Attributes

Networking attributes are added to members of NetworkBehaviour scripts to tell Mirage to do different things.

There are 4 types of attributes that Mirage has:

• RPC Attributes: Cause a method to send a network message so that the body of the method is invoked on either the server or client.
• Block methods invokes: Attributes used to restrict method invocation to specific contexts.
• SyncVar: Add to Fields to cause their value to be automatically synced to clients.
• Bit Packing: These attributes modify how values are written, providing an easy way to compress values before they are sent over the network. They can be applied to Fields and method Parameters.

RPC Attributes

Full details on RPC can be found on the Remote Actions page.

Both Rpc attributes support setting the channel to Reliable or Unreliable.

note

When using abstract or virtual methods, the attributes need to be applied to the override methods too.

• ClientRpcAttribute
  The ClientRpcAttribute allows the server to use a Remote Procedure Call (RPC) to run a function on specific clients, with options to target the owner, all observers, or a specified player. See also: ClientRpc

• ServerRpcAttribute
  The ServerRpcAttribute is used when you want to call a function on the server from a client. Make sure to validate the input on the server. Note that you cannot call this attribute from the server itself. You can use this attribute as a wrapper around another function, allowing you to call it from the server as well. Additionally, you can return values from functions marked with this attribute. See also: ServerRpc

Block Methods Invokes

These attributes can be added to methods to block them from being invoked in the wrong place. These attributes can only be used in NetworkBehaviour classes and when the object is spawned. If the object is not spawned, all the flags like IsServer will be false so will block the methods even if the server is running.

By default, methods with these attributes will throw a MethodInvocationException if invoked improperly. However, you can add error = false to return instead of throwing an exception.

note

When a method returns early due to a blocked invocation, the method will return default values for the return value or out parameters.

These attributes can be used for Unity game loop methods like Start, Update or OnCollisionEnter, as well as other implemented methods that need to be restricted to certain contexts.

Available Attributes:

• ServerAttribute: Methods can only be invoked on the server.
• ClientAttribute: Methods can only be invoked on the client.
• HasAuthorityAttribute: Methods can only be invoked on the client when the player has authority of the object. See: Authority
• LocalPlayerAttribute: Methods can only be invoked on the client when the object is the local player. See: Authority
• NetworkMethodAttribute: Methods can only be invoked based on the flags set in the attribute. For example, NetworkFlags.Server | NetworkFlags.HasAuthority allows the method to be called on the server OR on the client with authority.

Examples:

[Server]
void SpawnCoin() 
{
    // This method is only allowed to be invoked on the server.
}

[NetworkMethod(NetworkFlags.Server | NetworkFlags.NotActive)]
public void StartGame()
{
    // This method will run on the server or in single-player mode.
    // It will only be blocked if the client is active.
}