## 3 M2M Information and Services
### M2M Information and Service Technologies  
The selected set of M2M information and service level technologies are reviewed in Table 2, and some of them are shortly analyzed in the following. ETSI M2M service capability layer has been defined to be horizontal in the sense that the service capabilities have been specified to be applied with multiple application domains. It uses a resources tree structure to represent the service capabilities layer of each M2M device [18,38]. This tree describes information such as registered SCLs, registered applications, access rights, subscription, groups, data containers, _etc._ ETSI M2M describes only data containers without specifying any information content, which means that information content is transparent and out of scope from ETSI M2M. In addition, device descriptions are not properly included, but interfaces with OMA DM and BBF TR069 device management are specified. Therefore, it is necessary to decide the containers, information content and device management of the devices and applications beforehand. \begin{table}
\begin{tabular}{p{85.4 pt} p{113.8 pt} p{113.8 pt}} \hline
**Technology** & **Forum(s), References** & **Main Contribution** \\ \hline ETSI M2M & ETSI M2M service capability layer [18,23,38] & Specification of a Horizontal M2M service capability layer. RESTful approach to represent information by resources which are structured as a tree. The content of the information is transparent and out of scope. \\ \hline OMA DM data model & Open Mobile Alliance [39,40] & Information model for management and dynamic service provisioning of OMA DM enabled devices. \\ \hline BBF TR069 data model & Broadband forum [41,42] & Information model for Auto-configuration and dynamic service provisioning of TR069 enabled customer premise equipment. \\ \hline UPNP & Universal Plug and Play [31,43] & Information model based on XML to describe device and its provided services for UPNP enabled devices. \\ \hline DPWS & Devices Profile for Web Services (DPWS) [44] & Information model defined in the WSDL file based on the XML Schema specification for DPWS enabled devices. \\ \hline oBix data model & Open building information Xchange [45] & Restful approach based on an object oriented data model to represent data for the mechanical and electrical systems in commercial buildings. \\ \hline OPC UA data model & OPC Foundation [46,47] & Information model based on object-oriented technics to represent data for Object Linking and Embedding for Process Control (OPC). \\ \hline OWL-S ontology & Semantic Markup for Web Services [48,49] & Semantic web services ontology that enables users and software agents to automatically discover, invoke, compose, and monitor Web resources offering services, under specified constraints. \\ \hline SSN ontology & W3C Semantic Sensor Networks [50,51] & Ontology that defines the capabilities of sensors and sensor networks, and to develop semantic annotations of a key language used by services based sensor networks. \\ \hline FIPA-device ontology & FIPA Device Ontology Specification [52,53] & Semantic device profile and service ontology that can be used by agents when communicating. \\ \hline Sensor Web & Sensor Web enablement [54,55,56] & Overlay architecture for integrating sensor networks and applications on the Web. \\ \hline OSGi & OSGi Alliance [57] & Modular system and service platform for Java. \\ \hline Service Delivery Framework (SDF) & TM Forum [58] & Providing a reference in the industry on management of “next generation services”. \\ \hline \end{tabular}
\end{table} 
Table 2: Review of M2M Information and Service Technologies. The devices offering services can be managed by Device Management Servers in OMA DM [39]. OMA DM devices are identified by a model number, and represent services as management objects in the OMA DM data model (Device Management Tree). These service objects are just service representations which contain nodes. These nodes contain properties for the actual service which can be managed by the ACS.