Monday, October 1, 2012

Node.js, the next web development platform?

Node.js has been gaining steam over the last little while, thanks to videos like this, showing how Node.js can handle 1000 concurrent requests. The development community has grown by leaps and bounds and new packages are constantly being added to NPM. In addition to this, Microsoft has thrown its weight behind it and has provided support for Node.js development in Windows Azure and their WebMatrix IDE. The selling features sound pretty good compared to existing frameworks and architectures:
  • Better memory efficiency under high loads compared to traditional thread based concurrency model
  • No locks and as a result no dead locks
  • HTTP is a first class protocol, this means it's a good foundation for web libraries and frameworks
  • Developers can write code in one language on the client and server
In order to jump right in and start learning Node.js I decided to write an adapter for the jugglingdb ORM. This is an ORM which is bundled in the very Ruby on Rails like framework Railway.js. The adapter was written to integrate into Windows Azure Table Storage and is available in github and on npm.

From this experience I've learned several things, the most important of which is that Node.js is not ready for primetime. While it's great for doing simple endpoints, complex applications seem to be very hard to troubleshoot and debug. This is due to the use of async callbacks all over the place. While this allows high concurrency, debugging becomes a muddled mess. Here is an example of the getTable function in the TableService class, provided by Microsoft.

TableService.prototype.getTable = function (table, optionsOrCallback, callback) {
  var options = null;
  if (typeof optionsOrCallback === 'function' && !callback) {
    callback = optionsOrCallback;
  } else {
    options = optionsOrCallback;
  }

  validateTableName(table);
  validateCallback(callback);

  var webResource = WebResource.get("Tables('" + table + "')");
  webResource.addOptionalHeader(HeaderConstants.CONTENT_TYPE, 'application/atom+xml;charset="utf-8"');
  webResource.addOptionalHeader(HeaderConstants.CONTENT_LENGTH, 0);

  var processResponseCallback = function (responseObject, next) {
    responseObject.tableResponse = null;
    if (!responseObject.error) {
      responseObject.tableResponse = TableResult.parse(responseObject.response.body);
    }

    var finalCallback = function (returnObject) {
      callback(returnObject.error, returnObject.tableResponse, returnObject.response);
    };

    next(responseObject, finalCallback);
  };

  this._performRequestExtended(webResource, null, options, processResponseCallback);
};

Not only is this hard to read, it's not clear why all of these layers of callbacks are even necessary. This could just be this one library, however, it also seems that Node.js is solving a problem that isn't there for a vast majority of people. The Railways.js and Express frameworks are great, however, if the problem you are trying to solve is concurrency, you are unlikely to use a heavyweight framework. You are much more likely to build a highly specialized and tuned end point, using low level platform constructs.

That is not to say that it's a lost cause. Projects like TypeScript are seeking to make Node.js development much more scalable. Tools like Jetbrains WebStorm with the Node.js plugin, provide a slew of  functionality for JavaScript development that you may be used to in other development environments. This includes refactoring, code completion, a nodeunit test runner, and debugging

Would I use Node.js on my next project? Potentially for small endpoints that may need high concurrency and throughput. However, I am interested in seeing where the development community takes the concept of JavaScript on the server. Perhaps at some point this will become a viable alternative to the existing platforms and frameworks.

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