The Internet of Things (IoT) aims for connecting Anything, Anywhere, Anytime (AAA). This assumption brings about several software engineering challenges that constitute a serious obstacle to its wider adoption. The main feature of the Internet of Things (IoT) is genericity w.r.t the variability of software and hardware technologies. Model-Driven Engineering (MDE) is a paradigm that advocates using models to address software engineering problems. It can help to meet the genericity of the IoT from a software engineering perspective. Existing MDE approaches for the IoT focus only on modeling the internal behavior of things but lack a comprehensive approach dedicated to network modeling. In the present paper, we introduce a network-oriented methodology based on MDE to unify the IoT's heterogeneous concepts. Fundamentally, we avoid the intrinsic heterogeneity of the IoT by separating the network's specification (i.e., the things, the communication scheme, and its constraints) from its concrete implementation (i.e., the low-level artifacts such as source code and documentation). Technically, the methodology relies on a model-based Domain-Specific Language (DSL) and a code generator. The former enables the modeling of the network's specification, and the latter provides a procedure to generate the low-level artifacts from this specification. Our results show that this methodology makes IoT's software engineering more rigorous, helps prevent bugs earlier, and saves time.