fcgi-tcl.htm

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            <P>
            </P>
            <UL>
               <LI>
                  Add the following three lines of code to the function <TT>Tcl_AppInit</TT> after the call to
                  <TT>Tcl_Init</TT> and after the comment about calling init procedures: 
<PRE>
    if (FCGI_Init(interp) == TCL_ERROR) {
        return TCL_ERROR;
    }
</PRE>
                  This registers four Tcl commands (<TT>FCGI_Accept</TT>, <TT>FCGI_Finish</TT>,
                  <TT>FCGI_SetExitStatus</TT>, and <TT>FCGI_StartFilterData</TT>), implemented in <TT>tclFCGI.c</TT>,
                  with the Tcl interpreter.
                  <P>
                  </P>
               </LI>
            </UL>
         </LI>
         <LI>
            <TT>Makefile.in</TT>:
            <P>
            </P>
            <UL>
               <LI>
                  Add <TT>tclFCGI.o</TT> to the <TT>GENERIC_OBJS</TT> variable, and add <TT>tclFCGI.c</TT> to the
                  <TT>SRCS</TT> variable.
                  <P>
                     This builds the FastCGI Tcl commands and links them into the Tcl interpreter.
                  </P>
                  <P>
                  </P>
               </LI>
               <LI>
                  Add <TT>-I../fcgi-devel-kit/include -include ../fcgi-devel-kit/include/fcgi_stdio.h</TT> to the
                  <TT>CFLAGS</TT> variable.
                  <P>
                     This includes <TT>fcgi_stdio.h</TT> when compiling C code for the Tcl interpreter, overriding the
                     normal <TT>stdio</TT> types, variables, and functions.
                  </P>
                  <P>
                  </P>
               </LI>
               <LI>
                  Add <TT>../fcgi-devel-kit/libfcgi/libfcgi.a</TT> before the <TT>@LIBS@</TT> part of the <TT>LIBS</TT>
                  variable.
                  <P>
                     This links the implementation of <TT>fcgi_stdio.h</TT> into the Tcl interpreter, for use by the
                     <TT>FCGI_accept</TT> command and any code that uses <TT>stdio</TT> variables or calls
                     <TT>stdio</TT> functions.
                  </P>
                  <P>
                  </P>
               </LI>
            </UL>
            <P>
               The last two edits will vary if you use a compiler other than gcc or install the <TT>tcl7.4</TT>
               directory somewhere else in relation to the <TT>fcgi-devel-kit</TT> directory.
            </P>
            <P>
            </P>
         </LI>
         <LI>
            <TT>configure.in</TT>:
            <P>
            </P>
            <UL>
               <LI>
                  Replace the lines 
<PRE>
AC_C_CROSS
CC=${CC-cc}
</PRE>
                  with the lines 
<PRE>
AC_PROG_CC
AC_C_CROSS
</PRE>
                  This selects gcc in preference to other C compilers.
                  <P>
                  </P>
               </LI>
               <LI>
                  Add the following lines just after the <TT>AC_SUBST(CC)</TT> line: 
<PRE>
AC_CHECK_LIB(socket, main, [LIBS=&quot;$LIBS -lsocket&quot;])
AC_CHECK_LIB(nsl, main, [LIBS=&quot;$LIBS -lnsl&quot;])
AC_SUBST(LIBS)
</PRE>
                  This ensures that the socket libraries used by FastCGI are linked into the Tcl interpreter.
                  <P>
                  </P>
               </LI>
            </UL>
            If GNU autoconf is not available to you, you&#39;ll leave <TT>configure.in</TT> alone and perform the
            following steps:
            <P>
            </P>
            <UL>
               <LI>
                  Execute 
<PRE>
    &gt; SETENV CC gcc
</PRE>
                  before running <TT>configure</TT>.
                  <P>
                  </P>
               </LI>
               <LI>
                  If you are running on a SVR4-derived Unix platform, edit <TT>Makefile</TT> to add <TT>-lsocket
                  -lnsl</TT> to the <TT>LIBS</TT> value after running <TT>configure</TT>.
                  <P>
                  </P>
               </LI>
            </UL>
            If you ever re-run <TT>configure</TT>, you&#39;ll need to repeat these steps.
            <P>
            </P>
         </LI>
      </UL>
      <H3>
         <A NAME="S4">4. Writing FastCGI applications in Tcl</A>
      </H3>
      <P>
         The Tcl program <TT>tcl/tiny-tcl-fcgi</TT> performs the same function as the C program
         <TT>examples/tiny-fcgi.c</TT> that&#39;s used as an example in the <A HREF="fcgi-devel-kit.htm#S3.1.1">FastCGI
         Developer&#39;s Kit document</A>. Here&#39;s what the Tcl version looks like:
      </P>
      <P>
      </P>
<PRE>
#!./tclsh
set count 0 
while {[FCGI_Accept] &gt;= 0 } {
    incr count
    puts -nonewline &quot;Content-type: text/html\r\n\r\n&quot;
    puts &quot;&lt;title&gt;FastCGI Hello! (Tcl)&lt;/title&gt;&quot;
    puts &quot;&lt;h1&gt;FastCGI Hello! (Tcl)&lt;/h1&gt;&quot;
    puts &quot;Request number $count running on host &lt;i&gt;$env(SERVER_NAME)&lt;/i&gt;&quot;
}
</PRE>
      <P>
         If you&#39;ve built Tcl according to the recipe and you have a Web server set up to run FastCGI applications,
         load the FastCGI Developer&#39;s Kit Index Page in that server and run this Tcl application now.
      </P>
      <P>
         The script invokes Tcl indirectly via the symbolic link <TT>examples/tclsh</TT>. It does this because HP-UX
         has a limit of 32 characters for the first line of a command-interpreter file such as
         <TT>examples/tiny-tcl-fcgi</TT>. If you run on HP-UX you won&#39;t want to sprinkle symbolic links to
         <TT>tclsh</TT> everywhere, so you should install <TT>tclsh</TT> with a shorter pathname than
         <TT>/usr/local/tcl7.4-fcgi/bin/tclsh7.4</TT>.
      </P>
      <P>
         The Tcl command <TT>FCGI_Accept</TT> treats the initial environment differently than the C function
         <TT>FCGI_Accept</TT>. The first call to the C function <TT>FCGI_Accept</TT> replaces the initial environment
         with the environment of the first request. The first call to the Tcl command <TT>FCGI_Accept</TT> adds the
         variable bindings of the first request to the bindings present in the initial environment. So when the first
         call to <TT>FCGI_Accept</TT> returns, bindings from the initial environment are still there (unless, due to
         naming conflicts, some of them have been overwritten by the first request). The next call to
         <TT>FCGI_Accept</TT> removes the bindings made on the previous call before adding a new set for the request
         just accepted, again preserving the initial environment.
      </P>
      <P>
         The FastCGI-integrated <TT>tclsh</TT> also includes commands <TT>FCGI_Finish</TT>,
         <TT>FCGI_SetExitStatus</TT>, and <TT>FCGI_StartFilterData</TT> that correspond to C functions in
         <TT>fcgi_stdio.h</TT>; see the manpages for full information.
      </P>
      <P>
         Converting a Tcl CGI application to FastCGI is not fundamentally different from converting a C CGI
         application. You separate the portion of the application that performs one-time initialization from the
         portion that performs per-request processing. You put the per-request processing into a loop controlled by
         <TT>FCGI_Accept</TT>.
      </P>
      <P>
      </P>
      <HR>
      <ADDRESS>
         <A HREF="mailto:[e-mail]">Mike Shanzer // [e-mail]</A>
      </ADDRESS>
   </BODY>
</HTML>