TABLE OF CONTENTS This chapter begins its survey of technologies influenced by the UPnP architecture with an overview of Microsoft s Simple Control Protocol (SCP). SCP brings the UPnP device architecture to very small low-cost devices that wouldn t normally be able to afford a full UPnP stack. Devices such as light bulbs, lamps, and wall switches are prime examples of devices in this class. This chapter presents an overview of SCP, focusing on how it maps into the UPnP Device Architecture.
Perhaps the most frequent device implementer criticism of the UPnP architecture is the cost involved in supporting the technology. The requirement that a device have a full-featured TCP/IP network stack and HTTP 1.0 compliant web server in particular can be cost prohibitive to many devices. Furthermore, not all devices may have access to a highspeed IP-based home network. Yet, you d still like these devices to be able to communicate not only with each other, but also with existing UPnP nodes on the network. This is the role that SCP fills: It supports a lightweight implementation of UPnP technology style device protocols intentionally designed to run over low-bandwidth communication networks such as home power line networks. SCP also attempts to unify the home automation control network market, which is currently split between a set of proprietary protocols.
As illustrated in Figure 20.1, SCP devices consist of two major parts, the communication subsystem and the application subsystem. You...
