UNET Message Inheritance Broken

I am using messages, with child messages that contains additional bits of payload data in addition to the parent payload data. However, it does not seem that messages can handle a data payload split between parent and child. It does not throw errors, but the data does not get sent correctly.

My debug log reads this as being sent/recieved
MsgOut: KeyAudioClipIndex = 2 and Vec3=(2.4, 0.0, 1.1)
MsgIn: KeyAudioClipIndex = 0 and Vec3=(2.4, 0.0, 1.1)
***The short data is lost (sent as a value of 2, but received as a value of 0), but the Vec3 is sent.

However if I put all data in the child message class, then it works fine. (Both the short and vec3 are sent correctly)
MsgOut: KeyAudioClipIndex = 2 and Vec3=(2.4, 0.0, 1.1)
MsgIn: KeyAudioClipIndex = 2 and Vec3=(2.4, 0.0, 1.1)
***The short data is sent correctly (sent value of 2, received a value of 2)

This code causes issues with message data loss.

Code (csharp):

1.  
2. public abstract class MessagePlayAudioEffect : MessageBase
3. {
4.     public short keyAudioClipIndex; //msgData, index of the KeyAudioClip being played
5. }
6.  
7. public class MessagePlayAudioEffect3D : MessagePlayAudioEffect
8. {
9.     public Vector3 vector3; //msgData, position of effect
10. }
11.  

This code works properly

Code (csharp):

1.  
2. public abstract class MessagePlayAudioEffect : MessageBase
3. {
4.  
5. }
6.  
7. public class MessagePlayAudioEffect3D : MessagePlayAudioEffect
8. {
9.     public short keyAudioClipIndex; //msgData, index of the KeyAudioClip being played
10.     public Vector3 vector3; //msgData, position of effect
11. }
12.  

Is message inheritance not supported, or bugged? Anybody else having this issue?

As a work-around I can just copy and paste all fields into all message classes and not use inheritance. But this is very bad practice... you should never copy & paste code in multiple locations!!!

Thanks in advance.

 

Hi Zullar

I ran into the same issue. I've researched and tried different ways. The only reliable way I found to get it working is by overriding the default Serialize() and Deserialize() implementations and call their base, like so:

Code (CSharp):

1. using UnityEngine;
2. using UnityEngine.Networking;
3.  
4. public abstract class MessagePlayAudioEffect : MessageBase {
5.     public short keyAudioClipIndex; //msgData, index of the KeyAudioClip being played
6.  
7.     public override void Deserialize (NetworkReader reader) {
8.         base.Deserialize (reader);
9.         this.keyAudioClipIndex = reader.ReadInt16();
10.     }
11.  
12.     public override void Serialize (NetworkWriter writer) {
13.         base.Serialize (writer);
14.         writer.Write(this.keyAudioClipIndex);
15.     }
16.  
17. }
18.  
19. public class MessagePlayAudioEffect3D : MessagePlayAudioEffect {
20.     public Vector3 vector3; //msgData, position of effect
21.  
22.     public override void Deserialize (NetworkReader reader) {
23.         base.Deserialize (reader);
24.         this.vector3 = reader.ReadVector3();
25.     }
26.  
27.     public override void Serialize (NetworkWriter writer) {
28.         base.Serialize (writer);
29.         writer.Write(this.vector3);
30.     }
31. }

You can see in the Documentation that, should you not provide your own overrides, Unity will in fact auto-generate default ones. I'm not sure if it's an oversight or if there's some possible problems related to auto-generating that, but the Unity-generated code does not call into base.Serialize() and base.Deserialize() sadly.

This causes a bit of boilerplate code, but at least you also get more control over serialization as a benefit, and it keeps your Message hierarchy intact.

Hope this helps!