fortran-nginx

A collection of ISO C binding interfaces to the 3rd party module nginx-link-function for nginx, to write server-side web applications in Fortran 2003.

Shared memory features (cache, palloc, shm, shmtx) that allow resource sharing between nginx workers are not supported.

Dependencies

Either install nginx or OpenResty with the nginx-link-function module.

On FreeBSD, build www/nginx with the LINK option enabled from ports:

# cd /usr/local/ports/www/nginx/
# make config
# make
# make install

Or, just install a package that has been compiled with LINK:

# pkg install www/nginx
# pkg info www/nginx

Build

Use the provided Makefile to build the static library libfortran-nginx.a.

Example

Your Fortran web application must implement at least the routines ngx_link_func_init_cycle() and ngx_link_func_exit_cycle(). All routines callable from outside must have the bind(c) attribute.

! webapp.f90
module webapp
    use, intrinsic :: iso_c_binding, only: c_null_char
    use :: ngx_link_func
    implicit none
    logical, save :: is_service_on = .false.
contains
    subroutine ngx_hello(ctx) bind(c)
        character(len=*), parameter           :: str = 'Hello, from Fortran!'
        type(ngx_link_func_ctx_t), intent(in) :: ctx

        call ngx_link_func_log_info(ctx, 'Sending response ...' // c_null_char)
        call ngx_link_func_write_resp(ctx          = ctx, &
                                      status_code  = int(200, kind=8), &
                                      status_line  = '200 OK' // c_null_char, &
                                      content_type = 'text/plain' // c_null_char, &
                                      resp_content = str // c_null_char, &
                                      resp_len     = int(len(str), kind=8))
    end subroutine ngx_hello

    subroutine ngx_link_func_exit_cycle(cyc) bind(c)
        type(ngx_link_func_cycle_t), intent(in) :: cyc

        call ngx_link_func_cyc_log_info(cyc, 'Shutting down the web app ...' // c_null_char)
        is_service_on = .false.
    end subroutine ngx_link_func_exit_cycle

    subroutine ngx_link_func_init_cycle(cyc) bind(c)
        type(ngx_link_func_cycle_t), intent(in) :: cyc

        call ngx_link_func_cyc_log_info(cyc, 'Starting the web app ...' // c_null_char)
        is_service_on = .true.
    end subroutine ngx_link_func_init_cycle
end module webapp

Compile the shared library webapp.so with:

$ gfortran -shared -fPIC -o webapp.so webapp.f90 libfortran-nginx.a

If you use GNU Fortran, make sure that nginx can find the run-time library libgfortran.so.

Load the shared library by setting ngx_link_func_lib and ngx_link_func_call in your nginx.conf:

# Load shared library if module is not linked statically:
load_module "/usr/local/libexec/nginx/ngx_http_link_func_module.so";

server {
    listen            80;
    server_name       localhost;
    ngx_link_func_lib "/usr/local/etc/nginx/webapp.so";

    location / {
        ngx_link_func_call "ngx_hello";
    }
}

Start the nginx daemon:

# service nginx start

Then, open http://localhost/ in your web browser.

Further Examples

Additional examples can be found in examples/:

hello returns a basic HTML response.
laas (LAPACK as a Service) solves a system of linear equations A · x = B using LAPACK95.
plot returns a plot of the Lotka-Volterra ODEs in PNG format, using the DISLIN library. Pass the initial population sizes through HTTP GET parameters u and v (example output).
post parses HTTP POST parameters.

Build the examples with:

$ make <name>

Licence