Hiya there !
First thoughts : that's a great idea !
I'm quite new here, so I don't know what has been done about this before, and since April 2021, but as I come from ServUO, was a JustUO dev and I've been there since RunUO 1.0, I thought I could share some ideas about what we used to do on RunUO based projects. Remember those are written in C# mostly, but I guess for my answer the most important aspect is the analysis of what is done about versioning on RunUO and forked projects.
So we used to call that Serialization/Deserialization. Basically, it's a versioning system. I think the update command is a very neat idea and isn't part of ServUO. It's just done automatically when you save your world (Serialization) and then load your world (Deserialization).
So each object has those two functions, and they're both based on a global persistence system. Saves are done in a subfolder 'Saves' and there you can find all sorts of bin/idx/tdb files, some XML's.
Welp, coming from Legends of Aria community admin program, I can share this also: they use 'db' files for all the saves and it seems a strong option. On UO emulator, and the serialization/deserialization system, you kinda work blind and if anything goes wrong, it's a world wipe. So there are improvement to make to what I'm going to explain.
Btw, LoA is written in Lua for scripts and mods, XML's for templates and Unity3D for any client modifications (so C#)
Anyways, let's focus on Ser/Deser function in ServUO.
Let's take an example, it's easier
e.g. PlayerMobile, which is the script for any player 'object', or in other words any 'Mobile' in game that is a player. The base script Mobile is split into two: PlayerMobile and BaseCreature.
You have inside that script two functions that can be useful to illustrate my thoughts : Serialize and Deserialize.
Serialize is triggered on world saves, wether they are automatic or manual.
Deserialize is trigger when the world is loading from saves, basically at every restart.
Just that, I really like your idea of a command, as it's something you can't do on ServUO. Over the years, when mixing with Ser/Deser, I had to do workarounds to simluate a command. Example : I wanted to convert old saves to a newer version. So I had to play with an old version of a Deserialize function, a new version of a Serialize version. Launch the server that way. Save manually to generate new world saves. Then switch to the new Deserialize function and run the server again.
Now imagine, how it was done, you have to do that for every 'object' in game that was modified with a newer version.
But it's a very good system that would require a bit of improvement.
If we look deeper in the Serialize fuction (I'll skip any code here, as I guess it's just food for thoughts ^^):
- First step, you call the base function Serialize. It's the common part from the persistence scripts.
- Then you write a version number to your saves: e.g. Version 28. Remember, this is for the BaseCreature script, to any other objects can have different version numbers.
- Then you consider reading from version 28 to version 0. Going from the newest, to the oldest. We usually seperated the sections for each version with a comment: //version 28 .. //version 27 ... and so on.
- Basically, no IFs, no ELSEs, no CASEs, nothing. Just writing all the properties from the newest to the oldests in the world saves files.
- There is an exception though, when you reach version 0, or along the way, you may need to put an IF for later corrections. Delicate though.
And that's it for the serialization !
Any modification you want to do to a player, and you want it kept on worlds saves and restarts, it had to be added as a new version. For example, we want our players to become Bio Engineers, something very custom, well, you'll have to create version 29 (just by giving that variable the value of 29 when it was 28 before your modifications), add the comments (//version 29) and start writing all the new properties linked to a player there, on the top of the Serialize function.
Here's an example of C# Serialize function. Btw, you can find that on any GitHub related to RunUO and children.
Code: Select all
public override void Serialize(GenericWriter writer)
{
base.Serialize(writer);
writer.Write(28); // version
// Version 28
writer.Write(m_PeacedUntil);
// Version 27
writer.Write(m_AnkhNextUse);
// Version 26
writer.Write(m_AutoStabled, true);
// Version 25
if (m_AcquiredRecipes == null)
{
writer.Write(0);
}
else
{
writer.Write(m_AcquiredRecipes.Count);
foreach (var kvp in m_AcquiredRecipes)
{
writer.Write(kvp.Key);
writer.Write(kvp.Value);
}
}
...
Now Deserialize function. That one is easier to read and I like the way it was done.
It's just you read the version number. So if we added a number every time, not passing one, or not mixing too many exceptions, it should be clear how to read this. First you read the version number, then start a switch with cases to browse all the version from up to down.
Illustration (still C#) :
Code: Select all
public override void Deserialize(GenericReader reader)
{
base.Deserialize(reader);
int version = reader.ReadInt();
switch (version)
{
case 28:
{
m_PeacedUntil = reader.ReadDateTime();
goto case 27;
}
case 27:
{
m_AnkhNextUse = reader.ReadDateTime();
goto case 26;
}
case 26:
{
m_AutoStabled = reader.ReadStrongMobileList();
goto case 25;
}
case 25:
{
int recipeCount = reader.ReadInt();
if (recipeCount > 0)
{
m_AcquiredRecipes = new Dictionary<int, bool>();
for (int i = 0; i < recipeCount; i++)
{
int r = reader.ReadInt();
if (reader.ReadBool()) //Don't add in recipies which we haven't gotten or have been removed
{
m_AcquiredRecipes.Add(r, true);
}
}
}
goto case 24;
}
...
So actually, imho, the order you add new version and insert them inside the scripts is really important. At least, unless you want a big spagetthi code lol
Hopefully this helps a little. Myself very very new here, less than a week, I'm discovering the amazing work you did there, Xuri, and all your mates of course, over the years. It's a really strong system with options that open so many possibilities.
I'll be there around working on my learning curve. Hopefully one day I can help more than this 'food for thoughts' answer
Take care ! Thanks a lot for UOX3 and keeping the project up over sooooo many years. Respect.
-Rek-
