async function getPositionUpdatesHandler(res, workspaceId) {
  try {
    const positionUpdates = await database.getPositionUpdates(workspaceId);
    res.setHeader('Content-Type', 'application/json');
    res.statusCode = 200;
    res.write(JSON.stringify({positionUpdates}));
    res.end();
  } catch {
    res.statusCode = 401;
    res.end();
  }
}
Handler for a getPositionUpdates message. Query the database for a
PositionUpdate for the specified user or all if no user is specified.
@param {!Object} res The HTTP response object.
@param {string=} workspaceId workspaceId for specified user.
@private