January 2006, Issue 186

Portable Web Server
Renesas M16C Design Contest 2005 Entry

SIMPLE SITES

The usual process for setting up a simple low-cost web site involves getting an account with a local Internet service provider (ISP) and setting up a series of web pages on its server. The URL often ends up being something like www.ispname.com/~accountname. In addition to being clunky, this URL makes it difficult for people trying to find your web site. It also contains the ISP’s domain name, which can be a pain if you decide to change ISPs.

A common solution to this problem is to use a stealth redirection service, which enables a registered domain URL such as www.seriouswebsite.com to point to your local ISP’s URL by inserting it within a stealth frame generated by the redirection service. This solves one problem but creates another. Search engines like Google ignore frames and drop such web sites from their indexes. 

A more recent approach involves using a dynamic domain name system (DNS) service, which enables a URL such as http://seriouswebsite.dyndns.org to point to a registered IP address. These services have a couple of advantages. You don’t have to formally register and maintain a domain name. In addition, you can dynamically change the resolved IP address by sending a simple automated command to its central server.

Implementing a dynamic DNS approach eliminates the need to use frame redirection and ISP web space. It also enables the web site to be truly portable because the IP address can change to whatever the assigned IP address happens to be set to. 

The embedded web site approach is also a better solution than using a desktop or server PC. Less power is needed for operation. Plus, the relative simplicity of the hardware and software enhances reliability and keeps costs down.

The data served by the web site is stored on a low-cost CompactFlash card. The CompactFlash card supports large web sites that can be easily updated with the built-in FTP server or offline using an external PC that has a CompactFlash reader. The Renesas Technology M32C/84 microprocessor I used for this project had a minimum number of additional ICs. It allowed for a fast memory-mapped interface to the CompactFlash card using its Expansion mode.