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the simplest of libhtdb-driven programs have the following as programmatic structure, and need to be compiled against libhtdb.a.

here is the source code for main() of htdb itself.

/*
  This software (HTDB and its components)
  Copyright 1994-2024 David Whittemore del-at-htdb.org
 */
#include  "htdb.h"

/*
   the application information structure
 */
appinfo_t  appinfo = {
  /* the application name */
    "htdb",
  /* the application version */
    "1.2.3",
  /* command-line usage information */
    "this program utilizes the built-in handler " 
    "to process .htdb documents. \n\n" 
    "in short, URI strings of the form \n" 
    "\t /htdb/site/index.html \n\n" 
    "are parsed into the values of " 
    "`db'=site and `page'=index.html \n\n" 
    "the `db'.htdb file is then processed " 
    "and we spit out what document \n" 
    "we find defined for `page'.",
  /* initial htdb values */
    "",
  /* address of handler function */
    htdb_page_handler,
  /* serve this many pages per fastCGI loop */
    FCGI_KEEPALIVE
};

int  main(int argc, char **argv)
{
  exit (htdb_main(argc, argv, &appinfo));
}

observations:

• note that all work is actually performed in htdb_main(), so there's not a whole lot to look at in such a simple program.
• the 1st and 2nd arguments allow access to standard UNIX command line parameters. these values are only available when running libhtdb-based applications from the command line, otherwise, they are not used, since the webserver process does not make them available. when processed, the values will be available via the `argv[]->name' and `argv[]->value' resource structures. `argv->numResults' will contain the result count.

typedef struct  {
    char    *name,
            *version,
            *description,
	    *args;
    void    (*func)(void);
    int fcgi_keepalive;
}   appinfo_t;

• the 3rd argument is a pointer to the appinfo control structure, whose elements are described below.
  • name - the name of the application. used only for command usage messaging.
  • version - the version of the application. used only for command usage messaging.
  • description - usage message for improper command-line invocation.
  • args - "initial htdb values". if given, would be in GET argument format:

        arg1=val1&arg2=val2

    these values are shoved into the environment after normal GET/POST argument decoding so as to over-ride any values set by the server. used to disable sessioning for a specific application, for instance.

  • func - the address of the function to call to process requests. HTDB provides the default page handler htdb_page_handler. if you were writing your own CGIs, this value would be the address of your handler routine.
  • fcgi_keepalive - all libhtdb CGIs can be run as fastCGI applications, which allows for vastly more efficient CGIs. fcgi_keepalive is an integer value that tells the fastCGI subsystem how many requests to serve before cleaning up and re-initializing.