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Web Server Overview - SC12 @CHIP-RTOS V1.10

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Web Server Overview

The explanations here assume the reader is somewhat familiar with the HTTP protocol.

Web Server / CGI topics:

  • CGI_API Functions
  • CGI_in the IPC@CHIP
  • Built-In_CGI Functions
  • Building_a CGI function using a C compiler
  • File_Upload

    • CGI API Functions

      The CGI API uses interrupt 0xAB, enabling the application programmer to install their own DOS program CGI functions in the IPC@CHIP Web server's CGI table.   This makes it possible to visualize and control an application running in the IPC@CHIP via an Internet browser, using all features of modern Internet technology.

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    CGI in the IPC@CHIP

      The Web server of the IPC@CHIP uses an internal CGI table.   The CGI table is an array of CGI_Entry type structures.   Defined for each entry is the URL name, the expected HTTP method (Get, Head or Post) and a pointer to a function which will be executed if a matching browser request arrives at the IPC@CHIP.

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    Built-In CGI Functions

      There are two pre-installed CGI functions in the IPC@CHIP, one of them named "ChipCfg".   The preset entry in the internal CGI table has the name "ChipCfg" (Note: Since SC12 @CHIP-RTOS V1.10 Beta, SC13 @CHIP V0.92 Beta, URL names of CGI are no longer case sensitive!).    A CGI callback function for this entry supports the method "Get" by producing a Web "file" in RAM.   This function is executed if a browser makes the following request to an IPC@CHIP device with an IP address of 192.168.205.4 :

        http://192.168.205.4/ChipCfg

      The CGI function then produces a HTML page in memory which contains specific configuration data, like IP address, subnet mask, serial number, etc..

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    Building a CGI function using a C compiler

      A CGI function built with the Borland C compilers must be declared as:
        void huge _pascal CGI_Func(rpCgi far *CgiRequest);

      Using the Microsoft Visual C compilers the CGI functions are declared as:
        void far _saveregs _loadds _pascal
                    CGI_Func(rpCgi far *CgiRequest);

      The Web server calls this function with the address of a rpCgi type data structure, which contains all needed information about the browser request.   Another part of this structure is the response fields.   These fields must be set by the CGI function.   They hold information needed by the Web server.
      Important: The max. length of a web page in RAM produced by a users CGI function is 65519 characters.

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    File Upload

      It is possible to upload a file to the Web server.   This feature is not available with the standard @CHIP-RTOS variants (Tiny, Small, Medium, Large, ..).   If you want a special @CHIP-RTOS variant with this feature, you have to request it from us via email.

      The Upload will be handled using a HTML Form.   The form has to include the following field:
        DESTINATION-PATH (e.g. "A:\HELLO.EXE")
        REDIRECT-PATH (e.g. "A:\WEB\SUCCESS.HTM")
        FILE-CONTENT
      The DESTINATION-PATH defines the name and the location where the file will be stored on the IPC@CHIP's drive.   REDIRECT-PATH links to a file, which will be returned on a successful upload to the Browser.   The file must be located on an IPC@CHIP's drive.   The value of the field FILE-CONTENT will be handled from your Web Browser automatically.   It allows the user to choose a local file from the PC's drive using the browse button (which appears with the type "file").

      Password and user name for the File Upload are defined in the CHIP.INI (standard: web, web).   For example your can use a form like the following one to upload a file to the IPC@CHIP's Web server:
                
    <html>

<head>

<title>FileUpLoad to the IPC@CHIP Web Server</title>

</head>

<body>

<form action="http://192.168.201.4" enctype="multipart/form-data" method="POST">

<p>

  Choose file from your PC for Upload:<br>

  Destination Filename:

	 <input type="text" name="DESTINATION-PATH" value=""><br>

  Linkto:

	 <input type="text" name="REDIRECT-PATH" value=""><br>

  Local File Path:

	 <input name="FILE-CONTENT" type="file" size="50" ><br>



	 <input type="submit" value=" Absenden ">

</p>

</form>

</body>

</html>



Comment:

You can also use the Type "hidden" if you want to hard code some value.

e.g: <input type="hidden" name="REDIRECT-PATH" value="success.htm">

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