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Vely 15.2.0 released on Jan 18, 2023
Articles updated Jan 17, 2023

C performance for web applications? Say hi to Vely

Jan 4th, 2023 by Sergio Mijatovic


Image copyright (c) Sergio Mijatovic 2023

C performance for web applications? Say hi to Vely

Vely is a framework for C programmers. It works by precompiling simple statements into C.

It's Free Open Source Software (FOSS), of course.

I created Vely for rapid development of back-end applications (especially web) that are safer than pure C, while keeping C's powers of high performance.

To get started, here is a Hello World application. It is super simple. You'll get a web page from your own FastCGI application server in minutes!

Install Vely

Go to to install Vely using standard packagers like apt, dnf, zypper or pacman, or you can download the source and build it yourself. It's pretty basic.

Get all shiny in vim

It's nice to have everything highlighted and color-coded in vim editor. So do this to get it going forward:

vv -m

Hello World

Create a directory where your code will reside:

mkdir hello
cd hello

Create the application using vf:

sudo vf -i -u $(whoami) helloworld

Create hello.vely file:

vi hello.vely

and copy this to it:

#include "vely.h"

void hello()
    out-header default
    @Hello World!

Make the application with vv:

vv -q

That's it. Now you can start your FastCGI application server:

vf helloworld

You can connect to it from Apache, Nginx or any other web server. Before doing that, you can test your server from command line, by simulating a web server reverse-proxy request:

export SCRIPT_NAME="/helloworld"
export PATH_INFO=""
export QUERY_STRING="req=hello"
cgi-fcgi -connect /var/lib/vv/helloworld/sock/sock  /

Unsurprisingly you'll get:

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

Hello World!

You've got a response a web client (like browser) can understand!

See it from browser

Now, you can try Apache or Nginx, here you will do Nginx (if you got Apache running, stop it for a moment). Needless to say, you got to have Nginx installed and running. Typically, that's done for Debian systems like:

sudo apt install nginx

or for Fedora systems like:

sudo dnf install nginx

First, you need to open Nginx configuration file, typically for Ubuntu:

sudo vi /etc/nginx/sites-enabled/default

though for others like RedHat it may be at:

sudo vi /etc/nginx/nginx.conf

and find a server{} block (it has to be there!). Then within it, copy this in a new line after "server_name" directive:

location /helloworld { 
    include /etc/nginx/fastcgi_params; 
    fastcgi_pass  unix:///var/lib/vv/helloworld/sock/sock;

It will tell Nginx where is your FastCGI application server listening, in this case it's a socket file above, but it can be a TCP port too. Restart Nginx:

sudo systemctl restart nginx

Assuming you're doing this on your local computer, go to browser and copy this:

Voila, Hello World! Of course, change "" to your server name or IP if you're not local. If you don't have a browser handy, use cURL to test from command line:

curl -s ""

Customize your Hello World
Want to tinker with it a bit? Easy. Here, you'll first create a string that's a bit more involved, then output it. Edit hello.vely, and copy this:

#include "vely.h"

void hello()
    out-header default
    num x = 3;
    char *y = "have a nice day";
    write-string define mystr
        @Hello World <<p-num x>> times and <<p-out y>>!
    end-write-string notrim
    p-out mystr

Make it again:

vv -q

Your application server will automatically reload with a new executable, so you can try it again right away, the result is:

Hello World 3 times and have a nice day!

Command line

The same code that runs as an application server also runs from the command line. So do this to run it like that:

export SCRIPT_NAME="/helloworld"
export PATH_INFO=""
export QUERY_STRING="req=hello"

You will get same output but without headers, and if you skip setting VV_SILENT_HEADER, you'll get headers too.

What else?

You guessed it right, you can do more than Hello World in Vely. In fact, quite a bit more.

First off, Vely's got automatic memory allocation and garbage collector for all its statements. That makes it safer because it helps avoid memory issues and leaks.

You can easily access MariaDB/mySQL, PostgreSQL and SQLite databases, create and access web services including upload and download files, deal with web stuff like GET or POST or cookies. You can write complex strings safely and easily. You can encrypt, encode, do regex search and replace, use files, execute programs.

Use Vely for just about any back-end server application or program you can think of.

There's a bunch of examples and crisp-clean documentation to help you get productive quick with Vely.

Copyright (c) 2022 DaSoftver LLC. Vely is a trademark of Dasoftver LLC. The software and information herein are provided "AS IS" and without any warranties or guarantees of any kind. Vely elephant logo (c) 2022 DaSoftver LLC. This web page is licensed under CC-BY-SA-4.0.