## 1 Introduction  
In the Internet of Things (IoT) scenario, strong and deep investigations have been carried out to define a unique global standard that can allow objects to communicate with each other through the Internet, despite their diversity in technologies and capabilities. Different approaches have been investigated [1; 2; 3; 4; 5; 6; 7; 8]. Major contributions in this direction has been given by the IETF StandardizationGroup which started three Working Groups (WG) that basically propose to use IPv6 for object-related operations [9]. In particular, the _IPv6 over Low power Wireless Personal Area Networks_ (6 LoWPAN) WG [10] defined encapsulation and header compression mechanisms that allow IPv6 packets to be sent to and received from over IEEE 802.15.4 based networks. The _Routing Over Low power and Lossy networks_ (ROLL) WG [11], instead, is specifying a new routing protocol for IP smart object networks. Finally, the _Constrained RESTful Environments_ (CoRE) WG [12] is devoted to the definition of a framework for resource-oriented applications intended to run on constrained IP networks. The overall logic is quite linear: the knowledge already acquired for the world-wide Internet deployment is exploited and Internet pre-existing structures are adapted to the needs of constrained nodes [13, 14]. This paper, in line with the IETF logic, introduces a solution for further reducing the constrained nodes' resource exploitation in terms of energy. According to the adopted IoT vision, services are the main actors. In the _traditional Internet_, nodes at the lowest levels of the network hierarchy were basically clients accessing services run by remote server. The advent of IoT pushed towards a vision of \"leaf\" nodes as _servers_ to all intents and purposes, since they deliver services. Therefore, an accurate _service management_ design is required to fulfill three IoT fundamental tasks: _autonomy_, _scalability_, and _adaptability_. The contributions that mostly come near to a service management approach are those of the CORE WG, which defined the _Constrained Application Protocol_ (CoAP), a specialized web transfer protocol to use with constrained networks and nodes for Machine-to-Machine (M2M) applications. _Service Management_ deals with those procedures which allow the access, the advertising, the discovery, and the configuration of services in a network. In any of these cases, a packet exchange between a client (the requestor) and a server has to take place. This exchange may either happen among peer entities or by means of an intermediate node which works as a proxy. CoAP proposes a _Representational state transfer_ (RESTful) solution where this exchange takes place among two peer entities at the application level. The present study stems from the observation of some critical issues associated to the CoAP behavior in terms of _fragmentation_ and from their consequences on the constrained nodes' performance. The proposed approach (complementary to CoAP) suggests to keep communication at a lower level (just up to the _Network_ level) to access the most constrained nodes' services, while leaving more powerful nodes to rely on application-level communication. Throughout the paper we will show that our proposal leads to energy improvements as well as to a more appealing way to address constrained nodes' services. In more detail, the focus is on the CoAP interaction model which is based on the existing _HyperText Transfer Protocol_ (HTTP) methods (GET, PUT, POST and DELETE). The intended contributions of the paper are:  
* performance analysis and comparison of the fragmentation dynamics of two standard CoAP existing solutions;
* proposal of a service-oriented exchange model that could substitute CoAP _under certain conditions_;
* performance assessment of the proposed method. The paper is organized as follows: Section 2 introduces the research problem. Section 3 describes the proposal and compares it to a standard approach based on CoAP. Section 4 presents a performance evaluation and comparison activity.