[Design Application]
Designing The Next Step In Internet Appliances
Web-Enabled Information Appliances Are Showing Up In Many Places, But The Challenge Is Supplying Web Pages with Dynamic Content.
As electronic devices evolve, they are becoming more intelligent and complex. In addition, the need for people to interact with them is becoming much greater. One obvious choice for person-device interaction is use of the ubiquitous web browser. More electronic devices are being designed today to be network accessible through a web browser. Such devices are often referred to as web-enabled information appliances or Internet appliances.
While benefits of merely web-enabling a device are large indeed, to fully tap the power of the Internet, the device capabilities must go beyond web enabling. For an Internet appliance to be practical and versatile, it must include a variety of hardware and software subsystems. Hardware subsystems must include a processor, an Ethernet controller, a memory and I/O controller, and support logic. Software subsystems, as a minimum, must include an RTOS, a web server (HTTP server), a TCP/IP protocol stack, and an e-mail and FTP server. Today's conventional design approaches dictate that the engineer choose and integrate these discrete hardware and software subsystems from a multitude of choices (and vendors) into an elegant, cost-effective solution.
Until now, such a conventional approach has been cost and time prohibitive for most engineers outside the computer industry. As recently as three years ago, web servers still ran only on high-end Alpha or Sun computers with massive disks. As a result, network-enabling was limited to people-centric applications—people connected to the Internet or Ethernet through computers.
Over the past few years, peripherals such as printers, faxes, and disk drives have been web-enabled, but the power of the Internet and Ethernet remains largely untapped by all devices that have anything to do with information, measurement, or control. Examples of such potential applications abound in a broad range of industries and consumer products; from digital video cameras and medical devices to industrial and building control systems.
Today's Web Devices Recent advances in system-on-silicon technology promises to change all that. Embedded technology has evolved far enough to let web-servers run on single board computers with flash memory as their mass storage. Known as "thin servers" and "thin clients," embedded versions of web servers, such as Spyglass MicroServer, are now readily available. This shrinking of technology has allowed these smart devices, now embedded with a web server, to be accessible through a familiar web browser. Complete network connectivity system-on-silicon, such as the NET+ARM chip, can significantly reduce design time and lower the unit cost of network-enabling products. These compact, low-cost solutions will enable engineers, even from noncomputer industries, to quickly transform their products into fully functional Internet appliances.
With the rapidly increasing popularity of the World Wide Web, embedded systems designers are discovering the advantages of enabling their devices to work on the web. One typical application is to allow the device to be configured using a web browser. Another application is the addition of status reporting by the device utilizing web content. Web content is defined as Hypertext Markup Language (HTML) pages images and applets sent by the device in response to Hypertext Transport Protocol (HTTP) requests from web browsers.
Use of Internet technology doesn't have to stop with mere web-enabling. As we shall discuss shortly in two example applications, for these devices to be practical, they need to handle messaging, data transfer, and diagnostics.
Messaging can be implemented using Internet e-mail protocols such as standard SMTP and POP3. Reliable and error-free data transfer is easy to implement using standard FTP, which can be used to either upload periodic measurement data to a specified host or download software for revision updates. The diagnostics are usually part of a user application software, which, for example, may monitor temperature, pressure, or flow in measuring devices or status such as "paper jam" in a printer. The alerts generated from the diagnostic program use messaging to inform people, and data transfer capability can upload files containing error logs for further analyses.
Before we examine the designing of an Internet appliance, let us look at two application examples that show the dramatic benefits that are possible when a device is transformed into an Internet appliance.
Today, most printers can be connected to Ethernet or the Internet as a shared resource. A long-time problem for customers and vendors is the difficulty of installation and configuration for network printing. Each vendor provides proprietary software which runs on some but not all platforms. Furthermore, each vendor's graphical-user interface (GUI) has a different look and feel, making it difficult for one person to use products from multiple vendors.
One solution is to embed an HTTP server in the printer. This enables HTML screens to display information that can be viewed through a browser. The user benefit: the GUI now becomes a familiar web-browser, which enables the user to interact with a printer remotely. The vendor benefit: the GUI needs to be written only once for it to work on all platforms. Shown is an example of a typical HTML page from a printer (see the figure).
Now that the printer is web-accessible, some of the parameters that can be set or viewed include printer IP address; default gateway; subnet address; AppleTalk name and zone; Novell printer server name, which directory services tree to attach to; which paper tray to use; type of paper; amount of toner; number of pages printed; and printer status, such as ready, in-use, or paper-jam. All these parameters can now be accessible to any authorized person across the network.
Adding messaging or e-mail capability can further extend the functionality of the shared printer. For example, when the toner is low, the printer can send an e-mail message directly to the supplier to deliver the toner cartridge. By adding diagnostic capability, the printer can now alert the office manager whenever there is "paper jam" through an e-mail. Finally, data transfer capability such as FTP can allow vendors to download firmware upgrades and bug fixes directly to the printer.
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