QoS Model for Web Service Selection on Pervasive Devices
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Solution Overview
Problem
Pervasive devices face resource constraints such as limited processing power, memory, and bandwidth, leading to excessive airtime and power consumption when interacting with web services that provide large or complex data responses, necessitating methods to optimize resource usage and reduce computational loads.
Innovation Solution
A Quality of Service (QoS) model is introduced to enable pervasive devices to evaluate and select between base and extended web services, allowing offloading of computational tasks to the web service, which reduces response size and processing time, and utilizes XSL transformations to filter and process data efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If web services provide comprehensive data responses to cater to diverse client applications, then service versatility is improved, but device power consumption and airtime requirements increase
Solution Approach 1:
The web service response is segmented into base service response and extended service response. The base service provides comprehensive data to all clients, while the extended service provides additional processed data only to clients that need it and can afford it. This segmentation allows the system to maintain service versatility while reducing power consumption for devices that use only the base service.
Solution Approach 2:
The system dynamically selects between base and extended web services based on client device characteristics and QoS model attributes. The selection is made at runtime based on evaluated attributes such as device capability, network conditions, and service requirements, allowing flexible adaptation that balances versatility and power consumption.
2Loss of information
If web services provide comprehensive data responses, then information completeness is improved, but device processing load and parsing time increase
Solution Approach 1:
The response is segmented into base and extended versions. The base service response contains all necessary information for basic functionality, while the extended service adds additional processed information. Clients can choose to parse only the base response or the extended response based on their needs, reducing parsing time for devices that don't require the additional information.
Solution Approach 2:
The extended service performs data processing and filtering actions before delivering the response to the client device. By pre-processing the data and only including necessary information in the extended response, the system reduces the parsing burden on the client device while maintaining information completeness for devices that need it.
3Productivity
If client devices process all web service response data, then data processing capability is improved, but device resource constraints are exceeded
Solution Approach 1:
The service is segmented into base and extended versions with different processing requirements. The base service requires minimal processing and is suitable for devices with limited resources, while the extended service provides additional processed data for devices with greater processing capability. This segmentation allows devices to select the appropriate service level based on their resource constraints.
Solution Approach 2:
The QoS model acts as an intermediary between the web service and the client device. It evaluates service attributes and device characteristics to determine the appropriate service level, mediating the interaction and ensuring that devices select services appropriate to their resource constraints while maximizing their processing capability utilization.
Data Source
AI summary
A system is described for selecting web services accessible over a network (380). The system comprises a pervasive device (10), one or more servers (20) in communication with the network (380) and supporting at least one base web service (502) that provides an output in reply to a request from the pervasive device (10). The system further comprises one or more servers (20) supporting at least one extended web service (606) operable to reduce a computational load of the pervasive device (10) in an interaction with the base web service (502). An application (504) running on the pervasive device (10) evaluates attributes of a Quality of Service (QoS) model relating to interactions between pervasive device (10), a base web service (502) and corresponding expanded web service (606). The application (504) chooses whether or not to use the corresponding web service based on the evaluated attributes.