Introduction

My last post triggered quite a few questions. I had no idea so many people read my blog. The emails mostly asked "Why Node?" or "What's good about Node?".

In my previous blog I expressed my frustration learning Node and how I overcame my issues. Perhaps it's time to explain why I'm using Node even when I had every possible option of technologies for the project I just started. So… here I'll try to explain why I use Node and what I like about Node.

NOT an advantage: Wide Recruiting Base

Before I start, I'll make address what I think is a common misconception. I've seen this argument made in multiple places and I could not disagree with it more. The argument for node goes something like this:

Node is great because we can use JavaScript. JavaScript is an easy language that is widely spread and recruiting will become much easier.

If this is your reason to go to Node, I suggest you don't! 

Here is my opinion. If you are going to transition your organization to Node, you probably need better programmers than you currently have. It is correct that you can find lots of resumes with JavaScript on them, but making a widget pop-up with JavaScript, validating fields in a form, that is the typical tasks of a client-side JavaScript programmer is quite different from maintaining a set of complex backend services.

If you are planning to use Node to build backend services, get the best programmers you can find. For large scale project, Node (and JavaScript) requires more professional engineering discipline. The freedom of Node/JavaScript invites clever and brilliant solutions, but at the same time opens up Pandora's Box for the worst possible engineering practices. Believe me, I've seen them...
If I were interviewing someone to work on my Node server, I would ensure that:

1. They have a solid Computer Science background
2. They fully understand the asynchronous model
3. They are fluent in Test-Driven-Development and embrace it

It may seem a bit strange to start arguments for Node by trying to kill one of the most commonly suggested advantages, but I wanted to address it so that I don't get a ton of other emails wondering why I don't list 'Easy to Program' as an advantage. Bottom line, if you are one of those companies that hire a ton of average programmers and have found that it is easier to find cheap JavaScript programmers… Node is not your answer! I seriously believe that you will be worse off with  Node than Java. Java and other strongly typed languages prevents a lot of errors that now are very commonin JavaScript.

Advantage 1: Code easily be migrated to and from the browser/server

Apart from using the Google Web Toolkit, there is really no way you can avoid JavaScript in a modern web application (and even if you use GWT, you most often end up doing a fair amount of JavaScript). If you have adapted the Web 2.0 paradigm, you would want to distribute some of the computing to the client side.

Using Node, the algorithms and data structures that you build can in theory run both on the client and on the server. With a bit of cleverness (remember, the best programmers) you can make modules context free and play around with where they run.

Using this advantage I can easily optimize performance by taking advantage of all the browsers accessing my application and fine-tune it as I go. This often significantly outweighs the performance disadvantage running my server algorithms through an interpreter.

Advantage 2: Consistently asynchronous

Everything is Node is asynchronous. This is quite powerful as it allows a single incoming request to (conceptually) fork off a set of threads at the same time. In most other environments you program every incoming request serially. This is a performance issue in many cases where the one may easily parallelize the algorithms. Since JavaScript has closures as first-class-citizens of the language, programming asynchronously is straight forward.

I have to say that most node applications, when complex, can be rather cumbersome to read because all of its nested functions, but I found the async.js library to pretty much eliminate this issue (this library is well worth a few hours of study).  With async, the parallelism is clear to see and the code reads like prose...

Advantage 3: It breaks down the boundaries between front- and back-end development

Because both the client-side and server-side development is using the same language, we don't have to separate the front-end developers and back-end developers. This means that a developer (or two developers if you use pair-programming) can work on a feature from start-to-end. This eliminates the waiting for front/back-end to finish. This is of course because we have no impedance mismatch between the two environments (you may still have some that prefer to work on U/I's and there is of course some advantage to have experts here… You still have to deal with browser idiosyncrasies, CSS, HTML, etc., but the boundary can be quite fluid).

This simplifies project management and helps spread knowledge.

Advantage 4: [Context specific] JavaScript is a dynamic language

For many problems, the ability to load code and execute it dynamically can significantly simplify the design. You can store code/functions as first-class objects and execute them upon need. You may even have customer produce JavaScript to be executed by your engine (this of course opens up security holes, but the option is there).

A few things I used to fear, but no longer do

Java has a tremendous number of open source components that you can learn download, learn and integrate. Node.js is rather fresh, so there are not that many components out there. Node is a newcomer and it doesn't have nearly as many battle tested components. This is of course an issue, but I've stop fearing it. It seems the Node community is very vibrant and productive. You can almost always find a suitable component for whatever domain independent problem that these open source components typically solve.

I had little hope that Node would be able to handle cross-open-source-dependencies (Maven does an excellent job of this for Java). However, it seems to me that the package manager of Node (npm) is almost as good (and sometimes better).

Conclusion

In this blog-post I've outlined the advantages that may make me select Node.js as my server environment (I would not always use it). I've also tried to debunk one of the commonly listed advantage, namely that you can get away with inferior engineers when working with Node.