Hi does anybody know how to put in place a quick code example of a Sinatra app running on top of Celluloid:IO and using websocket?
I know of the existance of Reel for Celluloid ("Reel is a fast, non-blocking 'evented' web server built on top of Celluloid:IO" ... and supports websockets straight away) but nonetheless I'd like to keep using Sinatra because I like it, I've become accustomed with it, and I'd rather not rewrite a lot of code...
Hope you can help.
Celluloid::IO has an evented HTTP/WebSocket server called Reel ( http://github.com/celluloid/reel ), which is best setup for what you want, but still, this is pretty new, apart from Thin and Rainbows. This goes beyond Sinatra and has to involve Rack itself. So far it has been specific to certain HTTP servers, and each "Rack Handler" had approached WebSockets their own way. Now it is somewhat standardized, but in Rack 2.0 it will become permanent. I'd guess this temporary way is going to remain, but become more mature in 2.0 than it is in +1.5.* now.
This is about to be released into the master branch of Reel, but is right now in a branch of halgorium's fork, here:
https://github.com/halorgium/reel/tree/hijacked-websocket
The ongoing progress of this issue is here:
https://github.com/celluloid/reel/issues/42
Implementation of this feature involves interacting with pretty new and somewhat temporary functionality called the hijack API in Rack, underneath Sinatra. It is fairly convoluted but once you get the hang of it, it is pretty cool. Complete information on this is here:
...where it all got decided in a github thread: https://github.com/rack/rack/pull/481
There is no formal support for WebSockets through Rack hijack for Sinatra yet, and none is planned except by Middleware, according to #rhk. So it'll always be something you selectively handle, based on your server and choice of implementation style.
The way I've handled it is to use Reel, but Puma ( http://puma.io ) is also very good. Any hijack_io capable HTTP server will operate the same. The way I do it is illustrated in a gist linked below. It uses websocket-protocol-ruby to actually handle interaction with the client, and on the client side, I use portal.js rather than just the plain HTML5 approach. I believe it to be much better.
Portal.js: https://github.com/flowersinthesand/portal
websocket-protocol-ruby: https://github.com/faye/websocket-protocol-ruby
It all hinges on this piece, as mentioned in the Rack API thread on github:
env['rack.hijack'].call
#env = env
#io = env['rack.hijack_io']
There are two ways to use hijack_io, but as I said, it is very Rack involved. There is no much Sinatra code out there, because it's not really a Sinatra thing. Again, as I mentioned, it's not even really planned to become seamless. It'll be a sinatra/contrib thing or some other Middleware. So here is my way, in one instance where I use hijack_io, as a rough sketch.
...a gist: https://gist.github.com/digitalextremist/5441315
Related
I need to do some basic networking for a Pygame project.
Basically, it's a 2D single player or cooperative game. The networking only needs to support two players, with one as a host.
The only information that needs to be sent is the positions of players, creeps and bullets.
I've been reading around and Twisted keeps coming up, but I haven't done networking before, and I'm not sure if that might be an overkill.
So, is it possible for a relative newbie to implement networking in Pygame?
This was asked recently on Reddit, so I'll more or less just copy my answer over from there. I apologize for not being able to provide more links, I have <10 rep so I can only post two at a time.
Twisted might work, but I don't have a whole lot of experience with it. I'd recommend going with sockets, as that's what Twisted uses in the background anyway. Beej's guide (google it) is pretty much the Holy Bible of sockets if you want to learn how they work (in C++, but the concepts extend everywhere). Python does abstract some of the complexity away, but it's still a good idea to know what's going on in the background.
For Python specific sockets, you can go ahead and just use the howto (user745294 posted a link above). Here's a nice article titled "What every programmer needs to know about Game Networking". It goes into the different types of major networking styles (client-server, p2p, udp v. tcp, etc.) and the history behind what some major games used for their networking.
Below is a link to a demo I did on making a networked "game" in Python 2.6/Pygame. It's not actually a game, but each client you create connects to the server and controls a character. You can move your character with the arrow keys and the character will move on all connected clients. I tried commenting the source code with some indication of what I'm sending back and forth, but you may need a little knowledge about sockets to understand it.
The source code is provided in the codepad links in the comment below this post. You will need to provide two images in the same directory as the scripts:
bg.png is the background sprite. It should be an image 400px wide and 300px tall (this can be changed in the GameClient class if needed)
sprite.png is the player character. It should be smaller than the background so that you can see it moving around.
You can use Twisted for networking with Pygame. The "game" project on Launchpad has some examples of how one might integrate the main loops together; basically, use twisted.internet.task.LoopingCall to draw Pygame frames and handle input, while letting the Twisted reactor of your choice run normally.
Since you are already using Pygame, I think this light networking library made for Pygame will do what you need and teach you, but not overwhelm you.
"Mastermind Networking Lib" via pygame.org
There is Pyro (Python remote objects) as another solution for networking in Python.
http://irmen.home.xs4all.nl/pyro/
Using raw sockets is low-level and full of danger. As said before, Twisted is complex and takes to time get up and running. To save yourself some headaches I'd try something like zerorpc.
You need the following solutions:
discovering other player(s) on the (local) network, you don't want player to enter some IP address
handle network errors
serialize messages containing your data (positions, player name, etc.)
handle threading as networking is asynchronous I/O
Above should still be called 'basic', you should really use some fancy networking library with idiomatic API.
Essentially you need to expose the network service (in its own thread) that will push messages to Python's Queue, and then access this same queue from your Pygame code, and if there is a message then you update whatever structures you use to store player's position and draw it on screen.
You shouldn't send stuff like bullet positions over the network as they can be easily (and faster) calculated locally. You just send an event like bullet_shot over the network with a source position and velocity vector.
I assume most Clojure experts have seen Rich Hickey's ants demo ( http://gist.github.com/1093917 and http://blip.tv/clojure/clojure-concurrency-819147). If one were to try to make a distributed version of the same app, but browser-based where each browser controlled one ant, is there anything from Clojure/ClojureScript that would aid in the transactional nature of the behave function (assuming behave was run on the client)? Or are Clojure/ClojureScript's STM features really not intended for distributed use?
i.e., if on the client I'm at (3,2) and want to move to (3,3), and in my client (browser)'s world (which could be slightly stale, the same way in Rich's original version that the Thread was slightly stale) that square is empty, but then I send the request to the server and in the server's world that square is full, is there any kind of distributed STM in ClojureScript that can tell me—nope that square was full and you have to revert that move so your next move will have to start from (3,2) again. In Rich's original presentation that was all automatic, built into Clojure's STM functionality. But distributed, will that have to be more explicit, or is there existing functionality built in to do this?
If that kind of thing is not built into Clojure/ClojureScript, are there other platforms that might be more suitable?
Yes this can be easily done using Clojure (for backend) and ClojureScript OR JavaScript (for frontend).
Basically the client js code will use websockets to connect to clojure server and on server you can have a state wrapped in an atom that is access by each client and each client is updated about the state through the connected websocket... something similar you do in a chat web application.
For websocket you can use Aleph.
How does ZeroC ICE compare to 0MQ? I know that 0MQ/Crossroads and DDS are very similar, but cant seem to figure out where ICE comes in.
I need to quickly implement a system that offloads real-time market-data from C++ to C#, as a first phase of my project. The next phase will be to implement an Event Based architecture with an underlying Pub/Sub design.
I am willing to use TCP.. but the the system is currently running on a single 24 core server.. so an IPC option would be nice. From what I understand ICE is only TCP, while DDS and 0mq have an IPC option.
Currently ,I am leaning towards using Protobuf with either ICE or Crossroads IO. Got turned off from the OpenSplice DDS website. Ive done lots research on the various options, was originally considering OpenMPI + boost:mpi, but there does not seem to be MPI for .NET.
My question is:
How does ICE compare to 0MQ? I cant wrap my head around this. Was unable to find anything online that compares the two.
thanks in advance.
........
More about my project:
Currently using CMAKE C++ on Windows, but the plan is to move to CentOS at some point. An additional desired feature is to store the tic data and all the messages in a "NoSql" database such as Hbase/Hadoop or HDF5. Do any of these middleware/messaging/pub-sub libraries have any database integration?
Some thoughts about ZeroC:
Very fast; Able to have multiple endpoints; Able to load balance on the endpoints; Able to reconnect to a different endpoint in case one of the node goes down. This is transparent to the end user; Has good tool chain (IceGrid, IceStorm, IceBox, etc); Distributed, high availability, multiple failover, etc
Apart from that, I have used it for hot swapping code modules (something similar to Erlang) by having the client create the proxy with multiple endpoints, and later on bring down each endpoint for a quick upgrade one by one. With the transparent retry to a different endpoint, I could have the system up and running the whole time i did an upgrade. Not sure if this is an advertised feature or an unadvertised side-effect :)
Overall, it is very easy to scale out your servers if need be using ZeroC Ice.
I know ZeroMQ provides a fantastic set of tools and messaging patterns and I would keep using it for my pet projects. However, The problem that i see is that it is very easy to go overboard and lose track of all your distributed components. This is a must have in a distributed environment. How will you know where your clients/server are when you need to upgrade? If one of components down the chain does not receive a message, how to identify where the issue is? the publisher? the client? or any one of the bridges (REP/REQ, XREP/XREQ, etc) in between?
Overall, ZeroC provides a much better toolset and ecosystem for enterprise solutions.
And it is open source :)
Jaybny,
ZMQ:
If you want real good performance and the only job for Phase 1 of your job is to move data from C++ to C#, then Zmq is the best option.
Having a pub/sub model for event driven architecture is also something that Zmq can help you with, with its in-built messaging pattern.
Zmq also supports your IPC requirements in this case. Eg: you can have one instance of your application that consumes 24 cores by multithreading and communicating via IPC.
ZeroC Ice:
Ice is a RPC framework very much like CORBA.
Eg.
Socket/ZMQ - You send message over the wire. Read it at the other end, parse the message, do some action, etc.
ZeroC Ice - Create a contract between client and server. Contract is nothing but a template of a class. Now the client calls a proxy method of that class, and the server implements/actions it and returns the value. Thus, int result = mathClass.Add(10,20) is what the client calls. The method, parameters, etc is marshalled and sent to the server, server implements the Add method, returns the result, and the client gets 30 as the result. Thus on the client side, the api is nothing but a proxy for a servant running on a remote host.
Conclusion:
ZeroC ICE has some nice enterprisy features which are really good. However, for your project requirements, ZMQ is the right tool.
Hope this helps.
For me.. the correct answer was Crossroads I/O . It does everything I need.. but still unable to pub/sub when using protobufs... im sure ZeroC ICE is great for distributed IPC, but 0MQ/Crossroads, gives you the added flexibility to use Inter-Thread-Communication.
Note: on windows, 0mq does not have IPC.
So, all in all, the crossroads fork of 0mq is the best. but you will have to roll your own windows/ipc (or use tcp::127..) , and publisher side topic filtering features for pub/sub.
nanomsg, from the guy who wrote crossroads and 0mq (i think).
http://nanomsg.org/
Hi
I'm starting windows application development on windows7 with C++. ( or C#/Java if necessary ).
The application in mind right now is a window that has a inner frame (kind like a iframe) displaying a web page in it, and to have the outer and inner frame be able to communicate ( ie. the webpage pass a message to the outer frame, possibly by JavaScript, and the outer frame recognize the message and starts the computer's camera ).
It would be something like this
http://html5demos.com/postmessage2
except that the outer frame is a windows application instead of a webpage.
Preferably, the inner frame displaying the web page is powered by web-kit.
I really don't have much experience so I was wondering if such thing is possible and where to start.
Any advice or resource is welcomed.
Thanks in advance.
I've seen projects use the status bar to communicate with Javascript in an embedded browser.
RichHtml4Eclipse is such a project ; while no longer in development, it demonstrates the general approach. Events with structured data are raised by changing the status text, which native code on the outside can pick up and deserialize. Javascript methods may be called on the code in the page by using the method calls provided on the browser control.
I would support the comment that encourages you to avoid C++. There are WebKit bindings for both Java and C# ; in my experience, Java has the edge in portability but C# / .NET makes for an easier experience when developing GUI components.
Why don't you take a look at Qt. It is cross-platform, comes with QtCreator - a nice IDE, and can be easily integrated with WebKit (in fact, WebKit is started by KDE, which is based on Qt).
If you're running Windows and aren't concerned with portability, using .NET could much quicker. Perhaps this article would be of some use.
i would like to develop a c++ application that would list all url accessed with its response time within the pc. this probably would be transparent to the user, so it would be a dll.
can anyone gve me some sample codes or tutorials on th said matter.
or any tips and suggestion?!..
thanks alot:))
You should take a look at the fiddler plug-ins. This is not a trivial exercise. You need to do dependency injection to capture the wininet calls. Even so not all apps use the high level windows api to initiate connections. Applications that make TCP connections might last for a long time since not all TCP calls are simple web requests.
As Byron has said, this is a non-trivial exercise. You could do it using libpcap http://sourceforge.net/projects/libpcap/ having installed http://www.winpcap.org/ on Windows. Tutorials for using libpcap are around and you'd need to learn to filter out everything but http/https traffic, although once you've got to that stage it shouldn't be too hard. Try http://yuba.stanford.edu/~casado/pcap/section1.html for starters or http://systhread.net/texts/200805lpcap1.php. Both tutorials look reasonable.
I also feel I should point out that "transparent to the user" and "dll" are not equivalent ideas. A DLL is a set of library functions separate from an application that can be used by many applications - see http://en.wikipedia.org/wiki/Dynamic-link_library. A "standard" executable file (i.e. file ending in .exe) can still be transparent to the user if run, for example, as a Windows Service, which might be more what you are looking for.