CONTEXT:
On UNIX, Metacard can be used as both a GUI development environment as
well as a CGI scripting language. If you running your own UNIX machine,
it's fairly trivial to set it up for either use, using the supplied
install script and the instructions.
If you are not using your own machine, but are hosted elsewhere, such
as on an ISP over the Internet, its likely not appropriate to attempt
X-Windows development, however, CGI scripting is very feasible. If you
have access to a shell account with reasonable permissions (telnet or
ssh), again, its a snap to install, or if not, and your ISP is willing
to install it, they should have no trouble. They can just download the
necessary files and run install.sh.
PROBLEM:
What if you have no shell account access, and your ISP says something like
'gosh, give us a few months to evaluate this, it is a possible security
risk, and by the way, its going to COST you..'. Are you out of luck?
Maybe not. If they allow you to install and run your own CGI programs
using FTP, then, you can still use MC as a CGI scripting language and
get it up and running without their help. You might need a bit of help
from your friends though, depending on how much UNIX experience you
have. The following describes how I got it working on our ISP.
SOLUTION:
The key fact is that, to use MC on your ISP's host, you only need one
file: mc. The file "mc" is the Metacard engine, or interpreter.
Writing an MC script is similar to writing a Borne shell or Perl script,
where the first line indicates the location of the interpreter.
Therefore, all you have to do is get the right interpreter for your ISP's
host, put it in the right place, and correctly refer to this place in
your metatalk scripts, and bingo, you are using MC on your web pages.
As indicated on the www.metacard.com site, use of MetaCard as a
script-only (non-graphical) language is FREE on all UNIX systems: no
license is required. This in turn means that it is supplied as a binary
file, not as source code. So, you don't have to compile it. All you
have to do is get the right version, it is supplied pre-compiled. You
may need a bit of help to determine this.
In our case, our ISP was running Sun OS, and this operating system
only runs on Sparc processors, so the file we needed to download was
sparc.tar. This is an archive made using the ubiquitous Unix tar program,
and here again, you may need some help from your friends to unpack it. In
our case, I just ftp'd it to my Linux computer and ran the command
tar xf sparc.tar
This gave me several files, namely, mc.gz, xanim.gz, and gunzip. The
gunzip was useless on my Linux (Intel) machine being compiled for Sparc,
but in any case, the only file needed is the mc.gz file. This in turn
is another compressed archive made with the GNU gzip program. So again,
depending on your ability to uncompress standard Unix archives, you may
need some help or have to acquire some tools. I simply ran the command
gunzip mc.gz
which produced the file I needed, mc.
On the other hand, perhaps Kevin or Scott or some kind soul will put the
uncompressed, ready to run versions of MC for all processors on their
ftp site so that all the decompressing steps would be unnecessary.
Next, ftp the mc file to the place your cgi scripts can run from,
typically public_html/cgi-bin. Set the correct permissions to make it
executable. For example, on our ISP it has to be chmod 700 or chmod 755.
(chmod 777 is a security violation and programs with these permissions
will not run on our site). You next have to determine what is the actual
location, that is, the absolute path name, of your mc engine.
In our case, our ISP supports SSI (server side includes) so the
pathname was determined by building a test html page using pwd
(print working directory) as an ssi command. More details on this
below. In our case, the full path name turned out to be something like
/export/vhost/org/g/ourhostname/www/public_html/cgi-bin and therefore,
the first line of our mc scripts has to be:
#!/export/vhost/org/g/ourhostname/www/public_html/cgi-bin/mc
To summarize, get the right mc file, put it in the right place on your
ISP, and set executable permissions. That is all there is to it!! Then,
you can write any MC scripts using the right first line to point to the
mc file, again, making them executable.
Regards,
Sadhunathan Nadesan
CIO, Cast & Crew
PS, Some helpful files:
This simple script can be installed as a cgi on your host to help
find the correct pathname. For example, you could call it pwd.cgi.
.................cut here....................
#!/bin/sh
# write minimal set of HTTP headers to stdout
echo "Content-Type: text/plain"
echo ""
pwd
.................cut here....................
If your ISP supports SSI, then you can use a web page like this to find
out the real path name of pwd.cgi. There are other ways, such as perhaps
a POST command from an MC stack. Here's the page I used:
...................... cut here ..................
<HTML>
<HEAD>
<TITLE>Sadhunathan Nadesan's Echo Test Page</TITLE>
</HEAD>
<!-- Background white, links blue (unvisited), navy (visited), red (active) -->
<BODY
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#000080"
ALINK="#FF0000"
>
<H1 ALIGN="CENTER">Sadhunathan's SSI Testing Page</H1>
<p>
<!--#echo var="DATE_LOCAL" -->
<p>
<!--#exec cgi="/cgi-bin/pwd.cgi"-->
<p>
Sadhu set this up to test SSI.
<P ALIGN="CENTER">
<a href="http://www.apache.org/";><IMG SRC="/icons/apache_pb.gif"
ALT="[ Powered by Apache ]"></a>
</P>
<p>
<!--#echo var="SERVER_SOFTWARE" -->
<p>
<!--#echo var="SERVER_NAME" -->
<p>
</BODY>
</HTML>
.......................cut here............................
If this works, it will return the full path name you need. You can then
test to see if MC is working by replacing the cgi line in the above html
page with
<!--#exec cgi="/cgi-bin/echo.cgi"-->
and then test, together with installing a modified version of the echo.mt
script from the Metacard site. We renamed ours as echo.cgi (because our
ISP only supports certain extensions as cgi scripts, such as .sh, .pl,
or .cgi) and we modified the first line of the script to point to the
mc interpreter, as follows:
......................... cut here ........................
#!/export/vhost/org/g/ourhost/www/public_html/cgi-bin/mc
# This MetaTalk script loops over all the environment variables
# set by the server when it runs a CGI application printing out
# its name and value.
on startup
# loop over all of the global variables, getting name and value
repeat for each item i in the globals
put i && "=" && value(i) & return after buffer
end repeat
# write minimal set of HTTP headers to stdout
read from stdin until empty
put it after buffer
put "Content-Type: text/plain" & cr
put "Content-Length:" && the length of buffer & cr & cr
put buffer
end startup
......................... cut here .....................
Note that our real hostname has been replaced with "ourhost" and that
this is just an example, you will have to determine the correct path
on your ISP. And again, this method of testing works only if your ISP
supports SSI, but any method of calling a cgi script will work. If the
HTML page shown produces a whole list of environment variables, then,
MC is working on your host.
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