For quite some time, I've been confused about whether Google chat is server based or is peer to peer like skype or as someone told me is it mix of both server and p2p communication?
Since Google chat history is stored on Google servers (unless you go off the record ), to me it indicates that it should be server based (but ofcourse if needed that's possible with p2p as well).
Now, the person who told me that Google chat is p2p (or that mix option if that makes sense) has quite a lot of experience in networking and I'd generally trust his words, but this time I'm just unable to convince myself that Google chat could be p2p and I'm looking for some citation or something which could help clarify the doubt. Is there someone who knows whether it's server based or p2p?
PS: Sorry if the question doesn't really belong to SO, please help me if another SE site is better place for this question. I just thought that since it's about networking and so it could possibly be fine here.
Google ditched XMPP recently and is now shifting to it's own closed sourced proprietary protocols. Which are still Server Based since google will now record all chat activity and going off record is not an option.
"They phasing out 'chat; with 'hangouts', which reneges on the server-to-server aspects of XMPP. More information on the implications (not directly related to the question) here" - Barney
Previos answer
They use XMPP ( jabber )
Extensible Messaging and Presence Protocol (XMPP)
As answered here
I guess reading Jabber would explain things a bit, it's an open protocol and much of the stuff would be available..
For instance Wikipedia explains a bit
Related
I have a general question here regarding the RSS and XMPP technology. I want to know what exactly makes XMPP a real-time alternative to RSS?
Right now, I'm assuming a one-way message stream (from server to client ONLY).
What I'm confused about is, let's say I program a RSS reader on my client side and make it scan for new feeds for VERY short interval of time. Will that not make my system real-time'ish? Or is there any negative impact on doing that which XMPP resolves (apart from the security features)?
Because there are some systems which uses a combination of the two to form a real-time feeding system (Eg : Superfeedr).
So, if someone can briefly explain why someone would implement XMPP over RSS when designing a real-time notification system, I'd highly appreciate that.
Sorry for the long post, I have recently begun with these two technologies and I'm very curious about their functionalities. I tried looking up on the internet but the answers were either too brief or insufficient.
These are very different things, but complementary.
RSS is just a data format. It does not involve any "latency" by itself. It's just the way it's being consumed which determines if it can be realtime or not.
XMPP is a communication protocol. It's connected and in that regard can be considered as "real-time". RSS itself (or rather Atom), as it's XML, can be transported quite easily over XMPP. That's one of the ways you can make RSS realtime.
And RSS can be realtime if it's served through the PubSubHubbub protocol (is not it, Julien :-) !
My knowledge about network programming is limited, so, all the comments are more than welcome. Essentially my question boils down to the following question:
Q1. Is there really such a thing as decentralized asynchronous cross-platform peer-to-peer communication?
Let me explain myself.
If we have two http servers running on computers with actual IP addresses, then clearly the answer is yes, assuming one writes a protocol for the interaction.
To go one step further, if one of them (or both) is (are) behind a router, then, with port forwarding the communication can still be established. However, here the problems start because if someone wants to run such a server on the background, say in a mobile phone, the app that is relying on this server really works when one is at home (we can not really expect to request port forwarding everywhere we go).
But even beyond that,
Q2. do mobile phones obtain an actual IP address from telecommunication companies when someone is not using a wi-fi?
If this is true, then clearly one can have cross-platform asynchronous peer-to-peer communication at the expense of not using wi-fi by running an http server on a smartphone. (I understand that this is not convenient, but it is certainly doable.)
Concluding, the two (perhaps there are more) relevant questions that I can think of are:
Q3. How does Skype really work?
Q4. How does Viber really work?
Based on the answer for Skype, it says: If one of the callee or both of them do not have a public IP, then they send voice traffic to another online Skype node over UDP or TCP.
So, it appears that there is no direct communication in Skype, because they have to use a man-in-the-middle for such a scenario.
Regarding Viber, I could not find a good-thorough answer to this particular question. Do people talk to each other through a Viber centralized server, or, do they establish a direct connection? Of course if they do establish a direct connection, then I really want to know how they manage such a thing since a mobile phone may or may not have a physical address. How is a Viber message routed to my cell phone from a friend of mine even when Viber is not running and I am behind a router?
I guess the answer to Viber is really push notifications, but as far as I can understand, all the variations of push notifications rely on open connections, and then the servers of the applications send the notifications to the clients through such connection(s). So, this approach gives us the feeling that it is asynchronous, but essentially it is not. We are cheating, in the sense that there is a constantly open connection to a server, and moreover, as far as I can understand, the application server has to push the notification through that server. Schematically:
A > Central App Server > Central Server w/ open connection to my cellphone > me
So, this seems to be once again a centralized approach.
Honestly, the only approach that I can think of that is both decentralized and asynchronous (on mobile phones as well) is to run an http server on every platform/device, but this comes at the expense of not using Wi-Fi and assuming that a telecommunication company really assigns a physical IP address to every mobile phone (which I do not know if it is true, do you?).
What about WASTE, darknets, F2Fs, etc? Do they offer advantages in the sense of a more direct asynchronous communication between some interested parties? Are there real-world applications (also including mobile phones) using such approaches for communication.
Really, this is not the actual problem that I would like to work on, but I would like to know what the state of the art is so that I can figure out how I can proceed from there. So, all comments are really more than welcome. If you have references for the state of the art I would like to know about them as well, but a brief description would also be nice.
I appreciate all your time and effort in advance.
You asked many questions, here is the beginning of the answers:
Q1: Yes. For example, take BitTorrent's very successful 10 million+ node network. Aside from the bootstrapping process, the protocol is entirely decentralized and asynchronous. See here for more info.
Q2: Yes! Go to www.whatismyip.com on your mobile telephone, and you will see your assigned IP. However, you are likely to be very filtered (e.g: incoming traffic on port 80 is likely to be blocked).
Q3: It has elements of P2P and clever tricks to get around NAT issues - see here for more info.
Q4: I don't know.
I am building a multiplayer game where players are simultaneously asked a question and they have to pick an answer. They have a few seconds to answer and they are asked the next question when the time is out or everyone has answered.
I am planning on using Java (or nodeJS if I feel like learning a new framework) on the server side and JS (jQuery and jQuery Mobile) on the client side. I might build native apps later too so I want to keep the option opened.
My question is: what server communication protocol would you suggest?
I was thinking of regular TCP (HTTP with Ajax) calls since latency is not really the issue but I am ready to review this choice if you suggest otherwise.
Thanks a lot for your help
When using UDP the burden to implement retry and congestion control will fall on you. Therefore, I recommend you stick with the reliable and easy TCP until there is a specific reason to switch. If latency turns out not to be acceptable, which I doubt in your case, you can switch to UDP.
Another thing to remember, if you are creating the game on mobile device and you don't want to lose the players connected over 3G, you will need to make sure you are using standard ports to connect to the server side, otherwise operators will disconnect you.
HTTP Streaming and WebSockets over TCP/IP is the best way to go. Lightstreamer, which leverages HTTP and WebSockets, uses TCP but tries to overcome some of its limits with some smart algorithms for latency reduction (which seems to be crucial for the game you described) and bandwidth optimization. Thus, it can be used with great benefits for any multiplayer games of any complexity (including MMORPGs, for example). At a first glance it seems it can fulfill your requirements, and it could be a good solution if you are also planning to develop native apps in a second step.
Lightstreamer is based on a publish/subscribe model, in which every item is defined by a set of fields whose values can change over time (in order of milliseconds). These could include "general items", subscribed by any users (e.g the game countdown; who is the first responder) and delivered in real-time. This way, the data delivery mechanism underlying your game logic seems quite easy to implement with Lightstreamer.
Have a look at this recent article (Optimizing Multiplayer 3D Game Synchronization Over the Web). You can walk through an online demo of a simple multiplayer 3D world in which Lightstreamer has been integrated for real-time synchronization.
The demo allows you to tweak each parameter of the scenario and simulate any flavor of data delivery, while checking the actual bandwidth consumption. Of course, full source code is available for free on GitHub. You could give it a try. Let me know if you need some help :)
[full disclosure: I work for Lightstreamer]
I want to build a decentralized, reddit-like system using P2P. Basically, I want to retain the basic capabilities of reddit, but make it decentralized, to make it more robust and immune to censorship. This will also allow people to develop different clients to match the way they want to browse it.
Could you recommend good p2p libraries to base my work on? They should be open-source, cross-platform, robust and easy to use. I don't care much about the language, I can adapt.
Disclaimer: warning, self-promotion here !!!
Have you considered JXTA's latest release? It is probably sufficient for what you want to do. Else, we are working on a new P2P framework called Chaupal, but it is not operational yet.
EDIT
There is also what I call the quick-and-dirty UDP solution (which is not so dirty after all, I should call it minimal).
Just implement one server with a public address and start listening for UPD.
Peers located behind NATs contact the server which can read how their private IP address has been translated into a public IP address from the received datagrams.
You send that information back to the peer who can forward it to other peers. The server can also help exchanging this information between peers.
Then peers can communicate directly (one-to-one) by sending datagrams to these translated addresses.
Simple, easy to implement, but does not cover for lost datagrams, replays, out-of-order etc... (i.e., the typical stuff that TCP solves for you at the IP stack level).
I haven't had a chance to use it, but Telehash seems to have been made for this kind of application. Peer2Peer apps have a particular challenge dealing with the restrictions of firewalls... since Telehash is based on UDP, it's well suited for hole-punching through firewalls.
EDIT for static_rtti's comment:
If code velocity is a requirement libjingle has a lot of effort going into it, but is primarily geared towards XMPP. You can port off parts of the ICE code and at least get hole-punching. See the libjingle architecture overview for details about their implementation.
Check out CouchDB. It's a decentralized web app platform that uses an HTTP API. People have used it to create "CouchApps" which are decentralized CouchDB-based applications that can spread in a viral nature to other CouchDB servers. All you need to know to write CouchApps is Javascript and learn the CouchDB API. You can read this free online book to learn more: http://guide.couchdb.org
The secret sauce to CouchDB is a Master-to-Master replication protocol that lets information spread like a virus. When I attended the first CouchConf, they demonstrated how efficient this is by throwing a "Couch Party" (which is where you have a room full of people replicating to the person next to them simulating an ad hoc network).
Also, all the code that makes a CouchApp work is public by default in special entities known as Design Documents.
P.S. I've been thinking of doing a similar project, but I don't have a lot of time to devote to it at the moment. GOD SPEED MY BOY!
My first question so go easy on me :)
I've been developing for years and have written WAY too many apps (mostly web apps) using web services - I'm happy with SOAP/WSDL/etc... I also used to write TCP/IP client-server apps back in the day using good old winsock.
I'm a bit bored and looking for a new project to expand my skills so decided to have a go at doing either a game or some sort of server monitoring and remote control application
I haven't decided which and the answer to this question will hopefully inform my decision.
What I'd like is some advice as to which methods I should be looking to handle the communication.
Let's assume I'm doing thew game for the moment - I want 2-way communication with low latency and the ability to handle as many simultaneous connections as possible.
I've considered web services but it seems like a lot of overhead - especially as I'd need the client to expose one as well.
TCP/IP would do the job but seems like it's a little low-level and I lsoe a lot of the advantages like definitions. Presumably I'd need to formulate a new protocol for the communications etc... I'm also unsure how I'd have one client use multiple channels for concurrent information - eg a chat and updating location information. I could attempt to multiplex this in some way but my initial ideas re: the queuing seem quite messy
.Net remoting - I've not really touched this much at all. Seems to have low overhead and more flexibility than webservices but I don't know enough to evaluate properly.
I'd really appreciate any input you can provide (and a link to a tutorial would be fantastic)
Thanks in advance for your help
EDIT: I've had an answer which points me at a UDP library. Is UDP appropriate for this? For location information/similar which requires no history, I can see how this is advantageous but for a chat, a lost packet could be an issue - or do I manually send back an acknowledgment of receipt? If so, aren't I duplicating TCP/IP functionality for limited advantage?
Apologies if this is an incorrect way to expand on the question - guidance for that appreciated too :)
If you're up to date on .NET 3.5 SP1, then you should use WCF. You say you don't want to use web services, and I assume from that you mean you don't want to use SOAP over HTTP. WCF does a lot more than SOAP over HTTP. In particular, it can do binary over TCP/IP using the same infrastructure. It also has support for peer-to-peer.
Take a look at something like Lidgren and see how that work's. Its written in c# so its able to be used with VB.Net
Lidgren is a socket wrapper, Ive used it in a few small scale multiplayer games, ( mainly by using a header stating packet type. ie first byte represents packet type,
Lidgren