Advanced network technologies and ubiquitous connected devices are boosting the development of the Internet of Things (IoT) at an unprecedented pace. However, as most of the connected IoT devices are battery powered, the energy consumption issue has become the bottleneck of the IoT’s development. Caching is a promising approach to reducing the energy consumption of the battery-powered devices since the requested data packets can be retrieved from intermediate nodes in the network, e.g., routers, instead of from the remote battery-powered IoT devices, which allows the IoT devices to spend more time in the sleep mode. To realize in-network caching and overcome the IP-based networks’ inefficiency support for IoT, building IoT over information-centric networking (ICN) is a promising approach advocated by researchers. However, existing works in this area assume the network environments are static, which hinders the development of existing approaches in the real dynamic network environments. In this article, we leverage the deep$Q$-networks (DQNs) to propose an intelligent caching scheme (named as iCache) that can automatically adjust the caching nodes’ caching parameters to make caching decisions for the dynamic network environments. Extensive evaluations were conducted and the results show that the proposed iCache outperforms the existing approaches in terms of the total energy consumption (e.g., more than 29% reduction compared to the caching transient data (CTD) caching scheme) and the average number of hops (e.g., more than 20% reduction compared to the CTD caching scheme).

Recommender systems relieve users from cognitive overloading by predicting preferred items for users. Due to the complexity of interactions between users and items, graph neural networks (GNN) use graph structures to effectively model user–item interactions. However, existing GNN approaches have the following limitations: (1) User reviews are not adequately modeled in graphs. Therefore, user preferences and item properties that are described in user reviews are lost for modeling users and items; and (2) GNNs assume deterministic relations between users and items, which lack the stochastic modeling to estimate the uncertainties in neighbor relations. To mitigate the limitations, we build tripartite graphs to model user reviews as nodes that connect with users and items. We estimate neighbor relations with stochastic variables and propose a Bayesian graph attention network (i.e., ContGraph) to accurately predict user ratings. ContGraph incorporates the prior knowledge of user preferences to regularize the posterior inference of attention weights. Our experimental results show that ContGraph significantly outperforms 13 state-of-the-art models and improves the best performing baseline (i.e., ANR) by 5.23% on 25 datasets in the five-core version. Moreover, we show that correctly modeling the semantics of user reviews in graphs can help express the semantics of users and items.

Different web services can be composed to perform increasingly complex tasks (e.g., making an on-line payment). However, existing approaches compose web services with hard-coded control and data flows. To proactively and autonomously compose web services, developers can develop agents. However, the development of agents for service composition is complex, due to the reasons that: 1) developers may not have the knowledge from various domains to identify the necessary tasks to carry out the required web services; and 2) a deep understanding of the agent specific code is required in order to implement agents. To alleviate the required efforts to develop agents, we propose an approach to separate the development of agent specific code from the business logic code in the service composition. More specifically, we provide an easy-to-understand syntax that abstracts agent specific code and automatically generates executable agent code. Our experimental results show that our approach can accurately identify tasks for service composition with an Area Under the Curve (AUC) of 0.88. Our experiments also demonstrate that our approach can correctly generate agent code from seven agent specifications. Finally, our user studies reveal that developers are satisfied with our approach to develop agents for service composition.

With the rapid growth of the web services technologies, users often leverage various web services to perform their daily activities, such as on-line shopping. Due to the massive amount of web services available, a user faces numerous choices to meet their personal preferences when selecting the desired services from the web services with the similar functionality. Therefore, it becomes tedious and cumbersome tasks for users to discover and compose services. To reduce user's cognitive burden, it is critical to support automated service composition and make efficient recommendation of personalized services to achieve user's overall goals. However, existing approaches only offer users with limited options designed for the interest of a group of users without considering individual users' interests. To allow users to compose personalized services without much manual specification, we propose a machine learning approach that applies a learning-to-rank algorithm, RankBoost, to automatically learn user preferences and the prioritization of the preferences from users' historical data. Moreover, our approach uses the multi-objective reinforcement learning (MORL) algorithm to make trade-offs among user preferences and recommends a collection of services to achieve the highest objective. We conduct an empirical study to evaluate our approach by collecting the historical data from 12 subjects. The results demonstrate that our approach outperforms the two well-established baseline approaches by 100%-200% in terms of precision on recommending services.

Background: Bug fixing is one major activity in software maintenance to solve unexpected errors or crashes of software systems. However, a bug fix can also be incomplete and even introduce new bugs. In such cases, extra effort is needed to rework the bug fix. The reworking requires to inspect the problem again, and perform the code change and verification when necessary. Discussions throughout the bug fixing process are important to clarify the reported problem and reach a solution. Aims: In this paper, we explore how discussions during the initial bug fix period (i.e., before the bug reworking occurs) associate with future bug reworking. We focus on two types of "reworked bug fixes": 1) the initial bug fix made in a re-opened bug report; and 2) the initially submitted patch if multiple patches are submitted for a single bug report. Method: We perform a case study using five open source projects (i.e., Linux, Firefox, PDE, Ant and HTTP). The discussions are studied from six perspectives (i.e., duration, number of comments, dispersion, frequency, number of developers and experience of developers). Furthermore, we extract topics of discussions using Latent Dirichlet Allocation (LDA). Results: We find that the occurrence of bug reworking is associated with various perspectives of discussions. Moreover, discussions on some topics (e.g., code inspection and code testing) can decrease the frequency of bug reworking. Conclusions: The discussions during the initial bug fix period may serve as an early indicator of what bug fixes are more likely to be reworked.

End-users repetitively perform various on-line tasks and invoke multiple web services for their re-occurring activities, such as planning a trip. Usually, end-users have to complete different tasks in order to achieve a goal, and look through large volumes of services to find the best ones that satisfy their constraints, such as a budget limit. Current approaches on service composition require programming skills and domain knowledge to accomplish goals. Moreover, existing approaches lack an automatic way to analyze end-users' goals and extract relevant tasks for achieving goals. In this paper, we provide a lightweight service composition framework for end-users with limited technical background. Our framework analyzes endusers' goals expressed in natural languages to mine tasks (e.g., plan a trip) and non-functional constraints (e.g., budget <; 500). Our framework extracts task models from textual descriptions of tasks (e.g., eHow, a How-to instruction website) to guide the selection of services and recommend web services that can finish tasks and satisfy constraints. We have designed and developed a prototype as a proof of concept. We conduct case studies to evaluate the effectiveness of our framework. Our framework can identify tasks with a precision of 93% and a recall of 77%, and extract non-functional constraints with a precision of 89% and a recall of 76%. A user study shows that our framework is helpful for end-users to compose services.