SQL Concurrency versus JDO, and why I want to make the switch

Small update tonight. I managed to not do much tonight except think. And think. And plan. The outcome is a decision to "scrap" what I have so far on the simulation and start new. Including, (most likely) the database.

And here I was promising the material decoder, huh? Not that it took very long to get nearly finished with that. Another couple of days and I'll probably have that finished, I just need to go through some organization first.

So what am I changing in starting new? Let's go into one of my standard bullet lists:

• (Probably) Removing the SQL from my side of the coding by using Java Data Objects.
• Creating classes for the different objects (like planets and ships) rather than tables per se.
• Truly attempting to take advantage of the object-oriented nature of Java, a la Budd.
• Avoiding so-called "Concurrency" issues
• (Probably) Making the code easier on me to develop.

Java Data Objects, or JDO, are a method of storing entire Java Objects within a database. In my case, by creating a class for each in-game item, I can then store the classes in the database. This becomes useful in terms of the concurrency issues mentioned above. Concurrency in SQL is a problem where multiple users attempt to access the same data at the same time. When one person edits the data, the second person may well overwrite those changes even though the information they based it off of is no longer accurate. Generally this is handled by locking the row, so that only one person can access data at a time.

This is a major problem in my program because of the nature of the database I built, and how it would be accessed. The database is built with 'foreign keys,' or references to other tables, so that all of the data is interconnected. If one user is accessing all of the necessary data to run their empire, then a significant portion of the database is locked up while they're doing that work. Not a very user-friendly methodology. On the other hand, if the planets and ships and everything else are stored as independent objects, the user only accesses those that belong specifically to them and there aren't concerns about simultaneous edits.

I'm not too well-versed in the JDO things yet (I've just stumbled upon them today, really), so I'm not certain, but I do get the impression that using JDO means not needing to use SQL, and this simplifies my coding as well as removing the SQL altogether. Unfortunately, while I've found books that cover JDO, I can't find any at a library near me. I'm considering purchasing a copy somewhere off the web, but for now I'm going to try using the online documentation for it. Until I run into major issues, I'll probably stick with that.

My next couple of days are pretty slim in terms of time spent in-school, so hopefully I'll have a nice structure fleshed out and work started by... the weekend, at the latest? Wish me luck on that!

Project Introduction: Java Simulation Game

While I'm doing some fine-tuning on the MATLAB project before posting the code, I figure now's a good time to introduce the other main project I'm working on. This one's a bit more complex and will probably be in production for ages (an unfortunate side-effect to lack of deadlines).

The simulation game I know and love doesn't really have much in terms of graphics. It's much more a thought-based, economy/diplomacy/strategy simulation, with rules governing interactions, extraction and deployment of resources, and the like. If you have an imagination, it's a real fun game to play because literally anything is possible--you have an administrator or two running it and keeping it balanced, but otherwise if you can think it, it can be done. My version, and all the ones I've played, are sci-fi, galactic empire style games. You rule planets, not cities, basically.

In the versions of these games that I've played, the major downfalls were (discounting admin inactivity and small player base):

• Problems with cheat-detection. All of these I've played so far were excel-based (or worse, simply forum-based), meaning if a player modified the excel file it becomes tough to notice it.
• Reliance on other players. As all interaction requires a response from someone else, things went slow. For diplomacy and trade, this isn't a problem. But what happens when your fleet is at another player's planet, waiting for the other player to respond to continue the battle, and another enemy comes to your planet knowing you've got no defenses?
• Lack of 'realism.' Mostly in the fact that the player controls EVERYTHING in the past games I've played, which makes playing tougher. Sure, it's nice having absolute say over everything, but it isn't necessary and adds a lot of work.

Therefore I've set out to create my own version of the simulation-style game:

• Programmed in Java, with no access to source code, to prevent cheating but allow essentially any computer to run it.
• More administrator decision-making. A player entering a battle will get to dictate what the general strategy is, what the main targets are, under what circumstances the forces are to retreat, large-scale strategic things like how much of the fleet actually enters the battle to begin with and what remains as mid-fight reinforcements. The defending player then gets told what he knows of the situation (the ships currently in the fray, essentially), and issues main targets and defense objectives. The generals do the micromanaging, and the end result is a battle decision created in a short time through the administrators.
• The concept behind my game in practice is that the leader does leader things. The economy is essentially entirely controlled by the player, but research is done more true-to-life. If a player wants to develop a new fighter craft, they don't tell the admin what exactly goes into it and receive a yes/no answer as to whether it works. Instead, they put the offer out to companies, who create prototypes and bid on contracts, and it's up to the player to choose from a few different options given to them.

Now, some of you may be thinking "this really doesn't sound like fun." For many of you, that'd actually probably be true. This style of game is certainly not everyone's cup of tea. Do bear in mind it isn't simply number crunching. Every action has an outcome on the whole of the galaxy, based on other players' political responses and the NPCs. And a battle doesn't simply go: X ships vs Y ships, Y wins, no ships remaining for X, Y-n ships remaining for Y. It's the administrator's job to narrate, tell a story, and entertain.

Some other features I'll be including in the game concept are:

• Realistic (pythagorean-theorem based) travel times via galactic map coordinates.
• In-depth trading system. All planets will have some of a predetermined list of resources, and most will have their own unique (though questionably useful) resources. Probably will also include a materials market much like the stock market, based on quasi-realistic supply and demand.
• Through the material system, potentially interesting design quirks, waiting to be discovered, in nearly everything. A leader may find a nasty surprise waiting for him when he suddenly discovers his troops are carrying extremely magnetic weaponry, and his enemy knew this before he did, disarming them by way of electromagnets (for a top-of-my-head example).
• By definition, each race will have (aside from preset starting 'equipment') completely unique armies, infrastructures, and economies.
• Dynamic game structure--because the game is coded by the eventual administrator, things can be changed. Want to play a socialist utopia? The economy for your race can be re-coded to be more befitting. For example.
• Espionage that provides both real and incorrect data, and most often time-sensitive. You'll be more likely to find out an enemy fleet's location than its composition. Like the real-world, using acquired intelligence is a gamble that can have huge rewards.

My current status is pretty bleak. The MySQL database structure to go behind it is essentially complete. It's a complex mess of inter-related tables, but it covers essentially everything. The Java work I had done (which was almost nothing anyway) is lost to my last computer wipe, but I've started fresh and am currently at work coding a material property display. Each material has 11 properties, with a range of values from 0-25 (Z-A respectively). I'm working on a 'decoder' that displays the properties in one of those attribute 'star-charts.' The only example I can find easily is this. Imagine the colored section moving around to fill in the shape depending on how high each stat is. Mostly I'm making this for my purposes so I can try to visually see the balance between materials found on varying planets.

Boredom and a Whim

What do you get when you cross an engineering student and a boring materials lecture? I suppose if you asked all of the 180-odd students in the lecture theater that day, you'd wind up with at least 50 answers (the most common one being 'Nap time.")

In my case, it was a trip to the library to pick up a "Java book," as it would come to be called. This was (according to my library record) about 2 or 3 months ago. Since then, I've become obsessed with programming (or so I'm told). I stormed through Java basics, swallowed up a decent bit of SQL, and due to an assignment just last week, have powered through MATLAB.

A friend of mine today warned me about mixing work and pleasure, jokingly of course. I've gone overboard on my latest assignment, and it's because I like what I'm doing.

Why aerospace engineering, people ask (and that's not a joke, in those two months, I've been asked this many times, carrying and reading my Java, and later SQL, books at any opportunity). I don't think I could actually do programming for a living. I like it as a hobby, as a challenge. That's what this blog is for: documenting "Charlie's Crazy Computer Coding Capers," hopefully giving and getting hints and tips, and maybe some programming challenges here and there. I'll do a brief summary of my current projects:

• International Standard Atmosphere Calculator (MATLAB), for an assignment due in just a few days. I'm in the home stretch here.
• Sci-fi 'Simulation-Style' Game (Java, SQL), for fun. This was the project that started it all, originally planned as an elaborate excel file and evolving from there. Most of the SQL is complete, Java is still thoroughly in development.

Specific details to come on these later. For now, I'm open to suggestions for projects to try, languages to learn, or whatever else.