Building Scaleable Middleware for MMORPGs

CowboyRobot writes "ACM Queue has an article exploring the challenges of developing a reliable platform for an MMORPG, specifically looking at Wish by Mutable Realms. From the article: 'A common scalability problem for distributed multiplayer games relates to managing distributed sets of objects... A player may not be a member of more than one guild, or a guild may have at most one level-5 mage (magician). In computing terms, implementing such behavior boils down to performing membership tests on sets of distributed objects.'"

Comments

MMORPGs need better real-time characteristics

[Bryan Ischo]

I've tried a few MMORPGs and have found them all to be lacking in the same key area: one's control over one's character is not real-time. This is a generic description of a problem which surfaces in many ways in MMORPGs, most notably in the combat system. I haven't found one yet that allows real-time combat; it's always "click on the guy you want to fight and press the 'attack' button", then sit back and watch. Typically can do things like cast a spell or use a buff or otherwise make strategic changes to the way that your character is fighting, but you can't aim, run around, swing at the monster, etc, as you can with first person games.

The game that comes closest to the combat system I would want is Jedi Academy, in which the multiplayer mode works just like the first-person real-time perspective of the single player game. You do have to aim, you do have to run around and avoid shots, you do have to swing your light saber yourself. I find this to be infinitely more enjoyable than the MUD-like "you hit the spider for 10 points, it hit you for 5 points" back-and-forth that is common on all of the MMORPGs that I have played.

One gets the feeling in playing these MMORPGs that your client view of the world only loosely approximates what is happening on the server. You can make your character run from here to there and find that other people are "sliding" by or popping in and out as you get only sporadic notification from the server of what's really happening. It all gives a very disconnected feel that I really find unappealing about MMORPGs.

There must be some kind of scaleability limitation though because Jedi Academy only supports about 30 players or so at a time in an area that is far smaller than a play area in an MMORPG. I think that if someone could design an MMORPG that played like an FPS, but had all of the depth and breadth of one of these not-so-real-time MMORPGs, it would be ideal.

As an aside, has anyone beta tested Worlds of Warcraft? It like an excellent execution of the MMORPG genre, but I have yet to read any comments from beta testers on whether or not the fighting is real-time or "faked" like other MMORPGs is ...

Re:MMORPGs need better real-time characteristics

[Dodger73]

This burns down to the scalability problems the article is mentioning. Real-time characteristics always mean more frequent transfer of potentially larger data packages, and the more frequent processing of those packages. While you may be able to run Jedi Academy with 30 players on a cable connection, the same is not necessarily true for 300 players.
There are ways to at least make bandwidth and processing requirements scale less than linearly with the numbers of players, but the actual problem persists. The more players, the more data. The more data, the more bandwidth requirements and the more latency. The more latency and bandwidth requirements, the more the realtime characteristics suffer. Needing halfways reliable security (read: hack protection) methods doesn't make it any easier.

It is not only the reason why MMOs aren't realtime like an FPS, but also why FPSs aren't MMP like MMOs ;)

Re:MMORPGs need better real-time characteristics

[Surlyboi]

There must be some kind of scaleability limitation though because Jedi Academy only supports about 30 players or so at a time in an area that is far smaller than a play area in an MMORPG.

You hit the nail on the head with the scalability issue. Unless you're playing a game like Planetside where there's no significant penalty for dying, (other than just having to respawn and grab more gear) you're going to have a lot of unhappy players who get 0wned by the LPB twitch freaks.

I think that if someone could design an MMORPG that played like an FPS, but had all of the depth and breadth of one of these not-so-real-time MMORPGs, it would be ideal.

I agree, it would be spectacular. But as it is, there're a ton of people playing SWG who'll just spam damage on players as they load into new zones. Unless everyone in the world is on the same footing connection-wise and the ganeworlds are seamless; a real-time implementation of a combat system would only compound this kind of grief play.

Re:MMORPGs need better real-time characteristics

[Bryan Ischo]

Well you are lucky that there are DOZENS of MMORPGs that satisfy your gameplay requirements. I am just looking for ONE which satisfies mine.

For what it's worth, the MMORPGs that I have played are pretty weak in the strategy area anyway. Really there is no reason for a fight to last more than 1 second anyway. It might as well work like this: you click on the spider, the server pre-calculates how much damage it would do to you and you would do to it, and the server does the damage and it's done. There is no reason to have to sit and wait while your avatar hack smindlessly at the spider at a pre-determined rate and the spider does the same to your avatar. If there is no skill involved in the actual fight, then just skip it and go to the results!

Yes, it is true that you can cast spells and such, or switch to a different weapon normally. But I've found that it just leads to a formula which you use over and over again when fighting. You click on the spider, you say attack, when it hits you you heal, you watch the attack while you want for your mana to recharge so you can heal again, etc. You might as well just code all that up into a script that you run whenever you want to attack a spider.

I like real time fighting because it brings a fun arcade-y aspect to the game. It also makes it feel like you're more "in" the world and actually controlling your avatar, instead of just sitting back and watching what could have been a MUD anyway if it weren't for the 3d graphics.

Re:MMORPGs need better real-time characteristics

[cbreaker]

Exactly. A 20 person UT match requires a surprising amount of bandwidth alone to make it as "realtime" as it can get, and a lot of CPU usage. If they were to try and accomplish the same thing on a scale of 5,000 players per server cluster at any given time, it would require too much bandwidth and resources to be profitable.

I see this becoming better in the future as CPU power and bandwidth get more and more available, and the prices of these games get higher and higher.

Re:MMORPGs need better real-time characteristics

[harlows_monkeys]

I've tried a few MMORPGs and have found them all to be lacking in the same key area: one's control over one's character is not real-time....Typically can do things like cast a spell or use a buff or otherwise make strategic changes to the way that your character is fighting, but you can't aim, run around, swing at the monster, etc, as you can with first person games.

That's because of the RPG in MMORPG. In an FPS game, it is supposed to be a contest of your skill and reflexes vs. mine. In an RPG, on the other hand, if I'm a 20th level Fighter and you are a 10th level Fighter, I should be able to always beat you on physical skill. The only way you should be able to win is if I do something strategically wrong. Hence, the lack of detailed control over the physical aspects of combat.

Its not fake, its a dice game

[rufusdufus]

The RP in MMPORG means Role Playing ala Dungeons and Dragons. Thus, the focus is on character development, not first person shooter style twitch. RPGs are based on a dice game, and is really about mathematics. The people with powerful characters are the ones who can do math, not the once with a cable modem in the same town as the server.

Do some of the work client-side...

[mooman]

Given their monstrous system requirements:
* P4 2.0GHz; P4 2.8GHz recommended (or Athlon equivalent).
* 512MB RAM; 1GB recommended.
* 64MB DX 9.0 Video Card (GeForce 3/4 Ti; ATI 8500+); 128 MB GeForce FX or Radeon 9600+ recommended.
* 16bit Sound Card; 24bit recommended.
* 8 GB free disk space; 7200+ RPM recommended.
* Connection to the Internet; 33 Kbps modem minimum; broadband recommended.

...maybe they should find a way to send datasets to the client machines and let them do their own manipulations.. Needing 8 Gig of disk on a 2+ GHz machine has to imply that the server doesn't handle all the real-time work... They are prime candidates for middleware that does some distributed computing and let all the customers' beast machines do the grunt work...

Re:Scalability and joining guilds

[Anonymous Coward]

This problem is in no way limited to MMORPG, the problem of authenicating and managing objects across multiple servers/clients is central to all online games. As a hobby games developer with a pretty good understanding of this I suggest you read Policing Online Games and then compare the conceptual pitch to issues in digital cash and online money transfers etc.
These ideas also overlap with the much hated and draconian 'trusted computing' models.

Enforcing a set of rules across a network of untrusted hosts is a fascinating problem. For example Gnunet and Freenet forgo a centralised trust agent and allow trust to emerge from the interaction, and recorded past behaviour, of individual nodes.

Digital 'trust' is sure to remain a huge area of interest. However it will also continue to be an area dominated by soothsayers, witchdoctors and charlatans because it contains a numer of fundamental logical problems which are not solved in the traditional human way of appeal to authourity.