文章資訊

原始檔案
Journal/Conference: Springer
Year:2013
Authors:
Units:
  1. Software Engineering Group, University of Fribourg, Switzerland
  2. SAP Research, Switzerland

摘要

這篇文章以雙向的方式來探討現有BPM(用在ERP上)與WoT該如何整合,一方面評估BPMN應該要如何調整才能滿足WoT特殊的需求。另一方面,也試圖用現有的商業流程是否可以直接套在WoT的架構上。

看完心得


認同之處


懷疑與問題


改進建議



介紹


願景、動機、概念

IoT環境中裝置的異質性一直是一個主要的問題,目前沒有標準來統合這些不同的智慧裝置,WoT便是希望能夠解決這樣的問題,其所運用的方式就是RESTful Web Service,而採用REST的最主要的優勢就是全部使用標準的HTTP協定,同時運用GET、POST、PUT及DELETE的介面與裝置進行互動。
雖然SOAP及BPMN已經是企業軟體整合上很基本的整合方式及標準,但是它們還不能完全地套用在WoT上,要如何彌補這方面的不足則是這篇文章的重點。
本篇文章分爲兩個部分:
  • 爲什麽Business Process要能夠支援WoT以及如何支援?
  • WoT將Business Process引入後所帶來的效益

研究的內容


研究過程

REST

REST 是一種用資源驅動的架構 Resource Driven Architecture,而資源可以是任何會被其他物件互動的所有東西,例如:溫度感測器,將詢問溫度數值的介面包成以GET方式的URI,讓其他裝置或軟體能夠透過標準的HTTP協定詢問溫度感測器目前的溫度數值是多少。另外,因爲REST所存取的資料是不具有狀態概念的(Stateless),換句話説,裝置本身不需要具備額外的記憶模組來記錄歷史數值,這樣的概念符合部分物聯網裝置必須輕量的特性。另外就是REST具有位置概念,因爲URI本身必須能夠辨識出到底是哪個裝置的介面,這也符合物聯網中裝置必須能夠被辨識的需求。所以物聯網加上REST的操作模式便形成了Web of Things的概念。

BPMN

A Web of Things for a BPM Web of Things Integration

How the power of BPMN can be leveraged to the Web of Things?
Having a BPMN modeling environment and an execution engine capable of taking WoT specificities into account is a necessary precondition.
If BPMN processes are unable to handle WoT specific requirements, it decreases the interest of the hereby presented integration.

Including the Web of Things in a Business Process Model

這裏討論如何將WoT整合至Business Process Model之中。

To integrate the general components of the WoT to the Business Process Model we start our work based on [18].

We consider four main components where each of them is termed resource in the WoT vocabulary as Fig1.
Business process binding a RESTful API.JPG
Fig.1 Business process binding a RESTful API of WoT service component


A fully automated software component with a standardized interface as the WoT service could though be represented as a task.
To address a separate functionality during the resolution of the process model specific to the WoT service, it is advised in [19] to establish a separate subclass.
Fig. 2 shows the described WoT specific components and their relationships from a process model perspective. It is provided by [20]. [1]
WoT specific components and their relationships from a process model.JPG
Fig.2 WoT specific components and their relationships from a process model


Fig3. 是一個簡單的範例在説明在流程模型中是如何將WoT Device、Actuation Task、Sensing Task、Thing要如何表現。

Graphical BPMN model of business process with WoT extensions.JPG
Fig. 3 Graphical BPMN model of business process with WoT extensions


在流程管理上基本分爲三個階段,分別是設計階段、評估階段及執行階段,在設計階段如同Fig. 3一樣規劃及描繪流程模型。而在評估階段則需要靠如[2]中所提的解析方式來找到正確的感知模組或是反應模組。而在執行階段應該會像原本在進行ERP系統整合一樣,透過中央控制流程引擎,如Activiti來執行定義好的流程模型。

Including Business Process Models in the Web of Things

這裏討論如何將Business Process能夠融入至WoT的環境之中?

Since the foundation of the WoT are RESTful architectures, which have been studied for some time now, we state that it is possible to embed existing business process and their execution engine in the WoT. We face two types of interactions when speaking of the WoT. 決定要互動的裝置時,有兩種方式
  • 設定好的:The first ones are classic scenario implying smart objects either delivering sensor readings or offering actuators over a RESTful interface.
  • 算出來的:The second are computational ones. 在流程定義時不會綁定裝置,而是在執行階段才根據實際的狀況來決定要和哪個裝置互動。

最後提出的方式就是將Business Process外套一層RESTful Web Service,使得其他裝置能夠透過標準的介面與Business Process互動。
Overview of the available Resources with REST.JPG
Overview of the available Resources with RESTful API


本篇文章實驗的劇情如下:
"For a given patient, measure each 30 minutes and during 10 minutes the patient’s temperature. If it exceeds 39 degrees Celsius alert whoever is responsible and available for this patient. Further, log the results in a new analysis sheet associated to this patient."

In our case the instantiated mock process, will look up for a thermistor device and the patient to which this thermistor is linked. The results form the measures are then stored in a newly created Analysis associated to the patient the thermistor belongs to. For the mock-implementation, the process stops itself after a few seconds, proving that it has successfully read from the smart device, and saved the information to a new Analysis associated to the patient. This Analysis and the associated patient are also available over a RESTful API. Thus, the system becomes a whole and is browsable with any modern webbrowser. Coupled to a real execution engine, this process could do more complex scenario. As such, it could examine the thermistor values and raise an alert when a given temperature is exceeded. With the current implementation we have shown that it is possible to integrate BPM Processes seamlessly into the WoT, leveraging the power of BPM to the WoT and vice-versa without changing the principles of one or the other world.

總結

With this paper we have introduced our bidirectional integration approach:
  • First, we followed a classical BPM-lifecycle for business process automation and investigated how the CMOF metamodel of the standard BPMN 2.0 could be extended to express WoT components.
  • Second, we examined how the existing information occurring during the three BPM-phases can be seamlessly integrated as resources into the WoT.

Finally, for a use case we have shown how this component-based approach allows creating new applications that combine the physical and the
business world.

Next we will replace the mock engine by our real resolution and execution infrastructure. Our future work will deal with the creation of a WoT Reference Architecture. Further, we will deal with the stepwise implementation of the presented BPMN metamodel extensions in a web-based editor tool.


相關資料


相關專案


相關研究

  • In [12 ] the authors propose a high level abstraction from Things. They argue that the raw information produced by smart devices is just too huge to be processed by humans. They provide an easy way to integrate linked algorithms to distill the information.
  • In [13 ] the authors describe the integration of smart devices in the WoT thus, allowing forming complex business processes out of smart devices.

參考文獻


12. Mayer, S., Karam, D.S.: A computational space for the web of things. In: Proceedings of the Third International Workshop on the Web of Things. WOT ’12, New York, NY, USA, ACM (2012) 8:1–8:6
13. Pautasso, C.: BPMN for REST. In: 3rd International Workshop on BPMN, Luzern, Switzerland, Springer (November 2011)

18. Magerkurth, C.: Converged architectural reference model for the IoT. EC FP7 IoT-A Deliverable 1.4 (2013)
19. Meyer, S.: Concepts for modeling IoT-aware processes. EC FP7 IoT-A Deliverable 2.2 (2012)
20. De, S., Barnaghi, P., Bauer, M., Meissner, S.: Service modelling for the Internet of Things. In: Computer Science and Information Systems (FedCSIS), Federated Conference on IEEE (2011)
22. De, S.: Concepts and solutions for entity-based discovery of IoT resources and managing their dynamic associations. EC FP7 IoT-A Deliverable 4.3 (2012)
24. Guinard, D., Mueller, M., Pasquier, J.: Giving RFID a REST: Building a Web- Enabled EPCIS. In: Proceedings of Internet of Things 2010 International Conference (IoT 2010), Tokyo, Japan (2010)
  1. ^ 比照Activity,我覺得Event也需要由能夠支援WoT的Event。