Become a fan of Slashdot on Facebook

 


Forgot your password?
Close
typodupeerror
×
Role Playing (Games) PC Games (Games) Entertainment Games

Building Scaleable Middleware for MMORPGs 163

Posted by simoniker from the complexity-plus-plus dept.
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.'"
This discussion has been archived. No new comments can be posted.

Building Scaleable Middleware for MMORPGs More

Building Scaleable Middleware for MMORPGs

Comments Filter:

  • Scalability and joining guilds (Score:5, Interesting)

    by Space cowboy ( 13680 ) on Monday March 01, 2004 @07:20PM (#8434765) Journal

    Surely this is a classic example of the Manager pattern. You have a bunch of objects [Avatar] (all alike, at least programmatically :-) who want to perform operations on other objects. If the system has a [GuildManager] class, then access to this distributed network of avatars can be forced through the choke-point of 'can this avatar join this guild'.

    The trade-off in terms of scalability is in frequency versus computation. If the operation is commonplace (such as moving around), then a distributed system has a problem. If the operation is not commonplace (such as joining a guild!) then it's painless to use the 'choke' of a manager class to resolve any issues.

    Even in the commonplace situation, I would have thought it useful to use overseer-objects whose job it is to remove the extra (unnecessary) information from the problem before trying to solve it... There's no need to care about the avatar in sector (-1000,-1000) if we're currently in sector (0,0)...

    It's a cliche, but the rule is 'divide and conquer'. Screaming and leaping is a satisfactory, but usually fatal approach to problem solving, unless you're Kzin.

    Simon

    • Surely this is a classic example of the Manager pattern.

      I dunno, I've seen groups where there are 5 managers and one peon. Managers seem to accumulate.

      You have a bunch of objects [Avatar] (all alike, at least programmatically :-) who want to perform operations on other objects. If the system has a [GuildManager] class, then access to this distributed network of avatars can be forced through the choke-point of 'can this avatar join this guild'.

      Uh. By the time you're an Avatar you shouldn't be joinin

    • Re:Scalability and joining guilds (Score:5, Insightful)

      by Anonymous Coward on Monday March 01, 2004 @07:41PM (#8434957)
      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.

      • Re:Scalability and joining guilds (Score:4, Interesting)

        by MMaestro ( 585010 ) on Monday March 01, 2004 @09:23PM (#8435797)
        Indeed, digital 'trust' is something that cannot be easily handed to, let alone established. Not counting real life relationships, anybody who meets another person online immediately (should) distrust that person. In a sense, this is destroying the foundation of the internet (the sharing of information openly and freely) but it not only works, it is also necessary (sadly). Why? Simple.

        When you play a game online, would you rather trust "HarryGoatDeezNtz" who has an absolutely offensive name but you've seenen play online and play well for over 3 months, "UnnamedNewbie(6)" who you've never seenen before and is asking how to play in the chat, or "KingofSpades" who is an absolute asshole with no skills but has been playing the game longer than anyone other than the developers?

        The same thing is true with businesses trying to estabish themselves online.

        Would you trust Microsoft's Windows which is virus/bug/hack/etc prone, Linux which would require you to hire a full time IT staff just to keep your servers and computers working, or Macs and have your staff constantly ask 'wheres the right mouse button?'

        So the question remains? Do you trust the 'veteran' of the three? The 'pro' or take a chance and give the 'newbie' a try?

    • Re:Scalability and joining guilds (Score:5, Interesting)

      by t0qer ( 230538 ) on Monday March 01, 2004 @07:45PM (#8434993) Homepage Journal
      Even in the commonplace situation, I would have thought it useful to use overseer-objects whose job it is to remove the extra (unnecessary) information from the problem before trying to solve it... There's no need to care about the avatar in sector (-1000,-1000) if we're currently in sector (0,0)...

      Been there, seen that. Alternate Reality [metalmouth...ctions.com] had a creature in place for doing just the thing you were describing above. Taken from the AR Faq.
      The problem with this was that in the AR system each object was unique (except commodities like food, money, gems) and had a structure with attributes (like "spells" which were small intrepreted programs embedded in objects). Those data structures took up memory (16 bytes to about 64 bytes) and on an 8-bit 64K (or 48K) computer we had to limit the amount of items somehow. The way we came up with that was least artificial was to introduce a creature that would eat up objects when the object queue was getting full.

    • Re:Scalability and joining guilds (Score:5, Interesting)

      by humankind ( 704050 ) on Monday March 01, 2004 @08:25PM (#8435319) Journal
      Even in the commonplace situation, I would have thought it useful to use overseer-objects

      I know this is done to some degree in Everquest. There are NPCs in each zone that exist to augment existing zone-related, PC and NPC situations.

      For example, in each zone in EQ, there's an invisible NPC called, "pain and suffering" which appears to inflict damage on a player in certain situations (falling or bleeding to death). I would imagine that similar objects exist to control the weather, which in many cases might signal the client to narrow a player's depth of view and receive less information on objects in the vicinity.

  • MMORPGs need better real-time characteristics (Score:5, Insightful)

    by Bryan Ischo ( 893 ) * on Monday March 01, 2004 @07:22PM (#8434788) Homepage
    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 ...
    • 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 (Score:5, Insightful)

        by cbreaker ( 561297 ) on Monday March 01, 2004 @07:54PM (#8435066) Journal
        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.

        • UT Design Is Not MMOG (Score:4, Insightful)

          by meehawl ( 73285 ) <{moc.liamg} {ta} {todhsals+maps.lwaheem}> on Monday March 01, 2004 @08:30PM (#8435354) Homepage Journal
          A 20 person UT match requires a surprising amount of bandwidth alone to make it as "realtime" as it can get

          The large quantity of bandwidth exchanged in a UT (or similar peer-based FPS game) is an artifact of a design as single object view game with no distributed Server-side processing. Instead of waiting for bandwidth and CPU nirvana, there are smarter ways to maximize Server-side entity state updates [slashdot.org] while optimizing Server-Client bandwidth and delivering only environmentally-relevent data. Also, using multiple, distributed Servers enables you to multiplex Server-Client entity state updates using multiple pipes so you don't get a blocks or racing on a single message broker.
          • Cool, program me one and let's see how it works!

            Last I heard, computing everyone's 'environmentally relevant' data uses a lot more server processing for a game like UT. Some games have tried this (I know of a couple mods for UT that did this) but it ended up being very difficult for them to keep track of where everyone was looking and what they should see. I turned this feature off on my TacOps servers because it used WAY too much CPU cycles. There were a lot of problems with it. A perfect implimentat

        • Re:MMORPGs need better real-time characteristics (Score:5, Informative)

          by RollingThunder ( 88952 ) on Monday March 01, 2004 @11:20PM (#8436626)
          World War 2 Online [wwiionline.com] has sort-of beat that. It's a MMOG FPS, in essence.

          Basically, there is a 64 unit "visibility limit". You're only ever told about 64 units max (and sometimes, due to oddities, less) player entities around you, prioritized among several criteria (distance, threat, minimum friend/foe allocations), etc.

          It works fairly well, and the structure of the game is such that you have dozens of 30-60 player battles going on at all times, and can move anywhere around the map as you choose, realtime, either by slogging it on foot, driving, flying, or steering your ship. You can also jump from place to place but leave your equipment behind.

          Best estimates put the peak server load at about 3-4000 players, with 500-1000 during the low tide, but the game runs 24/7 on a single arena.

          The developers aren't swimming in money, but they're in the black and have recently turned up the data update rates to make it more smooth, so there's evidently some room in the budget for bits.

          Disclaimer: I'm a day one player, from June 6 2001 on, aka Krenn, of the 1/16 Panzerdivision "Windhund".
          • It sounds interesting.

            I think you can download Planetside. I've always been a fan of FPS's, and this looks like a pretty neat game if it's done well. From what you're saying, it sounds pretty good (at least no worse then your average server running single-map online games like Quake.)
          • Another point worth mentioning (and one of the best kept secrets of the game, IMHO) is a fairly revolutionary update system which virtually eliminates lag differences due to bandwidth constraints. I've played this on 56K and DSL, and there is absolutely no difference between the two. Although there is still lag, of course, it's not dependent on your own connection speed, but rather the more even latency rates across the Net. It's a huge equalizer for HPBs who are typically pwned in most online FPS contes

    • Re:MMORPGs need better real-time characteristics (Score:4, Informative)

      by MaineCoon ( 12585 ) on Monday March 01, 2004 @07:36PM (#8434906) Homepage
      The issue here is you are looking at MMORPGS. RPGs are traditionally turn based combat. I haven't seen many successful RPGs that required one to actually swing or fire their weapon manually.

      There are two massively multiplayer games that feature realtime combat

      * Planetside, which is an MMOFPS with RPG characteristics (levelling, improving your character by gaining extra implant slots and additional simultaneous skill sets)

      * Neocron, which is an MMORPG/FPS (I may be wrong on this one, it was a while ago and I only played the offline trainer, which was supposed to simulate online play)

      One of the biggest issues is lag; to reduce lag, which would get horrendous when there are many people in close promixity doing things, the client-side visual representation and simulation, and the server side simulation are never in sync with each other. The server is the final arbiter, but the client tries to the best of it's ability and available information to provide a visual representation of what is going on.

      Planetside (and I assume Neocron) solves the lag issue by moving combat resolution for attacks to the attacker's client, and trusting the client's integrity. As a result, you can easily die 3-4 seconds after running behind cover; likewise you can run through an intersection, be in the clear on your end, yet be shot and killed 5 seconds later as someone sees you go through the gap 3 seconds earlier and shoots you.

      - MaineCoon

    • Its not fake, its a dice game (Score:5, Insightful)

      by rufusdufus ( 450462 ) on Monday March 01, 2004 @07:37PM (#8434913)
      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.

      • "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."

        Basically true (about D&D and other RPGs, I mean), although it's not the ideal. The Holy Grail of both P&P (Pencil & Paper) and MMO- RPGs is a system that conforms to common sense, so that math enters your gameplay only a little more than it enters the processes by which you live your everyday life.

        Th
      • No, they're the ones with no lives that have been logged on and fragging critters since time immemorial. I prefer games that don't preclude a social life, thankyou.

    • Re:MMORPGs need better real-time characteristics (Score:5, Insightful)

      by Surlyboi ( 96917 ) on Monday March 01, 2004 @07:37PM (#8434920) Homepage Journal
      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.
      • The more that I've been reading /. lately, the more it seems that Game Myth [gamemyth.com.my] aka Risk Your Life has the right way to go about it (at least in terms of the various games that I've been looking at [mmorpg.com]). Although the English engine is currently in development, it seems to be the solution that a lot of pvp type MMORPG players are looking for. It is a persistent world with character development and learned skills and such, but the combat (spell, ranged, and melee) is all FPS like. Meaning you have to pick and choose

    • Re:MMORPGs need better real-time characteristics (Score:4, Informative)

      by fewnorms ( 630720 ) on Monday March 01, 2004 @07:38PM (#8434930)
      Dunno, but I've been playing this Eve Online [eve-online.com] stuff and it seems pretty realtime to me. And it supports 7500 people at the same time with no lag... And I must say it's pretty fun to play too, if you like space rpg's ;)

    • Re:MMORPGs need better real-time characteristics (Score:5, Interesting)

      by AuMatar ( 183847 ) on Monday March 01, 2004 @07:42PM (#8434967)
      I've played damn near every MMO out there. if one came out that made me aim and run around dodging, I wouldn't play it. Its not what I want from the genre. I've done twitch combat. I've done it for 20 years. It bores me. So you can hit the left arrow button faster than me. I don't give a damn. Currently MMOs test if you can use your skills and tactics to out think me. That is fun. And luckily, it seem the genre will stay like this for some time to come.

      • Re:MMORPGs need better real-time characteristics (Score:5, Insightful)

        by Bryan Ischo ( 893 ) * on Monday March 01, 2004 @07:49PM (#8435029) Homepage
        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.

        • Have you tried Dark Age of Camelot? Combat is "turn-based" like most MMORPGs but because of the way the combat system is designed, competitive player-versus-player combat is really more like FPS than "traditional" MMORPG.

          It may not be quite what you're looking for, but combat in DAoC is certainly not "click attack and wait for someone to die".
          • I did, but I didn't get very far. I found it boring to have to run around the initial little town performing mindless tasks (take this letter to that guy over there, only we won't tell you where he is so you have to run around all over the place looking for him), and then when I did get out of the town and had to fight a bunch of hyenas or whatever, the combat was just point-and-click-and-wait like the other MMORPGs I have played, and then when they died they dropped *bags* that were supposed to represent
        • I too wish that there was more strategy in the fighting for most mmorpgs...I play final fantasy XI, and there are elements of strategy(you have specific abilities that can be used in succession with other characters that do more damage, heal life, ect.) but for the most part it lacks what you are looking for. Also, such a heavy reliance on other party memebers is particularly frustrating sometimes, but that is another story altogether.
        • No offense intended, but I'm thinking you might have the wrong idea.

          Yes, you are right: the current crop of MMO games are dead boring and involve no strategy. They're a boring, repetitive affair in which you just click on the monster, then wait and see when you have to heal. And, yes, it's such mindless repetition that you could just write a simple script that does it.

          (And some people on MUDs do. It's a banning offense on many MUDs.)

          Worse yet, there is no story, no plot and no justification at all. Why a
        • http://games.slashdot.org/games/04/02/29/1642223. s html

          There are several people who added comments about how they had to do some very complicated interactions to overcome others - http://games.slashdot.org/comments.pl?sid=98732&ci d=8424235 about Planetside. The one I liked the most was this one http://games.slashdot.org/comments.pl?sid=98732&ci d=8426037 about an early UO player's play-by-play of conquering some ambushers.

          So at some point the dexterity/skill-players can find a decent game or

    • Terazona (Score:5, Interesting)

      by meehawl ( 73285 ) <{moc.liamg} {ta} {todhsals+maps.lwaheem}> on Monday March 01, 2004 @07:45PM (#8434988) Homepage Journal
      one's control over one's character is not real-time.

      If you've attended GDC then you may have played ZonaBattle, a real-time mechanized battlecar demo game for the Terazona MMOG system. Disclaimer: I work for Shanda Zona [zona.net], the developer of this MMOG architecture, and my views may not represent those of the company, etcetera.

      The purpose of the ZonaBattle technology demo is to illustrate that MMOGs do not have rely on sluggish, pseudo-turn-based gameplay. Using the right architecture produces excellent results.

      ZonaBattle is not as fluid as some FPS games, but it is peppy and, unlike peer-based FPS games with~64-138 players, Terazona's client-server design enables you to scale the playfield to several tens of thousands of players and those players will experience no increased lag or message bottleneck.

      Of course, you can also use Terazona to build "classic" seamless MMOGs. Terazona games do not have to have zones or "shards" and feature a heuristic, autoconfiguring grid system for game servers with dynamic region ownership, environmental simulation, and load balancing. You want more performance to support more players or more complex environment? Just slap in a few more commodity servers, or racks. The game will integrate them automatically and immediately begin dispersing Players and Entities among them.

      Players can also exchange state with other local or non-local Entities using various bandwidth- and set-based configurable channels. This is not as easy as it might first appear.

      Finally, the entire Server-side system is Java-based, for maximum flexibility and cross-platform support.
      • Sounds cool. You lost me at the "java-based" though :)

        Question: how does the game world map get distributed amongst the grid servers? Does each one have to have a copy of the entire world, or do they split it up somehow?

        • Re:Terazona (Score:5, Informative)

          by meehawl ( 73285 ) <{moc.liamg} {ta} {todhsals+maps.lwaheem}> on Monday March 01, 2004 @08:04PM (#8435145) Homepage Journal
          how does the game world map get distributed amongst the grid servers

          Dynamic ownership, distributed object-view model. Very similar to the system described in Queue. You would never maintain a complete unitary in-memory representation of a world - that sucks up too server juice.

          I come from a CORBA background as well - what you see with all this kind of MMOG Middleware (Butterfly, Quazal, There.com, BigWorld) is a classic example of evolutionary convergent adaptation.

          I forgot to add a standard /. angle - we support MySQL for persistence, among others. In fact, any RDBMS with JDBC should work. We also support Entity creation, modification, bandwidth optimization using an XML-based schema editor (written in Java, of course). So game programmers don't have to fiddle forever making lots of structs and trying to optimize dirty bitmasks for message delta optimization. This lets you get past the tedious stuff quickly and get to the game logic.

          • Re:Terazona (Score:3, Interesting)

            by Bryan Ischo ( 893 ) *
            I probably wasn't very clear when I asked my question. Or maybe my question didn't make any sense.

            Maybe I could illustrate the problem I am wondering how Terazona solves, and you can tell me how you solve it (or at least give me a general idea) ...

            The world includes models of objects which the player interacts with. Let's say a player is in a certain location and wants to walk north. But they can't because a tree is in the way. Whatever server is keeping track of the player's movements and doing colli

            • Region Ownership (Score:4, Interesting)

              by meehawl ( 73285 ) <{moc.liamg} {ta} {todhsals+maps.lwaheem}> on Monday March 01, 2004 @09:14PM (#8435714) Homepage Journal
              I can't give you specifics because you have not signed an NDA. I can talk in generalities, but I can tell you that TZ's load balancing is not random. Much of the information about how to load-balance such systems can be obtained from reading "Distributing Object State" which ran in GamaSutra a while back [gamasutra.com]. The key is dynamic ownership, not static ownership. As you rightly fear, static ownership leads to slowdown and player hangs.

              The best way to maintain ownership would be dynamically, using some sticky heuristics to predictively anticipate where a player will "be" following a move, and alert Servers within some defined "neighborhood" or "ZOC" to update their state. This is non-trivial, because you may be dealing with non-Euclidean geometries, distance metrics, or set/guild membership. Therefore, each distributed Server can update its affected Clients on-demand, without those annoying lags you get with some systems when you can "feel" the Client loading the data from a new Server.

              Alerting Servers that currently "own" those possible Regions to prepare to update relevent Entities with info is also required. If no Server owns that Region, then you should have a whole other set of heuristics to determine which game server should own that Region. It may, or it may not, be the Server that "owns" the Entity that is moving into that Region. You probably need to do cost-benefit calculations for assigning/re-assigning Region ownership. You can run Monte Carlo simulations to see how best to describe possible Entity "walks" within the topology.

              Similarly, because of the expense of instantiation, you need some pretty tricky finagling to figure out when to relinquish ownership and purge any "ghost" copies of the Entity State that have been following the main Entity "around" within the topology. Of course, the nice thing is that Server-Server entity state exchanges will take place along a fat pipe backbone.

              Interestingly, such systems end up looking a little like a Kohonen n-tier feedforward neural network.

            • Re:Terazona (Score:2, Informative)

              by killmenow ( 184444 )

              Dynamic ownership, distributed object-view model.

              I'm obviously not the parent poster and I'm not familiar with Terazona, but I'll take a stab at your question based on this sentence.

              It sounds to me like what the guy is saying is this: The map is divided up (distributed object-view) among servers and no one server ever has the entire map in-memory. If everybody in the game moves to one part of the world, you've got servers sitting there doing nothing...so they switch (dynamic ownership) to the part whe

        • You lost me at the "java-based" though

          And oh yeah, only the Servers run Java only. The Client-side API is language-agnostic and platform-agnostic. So you can write Clients in C++ or Java and compile them to Win32, XBox, PS2, GameCube. The Servers don't care which Client belongs to which platform.

          The analogy I like to use is NTSC. In the early days of TV without NTSC you had no guarantee that your GE TVs would be able to pick up Motorola format broadcasts. TVs competed within closed markets and featured lock-in. Creating a common broadcast standard enabled all TVs to pick up all broadcasts. TVs could compete on quality anf fucntionality, and broadcasters could compete using content. Using a platform-agnostic MMOG Middleware lets you enjoy economies of scale because your Servers communicate with all kinds of Clients. Client experiences vary, of course, according to display resolution and frame rate ability.

      • What zona.net has developed sounds somewhat like the RTIME networking system. You might want to be careful here -- RTIME was issued a substantial patent covering their technology, and now that Sony owns the patent and the technology, zona might be getting a nasty letter sometime.

    • Re:MMORPGs need better real-time characteristics (Score:5, Insightful)

      by harlows_monkeys ( 106428 ) on Monday March 01, 2004 @07:55PM (#8435070) Homepage
      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.

      • Re:MMORPGs need better real-time characteristics (Score:2, Funny)

        by Anonymous Coward
        Right. Rather than by physical skill or some other merit, the combat is decided based on which fat guy spends more of his free time sitting in front of his computer, levelling up his character.

    • Re:MMORPGs need better real-time characteristics (Score:5, Funny)

      by Fourier ( 60719 ) on Monday March 01, 2004 @08:43PM (#8435450) Journal
      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.

      Yeah, that's always bothered me too. Why do you have to click to attack? Surely the computer can take care of the attacking all by itself [progressquest.com]. I'd rather just sit and watch, or maybe go grab a pizza and sit in front of the TV while my Half-Halfling Organist decapitates some Hair Elementals in the Killing Fields. Good times.
    • My answer is write a game that plays itself. Rather than be a contest between who can keep the most number of balls in the air (ala RTS), we should instead write a system where you code your own AI's, and let the computers to the dirty work.

      It would be like a stock-market simulator. You send your moves in, and you can check your porfolio, but the game goes on no matter how much (or little) attention you pay.

      My thought is that you set the game in a universe where it's only possible to send robot fleets e

      • Sure, no problem.

        http://www.phial.com/angborg/

    • Well the biggest problem with this idea is that, regardless of whether they could, very few companies would choose to design an rpg, let alone an MMORPG in the style which you suggest. It has been done to an extent(Morrowind is really the only example I can think of off hand), but one of the primary aspects of most rpgs of any sort seems to be the idea that your ability is determined more by your characters skill than by your own(even in morrowind all you can really do is hack and slash, blocking and armor
    • There are games that work close to what you want; however, as other people have pointed out there are problems with latency in heavily "twitch" based games. Appropriate "twitch" mechanics require fast reactions, faster than the time it takes for the client to communicate with the server in most cases.

      Another issue you run into is cheating. Think about the aimbots for most FPS games. When you're paying a monthly fee, there's the expectation that there won't be cheating in the game. Therefore, most onlin
  • That page is annoying. For anyone on low-bandwidth or Lynx connections, here is the printer/human-friendly page [acmqueue.com].
  • As my Econ professor used to say, "Economics is the study of scarcity." So they need a scalable economy engine, right? Compatibility of guilds is another matter.

  • "Authors thought of everything". (Score:4, Interesting)

    by SharpFang ( 651121 ) on Monday March 01, 2004 @07:29PM (#8434840) Homepage Journal
    Lots and lots of modern cRPG, online or not, have way less features than games like Nethack. Just think what you can do about a towel - wrap it around your head, dip it in a fountain, wipe your face. Lots and lots of options. Incredible richness. Seems it can be done after all...

    Are there any online rogue/nethack clones out there?

  • Who needs 10,000 people in a zone? (Score:5, Interesting)

    by bartash ( 93498 ) on Monday March 01, 2004 @07:31PM (#8434855)
    They say:

    Wish is the first Ultra Massive Multiplayer Online Role Playing Game (UMMORPG(TM)). "Ultra" means that Wish supports more than 10,000 simultanous players in a single, seamless world, without any zones or "shards".

    In EQ you can have an effect on other characters in your zone (say a hundred people) but you can talk with all the other people on your server (thousands, maybe tens of thousands of people). This is a limitation, but in practical terms it works OK. I don't actually need to interact with more than a few people at a time.

  • Scalability problem? (Score:1, Insightful)

    by Anonymous Coward
    I don't see a scaling problem in the example.

    Why not just keep a variable on each character associated with each guilds he's in. And then, each guild keeps a list of members.

    Thus, a query on the data is always fast and local.

  • Wish sacrifices (Score:5, Interesting)

    by Rexz ( 724700 ) on Monday March 01, 2004 @07:35PM (#8434896)
    You make major one major, major sacrifice for so many simultaenously players in Wish. Movement is point and click. It feels like you're playing a strategy game rather than living in a real world. Those of you complaining that you can't joust and dodge in today's MMOs will hate the stilted movement mechanism of Wish, where the path you take is left to a pathing routine.
    • I agree this kind of movement (point and click) is non-immersive. The same goes for third person view. The best I've seen for movement, viewpoint and most important, content, is Everquest.

      This is not an easy thing to solve. I would say that a MMORPG is not mature until it's been online for at least a couple of years. You can't reach a stable environment until you let the system find it's equilibrium. After this, it becomes tweaking and expansions. But let's face it, the average player's bandwidth and

  • Lacking confidence here... (Score:5, Interesting)

    by Fiz Ocelot ( 642698 ) <baelzharon.gmail@com> on Monday March 01, 2004 @07:37PM (#8434911)
    I don't really get a warm fuzzy feeling of confidence after seeing things like this:

    "At ZeroC we used Java because some of our development staff had little prior C++ experience..."

    "...however, a few of us had previously built a commercial object request broker..."

    "...designing and implementing middleware is difficult and costly, even with many years of experience. If you are looking for middleware, chances are that you will be better off buying it than building it."

    Frankly, I'd feel rather uncomfortable using ICE 1.0 as middleware for my new MMORPG. Yes they could succeed and do a nice job, but that rarely happens especially in the world of MMOs where nearly all games are released way too early in beta form.

  • Do some of the work client-side... (Score:5, Insightful)

    by mooman ( 9434 ) on Monday March 01, 2004 @07:40PM (#8434948) Homepage
    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...

    • wtf?

      The seti-at-home-type approach doesn't work here for several reasons:

      First of all, they aren't implying that they're having scalability problems.

      Second, on a MMORPG server, many of these calculations have to 1) take place instantaneously (latency of communication over the 'net precludes this) and securely 2) and operate on enormous datasets (i.e. databases containing world/player/object/etc information) that can't exactly be sent down some DSL line due to size and security reasons.

      Third, you can nev
      • I disagree... I know everyone will say "Never Trust the Client" but it shouldn't be considered a rule, but taken as very sound advice. If it was to be considered a strict rule multiplayer FPS and MMORPG's just wouldn't be viable. In the mudding community there's been a few games that have tried to move to graphical versoins using a dumb client, they always suffer awfully from lag, very tilebased movement or slow movement.

        There are certain things that are still appropriate to be done on client, in fact so
    • The problem with this is you cannot trust the end user. They will find a way to catch this information and use it to cheat. Everquest was plagued by this. Encryption is the only way to go if you are going to do this. However, you may find that you are spending more time finding a _easy_ encryption that is _hard_ to break.
      • The data will be found. Exactly as your example. Everquest. It still has the same old issues, if not worse, in that now it can all be wrapped up in the easy to use 'Macroquest', which, ironically enough, doesn't sniff packets, it attaches and reads the memory..
    • That is one of the things to be done to improve on scalability issues. However, to prevent hacking, most of the data has to be at least verified by the game servers. Otherwise you end up with players using speed hacks to outrun you at 150MPH, fight four times as fast, or cast fifteen devastating uber-magic-spells at a time. So, again, you end up with the game server having to know everything, even if the frequency of processing here doesn't have to be quite as high.

      Another problem, and this is the major
    • ...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...

      Rule #1 of online games: Never trust the client.
    • The client itself probably takes up only a small fraction of that requirement!

  • Truly a Dilbert moment. (Score:5, Interesting)

    by psoriac ( 81188 ) on Monday March 01, 2004 @07:58PM (#8435089)
    I came across this quote:
    At ZeroC we used Java because some of our development staff had little prior C++ experience.

    and immediately though of that Dilbert strip (sorry, no link) mocking the "if all you have is a hammer, every problem looks like a nail" saying. That strip was particularly memmorable to me because the last panel featured a porcupine saying "we must stick them with quills! it's the only way!"

    • This is a typo in the article. It should say that some of the Mutable Realms staff don't have a lot of experience with C++. The authors of Ice have many years of experience with both C++ and Java.

      Also, the philosophy of Ice is the exact opposite of the "golden hammer" anti-pattern. We fully recognize that there is no one-size-fits-all with respect to programming languages. That's why Ice works with C++, Java, PHP, and soon also with C#.

      For Wish, C++, Java, and PHP are used. The client is pure C++, for

    • I agree with you and this is what really, really disturbs me about programmers and development projects these days.

      In the classic sense, you select the tools/language best suited for the job. When you're dealing with huge amounts of data and lots of simultaneous usage, performance is going to be the difference between success and failure.

      Yet, what do these people do? They choose a set of tools because development would be less problemmatic? Catering to the narrow specialties of their development team is

  • it's all about design & bandwidth (Score:5, Informative)

    by humankind ( 704050 ) on Monday March 01, 2004 @08:08PM (#8435184) Journal
    I really think computing power is less significant than the overall game development design when it comes to MMORPGs. After design, bandwidth becomes a factor, and only then is computing power a factor. The only exception I can think of would be requiring power for encryption/decryption.

    The notion of parsing datasets for something like guild membership is really trivial. If you want to design a solid MMORPG, it's going to come down to how the world, objects and players are represented.

    I continue to be in awe of the capabilities of games like Everquest and SWG. SOE has really created a very robust MMORPG technology -- it's hard for any other game developer to really say they have anything comparable when they can't demonstrate superior performance under the same conditions due to no other MMORPG having anywhere near the quantity of simultaneous players (as Everquest).

    IMO, the client side of EQ is pretty straightforward. What makes the game special is the server side and how they manage to manipulate so many players and objects in real time. People complain that too many objects/players per "zone" can lag things down, and that is true, but I have yet to see a better implementation than Everquest. SWG has done away with the concept of "zones" to some degree, but basically, they seem to have implemented some client-side intelligence to indicate at which point additional graphics and information on objects in the distance should be loaded or reported. There are still "zones" in all these games. Some of them implement noticeable loading lags, and others don't.

    My outside impression of the technical layout of Everquest is something like this... and I'd love anyone with more info/insight to correct me or elaborate further. I ASSume their system is made up of racks of servers, running Solaris I think. The have some low-level, propietary engine that manages the objects in the world, probably to a back-end database like Oracle. The reason for zones in EQ is that when you enter a new zone, you may actually be switching from one physical server to another. Not only do they have different servers for different shards/worlds, but different servers for different zones. When I see a system message such as, "North Karana, Velketors and Plane of Mischief going down for a brief update", I think that perhaps that's one server they're rebooting, which runs those particular zones. I suspect they stagger high-traffic zones with low-traffic zones on servers, and occasionally when the X number of zones managed by a single server have an unusually high amount of traffic/visitors, you get lag.

    What's interesting about MMORPG game design is the balance between handling as much client-side as possible without creating security issues. If the server keeps track of players, NPCs and objects, it's much more difficult for someone to hack, or at least, logs are available to identify issues. The more client-side processing done, the more likely the game can be inappropriately manipulated.

    When you take into account the amount of real-time data that goes back and forth, EQ (and SWG) are quite impressive. I don't think database/dataset issues are really the problem as being able to efficiently encapsulate, protect and send/receive the large amounts of data in the real-time world.
    • The EQ "zones" computers were running on NT 4 when it first came out, and for about the first 2 years. I don't know what it has switched to now.
      The application basically only used the TCP/IP stack of NT, but yes, Virgina, it was on NT4.

      I can't "prove" it, but I got that straight from a friend of mine, that was one of the original EQ team (and you would instantly recognize his Avatar name).
    • You're right in that zones are on different servers but the real reason for the "Loading .... " is to load stuff client side. Remember when EQ first came out computers had a lot less memory, so they couldn't keep all those textures/models in memory.

      The transfer from server to server shouldn't take long at all, the time to write the character file to database and load it again.

      Everquest puts real variety in textures/models between zones, For example, a zone as a sunny green pasture with animals is adjacen

  • Whatever you do in this model, for christ's sake start with a real RDBMS. I know a couple people who work at an Austin-area MMORPG studio (not EA's Ultima-- that Austin office was shut down last week) and their developers have decided to go with flat files for storing all the data. This is just out of half-assed design specs from day one. Now, the game is several years released and it'd be too much work to re-write code to pull all their flat-file rewrites and have it do proper DB transfers.

    Can you possi

    • Flat files? Wow! I admire those people's courage :-)

      For what it's worth, Ice and Wish use Berkeley DB (http://www.sleepycat.com). It's a DB with a small footprint, high performance, and good transaction support. Nice licensing conditions too -- you pay only if you want to keep your source code secret.

      Cheers,

      Michi.
    • Or in other words, you're another case of the "if you only know how to use a hammer, everything looks like a nail" syndrome, huh?

      "Can you imagine race conditions?" Well, can you imagine that there may be _none_?

      There are millions of servers out there -- HTTP, mail, whatever -- which work directly on files. And they have _no_ race conditions. Why? Because the operating system itself is built to allow multi-threaded access to those files.

      Do those files need random read/write access? I've coded on MUDs whic
  • JavaSpaces [sun.com] is more or less Sun's Jini take on distributed processing.

    From a programmer point of view, you start up a "space", and then you can write objects in, take them out, and read them. And that's all. So there are a very few simple operations, and you structure your app around those.

    Anyhow, it seems like a couple of JavaSpaces on a rack of servers might serve as a good way to distribute processing/notification/etc. Of course, you're limited to Java and to moving around Serializable objects....

    • JavaSpace isn't anything new. It was based on LINDA developed in Yale in early 80s. The problem with it is that it has a very easy abstraction but it's intended as a synchronization system for distributed system rather then a data moving middleware. It's hard to "tune" it.

  • I find their choice of RPC as the middleware layer surprising. I would imagine that a vast majority of events in a MMP game need to be passed on to a fairly large subset of players, for example, anytime someone moves, attacks, casts a spell, etc. the people visual or audio range of that player need to be informed. RPC is better suited to one-to-one interactions, not the one-to-many interactions we get in MMP games. It seems to me that a distributed publish/subscribe system like Elvin [dstc.edu.au], SIENA [colorado.edu] or even Mercury [cmu.edu]
  • This project is going to fail, or at least be severely delayed. Why? Well most of the article talks about how they rewrote COM/COMBRA/KOM (etc..), creating their own IDL, their own protocol etc.. However the article is not about rolling your own ORB, it's about designing a MMORPG middleware, which can have little to nothing to do with an object broker.

    They even start of the article with some nice pie in the sky requirements. Like a truly scalable world capable of "tens of thousands" of people in the same w

    • However the article is not about rolling your own ORB, it's about designing a MMORPG middleware, which can have little to nothing to do with an object broker.

      Hmmm... To build a game on that scale, we needed a distribution platform of some kind. Having looked at what we needed, and having considered CORBA (which some of us knew a lot about, having previously built a commercial ORB), we knew that CORBA wasn't going to meet our requirements. So, we ended up building a new middleware.

      It's quite surprising

  • I do or have done distributed, persistent middleware with tons of threads, caching, dynamic persistence, multiple-databases, multiple-languages and so on middleware for enterprises or those who wish to sell to them many times in the last couple of decades. It didn't occur to me that most of the same talents are essential to games and various virtual spaces.

    Thanks! :-)
  • This would have been much easier if they had used Jini [jini.org] and JavaSpaces [artima.com]technology. There is even a commercial implementation [intamission.com] that supports incremental evolution of the distributed model.

    Jini and JavaSpaces are being used in a variety of organizations to build large, distributed, reliable, scalable systems that integrate a wide variety of existing systems, including those written in languages other than Java. The technology seems a good match for this problem.

    Patrick

    • You can't be serious! JavaSpaces is NOT a general distributed system middlewware. The concept of Space is developed for LINDA in 1982! and it's intended to be a synchronization machinism for distributed system. JINI is a service discovery framework. It doesn't specify the object in the system.

      Why do people keep thinking about Java and related technologies as innovation? Do you think the entire IT industries and reasearches only started after Java was invented in 1994?

Slashdot Top Deals

"Protozoa are small, and bacteria are small, but viruses are smaller than the both put together."

Close