fortran-zeromq

A work-in-progress collection of Fortran 2018 ISO C binding interfaces to the ZeroMQ core library libzmq (≥ Version 4.3.5) and the high-level C binding CZMQ (≥ Version 4.2.1). For older Fortran 2003 bindings to ZeroMQ, see FZMQ.

Build Instructions

Install ZeroMQ 4 and CZMQ 4 with development headers. On FreeBSD, run:

$ doas pkg install net/libzmq4 net/czmq4

On Linux, run instead:

$ sudo apt install libzmq5 libzmq3-dev libczmq4 libczmq-dev

If the packages provided in the repository are too old, you may want to build ZeroMQ 4 simply from source and install it to /opt:

$ cd /tmp/
$ curl -O -L -s https://github.com/zeromq/libzmq/releases/download/v4.3.5/zeromq-4.3.5.tar.gz
$ tar xfvz zeromq-4.3.5.tar.gz
$ cd zeromq-4.3.5/
$ ./configure --prefix=/opt
$ make
$ make install

And to build CZMQ 4 from source and install it to /opt:

$ cd /tmp/
$ curl -O -L -s https://github.com/zeromq/czmq/releases/download/v4.2.1/czmq-4.2.1.tar.gz
$ tar xfvz czmq-4.2.1.tar.gz
$ cd czmq-4.2.1/
$ ./configure --prefix=/opt
$ make
$ make install

Make

Execute the Makefile to build all bindings (libfortran-zeromq.a):

$ make

Build with ZeroMQ draft and poller procedure bindings:

$ make FFLAGS="-O2 -DHAS_DRAFT -DHAS_POLLER"

Build only libzmq bindings (libfortran-zmq.a):

$ make zmq

Build only CZMQ bindings (libfortran-czmq.a):

$ make czmq

Install the libraries and the module files to /opt:

$ make install PREFIX=/opt

Link your programs against /opt/lib/libfortran-zeromq.a and -lzmq (ZeroMQ) and -lczmq (CZMQ). Make sure to pass the path to the fortran-zeromq module files, for instance, with argument -I/opt/include/fortran-zeromq.

Examples are provided in directory examples/. Build them with:

$ make examples

Fortran Package Manager

Run FPM to build the library:

$ fpm build --profile release

You can add fortran-zeromq as a dependency to your fpm.toml:

[dependencies]
fortran-zeromq = { git = "https://github.com/interkosmos/fortran-zeromq.git" }

Example

The following programs client.f90 and server.f90 implement the REQ/REP pattern using CZMQ. The fortran-zeromq library is assumed to be installed to /opt.

Client

The client opens a REQ socket and sends string Hello to the server, expecting a response:

! client.f90
program main
    use :: zeromq
    implicit none (type, external)

    character(:), allocatable :: msg
    integer                   :: rc
    type(c_ptr)               :: req

    req = zsock_new_req('tcp://localhost:5555')
    if (.not. c_associated(req)) error stop

    rc  = zstr_send(req, 'Hello')
    msg = zstr_recv(req)

    if (len(msg) > 0) print '("received reply: ", a)', msg
    call zsock_destroy(req)
end program main

Build and run the client:

$ gfortran -I/opt/include/fortran-zeromq -o client client.f90 /opt/lib/libfortran-zeromq.a -lzmq -lczmq
$ ./client

Server

The server opens a REP socket and replies to requests:

! server.f90
program main
    use :: zeromq
    implicit none (type, external)

    character(:), allocatable :: msg
    integer                   :: rc
    type(c_ptr)               :: rep

    rep = zsock_new_rep('tcp://localhost:5555')
    if (.not. c_associated(rep)) error stop
    print '("server waiting on port 5555 ...")'

    do
        msg = zstr_recv(rep)
        if (len(msg) == 0) exit
        print '("received: ", a)', msg
        rc = zstr_send(rep, 'World')
    end do

    call zsock_destroy(rep)
end program main

Build and run the server:

$ gfortran -I/opt/include/fortran-zeromq -o server server.f90 /opt/lib/libfortran-zeromq.a -lzmq -lczmq
$ ./server
server waiting on port 5555 ...

Further Examples

Additional example programs are provided in examples/. Run:

$ make examples

If ZeroMQ and CZMQ are installed to /opt, run instead:

$ make examples LIBZMQ="-Wl,-rpath=/opt/lib -L/opt/lib -lzmq" LIBCZMQ="-Wl,-rpath=/opt/lib -L/opt/lib -lczmq"

References

• CZMQ – High-level C Binding for ZeroMQ
• ZMQ API reference
• ZMQ man pages
• ZeroMQ web site
• ØMQ – The Guide

Licence

ISC