I've seen many good tcp-based projects in other languages, for example C/C++.
Is there any good one in Node.js? I'm implementing a tcp-based real-time pub/sub system using Node.js, but have some problems when high pressure.
I don't really need those simple tcp server examples or baby-steps tutorials. I need some real projects.
Thanks!
EDIT:
I write a chat-like node.js program to exchange data from clients. It's pretty good when I test it with only few people.
However, when more people, like hundreds people, join in, it starts to loss data. Check out this: How to deal with 'read ETIMEDOUT' in Node.js?.
The answer is good but cannot help on improving the stability.
I don't really expect people who dive into my dirty codes to find my errors. That's why I want some real projects to see how they do.
I believe this reading material might help you.
In his case, he was broadcasting mouse events to several clients. And the amount of data to publish was so great that he had to cluster users by "rooms"
Related
I'm currently working on an api for an app that I'm developing, which I don't want to tell too much about. I'm a solo dev with no patents so it's probably a good idea to keep it anonymous. It uses socket.io together with node.js to interact with clients and the other way around, which I might be swapping out sometime later for elixir and it's sockets, but that isn't relevant for now. Now I'm trying to look into cloud hosting, but I'm having a rough time finding a good service to use.
These are my requirements:
24/7 uptime
Low memory and performance necessary (at least to start with). About 1+ gig with 2+ cores will most likely suffice (need 2 threads or more for node to handle async programming well)
Preferably free for like maybe even a year, or just really cheap, but that might be munch to ask
Must somehow be able to run some sort of database. Haven't really settled on this yet, but I want to implement a custom currency at some point, and probably have the ability to add some cooldowns. So it can be fairly simple and small. If anybody has any tips on what database I should use, that would also be very welcome. I was thinking of Cassandra because of the blazing fast performance and expandability. But I also wanna look into remote databases, especially if I'm gonna go international with the product
Ability to keep open socket.io connections, as you've probably guessed :P
Low ping decently high bandwith internet. The socket.io connections are lightweight and not a lot of data has to be sent. Mostly packets of a few kilobytes every now and then for all of the clients.
If this information is too vague or you want to know some other requirements I haven't thought of, let me know.
Check out Heroku (PaaS), they have a free version to start with
We've made an application where two people can video chat with each other using TokBox, but are running into a lot of technical issues surrounding WebRTC and TokBox itself. I know that Twilio recently launched a Javascript version for their video service, but both TokBox and Twilio seem to be aiming for larger scale publish/subscribe operations. It also isn't as far along as TokBox.
Are there other services out there that can do web video 1 on 1's? Perhaps some that don't use WebRTC and therefore don't have the problems we are facing?
I can't help but to think back to ChatRoulette and similar apps.
If what you need is an application that needs to run within the context of a browser, then WebRTC is your only choice when it comes to the technology to use. There's just nothing else there now that Flash is officially dead.
If you need it to run purely inside a packaged PC/mobile application, then you can use something other than WebRTC, but I don't really see the need for that.
When using real time video technologies, one aspect to look at closely is the quality of the network you are using. The questions I usually ask myself are things like does Skype/Hangouts/FaceTime run any better? If the answer is "yes they do", then the problem is in the implementation you have done/used. If the answer is "no, they are just as bad" then you probably can't do a lot better either.
For alternatives, you can check out the vendors listed in this WebRTC Develoepr Tools Landscape: https://bloggeek.me/webrtc-developer-tools-landscape/
I don't know what you mean with "a lot of technical issues surrounding WebRTC and Tokbox itself", but I do know Tokbox handles millions of 1:1 streaming minutes every day, without issues, and it can even handle sessions with 1 publisher and 3000 subscribers at the same time, so, maybe the technical issues are not there, but in another place...
I am considering developing a web site which has many characteristics of a social networking site. The website, I am considering will have a lot of apps, which will interact with the database, and also, scraping other websites for information and a multiuser chat. Also, it will feature a forum, blog, and other similar CRUD applications. The key things I am looking at is
Response time
Max number of developers may be 1 to 3 during the initial stages
I expect the website to scale up to around 1000 concurrent users in a year, and then hopefully an exponential growth.
The users are expected to spend a lot of time, in the site.
With this requirements in mind, I looked at Django, and Web2Py, since I am knowledgable in Python. It fits the bill mostly, but, I am concerned about the scalability, and as it scales, I will require more servers to be added. This means, additional cost, and I don't have any ideas to monetize the app in the near future for various reasons. So, I have to be satisfied with a limited amount of resources.
Can you kindly advice me?
Thx
Ik
From what you had described, Node.js is perfect. Not only does it have a low memory footprint and can it handle thousands of concurrent clients out of the box, but you can definitely use it for scraping websites (see this and this), creating chats (check nodechat and this other nice tutorial)
The respond time depends on your application, but if you code the right way (don't block the event loop of Node.js, keep you 'heavy-lifting' outside the server process) Node.js is really fast.
This depends on you, but consider Node.js is JavaScript on the server-side, so there is already a great pool of developers that already know JS and could learn Node.js specific things fast.
There were some official benchmarks on the nodejs blog some weeks ago, look here: http://blog.nodejs.org/2011/11/05/node-v0-6-0/ A simple server with Node.js can handle 5-6 thousands of requests per second, so you can imagine that's really something.
Spending a lot of time on the site means that they'll be making many requests, so look at my point above 3).
http://highscalability.com/blog/2011/2/22/is-nodejs-becoming-a-part-of-the-stack-simplegeo-says-yes.html
Scaling node.js
Say I have a bunch of webservers each serving 100's of requests/s, and I want to see real time stats like:
Request rate over last 5s, 60s, 5 min etc
Number of unique users seen again per time window
Or in general for a bunch of timestamped events, I want to see real-time derived statistics - what's the best way to go about it?
I've considered having each GET request update a global counter somewhere, then sampling that at various intervals, but at the event rates I'm seeing it's hard to get a distributed counter that's fast enough.
Any ideas welcome!
Added: Servers are Linux running Apache/mod_wsgi, with a Python (Django) stack.
Added: To give a sense of the event rates I want to track stats for, they're coming in at over 10K events/s. Even incrementing a distributed counter at that rate is a challenge.
You might like to help us try out the beta of our agent for application performance monitoring in Python web applications.
http://newrelic.com
It delves more into the application performance rather than just the web server, but since any bottlenecks aren't generate going to be the web server, but your application then that is going to be more useful anyway.
Disclaimer. I work for New Relic and this is the project I am working on. It is a paid product, but the beta means it is free for now with all features. Later when that changes, if you didn't want to pay for it, their is still a Lite subscription level which is free and which gives you basic web metrics reporting which still covers some of what you are after. Anyway, right now would be a great opportunity to make use of it to debug your performance while you can.
Virtually all good servers provide this kind of functionality out of the box. For example, Apache has the mod_status module and Glassfish supports JMX. Furthermore, there are many commercial packages for monitoring clusters, such as Hyperic and Zenoss.
What web or application server are you using? It is difficult to provide a solution without that information.
Look at using WebSockets, their overhead is much smaller than a HTTP request, they are very well suited to real-time web applications. See: http://nodeknockout.com/ for Node based websocket examples.
http://en.wikipedia.org/wiki/WebSocket
You will need to run a daemon if you want to run it on your apache server.
Also take a look at:
http://kaazing.com/ if you wan't less hassle, but are willing to fork out some cash.
On the Windows side, Perfmonance monitor is the tool you should investigate.
As Jared O'Connor said, you should precise what kind of web server you want to monitor.
I need to set up a protocol for fast command/response interactions. My instinct tells me to just knock together a simple protocol with CRLF separated ascii strings like how SMTP or POP3 works, and tunnel it through SSH/SSL if I need it to be secured.
While I could just do this, I'd prefer to build on an existing technology so people could use a friendly library rather than the socket library interface the OS gives them.
I need...
Commands and responses passing structured data back and forth. (XML, S expressions, don't care.)
The ability for the server to make unscheduled notifications to the client without being polled.
Any ideas please?
If you just want request/reply, HTTP is very simple. It's already a request/response protocol. The client and server side are widely implemented in most languages. Scaling it up is well understood.
The easiest way to use it is to send commands to the server as POST requests and for the server to send back the reply in the body of the response. You could also extend HTTP with your own verbs, but that would make it more work to take advantage of caching proxies and other infrastructure that understands HTTP.
If you want async notifications, then look at pub/sub protocols (Spread, XMPP, AMQP, JMS implementations or commercial pub/sub message brokers like TibcoRV, Tibco EMS or Websphere MQ). The protocol or implementation to pick depends on the reliability, latency and throughput needs of the system you're building. For example, is it ok for notifications to be dropped when the network is congested? What happens to notifications when a client is off-line -- do they get discarded or queued up for when the client reconnects.
AMQP sounds promising. Alternatively, I think XMPP supports much of what you want, though with quite a bit of overhead.
That said, depending on what you're trying to accomplish, a simple ad hoc protocol might be easier.
How about something like SNMP? I'm not sure if it fits exactly with the model your app uses, but it supports both async notify and pull (i.e., TRAP and GET).
That's a great question with a huge number of variables to consider, and the question only mentioned a few them: packet format, asynchronous vs. synchronized messaging, and security. There are many, many others one could think about. I suggest going through a description of the 7-layer protocol stack (OSI/ISO) and asking yourself what you need at those layers, and whether you want to build that layer or get it from somewhere else. (You seem mostly interested in layer 6 and 7, but also mentioned bits of lower layers.)
Think also about whether this is in a safety-critical application or part of a system with formal V&V. Really good, trustworthy communication systems are not easy to design; also an "underpowered" protocol can put a lot of coding burden on application to do error-recovery.
Finally, I would suggest looking at how other applications similar to yours do the job (check open source, read books, etc.) Also useful is the U.S. Patent Office database, etc; one can get great ideas just from reading the description of the communication problem they were trying to solve.