Skip to content

Mirror::NetworkIdentity

The NetworkIdentity identifies objects across the network, between server and clients. Its primary data is a NetworkInstanceId which is allocated by the server and then set on clients. This is used in network communications to be able to lookup game objects on different machines. More...

Inherits from MonoBehaviour

Public Events

Name
ClientAuthorityCallback clientAuthorityCallback()
A callback that can be populated to be notified when the client-authority state of objects changes.

Public Functions

Name
NetworkIdentity GetSceneIdentity(ulong id)
Gets the NetworkIdentity from the sceneIds dictionary with the corresponding id
void ResetNextNetworkId()
Resets nextNetworkId = 1
delegate void ClientAuthorityCallback(NetworkConnection conn, NetworkIdentity identity, bool authorityState)
The delegate type for the clientAuthorityCallback.
void RebuildObservers(bool initialize)
This causes the set of players that can see this object to be rebuild. The OnRebuildObservers callback function will be invoked on each NetworkBehaviour.
bool AssignClientAuthority(NetworkConnection conn)
Assign control of an object to a client via the client's NetworkConnection.
void RemoveClientAuthority()
Removes ownership for an object.

Public Properties

Name
bool isClient
Returns true if running as a client and this object was spawned by a server.
bool isServer
Returns true if NetworkServer.active and server is not stopped.
bool hasAuthority
This returns true if this object is the authoritative player object on the client.
uint netId
Unique identifier for this particular object instance, used for tracking objects between networked clients and the server.
NetworkConnection connectionToServer
The NetworkConnection associated with this NetworkIdentity. This is only valid for player objects on a local client.
NetworkConnectionToClient connectionToClient
The NetworkConnection associated with this NetworkIdentity. This is valid for player and other owned objects in the server.
NetworkBehaviour [] NetworkBehaviours
NetworkVisibility visibility
Guid assetId
Unique identifier used to find the source assets when server spawns the on clients.
bool SpawnedFromInstantiate

Public Attributes

Name
bool isLocalPlayer
This returns true if this object is the one that represents the player on the local machine.
Dictionary< int, NetworkConnection > observers
The set of network connections (players) that can see this object.
ulong sceneId
A unique identifier for NetworkIdentity objects within a scene.
bool serverOnly
Flag to make this object only exist when the game is running as a server (or host).
readonly Dictionary< uint, NetworkIdentity > spawned
All spawned NetworkIdentities by netId. Available on server and client.

Detailed Description

class Mirror::NetworkIdentity;

The NetworkIdentity identifies objects across the network, between server and clients. Its primary data is a NetworkInstanceId which is allocated by the server and then set on clients. This is used in network communications to be able to lookup game objects on different machines.

The NetworkIdentity is used to synchronize information in the object with the network. Only the server should create instances of objects which have NetworkIdentity as otherwise they will not be properly connected to the system.

For complex objects with a hierarchy of subcomponents, the NetworkIdentity must be on the root of the hierarchy. It is not supported to have multiple NetworkIdentity components on subcomponents of a hierarchy.

NetworkBehaviour scripts require a NetworkIdentity on the game object to be able to function.

The NetworkIdentity manages the dirty state of the NetworkBehaviours of the object. When it discovers that NetworkBehaviours are dirty, it causes an update packet to be created and sent to clients.

The flow for serialization updates managed by the NetworkIdentity is:

Each NetworkBehaviour has a dirty mask. This mask is available inside OnSerialize as syncVarDirtyBits Each SyncVar in a NetworkBehaviour script is assigned a bit in the dirty mask. Changing the value of SyncVars causes the bit for that SyncVar to be set in the dirty mask Alternatively, calling SetDirtyBit() writes directly to the dirty mask NetworkIdentity objects are checked on the server as part of it's update loop If any NetworkBehaviours on a NetworkIdentity are dirty, then an UpdateVars packet is created for that object The UpdateVars packet is populated by calling OnSerialize on each NetworkBehaviour on the object NetworkBehaviours that are NOT dirty write a zero to the packet for their dirty bits NetworkBehaviours that are dirty write their dirty mask, then the values for the SyncVars that have changed If OnSerialize returns true for a NetworkBehaviour, the dirty mask is reset for that NetworkBehaviour, so it will not send again until its value changes. The UpdateVars packet is sent to ready clients that are observing the object

On the client: an UpdateVars packet is received for an object The OnDeserialize function is called for each NetworkBehaviour script on the object Each NetworkBehaviour script on the object reads a dirty mask. If the dirty mask for a NetworkBehaviour is zero, the OnDeserialize functions returns without reading any more If the dirty mask is non-zero value, then the OnDeserialize function reads the values for the SyncVars that correspond to the dirty bits that are set If there are SyncVar hook functions, those are invoked with the value read from the stream.

Public Events Documentation

event clientAuthorityCallback

static ClientAuthorityCallback clientAuthorityCallback()

A callback that can be populated to be notified when the client-authority state of objects changes.

Whenever an object is spawned with client authority, or the client authority status of an object is changed with AssignClientAuthority or RemoveClientAuthority, then this callback will be invoked.

This callback is only invoked on the server.

Public Functions Documentation

function GetSceneIdentity

static NetworkIdentity GetSceneIdentity(
    ulong id
)

Gets the NetworkIdentity from the sceneIds dictionary with the corresponding id

Parameters:

  • id

Return: NetworkIdentity from the sceneIds dictionary

function ResetNextNetworkId

static void ResetNextNetworkId()

Resets nextNetworkId = 1

function ClientAuthorityCallback

delegate void ClientAuthorityCallback(
    NetworkConnection conn,
    NetworkIdentity identity,
    bool authorityState
)

The delegate type for the clientAuthorityCallback.

Parameters:

  • conn The network connection that is gaining or losing authority.
  • identity The object whose client authority status is being changed.
  • authorityState The new state of client authority of the object for the connection.

function RebuildObservers

inline void RebuildObservers(
    bool initialize
)

This causes the set of players that can see this object to be rebuild. The OnRebuildObservers callback function will be invoked on each NetworkBehaviour.

Parameters:

  • initialize True if this is the first time.

function AssignClientAuthority

inline bool AssignClientAuthority(
    NetworkConnection conn
)

Assign control of an object to a client via the client's NetworkConnection.

Parameters:

  • conn The connection of the client to assign authority to.

Return: True if authority was assigned.

This causes hasAuthority to be set on the client that owns the object, and NetworkBehaviour.OnStartAuthority will be called on that client. This object then will be in the NetworkConnection.clientOwnedObjects list for the connection.

Authority can be removed with RemoveClientAuthority. Only one client can own an object at any time. This does not need to be called for player objects, as their authority is setup automatically.

function RemoveClientAuthority

inline void RemoveClientAuthority()

Removes ownership for an object.

This applies to objects that had authority set by AssignClientAuthority, or [NetworkServer.Spawn] with a NetworkConnection parameter included.

Authority cannot be removed for player objects.

Public Property Documentation

property isClient

bool isClient;

Returns true if running as a client and this object was spawned by a server.

IMPORTANT: checking NetworkClient.active means that isClient is false in OnDestroy:

public bool isClient => NetworkClient.active && netId != 0 && !serverOnly;

but we need it in OnDestroy, e.g. when saving skillbars on quit. this works fine if we keep the UNET way of setting isClient manually.

=> fixes

property isServer

bool isServer;

Returns true if NetworkServer.active and server is not stopped.

IMPORTANT: checking NetworkServer.active means that isServer is false in OnDestroy:

public bool isServer => NetworkServer.active && netId != 0;

but we need it in OnDestroy, e.g. when saving players on quit. this works fine if we keep the UNET way of setting isServer manually.

=> fixes

property hasAuthority

bool hasAuthority;

This returns true if this object is the authoritative player object on the client.

This value is determined at runtime. For most objects, authority is held by the server.

For objects that had their authority set by AssignClientAuthority on the server, this will be true on the client that owns the object. NOT on other clients.

property netId

uint netId;

Unique identifier for this particular object instance, used for tracking objects between networked clients and the server.

This is a unique identifier for this particular GameObject instance. Use it to track GameObjects between networked clients and the server.

property connectionToServer

NetworkConnection connectionToServer;

The NetworkConnection associated with this NetworkIdentity. This is only valid for player objects on a local client.

property connectionToClient

NetworkConnectionToClient connectionToClient;

The NetworkConnection associated with this NetworkIdentity. This is valid for player and other owned objects in the server.

Use it to return details such as the connection's identity, IP address and ready status.

property NetworkBehaviours

NetworkBehaviour [] NetworkBehaviours;

property visibility

NetworkVisibility visibility;

property assetId

Guid assetId;

Unique identifier used to find the source assets when server spawns the on clients.

The AssetId trick: Ideally we would have a serialized 'Guid m_AssetId' but Unity can't serialize it because Guid's internal bytes are private UNET used 'NetworkHash128' originally, with byte0, ..., byte16 which works, but it just unnecessary extra code Using just the Guid string would work, but it's 32 chars long and would then be sent over the network as 64 instead of 16 bytes

The solution is to serialize the string internally here and then use the real 'Guid' type for everything else via .assetId

property SpawnedFromInstantiate

bool SpawnedFromInstantiate;

Public Attributes Documentation

variable isLocalPlayer

bool isLocalPlayer => ClientScene.localPlayer == this;

This returns true if this object is the one that represents the player on the local machine.

This is set when the server has spawned an object for this particular client.

variable observers

Dictionary< int, NetworkConnection > observers;

The set of network connections (players) that can see this object.

null until OnStartServer was called. this is necessary for SendTo* to work properly in server-only mode.

variable sceneId

ulong sceneId;

A unique identifier for NetworkIdentity objects within a scene.

This is used for spawning scene objects on clients.

variable serverOnly

bool serverOnly;

Flag to make this object only exist when the game is running as a server (or host).

variable spawned

static readonly Dictionary< uint, NetworkIdentity > spawned = new Dictionary<uint, [NetworkIdentity](/Documentation/Cops%20And%20Robbers/Classes/classMirror_1_1NetworkIdentity/)>();

All spawned NetworkIdentities by netId. Available on server and client.

Updated on 27 January 2021 at 18:44:11 UTC