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Best architecture for online trading card game

Started by Hazerider Feb 2, 2010 at 1:24 PM 15 replies 7.6k views

Original Post

Feb 2, 2010 at 1:24 PM

I apologize if this has been answered in bits and pieces in different threads, but a brief look in this forum hasn't answered my question. I would like to write a game similar to Magic Online. In the game, players should be able to chat in rooms, chat with each other, join clans/leagues, enter rooms where they can challenge other players to a match, and enter rooms where they can sign up for tournaments. I would also like to eventually have auction capability for in-game items, similar to World of Warcraft. Game play itself will be very similar to Magic (turn based). My first question is the following: what technology should I use? Ideally I would like to get the networking part up and running as fast as possible. Initially, I think allowing up to a couple of hundred players should be sufficient for beta testing. Would using Python/Twisted be a good starting point? Should I write a server in C#? In the unlikely that the game turns out to be commercially viable, I think writing a full-blown C/C++ IO completion port server will be necessary and that can be done at that point. Also, is there a better choice between TCP and UDP? The messages between server and client will never be very large. I was also thinking of sending the messages in XML format in order to increase ease of use and facilitate later porting to other platforms - would that be a huge waste of bandwith? For the client, I was thinking of writing it in C#. Is there a better choice for rapid development? For the database I was going to use PostgreSQL. I would love to use SQLite, but that's probably not realistic for a decent sized project. I'd rather not use MySQL as I don't want to deal with license issues. I was told BerkeleyDB is very fast, but isn't a traditional SQL database and I have other things to learn for this project. Last question: what order should I implement everything in? My thinking was to start with chat, then inventory management/trading/auctioning (could do this last instead), then game play, then tournaments for last. About myself: my formal education was in applied math, and am self-taught in programming. I know C++ fairly well, and have picked up many languages/technologies over the years professionally and when working on personal projects (VBA - I know, not a real language :-) - C#, perl, Python, SQL, HTML/CSS/&#106avascript, Flash/Flex). I plan on hosting the server at home. I appreciate your taking the time to read this. Thanks, Marc.

Rycross

Feb 2, 2010 at 1:39 PM

First off, I think you're a bit over-concerned about per-server performance. Fundamentally, an online trading card game doesn't have a lot of shared state. You should be able to scale out very well by adding servers and load-balancing. I don't think you'll need to worry about a full-blown C++ IO completion ports solution. Use whatever technology you are most productive in. I know of at least one web-based trading card game (using Java applets).

I would say that using XML as a message-passing format is a waste unless you do not control both the client and the service. Even if that is the case, JSON is probably a better choice. If you do control both, then binary serialization is probably better, although the best choice is to use built-in serializers, unless you're finding you need to optimize for size. Frankly, a trading card game isn't likely to be very bandwidth heavy, so you should probably lean more towards reliability and ease of development in your message format.

As far as the database goes, I'd stay away from Berkeley DB. Its good at what it does: extremely fast, simple, local storage. However, you're probably going to want an actual relational database, and trying to turn Berkeley DB into one of those is going to be a lot of work and negate any gains you'd get from that technology. I don't have a lot of input into which RDMS you use, but I'd recommend that you write a data abstraction layer to accommodate schema/database changes.

hplus0603

Feb 2, 2010 at 2:43 PM

Start out with a web development framework, like ASP.NET or PHP, and build the app inside a web browser using &#106avascript and AJAX/AJAJ (I prefer JSON to XML).

Hazerider

Feb 2, 2010 at 4:18 PM

Thanks for your reply.

Quote:
Original post by Rycross
First off, I think you're a bit over-concerned about per-server performance. Fundamentally, an online trading card game doesn't have a lot of shared state. You should be able to scale out very well by adding servers and load-balancing. I don't think you'll need to worry about a full-blown C++ IO completion ports solution. Use whatever technology you are most productive in. I know of at least one web-based trading card game (using Java applets).

I would say that using XML as a message-passing format is a waste unless you do not control both the client and the service. Even if that is the case, JSON is probably a better choice. If you do control both, then binary serialization is probably better, although the best choice is to use built-in serializers, unless you're finding you need to optimize for size. Frankly, a trading card game isn't likely to be very bandwidth heavy, so you should probably lean more towards reliability and ease of development in your message format.

As far as the database goes, I'd stay away from Berkeley DB. Its good at what it does: extremely fast, simple, local storage. However, you're probably going to want an actual relational database, and trying to turn Berkeley DB into one of those is going to be a lot of work and negate any gains you'd get from that technology. I don't have a lot of input into which RDMS you use, but I'd recommend that you write a data abstraction layer to accommodate schema/database changes.

I haven't really had much experience with networking. How does load balancing work? When a player wants to log in, they contacts a "gate" server, and that server then assigns the player to a server that actually handles the connection for that player? Do you have any idea how many players a server with a quad core CPU could handle? I just want to find out so I don't go off on the wrong path from the get-go.

Since, as you said, TCG's don't use much bandwith, I was thinking using XML would be OK. The main reason that I wanted to use XML is to make it easier to develop clients cross-platform. I would love to create a framework that allows players who use a PC, Xbox, PS3 or iPhone to play against each other. However, realistically, the protocol shouldn't really matter I guess - smaller is better.

Hazerider

Feb 2, 2010 at 4:25 PM

Quote:
Original post by hplus0603
Start out with a web development framework, like ASP.NET or PHP, and build the app inside a web browser using &#106avascript and AJAX/AJAJ (I prefer JSON to XML).</td></tr></table></blockquote> My initial inclination was to write a perl CGI script, hosted on an Apache server. I just thought that such a server would slow down very quickly with any reasonable number of players online at the same time. What about writing a Flash application for the client? It would have the benefit of easily accommodating visual effects down the line. Thanks, Marc.

hplus0603

Feb 2, 2010 at 4:51 PM

On any modern machine, I'm pretty sure you can do at least 2,000 simultaneous online users with a perl CGI module. I'm basing this on utilization of the perl-based "perlbal" soft reverse proxy. Exactly where the limit goes is of course dependent on how expensive you make your application.

"load balancing" for bigger sites is generally done with hardware load balancer boxes, like your Nokia, Cisco or Foundry hardware. These will detect incoming connections, and pick the "least loaded" of your web servers, and do reverse NAT from the source IP to the target server. That mapping will generally persist for a while, to keep sessions in cache and whatnot.

rubicondev

Feb 2, 2010 at 4:55 PM

Hell man, Magic Online got it badly wrong three times out of three.

My advice: Look at what they did and do the opposite in every case.

(One-time server developer and long-suffering mtgo "player")

Antheus

Feb 2, 2010 at 5:12 PM

Write server in Python, host it on AppEngine. BigTable is an oddity, but nothing drastic.

Write client in JQuery, using Ajax to talk to server.

It's about as easy as it gets, and without much of deployment hassle.

Quote:
I would love to create a framework that allows players who use a PC, Xbox, PS3 or iPhone to play against each other

The above covers anything with non-archaic web browser and internet access.

hplus0603

Feb 2, 2010 at 7:37 PM

The Xbox does not have general web access -- even "native" Xbox games cannot download from the greater internet. Cross-gaming (as found in Shadowrun) is tightly controlled through Microsoft's data center, and has to use GFWL networking.

I don't know how well the PS/3 does with &#106avascript or Flash -- and I think the iPhone doesn't have Flash at all, but it does have &#106avascript, which means AJAX/AJAJ is a reasonable implementation strategy. Hosting on Google App Engine seems like a poor business decision, because you don't know where that is going, whether you can buy more capacity, should you need it, etc.

Hazerider

Feb 2, 2010 at 8:09 PM

Quote:
Original post by hplus0603
On any modern machine, I'm pretty sure you can do at least 2,000 simultaneous online users with a perl CGI module. I'm basing this on utilization of the perl-based "perlbal" soft reverse proxy. Exactly where the limit goes is of course dependent on how expensive you make your application.

"load balancing" for bigger sites is generally done with hardware load balancer boxes, like your Nokia, Cisco or Foundry hardware. These will detect incoming connections, and pick the "least loaded" of your web servers, and do reverse NAT from the source IP to the target server. That mapping will generally persist for a while, to keep sessions in cache and whatnot.

2K simultaneous users with a perl CGI module seems like a lot more than I would have guessed. I am assuming that some portion of users will be chatting, while the actual game messages will be small, something like a series of IDs (for the player, the action, the source, the target), the server will determine the state of the game based on the actions that the players take (managing player resources and checking win conditions etc.).

It seems like load balancing is something I will have to worry about only once there will be a very strong possibility of commercial viability.

Hazerider

Feb 2, 2010 at 8:17 PM

Quote:
Original post by Antheus
Write server in Python, host it on AppEngine. BigTable is an oddity, but nothing drastic.

Write client in JQuery, using Ajax to talk to server.

It's about as easy as it gets, and without much of deployment hassle.

Quote:
I would love to create a framework that allows players who use a PC, Xbox, PS3 or iPhone to play against each other

The above covers anything with non-archaic web browser and internet access.

I think I will be trying to use Twisted as a first shot. It seems like it should be able to handle a decent amount of traffic.

Why would I want to host on AppEngine? I was planning on hosting it at home, as I have Optimum with Boost, meaning port 80 is open.
Realistically speaking, if I write a game server that listens on port 80, what is the worst that evil-minded people could do to my machine?

Quote:
Original post by hplus0603
The Xbox does not have general web access -- even "native" Xbox games cannot download from the greater internet. Cross-gaming (as found in Shadowrun) is tightly controlled through Microsoft's data center, and has to use GFWL networking.

I don't know how well the PS/3 does with &#106avascript or Flash -- and I think the iPhone doesn't have Flash at all, but it does have &#106avascript, which means AJAX/AJAJ is a reasonable implementation strategy. Hosting on Google App Engine seems like a poor business decision, because you don't know where that is going, whether you can buy more capacity, should you need it, etc. </td></tr></table></BLOCKQUOTE> I am not really that worried about the client coding. I really want to get the server right. If I end up needing a client for non-PC platforms, it means I will likely be able to afford to hire someone to write it. That being said, is there a reason I should not go with Flash?</td></tr></table></blockquote>

hplus0603

Feb 3, 2010 at 11:35 PM

Quote:
I was planning on hosting it at home

That's a bad idea for a few reasons, some of which are:

1) Is this served on a PC you also do web surfing on? Coding? Photo editing? Gaming? Windows Updates, software installs, and other reboots?

2) Are you sure that the cable connection you have actually stays up for enough time that your service will be reliable?

3) Are you sure that, once you have 10, 100, 1000 players, that cable connection is still sufficient, especially if you split it with playing games, streaming Netflix and hosting Torrents? (Or whatever else happens on your link)

4) Does your city/locality allow you to run a business out of your home? (No, seriously, this might be a problem!)

You can pay between $10 and $40 per month, and get a "virtual private server" (or, at $40, a real private server). That will let you host in a datacenter with isolated bandwidth, back-up power, and no interference with your home usage.

Players tend to look very unfavorably on services that aren't up and performing well 99.99% of the time...

Flash for the client? As long as you're OK with Windows and MacOS, there's no reason not to use that if it supports what you need.

Hazerider

Feb 4, 2010 at 7:12 AM

Quote:
Original post by hplus0603
Quote:
I was planning on hosting it at home

That's a bad idea for a few reasons, some of which are:

1) Is this served on a PC you also do web surfing on? Coding? Photo editing? Gaming? Windows Updates, software installs, and other reboots?

2) Are you sure that the cable connection you have actually stays up for enough time that your service will be reliable?

3) Are you sure that, once you have 10, 100, 1000 players, that cable connection is still sufficient, especially if you split it with playing games, streaming Netflix and hosting Torrents? (Or whatever else happens on your link)

4) Does your city/locality allow you to run a business out of your home? (No, seriously, this might be a problem!)

You can pay between $10 and $40 per month, and get a "virtual private server" (or, at $40, a real private server). That will let you host in a datacenter with isolated bandwidth, back-up power, and no interference with your home usage.

Players tend to look very unfavorably on services that aren't up and performing well 99.99% of the time...

Flash for the client? As long as you're OK with Windows and MacOS, there's no reason not to use that if it supports what you need.

1) I currently use that machine to do some light web-surfing, and occasional coding (though not lately - I finally got my dream job last year, head of IT for a small hedge fund, and it satisfies most of my coding craving. At least until recently :-P). I stopped playing video games in college, I just occasionally play Magic Online and poker.

2) Cablevision seems to be quite reliable. I have the Boost option, which makes it faster and opens up port 80. I also have a UPS, which seems to counteract the occasional power outage in my building (not sure why, power goes off and right back on once in a blue moon). My router and cable modem are also plugged in to the UPS

3) I figure this would be adequate for 10 to 100 simultaneous players. I do think that as soon as I get over 100 players on a regular basis, it's worth investing a little money into a hosted solution

4) I used to be self-employed, and in NY you can write off up to a third of your home rent as a business if you work from home, so I think I am pretty safe there. It's a good point though. Down the line, I would be more worried with the legal aspects of auctions, account selling, tournaments and possible prize redemptions for cash etc.

Re: hosted solution, any recommendations? I am thinking I will need a Windows machine(s) with some sort of DB on it (don't care much which). Do they typically let you install things like perl or Python? What if I want to go with an open source DB like Postgres to avoid licensing issues?

No reason to think that Flash won't be able to provide what I need. If it comes to that, I am sure an iPhone version of the game could be done reasonably fast and cheap.

demonkoryu

Feb 4, 2010 at 7:24 AM

Quote:
Original post by Hazerider
Re: hosted solution, any recommendations? I am thinking I will need a Windows machine(s) with some sort of DB on it (don't care much which). Do they typically let you install things like perl or Python? What if I want to go with an open source DB like Postgres to avoid licensing issues?

No recommendations, just pointing out that (unless you've mentioned a dependency on Windows-only services) Windows hosts tend to be much more expensive than Linux hosts.
But the ability to install your own software should be available on any reasonable host.

Hazerider

Feb 4, 2010 at 7:37 AM

Quote:
Original post by Konfusius
Quote:
Original post by Hazerider
Re: hosted solution, any recommendations? I am thinking I will need a Windows machine(s) with some sort of DB on it (don't care much which). Do they typically let you install things like perl or Python? What if I want to go with an open source DB like Postgres to avoid licensing issues?

No recommendations, just pointing out that (unless you've mentioned a dependency on Windows-only services) Windows hosts tend to be much more expensive than Linux hosts.
But the ability to install your own software should be available on any reasonable host.

Thanks for the pointer. Technically, I don't really care which OS I use, but realistically, I'd like to avoid building a Linux development machine. I also hated the debuggers I've used on Linux (which is really only gdb). If it's a big monthly difference it's worth looking into but if it's less than $100 I won't bother.

demonkoryu

Feb 4, 2010 at 8:28 AM

You don't need a Linux machine to develop for a Linux host. As I write this, I'm sitting at a Windows machine and working on Linux code. Most Linux programs (Python, Perl, PHP, ...) are available on Windows. The standard GNU/Linux console toolset/environment (like bash and assorted tools) are also provided via Cygwin.

To rephrase: When you're programming portable code (which, in the case of CGI programming, isn't hard at all), you will be able to do all development work on Windows even when deploying to a Linux host.

hplus0603

Feb 5, 2010 at 6:58 PM

You can use something like Sun VirtualBox to install Linux locally for development. An X windows Linux system with Apache, MySQL, PHP and friends runs well in 768 MB of RAM, so you can typically fit it in alongside your normal machine load for development.

Windows hosting is generally about $20 more per month. Generally when you lease servers (virtual private servers, or dedicated "root" servers), you get administrator/root access to the machine, and you can install whatever you want.

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