The Salutation Consortium has made great strides in keeping with its commitment to achieving the full potential of the Salutation Architecture in providing service discovery consistent with pervasive computing requirements. With office automation products that take advantage of the Salutation architecture now shipping, we are now ready to expand our scope to additional pervasive computing areas.
We have recognized the need for additional Functional Units that describe display and operating environment capabilities. We have also recognized the special requirements of low bandwidth networks and battery powered devices. Support for wireless protocols are among the opportunities needed to meet the demands of this space. Finally, given that good things come in small packages, we have recognized that minimizing the footprint of our implementation is a requirement.
The Salutation-Lite project, unveiled at the June 1999 Windows CE Developer's Conference in Denver, will prototype the required architectural changes, validating that requirements are met and the resulting architecture can be implemented on multiple operating system platforms. Once successful, the Salutation Consortium intends to provide the industry with royalty-free access to the prototype code.
Operating Environment Functional Unit The Operating Environment Functional Unit will provide a means to determine the operating system, processor type, device class, amount of free memory, and input/output characteristics of a hand-held or palm-sized device. With this knowledge, a server can send and install an application designed for the environment.
Display Functional Unit
The Display Functional Unit will enable service providers to determine the capabilities of a display on a hand-held or palm-sized computer, or other ubiquitous computing devices. The service may determine if the display supports color or graphics. The footprint and pixel density of the display may also be determined. With this information, the service may format information to the capabilities of the display. Clearly, the Display Functional Unit has applicability in other areas. For example, the capabilities of the display on a printer, FAX machine or multifunction device may be determined, providing an information server the data it needs to effectively communicate with the user of this device.
Limited Bandwidth and Limited Power
Low bandwidth networks, such as IR and the proposed limited-distance, wireless Bluetooth network are sensitive to the amount of data transferred between entities using that network. To assure maximum availability of the limited bandwidth for all devices in the network, data traffic must be kept to a minimum. This is essential for polling operations such as service and capability discovery, where discovery may require a client to interrogate the capabilities of each service.
Many devices targeted for this type of network will be battery powered. Here again, limiting data traffic for such functions as service and capability discovery will preserve battery life for other transactions.
Through Salutation-Lite, the Salutation Discovery Protocol can be tailored to reduce the quantity of data exchanged during the Salutation Capability Exchange protocol sequence. Specifically, a method for specifying the type of response generated to the Capability Exchange call is provided. Three types of replies to the Query Capability call are proposed.
Maximum
The maximum Query Capability reply is defined by the current architecture. That is, the reply Service Description Record contains the union of the matching requested and registered Functional Unit Description Records.
Nominal
The nominal Query Capability reply is defined as the reply Service Description Record containing a copy of the matching requested Functional Unit Description Record, where the Functional Unit Handle is set to the Handle of the registered Functional Unit.
Minimum
The minimum Query Capability reply is defined as the reply Service Description Record containing only the Functional Unit IDs and Functional Unit Handles of matching registered Functional Units.
Wireless Protocol Support
Salutation-Lite is being modeled on the Infrared Data Associations (IrDA) infrared protocol. By using IrDA, Salutation-Lite is applicable to a host of devices indulging 3Com's Palm and derivative devices, WinCE hand-held PC (HPC) and palm-sized PCs (PPC), as well as many cell phones, pagers and laptops. Within the Windows environment, Salutation-Lite accesses IrDA through WinSock calls. By using this higher level interface, Salutation-Lite will be readily portable to other protocols, such as TCP/IP and the proposed Bluetooth protocol.
Footprint
By limiting Salutation-Lite limits function to Service Discovery, the code size, and therefore the amount of storage utilized by a Salutation-Lite implementation, will be greatly reduced. We believe the Salutation-Lite service discovery function will be among the smallest in the industry. Coupled with operating system and protocol independence, Salutation-Lite can provide a single service discovery implementation across the pervasive computing environment.
Note: For more Information on Salutation-Lite refer to the Salutation-Lite White Paper at http://www.salutation.org/whitepaper/Sal-Lite.PDF.