Web framework for C programming language

Golf has an "extended" mode, which allows for C code to be used directly. Normally, this is not allowed, but if you use extended-mode statement in your .golf file, then you can call C code from it.

In extended mode, Golf is effectively a web framework for C programming language; read this for more about implications on memory safety.

Here's the example of using Golf as a web framework for C. In this case it's a simple C function to calculate the factorial of a a number. Then we'll expose this functionality in an equally simple web application.

Create the Golf application

mkdir -p c-for-web
cd c-for-web

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Create "fact" application ("-k"):

gg -k fact

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Save the following into a file "calc-fact.golf". This is the web service which will interact with web clients (such as browsers); it will also call the C function we'll create a bit further below:

 extended-mode // extended mode in order to call C code

 %% /calc-fact public
     get-param par // get input parameter from URL
     string-number par to num // convert to number
     set-number result
     call-extended factorial(num, &result) // call C function
     // Output result
     @Factorial of <<print-out par>> is <<print-out result>>
 %%

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Add C code to Golf application

Next, create C file "factorial.c". This is the C function we're calling from Golf code above:

 #include "golf.h"

 // Compute factorial of f, and store result into res
 void factorial(gg_num f, gg_num *res)
 {
     *res = 1;
     gg_num i;
     for (i = 2; i <= f; i++) {
         *res *= i;
     }
 }

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And an include file "factorial.h" to declare any function(s) we will use in Golf code:

 void factorial(gg_num f, gg_num *res);

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Compile and start the server

Golf will pick up all .golf as well as all .c and .h file and make them into an application:

gg -q

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Start the server:

mgrg fact

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Test the server from command line

You can test this web application from command line (note --service flag!). This is useful because you can develop web applications just from command line:

gg -r --req=/calc-fact/par=12 --exec --service

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The result is:

Content-Type: text/html;charset=utf-8
Cache-Control: max-age=0, no-cache
Pragma: no-cache
Status: 200 OK

Factorial of 12 is 479001600

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This is the exact data that would be sent to an actual web client.

Test the server with web browser

Let's test on an actual web server. In this case we'll use Nginx. Also, we'll do it locally on your computer, since not everyone has a server on the web.

First, edit Nginx config file, which for Ubuntu/Debian is at:

/etc/nginx/sites-enabled/default

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and on Fedora/RedHat is at:

/etc/nginx/nginx.conf

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Note you might have to use "sudo" to edit these files as they're generally not writable by ordinary users.

Find the "server" section, and add this inside it (replace "your-user" with your OS user name):

location /fact/ { include /etc/nginx/fastcgi_params; fastcgi_pass  unix:///home/your-user/.golf/apps/fact/sock/.sock; }

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This will connect Nginx with the "fact" server you started above. Any requests with a URL path that start with "/fact/" will be delivered to your server, and the reply will go in reverse, ultimately being delivered to the client (such as web browser).

Restart Nginx server for this to take effect:

sudo systemctl restart nginx

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Try it from web browser with this URL:

http://127.0.0.1/fact/calc-fact/par=8

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If your Nginx runs on another port, specify it, for instance if it runs on port 81, use "127.0.0.1:81" instead.

The result is:

Factorial of 8 is 40320

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Of course, if you have a server on the web, just substitute "127.0.0.1" for your server's web address.