ViaLoadingBase

Universal ViaVersion, ViaBackwards and ViaRewind standalone implementation

This library is mainly designed for clientside implementations, it is also very abstract and doesn't give the
implementors much room to change ViaVersion, for a platform with less abstraction you can look at ViaProtocolHack.

Contact

If you encounter any issues, please report them on the issue tracker.
If you just want to talk or need help with ViaLoadingBase feel free to join my Discord.

Projects implementing ViaLoadingBase

ViaForge: Clientside ViaVersion for Forge
ViaFabricPlus: Fabric mod to connect to EVERY Minecraft server version (Release, Beta, Alpha, Classic, Snapshots, Bedrock) with QoL fixes to the gameplay

Add this to your own project

build.gradle

repositories {
    maven {
        url = "https://repo.viaversion.com/"
    }
    maven {
        url = "https://jitpack.io/"
    }
}

dependencies {
    // https://ci.viaversion.com/
    implementation "com.viaversion:viaversion:4.7.0-23w17a-SNAPSHOT"
    implementation "com.viaversion:viabackwards:4.7.0-23w17a-SNAPSHOT"
    implementation "com.viaversion:viarewind-core:2.0.4-SNAPSHOT"
    
    implementation "org.yaml:snakeyaml:2.0"
    
    implementation "com.github.FlorianMichael:ViaLoadingBase:4.5.0" // https://jitpack.io/#FlorianMichael/ViaLoadingBase
    
    // You also need Netty, Guava and Log4j in your class path, but they should be there if your project is based on Minecraft.
    implementation "com.google.guava:guava:31.1-jre"
    implementation "io.netty:netty-all:5.0.0.Alpha2"
    implementation "org.apache.logging.log4j:log4j-core:2.19.0"
}

Which library do I need?

If your platform is older than the latest Minecraft version, you need ViaVersion + ViaBackwards, if your platform is 1.8.x, you need ViaVersion + ViaBackwards + ViaRewind, otherwise you only need ViaVersion:

A 1.8.x Minecraft client for example would need ViaVersion + ViaBackwards + ViaRewind.
A 1.12.x Minecraft client for example would need ViaVersion + ViaBackwards.
A 1.19.x Minecraft client, for example, would need ViaVersion.

Example implementation

public void init() { // Basic code to load all platforms which are in the class path
    ViaLoadingBase.ViaLoadingBaseBuilder.
        create().
        runDirectory(new File("ViaVersion")).
        nativeVersion(47).
        build();
}

The most important part is the modification of your netty pipeline. This is needed for ViaVersion to translate the packets in both ways.

final UserConnection user = new UserConnectionImpl(channel, true);

new ProtocolPipelineImpl(user);

channel.pipeline().addLast(new VLBPipeline(user) {

    @Override
    public String getDecoderHandlerName() {
        return "decoder";
    }

    @Override
    public String getEncoderHandlerName() {
        return "encoder";
    }

    @Override
    public String getDecompressionHandlerName() {
        return "decompress";
    }

    @Override
    public String getCompressionHandlerName() {
        return "compress";
    }
});

In case your platform has compression, you can call the CompressionReorderEvent at the end of the compression code to correct the compression.

channel.pipeline().fireUserEventTriggered(new CompressionReorderEvent());

ViaLoadingBase will use the provided handler names in the VLB Pipeline in order to do that.

For a mcp based implementation you can have a look at the code in ViaForge

API examples

ViaLoadingBase also offers a system to compare the target version with other versions:

if (ViaLoadingBase.getInstance().getTargetVersion().isOlderThan(ProtocolVersion.v1_8)) {
    // Code is executed when the target version is < than 1.8
}
if (ViaLoadingBase.getInstance().getTargetVersion().isOlderThanOrEqualTo(ProtocolVersion.v1_16_4)) {
    // Code is executed when the target version is < = than 1.16.4
}
if (ViaLoadingBase.getInstance().getTargetVersion().isNewerThan(ProtocolVersion.v1_12_2)) {
    // Code is executed when the target version is > than 1.12.2
}
if (ViaLoadingBase.getInstance().getTargetVersion().isNewerThanOrEqualTo(ProtocolVersion.v1_14_4)) {
    // Code is executed when the target version is > = than 1.14.4
}
if (ViaLoadingBase.getInstance().getTargetVersion().isEqualTo(ProtocolVersion.v1_10)) {
    // Code is executed when the target version is equal to 1.10
}

The versions are compared according to the order in which they are loaded, each protocol version that is loaded gets an
index that is then used for comparison, so if a platform is loaded last, its protocols are treated as oldest.
Below is explained how to determine the pure sequence

To define a range of versions you can use the ProtocolRange class:

final ProtocolRange allVersionsAbove1_8 = ProtocolRange.andNewer(ProtocolVersion.v1_8);
final ProtocolRange allVersionsUnder1_12_2 = ProtocolRange.andOlder(ProtocolVersion.v1_12_2);
final ProtocolRange only1_18_2 = ProtocolRange.singleton(ProtocolRange.v1_18_2);

if (allVersionsAbove1_8.contains(ProtocolVersion.v1_10)) {
    // Check if a version is in the range
}

The class also has a toString() method that automatically formats the range

How to load platforms

public class ExampleImplementation {

    private final Platform examplePlatform = new Platform(
            "Example",
            () -> ViaLoadingBase.inClassPath("net.exampledev.exampleplatform.ExamplePlatform"), // Checks if the platform class is in the class path
            ExamplePlatformImpl::new,
            protocolVersions -> protocolVersions.addAll(ExamplePlatformVersions.PROTOCOLS));

    public void main() {
        ViaLoadingBase.ViaLoadingBaseBuilder.
                create().

                platform(examplePlatform). // will set the platform as last 
                platform(examplePlatform, 0). // will set the platform as first 

                runDirectory(new File("ViaVersion")).
                nativeVersion(47).
                build();
    }
}

For some example implementations and applications you can have a look at the code in ViaFabricPlus