On Libraries and Overall Architecture

A very useful tool if you may be reusing classes or large parts of code in different applications is a Library. A Library is a collection of classes one can use simply by adding a:

 using LibraryName.Subfolder;  
 import LibraryName;  

at the top of your code. (using for C# and import for Java). I have many classes i reuse on both the server and client, for example a Class.

##Note: from here on out, Class will indicate an RPG class. class will indicate a code class.

Eg: Class - Mage. I have to reuse a lot of the damage and or stat calculators as i calculate data both client and server side. Instead of simply copying classes from folder to folder and worrying about whether or not both classes are updated on both the server and client, i can simply edit my Mage class on the server and it will update on the client.

THE DOWNSIDE: You cannot address the client or the server from your library code. I'm running into problems where my network streams used to communicate from the client and server cannot speak directly to my client or server code. I have to use a retriever to extract variables from the stream classes. It is a work around, but not the best coding practice. Normally you'd want to use a method from inside the class to pass variables out.

Architecture is something many people over look when building their programs. Of course, the user will never see just how your code works, unless you a) open source it, or b) allow it to be read. (Blizzard has released a viewer so you may read their code, some funny comments in there.) I like designing architectures. The overall structure and order is needed for me. Some developers program as they think up ideas, or some dive right in. But i like to take it step by step. Today improved my class system with a better inheritance:

Classes:

      Caster                                                                                                                              Melee

Healer            Damage                                                                            

Monk,         Tempest, Mage                Knight, Reaper, Titan

Poorly formatted, but you get the picture. Healer and Damage(Caster) inherit class Caster. while at the moment  Knight, Reaper, and Titan inherit Melee. Monk can inherit both Healer and Damage, or just Healer, haven't decided. And Tempest and Mage inherit Damage. This does not mean one Class can only use Healing abilities or Melee abilities. Each Class will be able to use any abiliy, or a large range of them, however, one Class will be better suited to heal or deal melee damage.

Architecture is important, you have to know how your code will work and the most efficient use of code. Languages provide a powerful reuse system already with inheritance. In C# the only thing one must do to inherit is thus:

 public class Mage : Caster  

However , Java must supply a type of inheritance:

 public class Mage extends Caster  
 public class Mage implements Caster  

 The first means you may modify any existing methods in the parent or super class. The second means you are using an interface. More on interfeces later. They are very usefull for RGP's and being able to define many different classes with one statement. (Quick example to clear that up, horrible wording)

EG:

Player testMage = new Mage();
Player testKnight = new Knight();

Player would be the interface here. I'll explain them fully in the next entry. For now, tata.

Push on my friends! Many happy coding adventures.

TNariksan.

On TCP & UDP, aka Networking

Over the past week, I have been hard at work getting a working protocol system implemented. As of today I am capable of updating the client with player coordinates and sending and receiving text messages. At first i began with a basic chat client server set up. The server spawned a new thread every time a client connected to it. Before i moved on to implement it into the game the chat server would only receive messages, not echo them to other clients.

Now i have moved on to a dual network stream per client structure. After extensive remodeling to my current set up of the game, i decided to cut my losses and create one simple library to be shared between both the server and the client. That way i could reference my classes without having to copy them over and worry about dependencies. Previously I had a rather strange system of inheritance.

A class, as in RPG class, not programming class. Say for example, a mage class. The class mage inherited an interface and a super class containing only variables. After reexamining C#'s inheritance system, my super class now inherits the interface and mage inherits the super class. However, one could remove the interface entirely and only use a super class, but that would take a little more time and possibly bug fixes.

The problem i am currently facing, is with my library, i designed most of the classes to be server side, thus they are essentially backwards on the client side.

EG: The server waits for a connection, so the client is supposed to be the one actively seeking the connection. Yet my current system has both client and server waiting at first. Problem? I think so, no connection would ever be made.

So that's where i am. Oh, and I'm also attempting to send the world data (its size and client.player id) to the client instead of it loading from the client's computer.

A quick note about UDP vs TCP. (I think it's important to know the difference)

first: UDP and TCP are both internet data relay protocols. UDP is built for speed while TCP is built for dependibility.

UDP says:
Server: HERE! THIS IS DATA! TAKE MORE DATA! HAVE ALL THE DATA!
Client: .......

TCP says:
Server: Here my good sir, have a little bit of data.
Client: Why thank you, this looks like x data.
Server: Why yes it is.
Client: Cool, thanks.

So as one can see, TCP involves more communication, but will make sure your data gets to the right place, while UDP just spits data out and doesn't have any client to server communication.

Personally, i'd use UDP for less crucial tasks, like updating a player's money, or their items in inventory. But for stuff like, player position or health, it would be good to use TCP.

If you have any questions, just ask!

TNariksan

MULTITHREADING

One of the more advanced topics many programmers may eventually come to face: running multiple things at once. Today I wrote a simple multi-threaded chat server. It may seem trivial but the more advanced application would be to easily upgrade it with protocols to tell your clients what the server looks like.

There are two types of MMO servers:
Server Heavy or Client Heavy.

Server Heavy: This requires a more powerful server, as the name may hint. In this format the client simply sends a command to the server that the player is moving forward, not that the player moved x amount forward. This type of server is less liable to hacking but requires more processing power as the server is doing all the calculating and not the client machine.

Client Heavy: This is the inverse of the above. The client does all the heavy lifting and the server only relays positions of other players back to the client and the game state.

For an MMO server, one must multi-thread. You should have a thread for each player or their connection. In my server, a new thread is spawned for each new connection made to the server.

More to come,
TNariksan

Release of the Alpha

Today I release an alpha version of the game I will be integrating to MMO status. It is a very rough platform. There are nearly no comments and scraps of unused and obsolete code laying around. Later this week or early next I'll release a cleaned and commented version.

Cheers,
TNariksan

The Summary:

To the first post. First off, a history.

My name is Tony, and I am a coder. I have been interesting in the computer sciences for a few years now, about  five years in total. At first, I floundered about with Lua not knowing much about how anything worked. I clumsily bumped my way through Lua with World of Warcraft. I come from a medium intensity, recreational gaming background. This blog is to mainly focus on the gaming side of programming. After foolishly attempting to teach myself Lua, I found Java. Having worked with Java for three years now, I do much like the language. Very simple to understand and easy to learn (for me). I am an Object Oriented kinda guy. However, in my latest endeavors, I have mixed the two, OO and Procedural. About a year ago I discovered XNA (XNA = Xna is Not an Acronym). I have recently been working on an MMORPG game engine and thought I might document the process.

Post Script: Someday I will offer Java and XNA/C# video tutorials.

TNariksan