Object Pointer Research Articles

Study on Effective Temporal Data Retrieval Leveraging Complex Indexed Architecture

Current intelligent information systems require complex database approaches managing and monitoring data in a spatio-temporal manner. Many times, the core of the temporal system element is created on the relational platform. In this paper, a summary of the temporal architectures with regards to the granularity level is proposed. Object, attribute, and synchronization group perspectives are discussed. An extension of the group temporal architecture shifting the processing in the spatio-temporal level synchronization is proposed. A data reflection model is proposed to cover the transaction integrity with reflection to the data model evolving over time. It is supervised by our own Extended Temporal Log Ahead Rule, evaluating not only collisions themselves, but the data model is reflected, as well. The main emphasis is on the data retrieval process and indexing with regards to the non-reliable data. Undefined value categorization supervised by the NULL_representation data dictionary object and memory pointer layer is provided. Therefore, undefined (NULL) values can be part of the index structure. The definition and selection of the technology of the master index is proposed and discussed. It allows the index to be used as a way to identify blocks with relevant data, which is of practical importance in temporal systems where data fragmentation often occurs. The last part deals with the syntax of the Select statement extension covering temporal environment with regards on the conventional syntax reflection. Event_definition, spatial_positions, model_reflection, consistency_model, epsilon_definition, monitored_data_set, type_of_granularity, and NULL_category clauses are introduced. Impact on the performance of the data manipulation operations is evaluated in the performance section highlighting temporal architectures, Insert, Update and Select statements forming core performance characteristics.

A fully concurrent garbage collector for functional programs on multicore processors

This paper presents a concurrent garbage collection method for functional programs running on a multicore processor. It is a concurrent extension of our bitmap-marking non-moving collector with Yuasa's snapshot-at-the-beginning strategy. Our collector is unobtrusive in the sense of the Doligez-Leroy-Gonthier collector; the collector does not stop any mutator thread nor does it force them to synchronize globally. The only critical sections between a mutator and the collector are the code to enqueue/dequeue a 32 kB allocation segment to/from a global segment list and the write barrier code to push an object pointer onto the collector's stack. Most of these data structures can be implemented in standard lock-free data structures. This achieves both efficient allocation and unobtrusive collection in a multicore system. The proposed method has been implemented in SML#, a full-scale Standard ML compiler supporting multiple native threads on multicore CPUs. Our benchmark tests show a drastically short pause time with reasonably low overhead compared to the sequential bitmap-marking collector.

Object protection in distributed systems

With reference to a distributed system consisting of nodes connected by a local area network, we consider a salient aspect of the protection problem, the representation of access permissions and protection domains. We present a model of a protection system supporting typed objects. Possession of an access permission for a given object is certified by possession of an object pointer including the specification of a set of access rights. We associate an encryption key with each object and a password with each domain. Object pointers are stored in memory in a ciphertext form obtained by using the object key and including the value of the domain password. Each process is executed in a domain and can take advantage of a given object pointer only if this object pointer was encrypted by including the password of this domain. A set of protection primitives makes it possible to use object pointers for object reference and to control the movements of the objects across the network. The resulting protection environment is evaluated from a number of salient viewpoints, including ease of access right distribution and revocation, interprocess interaction and cooperation, protection against fraudulent actions of access right manipulation and stealing, storage overhead, and network traffic.

The Soprano Extensible Object Storage System

An efficient object manager, a middle layer on top of a storage system, is essential to ensure acceptable performance of object-oriented database systems, since a traditional record-based storage system is too simple to provide object abstraction. In addition, an object storage system–object managers in combination with storage systems - should be extensible to meet the various requirements of emerging applications. In this research, we design and implement an extensible object storage system, called Soprano, in an object-oriented fashion which has shown great potential in extensibility and code reusability. Soprano provides a uniform object abstraction and gives us the convenience of persistent programming through many useful persistent classes. Also, Soprano supports efficient object management and pointer swizzling for fast object access. This paper investigates several aspects of the design and implementation of the extensible object storage system. Our experience shows the feasibility of using an object-oriented design and implementation in building an object storage system that should have both extensibility and high performance.

Virtual memory on a narrow machine for an object-oriented language

LOOM (Large Object-Oriented Memory) is a virtual memory implemented in software that supports the Smalltalk-80(™) programming language and environment on the Xerox Dorado computer. LOOM provides 8 billion bytes of secondary memory address space and is specifically designed to run on computers with a narrow word size (16-bit wide words). All storage is viewed as objects that contain fields. Objects may have an average size as small as 10 fields. LOOM swaps objects between primary and secondary memory, and addresses each of the two memories with a different sized object pointer. When objects are cached in primary memory, they are known only by their short pointers. On a narrow word size machine, the narrow object pointers in primary memory allow a program such as the Smalltalk-80 interpreter to enjoy a substantial speed advantage. Interesting design problems and solutions arise from the mapping between the two address spaces and the temporary nature of an object's short address. The paper explains why the unusual design choices in LOOM were made, and provides an interesting example of the process of designing an integrated virtual memory and storage management system.