Web Feature Service Locking via Session Transferable Identifiers
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Solution Overview
Problem
Current Web Feature Service (WFS) systems lack a mechanism for long-term, transferable locking of feature instances across sessions without consuming storage space for versioning, which is essential for maintaining concurrency and consistency in geographic information systems where data updates can span multiple sessions and database shutdowns.
Innovation Solution
Implement a light-weight long transaction locking model that allows feature instances to be locked for extended periods, enabling session transferable identifiers to manage exclusive updates, ensuring only the owning session can modify the feature instances, and allowing lock transfer between sessions without releasing the lock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If versioning is used to manage long transactions, then concurrency and consistency are maintained, but storage space is consumed for maintaining version data
Solution Approach 1:
The patent extracts the versioning mechanism from the system and replaces it with a locking model. Instead of maintaining multiple versions of feature instances in storage, the system uses locks to control access and ensure consistency, thereby eliminating the storage overhead associated with version data while maintaining reliability.
Solution Approach 2:
The patent changes the fundamental parameter of transaction management from version-based to lock-based. By introducing session transferable identifiers that represent locks on feature instances, the system transforms how concurrency is managed, allowing long transactions without creating version copies, thus reducing storage consumption while maintaining data integrity.
2Reliability
If traditional locking is used to ensure serializability, then data consistency is maintained, but locks cannot be transferred across sessions
Solution Approach 1:
The patent creates a universal lock mechanism through session transferable identifiers that can be transferred across different sessions. The same identifier system serves both to maintain data consistency during long transactions and to enable seamless transfer of lock ownership between users, making the locking system adaptable to multi-session workflows without sacrificing reliability.
Solution Approach 2:
The session transferable identifier acts as an intermediary between the lock mechanism and user sessions. This identifier mediates the transfer of lock ownership by allowing the system to track and transfer lock state between sessions without releasing and re-acquiring locks, thereby maintaining consistency while enabling session transferability.
3Reliability
If locks are held for long periods to allow data updates, then data integrity is maintained, but other users cannot access the same features
Solution Approach 1:
The patent introduces dynamic lock management through session transferable identifiers. Locks are not static but can be dynamically transferred between sessions based on user needs. This allows the system to maintain data integrity during long updates while enabling other users to access different features or wait for lock availability, optimizing overall system productivity without sacrificing reliability.
Solution Approach 2:
The system performs preliminary locking actions with session transferable identifiers before actual data updates begin. This allows users to reserve locks in advance for long-running operations while the system maintains the ability to manage concurrent access requests, balancing data integrity requirements with user productivity by allowing queued access rather than complete blocking.
Data Source
AI summary
Locking feature instances in a web feature service by processing a web feature service data transformation request; identifying a table associated with the web feature service data transformation request from a feature type identified in the request; determining if the table associated with the web feature service data transformation request is enabled for long transaction locking; and, if the table is long transaction lock enabled, locking at least one feature instance associated with a filter condition of the web feature service data transformation request by associating a session transferable identifier with the at least one feature instance and identifying the client session as owner of the session transferable identifier; and enabling a transfer of the long transaction lock to another client session in response to a lock transfer request from the another client session that references the session transferable identifier in a web feature service transaction request.