I would like to know which server is the best to use for the Nitrogen Web Framework?
Of the 5 listed on the site, I have already removed Inets(not recommended for production) and WebMachine. Left with only Mochweb, Yaws and Cowboy. I also noted on the site that Nitrogen/Yaws windows binary is not available for download. Any particular reason?
There is no clear answer for what is the "best" to use. If you're just getting started, just pick one and go. Cowboy and Yaws are under the most active development as "full featured" Erlang webservers, and so if your limitation is to use Windows, just use Cowboy.
Each server has its own configuration for tuning, and if you're comfortable tuning and developing for one, Nitrogen provides the mechanism to use your server of choice.
As for not providing a Windows download for Nitrogen/Yaws, Yaws is not done in "pure erlang" (there are some C files that need compiling), and as a result, compiling Yaws on Windows is more complicated, so in order to just get the build out there, Yaws was left out on Windows. Enough time was spent optimizing Nitrogen's build in Windows that I just wasn't going to spend any more time trying to get Yaws running with Nitrogen on Windows. I wanted the release done, and so Yaws was left to the wayside for a future version.
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I need the VPS services for hosting my ASP.NET project.
However, it's not just asp.net hosting, I also need SQL Server, RabbitMq and either my running conrole app or my windows service.
So I read the suggestions to use Amazon Web Services as they provide first year for free.
However when I registered I found that I don't have a clue of where I am:
I don't see the option of creating a virtual machine with Windows
I don't see the option of setting up SQL Server on such the machine
and so on.
So I was wondering whether I'm in the right place?
Please advise if AWS can provide me with what I need or I came to the wrong place?
AWS can provide all that you listed, but you'll need to do some learning on your end.
Basically you create an EC2 instance, and then use RDP to remote into it, and you can install software and configure it to your hearts content - just like it was any other physical server.
If you want to use SQL Server, you'll have the choice of installing it directly on the instance using your own license, or using their 'hosted' version of SQL Server call RDS. You'll need to read about it and decide which option is better for your project - there is no single right way.
Lastly, I will point out that although the 'free-tier' is nice, except for a really small application (i.e. small db on a low traffic website), you may find out the 'free-tier' does not quite give you all the power you need to run a busy application. I would not base your decision on wether or not you should use AWS on how much 'free' stuff you can get. The free-tier is nice for learning, but plan on spending some money for a truly robust solution.
I'm planning on writing a control panel for Minecraft in Rails but I don't have much experience with Java at all, Minecraft seems to have some standard remote connection and query tools, but most conventional panels don't seem to use them. For example with McMyAdmin, I have disabled remote connectiona and the query, but it still seems to be able to communicate with the server after restarting it after I've edited the server configs to disable the settings.
What I'm asking is if anyone knows how McMyAdmin communicates with the Minecraft server, it comes with a plugin, but I've deleted that as well and it still seems to be able to communicate with the server, I know McMyAdmin is written in .NET and I believe it uses Mono as it's server, as it's cross platform.
If anybody could shed some light on this I'd be ever so greatful, just trying to get my head around the communication.
McMyAdmin uses the plugin to open a socket that it can interact with(Not sure which features are provided using this plugin). The rest of the features are just from the Process instance that it creates. It also just edits the config files for a few things as well or runs commands using the input stream of the process.
I would like to know if this is even feasible. And if so, what a possible approach would be.
I am thinking that the .exe would have to be made available through a web service running on a windows stack (asp.net or php) and that a direct heroku solution would not be the way to go.
If you do it as a externally, yes. The main trick there would be making the service on the windows box and making sure your service was secure. If you're going for cloud stuff, your best bet is probably to set your service up on a windows server on EC2 or Rackspace or [insert cloud provider here]. They're not as cheap as linux boxes because of the license cost, but shouldn't be too difficult to manage.
Unless Heroku has changed a lot from the last time I looked at it, the underlying OS was linux of some variety, so it's really unlikely that you could get an windows binary to run internally without bundling wine into your application (probably not worth trying to figure out).
Let's assume we have a web project in which we want to have ~10000 web clients connected to the server simultaneously. Let's also assume that one client session lasts about 25 minutes.
If we compare LAMP stack or any other popular web stack/framework (Ruby on Rails with Apache on Linux, etc.) to a web project built in Erlang/OTP - what does Erlang/OTP have in terms of fault tolerance that other frameworks don't?
What event can happen to a client that will cause the whole LAMP stack crash, while Erlang/OTP will stand its ground?
Note that a typical LAMP-stack does employ some fault tolerance. In particular, if a request in the LAMP stack fail, only that request will, while the rest of the code will run on. This kind of protection allows you to have faults in a single request without that hurting other requests.
Erlang provides this idea of "able to cope with smaller unforseen errors" at a much finer grained scale. You may have other subsystems in an application, and the same kind of tolerance to errors can be extended to those. You won't get it "for free", but the tooling is there to build a system which is robust. Imagine a client error in the LAMP stack. This will often lead to a disconnect of that client. It may not be so in Erlang and the client can keep on running.
For a system of 10000 clients, Erlang provides the advantage that you can have a process per client. Or perhaps 10 processes per client. That is much harder to pull of in many languages since a process/thread is rather heavy and expensive. Note that interprocess communication between the clients are easy, also if some clients are on another machine (imagine extending to a distributed cluster some day).
If you write your code in a certain way, you can make sure that if a client crashes, for one reason or the other, then its state is properly cleaned up by other processes. That can avoid lots and lots of small nasty leaks in state as well.
what does Erlang/OTP have in terms of fault tolerance that other frameworks don't?
Now, Erlang/OTP has very minimal if not, Zero side effects. Because of its concurrency, a web server like yaws literally spawns a small web server for every connection. If one user is affected by a given web service fault in your application, all other users will never notice and the only that users process may exit.
With OTP, you can build applications with a number of supervisors, such that if a server goes down, its restarted and many other functions and options you may need.
Erlang's distribution allows us to write distributed applications. I have personally used yaws web server in building a web application.
My experience is that which ever web server you may pick, say Mochiweb, a tutorial found here: http://alexmarandon.com/articles/mochiweb_tutorial/, is quite impressive in performance. Infact, a few years back, the oldest version of yaws web Server was bench marked with the (then) newest version of Apache, and the results of the bench mark are very awakening. When i went through a million user comet application with Mochiweb, which has Part 2 and Part 3, i was impressed. These are some of the few examples of powerful web frameworks built for the web.
And by the way, have you heard of these new NO SQL Databases with REST (HTTP) interface developed in Erlang/OTP e.g. Membase Server [home page here: http://www.couchbase.com/products-and-services/membase-server], Couch DB, and Riak, their performance is very impressive, meaning that their web/REST interface is very stable and due to their impressive , documented write through put, they have proved that their underlying Technology (Erlang/OTP), was built not only for high availability and fault-tolerant systems only, but for the web too! Just read through this document: http://blog.couchbase.com/why-membase-uses-erlang
Many more web frameworks built in erlang and are very impressive can be found listed on the wiki page here: http://en.wikipedia.org/wiki/Erlang_(programming_language). A probably better summary of its features that make it powerful on the web can be found in here: http://cs.nyu.edu/~lerner/spring10/projects/Erlang.pdf
I want to use Erlang for some background processing and stuff for a web app. I read about its concurrency handling and stuff and I have started learning it. What I want to do specifically is a persistent connection with the clients using COMET - with the Erlang process co-ordinating the HTTP client connections.
Do I need a Erlang based web server for this?
For the actual implementation, how does the "spawn"-ing work in Erlang. I downloaded the erlang ebook and read about spawning. In the case for my web based script, when two clients connect to the same Erlang script by making an HTTP request - can I automatically "spawn" new threads for each of them, and do message passing?
No, you didn't but it is simplest way. You can combine Erlang with libevent to achieve more http://www.metabrew.com/article/a-million-user-comet-application-with-mochiweb-part-3/
Yes, spawn new client is cheap, if you want cheaper see above.
I would highly recommend using an erlang based webserver to handle the comet connections. The lightweight processes in erlang are half the benefit of using it for this type of thing.
Most of the erlang webserver frameworks will handle the spawning for you. No need to reimplement it yourself. See nitrogen and mochiweb for examples of really dead simple comet implementations.
Did you see the page http://beebole.com/erlang ?
It contains:
how to setup an Erlang environment(with Mochiweb) on Ubuntu
how to install the Nginx web server
a video tutorial to build a small web app using Erlang
You should investigate 'YAWS' (high performance HTTP server) modules: easy to write, full flexibility. YAWS is easily installed: apt-get install yaws (on Ubuntu at least).
Another option would be to use Nitrogen - this allows an easy integration of Erlang code in web pages, including a fully-fledged webserver, and comet.