SSV - eWEB

SSV eWEB EMBEDDED INTERNET

Intranet, Internet, TCP/IP, World Wide Web - just about everywhere you go these days you overhear somebody using these words. The Internet and the World Wide Web (Web) is everywhere, and it is accesible from any computer that has a TCP/IP protocol stack and a Web browser (Microsoft Internet Explorer or Netscape Navigator and other). The Web offers an universal GUI (Graphical User Interface) - the Web browser and HTML (HyperText Markup Language). Any intelligent product or system can now use this universal GUI.

The Internet uses a client/server model. The program on one computer is a client application (for example the Web Client with a Web Client software). The program that runs on the other computer is the server application (for instance the Web Server with the Web Server software). Server applications are not very exciting. They don´t have a user interface. Server applications wait for client applications to ask for something, and then they process the request, and send whatever the client application was asked for or an error message over the Internet to the client application. The most important client applications are Web browser with an HTML- based GUI.

The basic protocol for the communication between the Web Client and and the Web Server is TCP/IP. TCP/IP (Transmission Control Protocol) is the foundation for all the other Internet protocols. TCP/IP are two protocols: TCP sits on the top of IP (Internet Protocol), and IP sits on the top of the local network protocol (for instance Ethernet). HTTP, FTP, and other top level Internet protocols sits on the top of TCP. The Internet Protocol (IP) is responsible for getting data from a Web Client to a Web Server and back. The most important top level protocol for the Web is HTTP (HyperText Transfer Protocol). HTTP uses a simple 4- step client / server model. A Web Client sends a request for a HMTL document in HTTP to the Web Server. The Web Server replies in HTTP with status information, the type and size of the data, and information concerning many other attributes of the document or a error message. HTTP contains commands to send and receive data and files over the Internet.

When you use a Web browser like Microsoft Internet Explorer or Netscape Navigator to view a Web page, the browser sends a HTTP request over the Internet to the Web Server, then displays the data returned by the Web Server. The data that comes back may be of almost any type, including HTML or, for example GIF graphics files, WAV sound files, or AVI movies.

Internet protocols like TCP/IP, HTTP, the Web technology, and other parts of Internet technology are very useful for embedded applications. The Internet technology offers robust networking capabilities through the TCP/IP protocol and a universal GUI over HTML and Web browsers. Some Web browsers will be free with every operating system (for instance Microsoft Internet Explorer comes free with Windows 95), and Internet tools are build into nearly every development tool. Many Real Time O/S offers embedded Web servers (for example QNX, VxWorks, Phar Lap´s TNT Embedded ToolSuite, and other).

Web servers for embedded applications needs only a small hardware. The SSV eWEB Server (embbeded WEB Server) runs with PC/104 based single board computers. The eWEB Server don´t need a hard disk drive. This Web server uses FLASH solid state disks. A eWEB Client can be any computer with a Web browser (Microsoft Internet Explorer or Netscape Navigator and other) or a embedded system with a LCD display and a touch screen based user interface.