I am going to write a client/server card game for learning/practice purposes, and intend to use Java for both the client and server to begin with. In the future I will be looking to continue to use this project for learning, and thus will want write additional clients in other languages such as C and C++.
The main detail I am unsure about is whether I need to use a MOM with a message broker, or if I can get away without using one.
My initial thought was I could handle the failure to send/receive a message on both sides, prompting an attempt to re-send the message resulting into the game being ended if the amount of attempts reaches a maximum.
However, instead of just having the game client and game server I was thinking about having a client, lobby server and game server. This way I would need the message broker to route the correct messages to the correct server, however I am unsure whether apart from that if I have any need for message broker, as I'm not sure if I really need to have any facility for message persistency.
I am leaning towards going for a MOM with a message broker, but I would welcome anymore lightweight solutions if I am doing so unnecessarilly. That said, if I did what would be a suitable cross-language MOM to use? I have seen quite a few suggested on SO before, but I'm not sure what would best meet my needs.
For cross language MOM - I suggest you use Apache ActiveMQ. It complies to the JMS spec and also has a robust C++ client library. It is open source (Apache license)
Yes the other lightweight option you could explore is HTTP. esp. for the client to server communication. (Since clients may need to connect to the server across firewalls etc - HTTP port is easiest to access etc).
For lobby server - game server communication - I like your idea of MOM.
Related
I've been reading about websockets and SaaS like Pusher and Socket.io recently, while working on my Laravel chat practice application. What I don't understand is, why do we need external software to establish a websocket connection? Can't the server code like Laravel just directly establish the connection with the front-end like Vue.js? Why does it have to go through the middleman like Pusher and Socket.io? Sorry for the noob question.
It doesn't have to.
Those pieces of software just happen to make it trivial to work with the Websocket protocol.
Remember, Laravel is an opinionated framework. This means that it will pick and choose its own libraries to abstract away these kinds of concepts for you so that you don't have to worry so much about what's going on under the hood.
Basically, there are two components that you need in order to be able to work with Websockets:
A Websocket Server
A Websocket Client
The reason Laravel doesn't communicate directly with the front-end using Websockets is because Laravel itself isn't a Websocket server. At least, not really. And while PHP does have support for working with the Websocket protocol - and even some libraries to leverage it a little more nicely - it just isn't used to handle long-lived processes as often as other languages.
Instead, Laravel uses the Pub/Sub functionality that Redis provides to listen to events that occur through Redis and the Predis library. The reason why it does this is because Laravel is better-suited as a middle-man for the websocket server, and all connected clients.
In this way, Laravel can both pass information up through to the Websocket server using Broadcasting Events, as well as receive event information from the Websocket server and determine if users have the ability or authorization to receive them.
If you don't want to use Pusher, there is a library that will allow you to run your own Websocket Server specifically for Laravel called Laravel Echo Server.
Under the hood, this library still uses Socket.io and Redis in order for all moving parts to communicate with each other seamlessly in a Laravel web application. The benefit here is that you won't need to worry about the number of messages being sent by the server.
The downside is that you now have to know how to manage and maintain this process on your server so that the Websocket Server will know to turn on every time you restart your server, or if a failure happens, etc.
Check out PM2 to learn more about running and maintaining server daemons.
If you don't agree with Laravel's opinions on how to handle Websockets, then you could theoretically use any other server-side language to handle the websocket protocol. It will just require a greater working knowledge of the protocol itself; and if Laravel needs to work with it, you'll have to know how to write the appropriate Service and Provider classes to be able to handle it.
Short answer? You don't have to use them. Knock yourself out writing your own server and client side websocket implementation.
Longer answer.
Why use Laravel? I can do all that with straight up PHP.
Why use Vue? I can do all that with vanilla javascript.
We use libraries and frameworks because they abstract away the details of implementation and make it easier to build products. They handle edge cases you don't think of or things you don't even know that you don't know about because they are used by thousands or millions of developers and all the knowledge and bugs they have encountered and fixed are baked into the implementation.
This is one of the hallmarks of software engineering, code reuse. Don't repeat yourself and don't write any software you don't have to. It allows you to focus on building a solution for your particular requirements, and not focus on building a bunch of infrastructure before you can even build your solution.
I've never used Pusher, but it looks like, yes, it is a SaaS product. But Socket.io is open source.
I am building a set of programs that consist of multiple clients and a single server.
The clients are frequently pushing small packets of data to the server, which will validate the information (returning an error if the data is invalid), and process the received information. The information may then incur the firing of events, which clients will be subscribed to, allowing for clients to be instantly (or as close as possible) notified (along with a small amount of data).
I have some ideas about how to do this, but I am trying to avoid creating a protocol of my own, mainly as I'm sure it would take forever and I would probably make a few errors. So I was wondering if there are any existing protocols that I could implement into my system that would provide such functionality.
The number of clients will initially be quite small, but will be growing over time to potentially include 1000's of clients (with their own subscriptions), and several front end servers (each one handling a subset of subscriptions) parsing the information back and forth with back end servers for improved capability.
So, if anyone knows of any existing protocols that implement these requirements and functionality, that would be fantastic.
EDIT
I am currently looking at the XMPP protocol, and the JXTA protocol suite (for reference, and implement with another language). Both seem quite good and provide the necessary connectivity, but I have not had the opportunity to test each of them out in my environment, or if they are even suitable for what I am attempting.
Additionally, some of the network clients will be outside of the local network and operating over WAN. Security is not so much of an issue, but I need to take into account the increase latency of this, and firewall rules (local to the connection that is hosting the application and ISP firewalls) that could be blocking certain ports or transport protocols (I have read some text that said that some ISPs where blocking UDP packets, but not sure of how wide this goes. I can do it at home, the office, mobile, friends houses, etc and have yet to experience it myself).
I'm sorry if the following is not exactly what you're after but I am slightly confused by your use of the word 'protocol'. I understand a protocol to be a 'communication specification' only, where the implementation is left entirely to you. If that is the case I always find the the following graphic usefull, link.
If on the other hand you are looking for a solution which allows you to easily implement the networking side of your application, helping save time, then checkout the following network libraries, which implement their own custom protocol:
NetworkComms.Net
Lidgren
ZeroMQ
Disclaimer: I'm a developer for NetworkComms.Net
I'm having a play around with websockets and I'm having a bit of trouble wrapping my head around some stuff. Specifically, being able to send a whole bunch of subscribers different data without using a stupid amount of resources.
For example, if you had some sort of twitter like service, how would you send all followers of a person a newly posted tweet that they have made (and do the same for the other hundreds of people doing the same). It just seems that handling that many separate people is a bit absurd.
Can someone talk me through how you would go about treating each client individually? Please tell me if I have the whole idea of websockets wrong.
Thanks in advance!
P.S. for reference, I'm probably going to play around using either node or clojure (with aleph)
Use an established messaging protocol and broker on top of websockets.
It seems you are looking at websockets at the application layer when it is more of a network protocol. A variety of messaging APIs exists (such as JMS) with open source message brokers that are designed to do the complex and scalable message routing.
I am making a turn-based card game that will have clients, a lobby server and a game server. What methologies are there that are both cross-language and bi-directional (e.g. client request -> server server response-> client, as well as server request-> client client response -> server)?
I have looked into JMS but believe it is too heavyweight for my needs (this program will just be small scale, and I don't think the complexities make this solution suitable). I have briefly looked into REST but I believe that wouldn't fit the bi-directional requirement. Of course, there is RMI but I would like to be able to develop clients in C++ and other languages as another learning exercise.
If I'm honest, I'm at a bit of loss because I don't want to use JMS as I think it is too complex for this, but I don't think just using TCP sockets and say using a basic XML based protocol for the messages will provide a good structure of communication for the program.
The research lab that I do some work with develops a system called "Object Oriented Distributed Semantic Services."
We leverage some work that we do with cross-language serialization to allow you to write clients/servers in different languages, and the underlying messages to be a format that be serialized and deserialized by clients/servers regardless of their implementation language.
Right now we mostly support Java/ObjectiveC. You can take a look at the chat room tutorial, which should give you a basic idea of how requests / responses work.
http://ecologylab.net/research/simplGuide/oodss/index.html
OODSS is designed to work well for game scenarios... the system was originally written to support a game one of the researchers in our lab was working on. The original paper on OODSS discusses the development of a game from the ground up. That may work out well for you: http://ecologylab.net/technicalReports/oodss_TR_10_01.pdf
You could apply a similar idea to allow for multiple clients in languages that aren't supported yet. (you may have to write some serialization/deserialization code on your own, to start.)
Good luck! Hope that helps!
I'm fumbling around a bit with WebSockets, and was pretty pleased with how easy it was to get a Tornado server running that does basic websocket connections. I've never used Tornado before today, and while I like what I've seen there's a few questions that I have regarding it's use.
Primarily, I'm using WebSockets so that I can have low-overhead communications between two or more client machines. (For the purposes of conversation let's just say it's a chat client) Obviously I can connect into the server from multiple machines, and they can all push messages to the server and the server can respond, which is great! But that's not too much better than your standard AJAX requests. If I have a persistent connection I want to be able to push data to the clients as well. The simplest possible scenario is user 1 posts a message to the server and upon receiving it the server immediately pushes it to user 2.
So what would be a good way to accomplish that? As far as I can see in Tornado there's no way to communicate between connections other than placing the message in a datastore somewhere and having all the other connections poll for new info. That strikes me as terribly clunky though, because all you're really doing at that point is moving the polling process from the client to the server.
Of course, I may be barking up the wrong tree entirely here. It's certainly plausible that Tornado simply isn't the right tool for this job, and if that's the case I'd be happy to hear suggestions for alternatives!
Here is a chat server using tornado, WebSockets and redis: https://gist.github.com/pelletier/532067 (Updated: link fixed, thanks #SamidhT)
Though the answer has already been accepted: Using a different service still seems very inefficient to me. Why don't you just go with shared memory + conditional variables / semaphores? You sound like you got a standard Consumer-Producer problem