Overview
ISO 8571-2:1988/Amd 2:1993 is an important amendment to the international standard ISO 8571-2, titled Information Processing Systems - Open Systems Interconnection - File Transfer, Access and Management - Part 2: Virtual Filestore Definition. This amendment introduces the concept of overlapped access to the virtual filestore model, significantly enhancing the efficiency of file access operations in networked environments.
The standard, published by ISO, extends the original file and filestore abstract model by allowing multiple read and write operations to overlap during file access. This improves performance in scenarios where a single initiator performs numerous sequential reading and updating operations, reducing control overhead and supporting more efficient data transfer.
Key Topics
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Virtual Filestore Model Extension
The amendment builds upon the existing abstract model for describing files and filestores, detailing how overlapped access can be integrated into the system without altering the fundamental definitions.
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Overlapped Access Concept
- Consecutive Overlap: Allows queuing of read and write requests while a previous action is in progress, enabling multiple operations to be scheduled efficiently.
- Concurrent Access: Enables simultaneous read and write data transfers in both directions, exploiting full-duplex communication paths to boost throughput.
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Serializability and Data Consistency
While overlapped access improves performance, the amendment carefully addresses the resulting nondeterminism. It ensures that the final effect of overlapped operations matches that of serialized executions, maintaining service consistency and reliability.
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Activity Attributes for Overlapped Access
New attributes such as current degree of overlap and vectors for access requests and processing states help manage and monitor overlapping file operations within the open regime of the filestore.
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File Access Actions Updates
Modifications to standard file actions like Locate and Erase accommodate the behavior of overlapped reading and writing by tracking separate file access data units (FADUs) for concurrent operations.
Applications
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Networked File Transfer Systems
Overlapped access facilitates more efficient file transfers over high-latency or bandwidth-constrained connections by enabling multiple file operations to be "in flight" simultaneously.
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Distributed File Management
Systems managing structured files in distributed environments benefit from the reduced control overhead, allowing applications to perform rapid and concurrent read-write cycles effectively.
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Open Systems Interconnection (OSI) Environments
ISO 8571-2 Amendment 2 aligns with OSI architecture principles, providing improved file transfer and access management capabilities within interoperable networked systems.
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Real-Time and High-Performance Computing
Applications that require fast and frequent access to file data, such as streaming or database management, can leverage overlapped access to enhance throughput and responsiveness.
Related Standards
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ISO 8571 Series
- Part 1: General Introduction
- Part 3: File Service Definition
- Part 4: File Protocol Specification
- Part 5: Protocol Implementation Conformance Statement Proforma
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ISO/IEC JTC 1 Information Technology Standards
The amendment is part of the broader set of standards developed by the ISO/IEC Joint Technical Committee 1 focused on Information Technology and Open Systems Interconnection.
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Open Systems Interconnection (OSI) Framework
Related OSI standards provide the architectural and protocol foundations over which ISO 8571-2 operates, ensuring interoperability between systems in network environments.
Keywords: ISO 8571-2, overlapped access, virtual filestore, file transfer, file access management, Open Systems Interconnection, FTAM, file operations, networked file systems, concurrent file access, file protocol, data consistency, file attributes.
This amendment ensures that information technology systems can achieve higher efficiency in file transfer and management while maintaining adherence to international best practices in open network communications.
Open preview (PDF)Information processing systems — Open Systems Interconnection — File Transfer, Access and Management — Part 2: Virtual Filestore Definition — Amendment 2: Overlapped access
