Device Shadowing Service for Offline State Management
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Solution Overview
Problem
Existing technologies face challenges in managing device representations for network addressable devices with intermittent connectivity, as they struggle to maintain accurate state information and execute commands efficiently across a network, especially when devices are unreachable or disconnected.
Innovation Solution
A device shadowing service is introduced to manage device representations, allowing for cached state information and command execution even when devices are offline, using a data-interchange format like JSON and supporting extended virtualized commands to expand device functionality beyond physical capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If device state information is maintained only when devices are connected, then network resources are conserved, but device state information becomes unavailable when devices are disconnected
Solution Approach 1:
The system performs preliminary actions by caching device state information in a shadow device representation before the actual device disconnects. This allows the state information to be preserved and accessible even when the device is offline, eliminating the need for real-time connection maintenance while avoiding information loss.
Solution Approach 2:
The system creates a copy of the device state information in the form of a shadow device representation that mirrors the actual device state. This copy maintains the state information independently of the actual device's connection status, allowing read access even when the device is disconnected, thus resolving the contradiction between information availability and resource consumption.
2Adaptability or versatility
If commands are executed only when devices are reachable, then command execution reliability is maintained, but command execution capability is lost when devices are offline
Solution Approach 1:
The system queues commands in advance when devices are offline, performing preliminary actions that prepare commands for execution. When the device reconnects, the queued commands are executed in sequence, ensuring that command execution capability is maintained during offline periods while reliability is preserved through proper sequencing and state verification.
Solution Approach 2:
The shadow device representation acts as an intermediary between the command source and the actual device. It receives and queues commands when the device is offline, then forwards them when the device is available, thus maintaining command execution capability across connection states while ensuring reliability through the intermediary's coordination.
3Measurement precision
If device representations are updated in real-time, then state accuracy is maintained, but network traffic increases during device connectivity
Solution Approach 1:
The system applies partial updates to the shadow device representation, updating only the specific state fields that have changed rather than performing complete real-time synchronization. This reduces network traffic and energy consumption while maintaining sufficient state accuracy for operational purposes, resolving the contradiction between precision and energy loss.
4Ease of operation
If cached device representations are maintained for offline devices, then device accessibility is improved, but memory resources are consumed
Solution Approach 1:
The system maintains cached device representations as lightweight, temporary objects that are discarded when no longer needed. These shadow representations use minimal memory resources and are automatically cleaned up after device reconnection or timeout periods, providing improved accessibility without significant long-term memory consumption.
Data Source
AI summary
A technology is described for operating a device shadowing service that manages device representations for physical devices that are network addressable. An example method may include associating a device representation with a representation type, where the device representation represents a copy of a state of a physical device in network communication with a device shadowing service that maintains the device representation, and the representation type may define a command that can be invoked through the device representation. After the device representation has been associated with the representation type, the command may be invoked through the device representation. Invoking the command may involve identifying the representation type associated with the device representation and determining that the command is supported by the representation type. Thereafter, the command may be executed.