# Chapter 5 - Using HTMLDOC on a Web Server

This chapter describes how to interface HTMLDOC to your web server using CGI scripts and programs.

## The Basics

HTMLDOC can be used in a variety of ways to generate formatted reports on a web server. The most common way is to combine HTMLDOC with a CGI script or program and send the output to the HTTP client.

To make this work the CGI script or program must send the appropriate HTTP attributes, the required empty line to signify the beginning of the document, and then execute the HTMLDOC program to generate the HTML, PostScript, or PDF file as needed.

Another way to generate PDF files from your reports is to use HTMLDOC as a "portal" application. When used as a portal, HTMLDOC automatically retrieves the named document or report from your server and passes a PDF version to the web browser. See the next section for more information.

## Calling HTMLDOC from a Shell Script

Shell scripts are probably the easiest to work with, but are normally limited to GET type requests. Here is a script called topdf that acts as a portal, converting the named file to PDF:

    #!/bin/sh
    #
    # Sample "portal" script to convert the named HTML file to PDF on-the-fly.
    #
    # Usage: http://www.domain.com/path/topdf/path/filename.html
    #

    #
    # The "options" variable contains any options you want to pass to HTMLDOC.
    #

    options="-t pdf --webpage --header ... --footer ..."

    #
    # Tell the browser to expect a PDF file...
    #

    echo "Content-Type: application/pdf"
    echo ""

    #
    # Run HTMLDOC to generate the PDF file...
    #

    htmldoc $options http://${SERVER_NAME}:${SERVER_PORT}$PATH_INFO

Users of this CGI would reference the URL "http://www.domain.com/topdf.cgi/index.html" to generate a PDF file of the site's home page.

The options variable in the script can be set to use any supported command-line option for HTMLDOC; for a complete list see Chapter 8 - Command-Line Reference.

## Calling HTMLDOC from Perl

Perl scripts offer the ability to generate more complex reports, pull data from databases, etc. The easiest way to interface Perl scripts with HTMLDOC is to write a report to a temporary file and then execute HTMLDOC to generate the PDF file.

Here is a simple Perl subroutine that can be used to write a PDF report to the HTTP client:

    sub topdf(filename);

    sub topdf {
        my $filename = shift;

        print "Content-Type: application/pdf\n\n";
        system "htmldoc -t pdf --webpage $filename";
    }

## Calling HTMLDOC from C

C programs offer the best flexibility and easily support on-the-fly report generation without the need for temporary files.

Here are some simple C functions that can be used to generate a PDF report to the HTTP client from a temporary file or pipe:

    #include <stdio.h>
    #include <stdlib.h>

    /* topdf() - convert a HTML file to PDF */
    FILE *topdf(const char *filename)	/* HTML file to convert */
    {
      char	command[1024];			/* Command to execute */

      puts("Content-Type: application/pdf\n");

      sprintf(command, "htmldoc -t pdf --webpage %s", filename);

      return (popen(command, "w"));
    }

    /* topdf2() - pipe HTML output to HTMLDOC for conversion to PDF */
    FILE *topdf2(void)
    {
      puts("Content-Type: application/pdf\n");
      return (popen("htmldoc -t pdf --webpage -", "w"));
    }