{"id":64617,"date":"2022-05-26T09:01:30","date_gmt":"2022-05-26T09:01:30","guid":{"rendered":"https:\/\/www.cryptocabaret.com\/?p=64617"},"modified":"2022-05-26T09:01:30","modified_gmt":"2022-05-26T09:01:30","slug":"write-c-applications-using-vely-on-linux","status":"publish","type":"post","link":"https:\/\/www.cryptocabaret.com\/?p=64617","title":{"rendered":"Write C applications using Vely on Linux"},"content":{"rendered":"

Write C applications using Vely on Linux<\/span>
\nSergio Mijatovic<\/a><\/span>
\nThu, 05\/26\/2022 – 03:00<\/span><\/p>\n

\n
Register<\/a> or Login<\/a> to like<\/div>\n
Register<\/a> or Login<\/a> to like<\/div>\n<\/div>\n
\n

Vely is a tool for writing web and command-line applications in C. Vely combines high performance and the low footprint associated with C programming with ease of use and improved safety reminiscent of languages like PHP. It’s free and open source software, and licensed under GPLv3 and LGPL 3 for libraries, so you can even build commercial software with it.<\/p>\n

Vely works on major Linux distributions and processor architectures. You can use webservers, such as Apache, Nginx, or others, and databases such as MariaDB, PostgreSQL, and SQLite.<\/p>\n

You can use Vely for web applications, command-line programs, as middleware, database applications, services software, data integration, IoT (Internet of Things), and anywhere else. It’s well suited for the cloud, works easily in a container, and, due to low resource requirements, it’s also a good choice when memory and processing power are at a premium.<\/p>\n

Install Vely<\/h2>\n

To try Vely, install the Apache webserver and MariaDB database<\/a>. You can use a different webserver and database, and the setup would be similar, but in this example, I use Apache and MariaDB.<\/p>\n

Next, install Vely. On Linux use a package manager such as dnf<\/code> or apt<\/code>.<\/p>\n

Stock tickers project<\/h2>\n

This example saves the names of stock tickers and their prices so you can view them in a list.<\/p>\n

Start by creating stock.v<\/code> file, and paste this code into it:<\/p>\n

\n
#include \"vely.h\"

\nvoid stock() {
\n\u00a0 \u00a0out-header default
\n\u00a0 \u00a0@
\n\u00a0 \u00a0 \u00a0 \u00a0@
\n\u00a0 \u00a0 \u00a0 \u00a0input-param action
\n\u00a0 \u00a0 \u00a0 \u00a0input-param stock_name
\n\u00a0 \u00a0 \u00a0 \u00a0input-param stock_price
\n\u00a0 \u00a0 \u00a0 \u00a0if (!strcmp (action, \"add\")) {
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \/\/ Add to stock table, update if stock exists
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 run-query#add_data@db = \"insert into stock (stock_name,
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 stock_price) values ('%s', '%s') on duplicate key 
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 update stock_price='%s'\" : stock_name, stock_price, 
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 stock_price
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0end-query
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0error#add_data to define err
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0if (strcmp (err, \"0\")) {
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0report-error \"Cannot update stock price, error [%s]\", err
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0}
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0@

\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 @Stock price updated!
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0@<\/div>
\n\u00a0 \u00a0 \u00a0 \u00a0} else if (!strcmp (action, \"show\")) {
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0\/\/ Show stock names and values
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0@
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0@
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0@
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0@
Stock name<\/td>
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0@		Stock price<\/td>
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0@<\/tr>
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0run-query#show_data@db = \"select stock_name, 
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 stock_price from stock\" output stock_name, 
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 stock_price
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0@

\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0query-result#show_data, stock_name
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0@<\/td>
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0@
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0query-result#show_data, stock_price
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0@<\/td>
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0@<\/tr>
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0end-query
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0@<\/table>
\n\u00a0 \u00a0 \u00a0 \u00a0} else {
\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0@
Unrecognized request!<\/div>
\n\u00a0 \u00a0 \u00a0 \u00a0}
\n\u00a0 \u00a0 \u00a0 \u00a0@
\n\u00a0 \u00a0@
\n}<\/div><\/div><\/pre>\n
Build the database<\/h2>\n
For this example, create a database named dbstock<\/code>, owned by user vely<\/code> with the password your_password<\/code>. These are arbitrary names, and in real life, you can use whatever values you want, as long as they’re consistent throughout your code.<\/p>\n
First, log in to the MariaDB database as root and execute this:<\/p>\n
\n
CREATE<\/span> DATABASE<\/span> IF<\/span> NOT<\/span> EXISTS<\/span> dbstock;
FLUSH<\/span> privileges;
CREATE<\/span> USER<\/span> IF<\/span> NOT<\/span> EXISTS<\/span> vely@localhost IDENTIFIED<\/span> BY<\/span> 'your_password'<\/span>;
FLUSH<\/span> privileges;
GRANT<\/span> ALL<\/span> privileges ON<\/span> dbstock.*<\/span> TO<\/span> vely@localhost;
FLUSH<\/span> privileges;
\nexit;<\/div><\/div><\/pre>\n
Now log in to MariaDB again and set the current database:<\/p>\n
\n$ <\/span>mysql -u<\/span> vely -pyour_password<\/code><\/span><\/pre>\n
Now you can create the database objects needed for the application. You need a stock<\/code> table in the dbstock<\/code> database for this example.<\/p>\n
\n
USE<\/span> dbstock;
CREATE<\/span> TABLE<\/span> IF<\/span> NOT<\/span> EXISTS<\/span> stock (<\/span>stock_name VARCHAR<\/span>(<\/span>100<\/span>)<\/span> PRIMARY<\/span> KEY<\/span>,<\/span> stock_price BIGINT<\/span>)<\/span>;<\/div><\/div><\/pre>\n
Finally, create a database configuration file named db<\/code> so that your application can log into the database. You must call it db<\/code> because that’s what the code in stock.v<\/code> uses. For instance:<\/p>\n
\n
[<\/span>...<\/span>]<\/span>
\nrun-<\/span>query#add_data@db =<\/span> \"insert into stock ...\"<\/span>
[<\/span>...<\/span>]<\/span><\/div><\/div><\/pre>\n
The database name is preceded by the @<\/code> sign, in this case, @db<\/code>, so the name of the database configuration file is db<\/code>. As with other values, you can name your database configuration file whatever you want, as long as your code is consistent.<\/p>\n
Here’s the configuration for the db<\/code> file:<\/p>\n
\n
[<\/span>client]<\/span><\/span>
user<\/span>=<\/span>vely<\/span>
password<\/span>=<\/span>your_password<\/span>
database<\/span>=<\/span>dbstock<\/span><\/div><\/div><\/pre>\n
The above is a standard MariaDB client options file<\/a>. Vely uses native database connectivity, so you can specify any options a given database allows.<\/p>\n<\/p>\n
\n
Programming and development<\/div>\n
\n
Red Hat Developers Blog<\/a><\/div>\n
Programming cheat sheets<\/a><\/div>\n
Try for free: Red Hat Learning Subscription<\/a><\/div>\n
eBook: An introduction to programming with Bash<\/a><\/div>\n
Bash shell scripting cheat sheet<\/a><\/div>\n
eBook: Modernizing Enterprise Java<\/a><\/div>\n<\/p><\/div>\n<\/p><\/div>\n
Build the application<\/h2>\n
Next, you can create your Vely application. For this example, you’re going to create a web app called stockapp<\/code>:<\/p>\n
\n$ <\/span>sudo<\/span> vf -i<\/span> -u<\/span> $(<\/span>whoami<\/span>)<\/span> stockapp<\/code><\/span><\/pre>\n
This creates an application home under the Vely directory (\/var\/lib\/vv<\/code>) and performs the required application setup steps for you.<\/p>\n
To build your application, use the vv<\/code> command:<\/p>\n
\n$ <\/span>vv -q<\/span> --db<\/span>=mariadb:db stockapp<\/code><\/span><\/pre>\n
Here’s what each option means:<\/p>\n