Instead of modifying the HTTP classes with SIP to localize modified program parts and reduce the modification, we write adapter program modules that convert a UPnP message to the corresponding SIP message and vice versa. © 2009 by Taylor & Francis Group, LLC Home Networking System with SIP UPnP library API SIP-based home network middleware FIGURE 7.4 Protocol stack for the redesigned SIP-based home network. (From Nakamoto, Y. and N. Kuri, Proc of 6th IEEE Int Conf Comp Info Tech, 2006, p. 99. With permission.) TABLE 7.1 Line Numbers in the Redesign Module name # of line RegisterClient RegisterServer SearchClient SearchServer All java files in CyberLink for Java 15279 Source: From Nakamoto, Y. and N. Kuri, Proc of 6th IEEE Int Conf Comp Info Tech, 2006, p. 99. With permission. The adapter modules are shown in Table 7.1. Since the total line number of all the class files is approximately 15,000 lines and the adapter modules can be implemented in the smaller program size, our intention is successful. Conclusion In this paper, we present a redesign of some aspects of the service functionali- ties within a home network system using SIP. Implementing UPnP using SIP leads to seamless connectivity between devices inside and outside the home C 2009 by Taylor & Francis Group, LLC SIP Handbook: Services, Technologies, and Security and integration of VoIP with home network applications. In future work, we plan to use SIP to implement the other functionalities in UPnP. One big effect of implementing this UPnP middleware in SIP is that a server is required to maintain relationships between a device and its services. In the UPnP world, however, no such server is necessarily required: relationships are transmitted upon request by an IP multicast server using the discovery protocol. In the redesign with SIP, a single server failure in a home networks brings out a single point failure. To avoid the single server failure, we have an idea that all participants in the network have a SIP server. In this idea, every device has a name s