# A Model Based Framework for IoT-Aware Business Process Management
## 4 IoT-Aware BPM Framework
### Rationale and Overview  
As outlined in Section 1, this paper introduces a conceptual framework for the analysis of IoT-aware BPs, e.g., processes which specifically monitor, exploit and manage data retrieved from a network of distributed IoT sensors. The strategy at the basis of the proposed framework development is outlined in Figure 2.  
As a first step, in order to describe from a conceptual point of view the addressed sensors network domain, an MOF-based metamodel has been initially specified, MOF being the key MDA standard that provides an abstract language and a framework for specifying, constructing, and managing technology neutral metamodels, e.g., models used to describe other models [30]. The IoT metamodel describes entities that compose a sensor network system and the relationships among them. As shown in the upper part of Figure 2, in order to identify the metamodel elements, existing ontologies and frameworks dealing with the addressed domain have been analyzed. Specifically, the proposed metamodel is inspired by the following elements:  
* _Sensor Web Enablement (SWE) framework_, which has been promoted by the OGC Spatial Consortium and includes various standards, each related to a particular aspect in the general context of sensors network development (e.g., sensors API, data representation, data encoding, etc.). Specifically, the proposed metamodel design is based on the sensor structural model and the data model provided by the SensorML and the O&M standards, respectively;
* _Semantic Sensor Network Ontology (SSN)_, which is one the most relevant ontologies for conceptual description of sensors network systems. The proposed IoT Metamodel is shown in Figure 3.  
Figure 2: Conceptual strategy for developing the framework for the analysis of IoT-aware BPs. According to the figure, a sensor network system (represented by the System entity) is defined as a collection of Sensors (or, in other words, sensing devices). Each sensor provides a _serviceEndPoint_ which is used for inquiring the device and retrieving the collected measures. Sensors might be single, stand-alone devices or they can be structured in a Platform, which is a physical component constituting the system deployment. A Position can be specified for sensors and platforms, to describe the entity Location (in terms of _latitude_, _longitude_ and _altitude_) and its Orientation (by specifying the entity _heading_, _pitch_ and _roll_). Sensors observe properties (ObservableProperty entity), which denote physical entities' characteristics subjected to a measure, and make observations (Observation entity). The observable properties of an entity can be grouped into features of interest (_Feature-OfInterest_ entity). As an example, let us consider a meteorological sensor for measuring the rainfall and the wind speed. The _weather condition_ is the _feature of interest_ observed by sensors, while the _rainfall_ and _windspeed_ are two _observable properties_ characterizing the _weather condition_ feature of interest. Properties and features of interest are characterized by a Definition URI, which allows one to associate a reference to an external ontology or dictionary that provides the relevant conceptual description. Any Observation (or measure) collected by a sensor includes one Result. As results are typed elements, the metamodel includes the following types:  
* **SimpleData**: metaclass which is further specified by the following subclasses:
* _Boolean_, which represents a boolean type. The value attribute provides the measured boolean value of the observed property;
* _Quantity_, which is a type representing a physical quantity whose measure requires the specification of a value along with the related unit of measure (unitOfMeasure attribute);
* _Category_, which is a type representing a property whose actual value is defined in terms of a limited and fixed set of possible values. It is characterized by the following attributes: value, which is the actual value of the measured property,  
Figure 3: IoT Metamodel.