I'm going to develop a collaborative site, and one of the features will be collaborative editing with realtime changes. i.e. when two or more users are editing the same doc, they can see each other changes as soon as they happen.
I have some experience with Ruby on Rails, so I was thinking about using EventMachine, but with all this hype around Node.js, I am know considering using it instead. So, what would be the main benefits of using Node.js instead of EventMachine?
tl;dr
What are the main differences between EventMachine and Node.js (besides the language)?
EventMachine has nothing to do with Rails apart from them both being written in the same language. You can get EventMachine as bare as Node.js; all you have to do is not add libraries to your project. In my experience the EventMachine libraries (like em-http) are much nicer than anything for Node. And you can use fibers instead of callbacks to avoid callback hell. Complete exception handling is pretty much impossible in Node because of all the callbacks. Plus Ruby is a nicer, more complete language than Javascript.
I tend towards the "use what you know" (even if it's a heavier architecture). Because of that, I don't see it being quite as simple as "EventMachine vs NodeJS." Mainly, the difference can be summarized as this:
NodeJS is a framework/language that was written to handle event based programming in JavaScript. That is its driving force. It's not an after thought, or a third party mechanism. It's baked right in to the language. You create callbacks/events because that's how the language is built. It's not a third party plug in, and doesn't alter your workflow.
EventMachine is a gem in Ruby that gives developers access to some of the goodness of the event based programming model. It's heavily used and well tested, but not baked directly in to the language. Both are locked to one CPU, but with event programming at Nodes core, it still has a leg up. Ruby wasn't written with concurrency in mind.
That said, technical problems can be overcome. The more important questions (from my view) that should guide your decision are these:
What will your production environment look like? Do you have complete control over the server? Can you host it however you want? Or will it be on a shared system to start with, and then you have to expand on that?
Do all the developers on your team have the ability to learn a new language very fast? How fast will they be able to understand an event-based language like JavaScript for the middle tier?
Do you need all of the architecture that Rails gives you (full Testing framework, scaffolding, models, controllers, etc)? Or is that overkill?
There are quite a few technical differences between the two. One is a language, one is a framework. Really, how heavy of a stack you want to run? How much learning will your developers have to do? Do you want a full stack the gives you a lot of niceties, that you may not use, or do you want a bare bones set up that runs extremely fast and concurrent, even though you may have to write extra boiler plate code and learn a new lanugage?
While Rails is not as heavy as some web application architectures, you're still going to need more processor power than you would to handle a similar amount of throughput in NodeJS. Assuming quality code for both systems. Bad code written on either stack is going to prevent the stack from shining. It really comes down to- Do you really want to learn a whole new way of doing things, or utilize your current understanding of Ruby to get things off the ground fast?
I know it's not really a definitive answer, but I hope this helps guide you to a decision!
One thing worth mentioning is the production story. EM, like most Rack stuff, has plenty of testing and monitoring tools available that are well tested, whereas Node.js falls well short in this respect.
At the time of writing, it seems almost impossible to get clear metrics from Node to answer questions like 'Do I need to scale'. There are options starting to form out there from the likes of Joyent, and always the roll-your-own argument, but nothing anywhere near tools such as NewRelic.
Node.js is very good from a performance / configurability point of view, but personally I wouldn't host it in production just yet.
Node.js
You get far better control low level control over what's going in. You can include general libraries to build on top of node.js to tweak your level of abstraction to your own liking. For example you can use connect or express depending on whether you want a view engine written for you.
You can use socket.io or now depending on how much you want your client-server connection abstracted. You can opt to include any of numerous MVC libraries or write your own.
Event-Machine
An asynchronous IO library just like node.js
It comes down to a Ruby vs JavaScript preference, how much flexibility you want with abstractions or lack of abstractions and whether you want to use node as your actual web server.
a detailed view at confusion has already been proposed... just a personal view
[] node.js will be better, if you are ready to learn and experiment more than you think because:
it's thread mechanism is awesome (inspired from that of 'erlang')
you can build a purpose specific server (easily) which will be real productive
Related
Up to now I've always used PHP with or without a framework but a month ago I decided to start something new: Ruby and Rails, I found them quite easy and similar to PHP and some PHP frameworks in how they works but using a simpler syntax and many other advantages.
Some days ago I started reading about Node.js, Node.js vs Rails, "why node.js is better"...
I'm a bit confused but my objective is to learn something modern that will not become obsolete in a few months so:
What are the main differences between Rails/Ruby and Node.js and a framework based on it like Express.js (except that one is written in JS and the other in Ruby)?
What are the main advantages/disadvantages of using Node.js and framework based on it instead of a Ruby based solution like Rails?
Thanks!
There aren't enough differences between Node.js and Rails for it to practically matter.
A lot of what Node.js can do can be pulled off in Rails with things like EventMachine and Pusher. So unless you are really familiar with Rails' limitations, and know you'll be pushing the boundaries, you'd be hard pressed to make something a seasoned Rails developer couldn't do.
Having built apps in Node and Express I can say that they alone aren't enough to make a sexy application. They can seem just as old and stale if you don't have an outstanding frontend UI to facilitate the backend possibilities. Instead of comparing backend servers, I think the real future of doing amazing things is in front-end JavaScript frameworks like Backbone.js that use Express/Rails/Node.js on the backend.
I have chosen to go in the direction of Backbone.js with Rails as my backend API server. Because it's so easy to rapidly create a very nice RESTful backend server in Rails. Rails also makes working with CoffeeScript and precompiling/organizing Backbone code a breeze. There are already decent Backbone.js gems out there for Rails.
The Rails core is also able to acknowledge and embrace the fact that frontend JS MVCs are logically a good next step, and they have been working to strengthen the bond between the two. For those same reasons they have also worked to make Rails an even better API server so that it can work with frontend JS easier. Node.js and Express aren't putting as much effort to coordinate with frontend JavaScript MVCs as the Rails community is.
Being good with a JavaScript frontend MVC and Rails as a backend makes you also great for both worlds in terms of getting a job. You will easily be able to hop onto a Node.js project and add value to that team with your superior frontend experience, and you can also roll with the punches on a Ruby on Rails team and add value to them as well.
As official Node.js website explains it:
Node.js is a platform built on Chrome's JavaScript runtime for easily building fast, scalable network applications. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, perfect for data-intensive real-time applications that run across distributed devices.
On the other hand Ruby on Rails official website says:
Ruby on Rails is an open-source web framework that's optimized for programmer happiness and sustainable productivity. It lets you write beautiful code by favoring convention over configuration.
Given this I guess that it is more appropriate to compare Ruby and Node.js, but even this is not quite right given that Ruby is programming language and Node.js is NOT. You could probably compare JavaScript with Ruby but I guess that is not what you meant to ask with this question :)
So, for me, key point in understanding what Node.js truly tries to accomplish is well described on Node.js about page. Key Node.js idea (for me) is described in this sentences:
Node is similar in design to and influenced by systems like Ruby's Event Machine or Python's Twisted. Node takes the event model a bit further—it presents the event loop as a language construct instead of as a library. In other systems there is always a blocking call to start the event-loop. Typically one defines behavior through callbacks at the beginning of a script and at the end starts a server through a blocking call like EventMachine::run(). In Node there is no such start-the-event-loop call. Node simply enters the event loop after executing the input script. Node exits the event loop when there are no more callbacks to perform. This behavior is like browser javascript—the event loop is hidden from the user.
What this should enable you, is that you should be able to easily write highly concurrent programs without even thinking about concurrency using JavaScript syntax and callback functions as basic concurrent runnable units.
Your fear that either Rails or Node.js will be gone in a week is unfounded. Rails has a large community and will be around for a very long time even though currently (early 2012) it's getting a bit of hate thrown its way. Node.js is just getting started and has so much attention I don't think it will have any problems getting to the Rails level some day.
That said I've been evaluating Node.js and Rails as options for a project and the reasons I choose Node.js over Rails are:
"The Rails Way" - In my (admittedly limited) experience with Rails it really seems like you either do it the Rails way or you are going to be in for a world of pain. A big part of the Rails way is to use the ActiveRecord model. The advantage of this is that there are a lot of gems that work with your code happily because they know you'll be using ActiveRecord. The disadvantage is you are mixing your data access & model. I am not a fan of this idea so the Rails way for me still seems a bit.. off.
JavaScript is a key part of client side web development and the idea of using it on the client and server is interesting. I'm not super strong at JavaScript and I can't imagine a better way to get better then to have to use it everywhere.
My project has real time communication needs which while I'm sure can be done in Rails there seems to be quite a bit of positive mention on Nodes ability to handle this with socket.io being the front runner option.
At the end of the day no matter which you choose you will have a great time & learn a ton of new stuff that will change how you write code. If you're not on a big time crunch I'd recommend building a small project management tool in both and see which you prefer.
Either way.. Good Luck!
2 things - performance & productivity.
Performance (more details here)
(source: jslang.info)
Productivity (how fast you can build that app)
Ruby on Rails is specialized and highly productive tool for creating so called Web 1.0 and Web 2.0 applications (99% of internet sites are such apps). In my subjective judgement and experience in this area Rails about 2-4 times more productive than node.js or express.js.
For Web 3.0 apps (realtime things, client-side MVC, etc.) this isn't true, RoR doesn't keep its advantage there.
So choice depends on use case and priorities.
I know a lot more about Node.js than I do about Ruby. That being said, Ruby is much more widely adopted. It is currently a very hot skill to have in the work place. Some may argue with me on this but I think that Node.js is still "under development" and will be for a little bit longer. It has a lot of promise but just hasn't been adopted by many companies and projects yet.
I'm trying to come up with things that Ruby (or Rails) either doesn't handle well, or things that are way too hard to do in Ruby.
So far I'm having a tough time, but I figured some people on here MUST have know some things that Ruby or Rails don't handle too well.
Anyone?
Ruby is a language. Rails is a framework. Many of the things Rails isn't good at, such as anything not relating to a web framework, Ruby handles with ease.
The other question of what Ruby as a language is not good at is simple. Anything extremely performance intensive is probably better written in C. Ruby won't run natively on most smart phone devices so mobile apps are out. Ruby is not designed for embedded devices, so powering the next space shuttle launch is also a no go. Furthermore the lack of a maternal instinct make Ruby a bad choice to watch young infants.
There is nothing, it's simply perfect. ;-)
Ok, some downsides:
Ruby has questionable parallelism and threading support. See for more details: http://www.igvita.com/2008/11/13/concurrency-is-a-myth-in-ruby/
Windows support isn't up to par since most Ruby developers simple don't care (like me)
The stuff you'll most commonly hear about scaling issues is a myth. Unless you're making a second twitter perhaps.
There's very little you flat-out couldn't do in Ruby, but there's a few things you wouldn't want to do, mainly involving highly numerical computation. For most of those you could easily write a binding to a C-based API (or some other more performant library.) Image processing, for example, is something that would be dog slow for any non-trivial example in pure Ruby, but you can use RMagick to do it, which is a binding to the much-faster ImageMagick library.
Just about any other use for Ruby is fair game. I've written GUI apps with it, a lot of system services and more one-off scripts than I could count.
Well, it's a framework, so it optimizes for the most common cases. If your app requires unordinary and bizarre things (eg huge performance requirements, needs to use non-Ruby libraries), then Rails might not be suitable.
It seems to me that whenever a company hits these cases (usually performance rather than functionality or integration with other systems) they have to write their own stuff - Google has Big Table, Facebook has their own webserver, etc.
If you're in this position, you're most likely rolling in money and spending some of it to rewrite your code isn't going to be an issue.
However, Rails is great for most normal apps! I don't think it has any gaps that might cause pitfalls in normal cases.
For the first time I'm creating a quite complex Rails app.
I'd like to know what's the best way to organize that app by folders. Until now, I'd do everything under one app (all the models, controllers, etC) but reading some open source code I realize that they put everything under different apps.
Like for example Spree Commerce. They have a general folder and inside that they have different apps (API, core, admin, etc). How is that done and is that the best way to do it?
I'd like to get pointed to the best way to do it (a book, blog, anything) so I can understand how I can architect my app for future maintenance.
thank you
As an aside I think the title of your question is a little confusing. Rails, by using convention over configuration, defines 'how to organise a Rails app'. I think your question is rather about how to architect your application as opposed to anything Rails-specific. Maybe tweak the title?
That aside, without knowing any more detail about your project it's a tricky question to answer, but I'll give it a go.
All applications should start off simple, if you believe (like I do) that you should start by building the simplest thing that could possibly work. Given this, since you're using Rails, then in all likelihood the simplest thing would be to structure your app as a vanilla Rails 3 application. This will probably (I say 'probably' because I don't know any specifics about the app) allow you to get a beta version of your app up and running pretty quickly without worrying about complexities which at this stage in the development of your project are not a problem.
If you need to create an XML or JSON-based API then Rails makes this really easy using the standard framework, which will allow you to spend more time thinking about the API design than how to code it, and it's the API design which is the most important thing to get right in the first instance.
Similarly, your Admin site can be part of the same app just in a different namespace. If you find later down the line that you want it as a separate app, you can do this (maybe you could use the awesome API you designed to facilitate this), but why bother designing it with this added complexity (and hence extended development time) in the first place if you don't have a good reason for doing so?
Once you have your app up and running and people are starting to use it, you start to get a picture of where the bottlenecks are and where the design could be improved. At this stage, if there's a need, you can start to move parts of the app to scalable solutions, such as running your API as a standalone service, introducing caching, changing data stores and other improvements and optimisations.
Even if your app is as wildly successful (and I hope it is!) then re-architecting your application whist continuing to run the existing service is still entirely possible, as Twitter have proved. Just stick to Knuth's statement and you'll be alright.
Regarding reading material, that's a tricky one. For me a lot of the XP and agile development classics taught me a huge amount about how to approach program and app design. I'd also check this StackOverflow topic for book inspiration.
Good luck!
Spree uses Rails' Railties (Rails::Engines). Railties are introduced in Rails 3 to make it more modular and easy to extend. Rails 3 itself is a collection of Railties (ActiveSupport, ActiveModel, ActiveRecord, etc.).
If you are developing a complex app I would suggest spending some time planing its' architecture. Designing a complex app without any initial planning would definitely end with a maintenance nightmare down the road. It also introduces a huge learning curve for the new team members, slow down your new feature introduction and of course, frustration.
Anyway, don't over optimize, but don't forget to design your architecture for your needs.
IMHO, I will create very complex projects as one app. I have reason to believe that Spree and Radiant build under seperate apps so that under the pretense of their open source communities, contributors can contribute code easily without tampering with the core data, and the core workings of the application.
Otherwise, you should be alright just building it as one app. Just keep it neat.
Here is what have kept me sane for several years of RoR development:
I use Rails Engines, but keep them in same codebase as the main app. Here is good starter for modular Rails app:
https://github.com/shageman/the_next_big_thing
Wherever I can I try to reduce coupling and use composition to make things easily testable, reusable and maintainable. This helps to eventually extract module or engine as separate gem. Composition is done by routes (mounting), directory overlaying (assets), dependency injection or configuration.
If I don't need to re-use an engine I put it in the same code base as the main app which is single deployment unit. Thanks to that I don't need to switch between projects in my IDE. While in development environment any changes to the engine code are instantly picked up by Rails reload mechanism.
I have a Rails webapp [deployed on Heroku] which makes a series of HTTP calls to other sites on a repeated basis, using Heroku's rake:cron feature. The current situation isn't ideal; the rake:cron process is executed in a single thread, which means HTTP calls are made sequentially; which means in turn that there's a long time between calls to the same site [typically 2 mins].
I'd like to execute this process in parallel, and reduce the time between calls to 10 secs. Having seen Kevin Smith's 'Erlang in Practice' I'm sold on the idea of using Erlang as a replacement backend. What I'm trying to figure out [given Damien Katz's comments], is whether I should a) re-write the entire webapp in Erlang, front end and all or b) maintain a split structure, with a Rails frontend / Erlang backend.
I like the idea of using a 100% Erlang stack for the project; I'll need to use some kind of Erlang web framework [Nitrogen ? Erlyweb ?]; I'm concerned they're not mature enough and I'll spend my time bogged down on the web part of the project with them.
Anyone any views ? Thanks.
What's the actual impact on your visitors (of the two-minute interval between HTTP backend calls)?
If there isn't much of a difference, I'd say this sounds like premature optimization and that you'd be much better off skipping Erlang for now.
The two previous posters have pretty much covered they philosophical aspects of your question. So I'll answer the framework maturity/getting bogged down part of your question.
In the event that you decide you do want to rewrite the webapp in erlang for whatever reason then I wouldn't be too concerned about the framework slowing you down. Both erlyweb and nitrogen are already feature complete enough that you can work pretty quickly with them. I've developed a fairly complex agile project management app in nitrogen and found it to be quite intuitive and not really lacking in features that I needed. A few hours in the evenings and a few weeks later and I had a working app up and running.
As to which one to use that depends on the type of app you want to build.
Nitrogen's target is extremely dyamic web applications. Most of the page is rendered using javascript and it is highly event driven.
ErlyWeb is more suited to a site where the content is the primary focus less so than a rich client type of application. It uses the MVC style of architecure.
Good luck on whatever you decide.
It depends. How much Erlang do you know? How much code have you already written?
How much project experience do you have? Is this for work or for fun?
Rewriting projects from scratch is often a recipe for disaster, especially if you are trying
to learn a new language along the way. It seems to me like you would not be asking this question if you were already fluent in both languages, in which case I would recommend that you just stick to Ruby if it's a work project.
I disagree with the above poster that changing the language is a premature optimization, if it is necessary.
Changing the language is a big deal. It can't be done at the last minute.
However, I would probably not change the language at all for the reason you outlined.
If you don't have any other reasons than performance for switching, you should probably just
look at multi-threading in Ruby or some other optimization.
I'm all about using the right tool for the job. Unless you have an absolutely dead on reason to port the front, there's absolutely nothing wrong with hooking the two together.
What language, framework, and hosting considerations should one make before starting development of a scalable web application?
The most important consideration is not to over-engineer to the point that it gets in the way of building and launching something. Analysis paralysis is the single biggest inhibitor to productivity, progress and results.
Yes, do some planning. Pick a framework. Perfection in a framework will be impossible to find because it doesn't exist, partially because you don't know what you need until you build it anyways. Chances are, if you pick something, it will be better than picking nothing.
Yes, try to pick flexible, inter-operable tools for where you see yourself going.
Yes, look for a good built-in feature set where you see yourself going in the next 6-18 Months. Trying to look beyond that is not really realistic anyways as most projects change so much anyways going towards the first release.
So, pick what you're comfortable with or what is familiar. Don't follow the crowd, do what gets you the best results, quickest, and often. Understand that you might have to change in the future. So, whatever you build now, try to use unit testing so you can re-factor if ever needed.
If what you're building is going to be super successful, it will be a great problem to have, and an easy one to work on once it's making money as you'll be able to get other talent to help you.
Share what you end up picking and why for your situation -- it helps the us learn from you too!
Don't necessarily marry yourself to one language or framework. It may be that some parts of your site work better with different languages and frameworks than others. For example, all of 37signals' sites are based on Ruby on Rails, but they recently wrote a blog post about how the underlying technology of one is actually written in Erlang now because it's much easier to do concurrency that way.
Obviously there's a level of complexity where things turn into a mishmash, but using the right tool for the job — even if that means different tools for different jobs — can simplify things.
Firstly on language, it largely doesn't matter. PHP, Java and .Net being probably the biggest three are all proven in the sense that they run some of the largest sites on the Web so don't listen to anyone who tells you one is more suited than any of the others.
Some might also put Ruby and Django/Python in this list. I have nothing against them but I'm not aware of any big (say top 50) sites using either.
Hosting considerations depend on how low you want to start but basically the order is:
Shared;
Virtual Private Server;
Dedicated.
Scalability will largely be about your application's design than any language, framework or provider. Efficient database schema, efficient delivery and use of Javascript/CSS and in-memory caching are all issues common to any language or framework.
Language - I'd recommend something with good frameworks and good testing libraries like Perl or Java.
Framework - it depends on what do you plan to do. If you start with a hosting that does not allow FastCGI, it is best to avoid such frameworks like Catalyst or Rails. That's why I love CGI::Application (primarily Perl, but ported to other languages too) - it can run as CGI, FastCGI or mod_perl. For development it can be run from it's own web server.
Hosting - nothing is better than you own server. It can be your own server, leased server or virtual server. But you can start with cheapest hosting and when you need more, you should be able to afford it.
It depends.
Start by looking at your requirements (Functional or user defined) (Non Functional - aspects that describe your desired system link text)
Next I would clarify what it means to have a scalable web application. Define it as test cases that can be clearly tested (must support X page views / second with response time < Y seconds).
Once I had those pieces in place I would look at what type of skills my development team can support (for the intial project and on going maintenance). Then find some case studies of applications out in the wild that use similar language or framework. If someone else has made a specific language / framework scale then chances are good that you can too.
Finally go out and look for some hosting providers that support your chosen language, framework and requirements.