Introduction of node.js

what’s node.js?

If you’re not familiar with node.js, it’s a new web programming toolkit that everyone’s talking about. It’s the one that makes you feel not hip if you don’t know what it is. Like Ruby on Rails was a few years back. Folks called it “Node” and it’s basically server-side JavaScript. The idea is that if you are doing a bunch of JavaScript on the client and you do JavaScript all day, why not do some JavaScript on the server also. One less thing to learn, I suppose.
If you are an ASP.NET programmer, you can think of node.js as being like an IHttpHandler written in JavaScript. For now, it’s pretty low-level. It’s NOT an HttpHandler, but I’m using an analogy here, OK?

 Why does node.js matter?

Why bother with node at all? There’s a number of interesting aspects to node as it sits. It uses a very fast JavaScript engine called V8, but more importantly its I/O is asynchronous and event-driven which contrasts with typical synchronous code.
For example, a naive hello world HttpHandler in ASP.NET that “does some work” for a few seconds (gets a file, accesses a service, etc) could look something like this:

And this is usually fine for most stuff. However, when I push this HARD with a load testing tool and a thousand virtual clients, I can barely get 60 requests a second. The request thread is tied up waiting for the “work” to happen and everyone else gets in line. I’m using up ASP.NET pool. It’d be nice if the work would get handled and someone would “call me back” when it’s finished. It’s like waiting on hold for tech support. You are effectively blocked as you wait for them to pick up their end. Wouldn’t it be nice if they just called you back when they were ready?
ASP.NET has always been able to do things with IHttpAsyncHandler but it’s always been a bit hard and almost no one knows about it. With the Async CTP and the Task libraries built into .NET, you can build a nicer abstraction on top of IHttpAsyncHandler

Why would I want node.js to run on Windows and IIS?

Some of the advantages of hosting node.js applications in IIS using the iisnode module as opposed to self-hosting node.exe processes include:

  • Process management. The iisnode module takes care of lifetime management of node.exe processes making it simple to improve overall reliability. You don’t have to implement infrastructure to start, stop, and monitor the processes.
  • Scalability on multi-core servers. Since node.exe is a single threaded process, it only scales to one CPU core. The iisnode module allows creation of multiple node.exe processes per application and load balances the HTTP traffic between them, therefore enabling full utilization of a server’s CPU capacity without requiring additional infrastructure code from an application developer.
  • Auto-update. The iisnode module ensures that whenever the node.js application is updated (i.e. the script file has changed), the node.exe processes are recycled. Ongoing requests are allowed to gracefully finish execution using the old version of the application, while all new requests are dispatched to the new version of the app.
  • Access to logs over HTTP. The iisnode module provides access the output of the node.exe process (e.g. generated by console.log calls) via HTTP. This facility is key in helping you debug node.js applications deployed to remote servers.
  • Side by side with other content types. The iisnode module integrates with IIS in a way that allows a single web site to contain a variety of content types. For example, a single site can contain a node.js application, static HTML and JavaScript files, PHP applications, and ASP.NET applications. This enables choosing the best tools for the job at hand as well progressive migration of existing applications.
  • Minimal changes to node.js application code. The iisnode module enables hosting of existing HTTP node.js applications with very minimal changes. Typically all that is required is to change the listed address of the HTTP server to one provided by the iisnode module via the process.env.PORT environment variable.
  • Integrated management experience. The issnode module is fully integrated with IIS configuration system and uses the same tools and mechanism as other IIS components for configuration and maintenance.In addition to benefits specific to the iisnode module, hosting node.js applications in IIS allows the developer to benefit from a range of IIS features, among them:
    • port sharing (hosting multiple HTTP applications over port 80)
    • security (HTTPS, authentication and authorization)
    • URL rewriting
    • compression
    • caching
    • logging

These are all compelling, but the most interesting bit here, in my opinion, is integration. The iisnode module is a proper IIS module, just like ASP.NET and PHP. This means you can have a single website that has multiple kinds of content. Restated from above:
For example, a single site can contain a node.js application, static HTML and JavaScript files, PHP applications, and ASP.NET applications.
folks you can have an ASP.NET WebForms app and a ASP.NET MVC app in the same AppPool as a “hybrid.” Frankly, Dear Reader, people don’t even realize the power and flexibility of IIS. When you plug in something new like node but run it the way you run other things it inherits all the coolness of the outer container, in this case, IIS.


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