SVG Rasterizer service for Node.js

index.js

var connect = require('connect')
  , exec = require('child_process').exec
  , fs = require('fs')
  , path = require('path')
  , seaport = require('seaport')


// Detect tmp dir
var TMP_DIR = (function() {
  var dirs = [process.env.TMP, '/tmp', process.cwd()]
  for (var i = 0; i < dirs.length; i++) {
    var dir = dirs[i]
    var isDirectory = false

    try {
      isDirectory = fs.statSync(dir).isDirectory()
    } catch (e) {}

    if (isDirectory) return dir
  }
}())

// Allowed mime types
var types = { 'image/png': 'png'
            , 'image/jpeg': 'jpg'
            , 'application/pdf': 'pdf'
            , 'image/svg+xml': 'svg'
            }




var app = connect()
app.use(connect.bodyParser())

app.use(function(req, res, next) {
  var type = req.body.type
    , ext = types[type]

  if (!ext) return next()

  var svg = req.body.svg

  if (ext === 'svg') {
    addHeaders(req, res)
    res.end(svg)
    return
  }

  var filename = getTmpName()

  var command = 'java'
              + ' -jar ' + __dirname + '/batik-1.7/batik-rasterizer.jar'
              + ' -m ' + type
              + (Number(req.body.width) ? ' -w ' + Number(req.body.width) : '')
              + ' -d ' + filename + '.' + ext
              + ' ' + filename + '.svg'

  fs.writeFile(filename + '.svg', svg, function(err) {
    if (err) return next(err)

    exec(command, function(err, stdout, stderr) {
      if (err) return next(err)

      // catch error
      if (~stderr.indexOf('SVGConverter.error.while.rasterizing.file')) {
        err = new Error('SVGConverter.error.while.rasterizing.file')
        err.svg = svg
        err.stdout = stdout
        err.stderr = stderr
        return next(err)
      }

      addHeaders(req, res)
      var file = fs.createReadStream(filename + '.' + ext)
      file.on('error', next)
      file.pipe(res)
      file.on('end', function() {
        fs.unlink(filename + '.' + ext)
        fs.unlink(filename + '.svg')
      })
    })
  })
})

function addHeaders(req, res) {
  var type = req.body.type
  res.setHeader('Content-Disposition', 'attachment; filename="' + req.body.filename + '.' + types[type] + '"')
  res.setHeader('Content-Type', type)
}

function getTmpName() {
  var name = ''
  for (var i = 0; i < 32; i++) {
    name += Math.floor(Math.random() * 16).toString(16)
  }

  return path.join(TMP_DIR, name)
}


var pkg = require('./package.json')
seaport.connect(7001).service(pkg.name + '@' + pkg.version, function(port, ready) {
  app.listen(port, ready)
})