carto MML object    { "srs": ... }
carto MML file      /path/to/map.mml
carto MML URL       http://example.com/map.mml
mapnik XML string   <?xml version="1.0" ...
mapnik XML file     /path/to/map.xml

npm install tilelive tilelive-mapnik

var tilelive = new Server(require('tilelive-mapnik')),
tilelive.serve({
    datasource: '/my/map/file.mml',
    x: 0,
    y: 0,
    z: 0,
    format: 'png'
}, function(err, data) {
    if (!err) throw Err
    // data[0]: PNG image
    // data[1]: HTTP headers object appropriate for PNG format
});