metaEngine.getAsync( id ).then( function( meta ){
    console.log( 'success!' )
    res.set( 'Content-Type', meta.mimeType )
    res.set( 'Content-Length', file.length )
    return storageEngine.getAsync( id )
  }, function(){
    console.log( 'failure!' )
    res.status( 404 )
  } ).then( function( file ){
    console.log( 'still running' )
    if( file.pipe ){
      file.pipe( res )
      return
    } else if( typeof file === 'string' || Buffer.isBuffer( file ) ){
      res.send( file )
    } else {
      res.status( 500 )
      throw new Error( 'Invalid file returned. Please return ReadableStream, string, or Buffer' )
    }
  }, function(){
    res.status( 500 )
  } )