UPnP Merges with Home API to Streamline Connectivity, Control

For home-networking professionals who've wondered where Universal Plug and Play ends and Home API begins, there's good news: The two initiatives have merged into a single effort.

Confusion surrounds the two standards because they appear to be so similar--both are being driven by Microsoft and supported by the same companies (especially Compaq, Honeywell, Mitsubishi Electric and Philips Electronics); both tout plug-and-play connectivity; and both have a common enemy--Sun Microsystems and its Java community.

But the two home-electronics standards are in fact fairly different. Home API is a Windows PC-oriented standard for home-automation applications, while UPnP is an Internet protocol (IP)-based standard for discovering electronic devices on a home network.

The difference between Home API and UPnP

Formed in 1998, the Home API working group, led by Microsoft and comprising leading computer and CE manufacturers, has been developing a common applications programming interface (API) for Windows-based control of home devices (see especially 10/98 HNN). Focusing less on connectivity and more on control, Home API aims to simplify the development of home-automation software and facilitate access to home electronics. The initiative, it is claimed, would grow the HA-development market from a handful of tiny enthusiasts to a thriving community of sophisticated software development firms.

Of course, for Home API to be effective, there must be connectivity between devices on a centrally controlled network--which is where UPnP comes in.

The Universal Plug and Play Forum, initiated by Microsoft in 1999, also has found a following among PC and CE manufacturers. But instead of caring about control, UPnP focuses on connectivity, especially the linking of PCs with peripherals, appliances and services. UPnP aims to define the characteristics of these electronics so that they may be recognized on a home network.

"Deliverables at the end of day are device control protocols (DCPs) that let PCs and non-PCs discover each other on a network,” says David Nash, manager of Intel's Connected Home initiative and the company's representative to the Home API working group.

Unlike Home API, which revolves around Microsoft's Windows operating system, UPnP utilizes the generic Internet protocol, which means it is applicable to any manufacturer whose products might bear an IP address.

Essentially, claims Nash, a Windows-based PC running Home API software will represent "just” another IP node on a UPnP network, albeit an extremely complex, robust node....

What about CAL and Home Plug & Play?

The Home API and UPnP camps may be wise to combine efforts to avoid duplicating the tedious process of defining devices and specifying how they communicate with each other. But if they're really in such a hurry, why don't the groups defer to the existing device definitions provided by the Common Applications Language (CAL) and Home Plug & Play?

A foundation of the CEBus home-control standard (EIA 600)—and later its own separate communications standard—CAL (EIA 721) is a universal language with a full database of industry-specific contexts for home-network products.

Its successor—but not its replacement—the Home Plug & Play specification is a set of rules that facilitate uniform implementation of CAL-communicating products.

Honeywell, which has been active in virtually all of the home-interoperability and -control standards since the conception of CEBus in 1983, is one company urging UPnP to utilize work already completed by the CAL Interoperability Council (formerly CEBus Industry Council), particularly when it comes to device-definitions or, in UPnP parlance, DCPs.

Spokesperson Larry Stickler of Honeywell's Home Technology Center explains: "Home P&P is a design that allows lower-cost devices to interoperate and be installed incrementally, without tools, on non-TCP/IP (CAL/CEBus) networks. The UPnP architecture supports bridges to non-TCP/IP devices and networks. In order to represent Home P&P devices in the UPnP world we need to make sure that the important functions of Home P&P devices are included in UPnP's device control protocols.

"This is similar to the requirements for Home API objects. The Home API Working Group has been creating a set of objects that include common functions required from a variety of networks, including CEBus, LonWorks and X-10.”

But then, so has Home Plug & Play--and in a much more robust way. "UPnP hasn't begun to address the huge interoperability issues between systems within the house, whereas Home P&P tackles these complex issues,” says home automation guru Grayson Evans of The Training Dept. "What do networked electronics do with each other? How are conflicts resolved? How does a network know if the TV is controlling the VCR or the other way around? How do two different devices with two different clocks keep from screwing each other up?...Home P&P addresses such things. UPnP specifies maybe 5 percent of the characteristics necessary for interoperable home networks.”

So why isn't there more cooperation between the CIC and the UPnP community?

Honeywell's Stickler explains, "Microsoft is understandably being very strict in only accepting DCP designs that are free from intellectual property constraints.” So?! The Home P&P specs are free and open for the asking.

Evans has a different thought: Coming from a fairly insular Microsoft-oriented world, UPnP members are only just becoming aware of existing networking efforts, including Home P&P. He suggests: "Microsoft, do some homework, read it [Home P&P documents], find out what's going on.”

Stickler recommends that, since UPnP membership is open to any company that signs the membership agreement, "the best way to include the Home P&P design in the UPnP DCPs is for members of the CIC to join and participate in UPnP's Home Control and Security committee.”

Until standards happen…

The residential-electronics industry might have Honeywell to thank for the last decade of progress in home networking and control. But, while Honeywell executives have been busy sitting on standards committees for the past decade, the company has missed the opportunity to bring product to the home market. Its one system, TotalHome, utilizes X-10 powerline technology and has seen almost no technological advances since it was introduced in the 80s.

Other home-automation developers like Apex, Crestron, Home Automation Inc., ITI, Leviton, Panja and Smart Corp. have forged ahead delivering to market scores of products based on CEBus, X-10 and proprietary communications buses—even while they endorse and participate in residential-standards initiatives.

"Standards are needed to turn niche markets into larger mass markets,” says Mike Isaacs, vice president marketing for Smart Corp., a manufacturer of CEBus-compatible products. "But markets can't wait for the boys in the lab to get it right….Now that Microsoft has brought two of its internal camps together, perhaps three years from now we will see something ready to be shown