[雙語翻譯]外文翻譯--restful架構(gòu)應(yīng)用程序的物聯(lián)網(wǎng)框架及其在智慧城市中的試驗(yàn)（英文）

1、This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination.IEEE SYSTEMS JOURNAL 1A Web of Things Framework for RESTful Applications and

2、 Its Experimentation in a Smart CityFederica Paganelli, Member, IEEE, Stefano Turchi, and Dino Giuli, Senior Member, IEEEAbstract—The Web of Things is an active research field which aims at promoting the easy access and

3、handling of smart things’ digital representations through the adoption of Web standards and technologies. While huge research and development efforts have been spent on lower level networks and software technologies, it

4、has been recognized that little experience exists instead in mod- eling and building applications for the Web of Things. Although several works have proposed Representational State Transfer (REST) inspired approaches for

5、 the Web of Things, a main lim- itation is that poor support is provided to web developers for speeding up the development of Web of Things applications while taking full advantage of REST benefits. In this paper, we pro

6、pose a framework which supports developers in modeling smart things as web resources, exposing them through RESTful Application Programming Interfaces (APIs) and developing applications on top of them. The framework cons

7、ists of a Web Resource informa- tion model, a middleware, and tools for developing and publishing smart things’ digital representations on the Web. We discuss the framework compliance with REST guidelines and its major i

8、mple- mentation choices. Finally, we report on our test activities carried out within the SmartSantander European Project to evaluate the use and proficiency of our framework in a smart city scenario.Index Terms—Internet

9、 of things (IoT), representational state transfer (REST), sensors, smart city, smart things, web, web of things, web services.I. INTRODUCTION THE WEB OF Things is an active research area that focuses on the specific chal

10、lenge of making smart things accessi- ble and manageable through open Web standards. This vision is correlated with the broader Internet of Things (IoT) research area aiming at enabling communication with and among smart

11、 objects, leveraging Internet standards and technologies [1]. As argued by the European Expert Group on Services in the Future Internet [2], huge research and development efforts have focused on lower level networks and

12、software technolo- gies, while “there is currently little experience with building applications for this new, emerging ecosystem of IP-enabled devices and objects.” As the Web facilitated both applicationManuscript recei

13、ved March 24, 2014; revised July 26, 2014; accepted August 28, 2014. This work was supported in part by the European Commission through the SmartSantander Seventh Framework Programme-Information and Communication Technol

14、ogies project. F. Paganelli is with the National Interuniversity Consortium for Telecommunications, University of Florence, 50139 Florence, Italy (e-mail: federica.paganelli@unifi.it). S. Turchi and D. Giuli are with the

15、 Department of Information Engineering, University of Florence, 50139 Florence, Italy (e-mail: stefano.turchi@unifi.it; dino.giuli@unifi.it). Color versions of one or more of the figures in this paper are available onlin

16、e at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/JSYST.2014.2354835development and use for the traditional Internet, it is now expected to “unleash the potential of the IoT by making it acces- sible and

17、 programmable by developers who are not necessarily experts in ubiquitous computing” [2]. The Web of Things is expected to ease the access to smart things’ capabilities and promote novel value-added services based on the

18、 combination of traditional web resources with those representing entities from the physical world (smart things, sensors, appliances, etc.) [3]. This has the big advantage of allowing the integration of smart things wit

19、h the impressive amount of information resources and services already on the Web, as well as exploiting available technologies and best practices for web resource publishing and management. On this perspective, the Repre

20、sentational State Transfer (REST) architectural style, developed as an abstract model of the Web architecture [4] is considered a reference paradigm for bringing sensors, and more generally smart things, into the Web [5]

21、–[7]. Indeed, REST defines a set of principles for de- signing distributed hypermedia application fulfilling scalability, simplicity, and loosely coupling requirements. Several research works have proposed approaches for

22、 im- plementing the Web of Things through REST principles, as discussed in the survey by Zeng et al. [8]. However, the path to the effective realization of the Web of Things is made difficult by the widespread misunderst

23、anding of REST basics [9] and, consequently, the lack of software development frameworks that comprehensively support them [10], [11]. As a consequence, a main limitation of related work is that poor support is provided

24、to web developers for speeding up the development of web applications for accessing, modifying, and composing information resources in the Web of Things domain [2] while taking full advantage of REST benefits. In this pa

25、per, we propose an approach toward the Web of Things based on a graph representation of web resources, which can be accessed and modified at the desired and meaningful level of granularity through a REST-compliant unifor

26、m inter- face. According to our approach, a smart thing can be modeled as a graph of individually addressable web resources whose edges represent simple structural aggregation (i.e., contain- ment) and reference relation

27、s. Graph-based representation of smart things can be interlinked with other types of information nodes to build a growing graph of globally addressable infor- mation resources that can be navigated, queried, and composed

28、 through a uniform REST interface. The proposed framework consists of the following: 1) a Web Resource information model for representing smart things as web-accessible resources; 2) a middleware for handling and exposin

29、g these resources through a uniform API; and 3) a set1932-8184 © 2014 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/public

30、ations/rights/index.html for more information.This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination.PAGANELLI et al.: WEB OF THING

31、S FRAMEWORK FOR RESTful APPLICATIONS AND ITS EXPERIMENTATION 3allows end users to access the virtual objects and compose them according to basic event-based rules. Uberdust [19] is a service-oriented platform that provid

32、es storage, sharing, and discovery of real-time and historical data from smart objects and sensor networks through the Web. These data can be accessed using REST and WebSocket APIs. Significant efforts are ongoing to dev

33、elop a Semantic Sensor Web [20] and integrate it with the growing body of knowledge available as Linked Open Data [21]. SemSense [22] is a system that collects data from physical sensors and publishes these data enriched

34、 with semantic anno- tations on the Web. SPITFIRE [23] is a service infrastructure that offers the semiautomatic generation of semantic sensor descriptions and efficient search for sensors and things based on their curre

35、nt states. Applications can issue search requests to SPITFIRE and then invoke retrieved services, directly.C. Motivation of Our WorkWhile most works focusing on semantic descriptions of smart things [20], [22], [23] aim

36、at providing efficient search and discovery capabilities, the scope of our work is to provide users with tools for accessing and programming the Web of Things, in compliance with REST guidelines. Towards this objective,

37、some previously mentioned works [16]–[19] provide tools for speeding up the exposure of REST APIs for accessing smart thing capabilities. The original contribution of our work with respect to the ones mentioned earlier [

38、17]–[19] is twofold: 1) the proposal of an information model representing web resources and their mutual relations and 2) the provision of tools supporting users in composing, publishing, and sharing the web representati

39、on of smart devices, which can be accessed through common web browsers. In the context of this study, we consider two different target users: 1) developers of the WoT (developers from now on) and 2) tech-savvy users with

40、 rudiments of web technologies (users from now on). In Section III-C, we will discuss tools created for both categories. Finally, the term end user will refer to people without particular domain competences, e.g., ordina

41、ry “Web surfers.” Our work shows more similarities with AutoWoT [16] since both adopt a Web Resource model and provide services sup- porting the exposure of smart devices as web resources. How- ever, a significant differ

42、ence exists in the modeling approach. The AutoWoT resource model relies solely on a hierarchical relation among resources; consequently, a physical thing is represented as a hierarchical collection of web resources. We a

43、rgue that a mere hierarchical relation is not fully compliant with the REST hypermedia constraint (i.e., reference links among resources drive the application state evolution and shall be advertised by the server at each

44、 interaction step). Since, as ar- gued by Vinoski, “relationships between resources and how the server makes those relationships available to applications are at least as important to REST developers as resource naming,”

45、 our approach relies on a graph-based model that includes two main types of relations among web resources (i.e., aggregation and reference). Purposely, these relations recall how, in fact, web resources are organized and

46、 can be navigated in traditionalweb sites. In addition, InterDataNet (IDN) is natively capable of handling sets of resources, and this has the following impli- cations: 1) using the Web Resource REST resource exposed by

47、the middleware it is possible to perform aggregated operations on graphs, e.g. to retrieve, create or update more vertexes at the same time; and 2) the Web Resource model describes sets of Nodes (at the limit, made of on

48、e element only) and is particularly suited for hosting properties which are strongly affected by information aggregation practices, such as privacy. Moreover, unlike AutoWOT, the IDN model offers a scriptable Node, calle

49、d Activity Node (see Section III-A), which is able to perform processing operations on other Nodes’ contents and output the computation result. This scenario seems to be very promising for device virtualization. Leveragi

50、ng this model, we propose a set of capabilities supporting developers and users in representing smart things as Web Resources and composing them with existing web resources, to build novel applications.III. WEB OF THINGS

51、 RESTFUL FRAMEWORKOur work aims at leveraging Web principles for making a Web of Things easy to access and program. Our framework provides tools for easing both exposure and handling of smart devices (and related informa

52、tion) as web resources. These web resources can be composed with “traditional” ones to facilitate the creation of web applications and services. This objective requires a dedicated adaptation layer mediating the interact

53、ion with sensor and actuator implementation technologies that have not been designed with the Web exposure requirement in mind. It is widely accepted that REST is the architectural style for the Web, and our approach for

54、 web resource exposure is based on its principles. Since the mere adoption of mainstream REST frameworks does not guarantee the compliance with all REST guidelines [10], [11], our work aims at helping developers in takin

55、g such constraints into account. More specifically, our framework provides support to the following.1) Resource type definition and design. We propose a graph- based information model for representing web resources, call

56、ed Web Resource model. 2) General-purpose software for exposing and handling op- erations on web resources. Our system includes a set of middleware services for exposing web resources through a REST uniform interface. 3)

57、 Mapping between web resource representation and legacy data sources. The middleware is based on a layered architecture that distinguishes the web exposure layer (dealing with web resource model and representa- tion, con

58、tent negotiation, and RESTful uniform interface exposure) and the layer dealing with storage of data entities and/or the retrieval from external sources. 4) Programming and Web Publishing tools. These consist of Java and

59、 JavaScript libraries for easing the development of web applications for the Web of Things, a web appli- cation allowing users to graphically access, modify, and create new web resources according to our model, and a plu