Internet of Things – Architecture © - 88 -
wonderful in its simplicity, but this simplicity is one of the reasons why it is
unsuitable for the IoT, since it is not able to address the aforementioned
interoperability issues.
Obviously this dates back to the beginning of the Internet, when developing an
Application Protocol for each application was best practice. While in principle
that is a reasonable approach, even in the current Internet we can perceive how
it is misleading. We are not here to discuss pros and cons of developing an
Application Protocol for each application but we have just to notice this is not a
common practice anymore, with the majority of applications leveraging on HTTP
or even on more specific HTTP constructs like REST protocols. So nowadays it
is crucial to have a distinction between Applications and the Application
Protocols.
Another major issue of the 4-layers Internet model arises from the lack of
expression for the so-called security layers, the two major examples being SSL
[IETF 2011]/TLS [IETF 2008] and IPsec [IETF 1998].
The main reference point for communication system developers is the ISO/OSI
stack, and, although its validity as an implementation guideline is out of
question, it fails to depict the overall complexity of IoT systems as it is meant to
represent single technology stacks.
After the considerations on the model discussed so far we felt necessary a
different approach for highlighting the peculiar features of IoT communication,
which are not directly evident using the ISO/OSI model alone.
Figure 20 : The interoperability aspects of the IoT CMIoT Aspects
ISO Stack