Cameron Albert

Ramblings of software development, games and technology.

Archive for the ‘Knights of the Realm’ Category

Silverlight 2.0 and My Game Engine

I got the chat portion of the game engine working with Silverlight 2.0 tonight. I am just using web services to send the commands back and forth for now. Once I complete incorporating the other portions of the engine into Silverlight I will start playing around with sockets. 

Written by Cameron

March 7, 2008 at 12:42 am

PBBG Engine Architecture

Thought I would go ahead and post a little about the architecture I have set up for my PBBG engine so far. Basically, the engine is a library that other projects can reference to make building PBBGs a little easier. All of the logic for handling incoming requests and parsing commands is contained within the engine. My PBBG engine is kind of like a MUD driver, it requires a MUDLib to define objects, persist data, etc. Some interfaces are defined within the engine library to make it extensible while it also contains base class implementations of those interfaces to make building on top of working logic possible. When the engine starts up it raises a set of events and when it processes commands it also raises events to allow the implementing application to control loading of commands, determining the server implementation and creating command instances.


Not the best diagram in the world but kind of gives you the idea of how it works. The column down the middle are the interfaces defined by then engine, which also define base classes, except for the CommandManager which is just a static class for processing commands.

In addition to the classes here are the Verb abstract class, the ICommand interface and the Command<Verb> instance for creating commands from Verbs. The CommandManager raises an event when it finds the command text that allows an external library to set the ICommand instance that will execute the current command. When the engine starts up though it raises an event that will allow the implementation library to set all the commands into memory rather than creating a new instance with each command.

The IServer interface defines an IConnectionManager property where connections into the server are managed, either socket or http.

On the WEB side, which is actually a namespace ".Web"; the "Server" instance writes out a JavaScript reference to an embedded js file containing the script required to submit commands to the engine using AJAX. A separate RequestHandler class actually parses the input from the AJAX call and then attempts to locate or create an IConnection instance on the Server's IConnectionManager instance. The Server in this namespace actually sends the command to the CommandManager.

On the NET side, which is actually a namespace ".Net"; the "Server" instance actually contains the socket used to listen for incoming connections on a port specified during startup. From there the individual IConnection instances contained in the IConnectionManager instance handle processing the input and formatting it into a command. The IConnection instance contains the connected socket and will send the command to the CommandManager.

Both IConnection instances in both namespaces allow messages to be sent to the client along with custom data such as stats, gold, map data, etc. The difference between the two is that the WEB instance sends all of this back as JSON in the HTTP response and the NET instance sends the messages down the socket as they are added to the IConnection instance and then sends the additional data once the command completes execution.

That is all I have completed at this point on the engine side, it processes commands from the web and the implementation library sitting on top of it handles the commands and persists the data. There is plenty of work on the implementation library side still yet to be completed.

Written by Cameron

February 26, 2008 at 10:37 pm

Perenthia Update

I haven't decided yet but am considering using Silverlight 2.0 with the next release of Perenthia. I've completed a good portion of my PBBG engine that will drive Perenthia but want to be able to take advantage of some the features of Silverlight 2.0 to provide better user experience. One of the features that really interests me is the socket support for 2.0. Once I get the 2.0 beta 1 bits I am going to start playing around with running my PBBG engine on a socket server application I wrote for Flash. If all goes well I should be able to provide some better multiplayer features in Perenthia such as real time chat and possibly player vs player combat.

Perenthia will still primarily be a text-based game but Silverlight could allow me to bridge the gap between web and client software. 

Written by Cameron

February 24, 2008 at 12:23 am

Processing Commands

I might have mentioned it before but my PBBG engine is basically a commands processor. In other words it accepts commands from the client, processes the information on the server and sends the response back to the clients as JSON. Not really different from a normal web request except it is specific to my PBBG engine and you don't request documents from the server you are telling the server you want your Character to "do" something.

My PBBG engine is essentially just the command processor and the classes surrounding processing commands. I have abstracted it completely from the data source. There are no data providers or data connections at all in the engine. Instead, if it needs to get data it raises events that a deriving library can handle and pass back the required data in the form of simple interfaces. Some assumptions I did make such as ID values defined in interfaces are int values rather than object since I don't design databases with primary keys other than int. 🙂

One of the things I also did for the CommandManager was to created an abstract Verb class that I can derive from to create command verbs such as move, say, attack, etc. These command verbs can be defined in the deriving library and set in the CommandManager when the game starts up. Another class to assist with commands was a generic Command<T> class where T has to be a derived Verb value. So I can create Command<Move>() and the call an Execute method on the class which in turn creates the Verb instance and executes the code in the Verb class.

This has been working pretty well so far and since the CommandManager raises an event each time if processes a command I can have any number of derived libraries executing their own commands. 

Written by Cameron

February 13, 2008 at 11:58 pm