribute Matching in a Database,” pending, and filed on the same date herewith.
U.S. patent application Ser. No. 09/044,931, entitled “Dynamic Lookup Service in a Distributed System,” pending, and filed on the same date herewith.
U.S. patent application Ser. No. 09/044,939, entitled “Apparatus and Method for Providing Downloadable Code for Use in Communicating with a Device in a Distributed System,” pending, and filed on the same date herewith.
U.S. patent application Ser. No. 09/044,826, entitled “Method and System for Facilitating Access to a Lookup Service,” pending, and filed on the same date herewith.
U.S. patent application Ser. No. 09/044,932, entitled “Apparatus and Method for Dynamically Verifying Information in a Distributed System,” pending, and filed on the same date herewith.
U.S. patent application Ser. No. 09/030,840, entitled “Method and Apparatus for Dynamic Distributed Computing Over a Network,” and filed on Feb. 26, 1998, pending.
U.S. patent application Ser. No. 09/044,936, entitled “An Interactive Design Tool for Persistent Shared Memory Spaces,” pending, and filed on the same date herewith.
U.S. patent application Ser. No. 09/044,934, entitled “Polymorphic Token-Based Control,” pending, and filed on the same date herewith.
U.S. patent application Ser. No. 09/044,915, entitled “Stack-Based Access Control,” pending, and filed on the same date herewith.
U.S. patent application Ser. No. 09/044,944, entitled “Stack-Based Security Requirements,” pending, and filed on the same date herewith.
U.S. patent application Ser. No. 09/044,837, entitled “Per-Method Designation of Security Requirements,” pending, and filed on the same date herewith.
BACKGROUND OF THE INVENTION
A. Field of the Invention
This invention generally relates to data processing systems and, more particularly, to leasing delegation certificates in data processing systems.
B. Description of the Related Art
Proper resource management is an important aspect to efficient and effective use of computers. In general, resource management involves allocating resources (e.g., memory) in response to requests as well as deallocating resources at appropriate times, for example, when the requesters no longer require the resources. In general, the resources contain data referenced by computational entities (e.g., applications, programs, applets, etc.) executing in the computers.
In practice, when applications executing on computers seek to refer to resources, the computers must first allocate or designate resources so that the applications can properly refer to them. When the applications no longer refer to a resource, the computers can deallocate or reclaim the resource for reuse. In computers each resource has a unique “handle” by which the resource can be referenced. The handle may be implemented in various ways, such as an address, array index, unique value, pointer, etc.
Resource management is relatively simple for a single computer because the events indicating when resources can be reclaimed, such as when applications no longer refer to them or after a power failure, are easy to determine. Resource management for distributed systems connecting multiple computers is more difficult because applications in several different computers may be using the same resource.
Disconnects in distributed systems can lead to the improper and premature reclamation of resources or to the failure to reclaim resources. For example, multiple applications operating on different computers in a distributed system may refer to resources located on other machines. If connections between the computers on which resources are located and the applications referring to those resources are interrupted, then the computers may reclaim the resources prematurely. Alternatively, the computers may maintain the resources in perpetuity, despite the extended period of time that applications failed to access the resources.
These difficulties have led to the development of systems to manage network resources, one of which is known as “distributed garbage collection.” That term describes a facility provided by a language or runtime system for distributed systems that automatically manages resources used by an application or group of applications running on different computers in a network.
In general, garbage collection uses the notion that resources can be freed for future use when they are no longer referenced by any part of an application. Distributed garbage collection extends this notion to the realm of distributed computing, reclaiming resources when no application on any computer refers to them.
Distributed garbage collection must maintain integrity between allocated resources and the references to those resources. In other words, the system must not be permitted to deallocate or free a resource when an application running on any computer in the network continues to refer to that resource. This reference-to-resource binding, referred to as “referential integrity,” does not guarantee that the reference will always grant access to the resource to which it refers. For example, network failures can make such access impossible. The integrity, however, guarantees that if the reference can be used to gain access to any resource, it will be the same resource to which the reference was first given.
Distributed systems using garbage collection must also reclaim resources no longer being referenced at some time in the finite future. In other words, the system must provide a guarantee against “memory leaks.” A memory leak can occur when all applications drop references to a resource, but the system fails to reclaim the resource for reuse because, for examp
Scheifler Robert
Waldo James H.
Wollrath Ann M.
Choules Jack
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Lewis Cheryl
Sun Microsystems Inc.
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