Distinguishing between Client & Server

[crdlpls]

Hi there,

I've just started learning about forge and how it works (Java's not an issue), reading as many tutorials as I can but also trying to go 'off book' so to speak. One thing has always been nagging at me that I really can't seem to find an answer for. 

I get that some things are "client only" and "server only", and that you need to send packets between the two. My issue comes with distinguishing when I need to keep something side-specific, and when things will just work without needing to manually send packets between the two. An example being lets say I write a handler (not copied from anything so it might be wrong, if so please correct me) :

@SubscribeEvent
  public static void onEntityJoin(EntityJoinWorldEvent event){
  Entity entity = event.getEntity();
  if (entity instanceof IMob && entity instanceof EntityLivingBase) {
    entity.setCustomNameTag("Boss");
    entity.getEntityAttribute(SharedMonsterAttributes.MAX_HEALTH).setBaseValue(100);
    entity.setHealth(100);
  }
}

That makes sense to be executed on both client & server to me, as both the client and the server need to know about these changes for HP tracking etc, but I don't know if I'm thinking about it the wrong way.

 

My issue comes basically from knowing what code is executed on the client side vs the server side (for example, would something like the snippit above i.e. event handlers execute on both sides?). Sorry if it's a really stupidly obvious question, I don't want to just be writing code just because that's how the docs are written, but I really want to understand how everything works. There's a lot of "just do this" in tutorials, but not so much why.

Edited November 7, 2018 by crdlpls

[V0idWa1k3r]

48 minutes ago, crdlpls said:

That makes sense to be executed on both client & server to me, as both the client and the server need to know about these changes for HP tracking etc, but I don't know if I'm thinking about it the wrong way.

I think that entity attributes are synced between the server and the client automatically(see NetHandlerPlayClient#handleEntityProperties).

 

48 minutes ago, crdlpls said:

My issue comes basically from knowing what code is executed on the client side vs the server side (for example, would something like the snippit above i.e. event handlers execute on both sides?).

The snipped above would be executed on both sides. You can trace the call hierarchy of any method using your IDE to see where it is called from. For example EntityJoinWorldEvent here is fired in World#spawnEntity. And World#spawnEntity is called from both WorldServer and WorldClient. So what I am trying to say is - use your IDE to answer questions like this. Either trace the call hierarchy or just place a breakpoint and see which side it is triggered on.

 

48 minutes ago, crdlpls said:

when I need to keep something side-specific

If anything is marked as @SideOnly at any point - that is a strong indicator to keep things side specific. Apart from that all logic should run on the server, the client should do as little as possible. The client's job is to render things and accept input. Mostly everything else should be handled on the server.

[crdlpls]

4 minutes ago, V0idWa1k3r said:

I think that entity attributes are synced between the server and the client automatically(see NetHandlerPlayClient#handleEntityProperties).

I'll take a look, if so that makes what I'm trying to do a lot easier, thanks!

5 minutes ago, V0idWa1k3r said:

So what I am trying to say is - use your IDE to answer questions like this. 

Hadn't thought about it that way, forge is a very different beast to anything I've worked with before. I'm gonna have a deeper look into the actual sever/client code and see what I can get heads and tails of. 

 

Thanks!