# Sustainable IoT Sensing Applications Development through GraphQL-Based Abstraction Layer
## 2 Related Work  
As the replacement of traditional web services based on REST architecture, Facebook released GraphQL [11] and Falcon [12] was introduced by Netflix. Such solutions mainly target decreasing bandwidth utilisation through implementing reduction in traffic generation involving connected nature data. We base our work in this paper on incorporating these approaches for sensing application scenarios in Contiki-based cloud IoT networks. In the literature, applying such an abstraction layer for IoT applications has limited existence related to work in this paper, as we are not using the traditional enhancement scheme of duty cycling which is found in many of the optimisations for energy usage. [PERSON] and [PERSON] analysed GraphQL to understand properties of the language and also gave details of semantics and complexity of its use [13; 14]. They provided a solution to handle large size of GraphQL response for Internet scenario and obtained computation as well as delay improvements, to show it is helpful for more robust web interfaces. [PERSON] et al. [15] looked into complex data-driven ecosystems which need high levels of interoperability and REST APIs are used as common approach to achieve it. They leveraged benefits of GraphQL protocol and presented a case study achieving benefits using GraphQL as main API in different parts of the ecosystem. [PERSON] et al. [16] presented GraphQL-LD, a linked data querying in linked open data cloud for application development, which is pushing for linked data consumption. [PERSON] et al. [17] stated that usage of energy can be decreased by utilising the data communication reducing schemes through power-aware applications. Our proposed approach in this work is also reducing the data traffic by utilising an abstraction layer for combining the queries to a single endpoint for multiple resources. [PERSON] et al. [18] emphasised reducing active slots in sensor devices and their focus is on optimising the duty cycling mechanism. [PERSON] and his co-authors [19] discussed hardware and networking details in low power wake-up radios. Our research is different as  
Figure 2: The energy-wave problem in sensor network architecture. we do not utilise the duty cycling scheme, as it is discussed in above section to be not fulfilling in the case of our target high data rate applications. We achieve the power conservation and delay minimising through incorporating the application layer for data transaction optimisation. [PERSON] [20] introduced a gateway as a service for transforming data from application layer protocol, for enhancing the performance. We also use the same protocol CoAP at the application level in our work but integrated it alongside the abstraction layer of graph-based querying and server layers. Translation like this between application layer protocols for IoT implementation has also been introduced in some other research works (e.g., [21; 22; 23]). These works mainly emphasise the mapping of IoT protocol CoAP and Internet communication of HTTP, using a service such as Firebase. Similarly, [PERSON] et al. [24] worked on comparing GraphQL-based cloud service and traditional REST scheme, which gives a helpful insight for transforming these implementations to one another for mapping purpose. In [25], the work introduced REST Query Language (RQL) to minimise the number of data transactions in mobile applications. The work presented in this paper is an extension of our previous study given in [26]. Previously, we used GraphQL for duty cycling-based sensor networks to optimise active time slots through round trips saving. The study presented in this paper, aims at achieving energy efficiency through communication optimisation using GraphQL layer, in active IoT applications involving high data sending. Several application layer frameworks and protocols are developed for IoT-based applications, e.g., IoTivity, CoAP, REST etc.