Jini faces competition

Electronics Times, April 19, 1999

To compete with Sun's Jini as a way of linking embedded systems in the home, Microsoft has presented three draft standards to the Internet community through the Internet Engineering Task Force (IETF), the organisation responsible for maintaining the technical standards behind the Internet.

Intended for Microsoft's Universal Plug-and-Play (UPnP) system, the protocols are based purely on UDP, TCP/IP and HTTP transactions, with no application-level interfaces for operating systems as yet.

Instead, Microsoft has built a demonstration server based on the protocols. HP and Microsoft worked jointly on a stripped-down version of the service location protocol that Sun proposed to the IETF. It is designed to let consumer appliances with very little hard-wired information in their roms to determine Internet addresses or server locations to find service providers when they connect to a home network.

For example, a home video camera will want to find some form of recorder or playback machine on a home network, but has no way of knowing where to look when it connects for the first time, other than it knows that it is a camera.

The simple service discovery protocol (SSDP) provides a mechanism for the device to find its desired network services. SSDP uses HTTP over multicast and unicast forms of UDP to provide two functions: `options' and `announce'.

Options is used to determine if a desired network service exists on the network. Announce is used by network services to announce their existence, in a similar way to the technique used by Novell's Netware.

The SSDP works alongside two other protocols that let a new device derive an Internet address automatically. Based on work performed at Carnegie Mellon University, the autoconfiguration technique proposed for UpnP looks first for a dynamic host configuration protocol (DHCP) server.

This is the same type of server as that used by Internet gateways. If no DHCP service is present, the device randomly selects an address, checks that it is not in use and employs it until further DHCP requests are successful. In this way, a device can connect to a home network while it is not connected to the Internet, then reconfigure itself once the connection is set.

The third protocol takes the form of a name look-up that lets other devices on the network work out which services are attached to which IP address, whether they have been assigned by a server or self-generated.