Identity & Sessions

UCrimsonOnlineIdentityService

Wraps IOnlineIdentity. Handles platform login and logout, and reports the cached profile of each local player. Every function takes LocalUserNum (default 0) as its last parameter.

Member	Description
Login(LocalUserNum = 0)	Starts platform login with empty credentials, which triggers the platform's auto-login flow. Result arrives on OnLoginComplete
Logout(LocalUserNum = 0)	Logs the local player out. Result arrives on OnLogoutComplete
GetLocalPlayerInfo(LocalUserNum = 0)	BlueprintPure. Returns FCrimsonOnlinePlayerInfo (DisplayName, PlatformUserId, LoginStatus, Platform)
GetLoginStatus(LocalUserNum = 0)	BlueprintPure. Returns ECrimsonLoginStatus: NotLoggedIn, UsingLocalProfile or LoggedIn
OnLoginComplete	Delegate: bool bSuccess, const FCrimsonOnlinePlayerInfo& PlayerInfo. Fires for both success and failure
OnLogoutComplete	Delegate: bool bSuccess

Async node

Login (Online) (UCrimsonAsyncAction_Login). Input pin: Local User Num (int32, default 0). Output pins On Success and On Failure, each carrying bSuccess and Player Info. On failure Player Info comes back with LoginStatus = NotLoggedIn.

There is no IsLoggedIn helper

Test GetLoginStatus(0) == ECrimsonLoginStatus::LoggedIn instead. UsingLocalProfile means the player has a local profile but no authenticated network session - treat it as offline for anything that needs the backend.

UCrimsonOnlineSessionService

Wraps IOnlineSession for the full session lifecycle: Create -> Start -> (players join) -> End -> Destroy. Session names are FString and default to "GameSession", the name UE's own travel and URL logic expects. Settings come from FCrimsonSessionSettings.

FCrimsonSessionSettings

Field	Type	Default	Description
MaxPlayers	int32	4	Maximum public connections advertised for the session
bIsLanMatch	bool	false	LAN session - skips the platform matchmaking backend
bUsesPresence	bool	true	Advertise to friends through platform presence (Steam Rich Presence, Epic overlay)
bAllowInvites	bool	true	Allow platform friend invites into this session
bAllowJoinInProgress	bool	false	Allow players to join after StartSession
MapName	FString	empty	Travel URL or level long package name, used for server travel on join
GameModeName	FString	empty	Free-form game mode label advertised with the session

Full API

Member	Description
CreateSession(Settings, SessionName = "GameSession")	Creates and advertises a session; the caller becomes the host. Completes on OnSessionCreated
FindSessions(MaxResults = 20, LocalUserNum = 0)	Searches for sessions using the platform's default filter. Completes on OnSessionsFound
JoinSession(Result, SessionName = "GameSession")	Joins one FCrimsonSessionSearchResult returned by OnSessionsFound. Completes on OnSessionJoined
StartSession(SessionName = "GameSession")	Moves the session to in-progress. Completes on OnSessionStarted
EndSession(SessionName = "GameSession")	Moves the session to ended. Call before DestroySession. Completes on OnSessionEnded
DestroySession(SessionName = "GameSession")	Destroys the session and frees platform resources. Completes on OnSessionDestroyed
GetSessionState(SessionName = "GameSession")	BlueprintPure. Returns ECrimsonSessionState
IsSessionActive(SessionName = "GameSession")	BlueprintPure. True when GetSessionState is neither NoSession nor Destroying
OnSessionCreated	Delegate: bool bSuccess, const FString& SessionName
OnSessionsFound	Delegate: bool bSuccess, const TArray<FCrimsonSessionSearchResult>& Results
OnSessionJoined	Delegate: bool bSuccess, const FString& TravelURL - pass TravelURL straight to ClientTravel
OnSessionStarted	Delegate: bool bSuccess
OnSessionEnded	Delegate: bool bSuccess
OnSessionDestroyed	Delegate: bool bSuccess

The connect string is handed to you

The service calls IOnlineSession::GetResolvedConnectString internally and delivers the result as the TravelURL argument of OnSessionJoined. There is no separate GetResolvedConnectString function to call, and no player registration API - registration is left to the engine's session travel path.

Host + client example

cpp

// Bind the delegates once (e.g. in your subsystem's Initialize), then call the actions.
// Handlers must be UFUNCTIONs - these are dynamic multicast delegates.
#include "CrimsonOnlineSubsystemGI.h"
#include "Services/CrimsonOnlineSessionService.h"
#include "Engine/World.h"

void UMyMatchmaking::HostGame()
{
    UCrimsonOnlineSessionService* Sessions =
        UCrimsonOnlineSubsystemGI::Get(this)->GetSessionService();

    Sessions->OnSessionCreated.AddDynamic(this, &UMyMatchmaking::HandleSessionCreated);

    FCrimsonSessionSettings Settings;
    Settings.MaxPlayers           = 4;
    Settings.bUsesPresence        = true;
    Settings.bAllowJoinInProgress = false;
    Settings.MapName              = TEXT("Level_Arena");

    Sessions->CreateSession(Settings);   // SessionName defaults to "GameSession"
}

void UMyMatchmaking::HandleSessionCreated(bool bSuccess, const FString& SessionName)
{
    if (bSuccess)
    {
        UCrimsonOnlineSubsystemGI::Get(this)->GetSessionService()->StartSession(SessionName);
    }
}

// ---- CLIENT ----
void UMyMatchmaking::FindAndJoin()
{
    UCrimsonOnlineSessionService* Sessions =
        UCrimsonOnlineSubsystemGI::Get(this)->GetSessionService();

    Sessions->OnSessionsFound.AddDynamic(this, &UMyMatchmaking::HandleSessionsFound);
    Sessions->OnSessionJoined.AddDynamic(this, &UMyMatchmaking::HandleSessionJoined);
    Sessions->FindSessions(20);
}

void UMyMatchmaking::HandleSessionsFound(bool bSuccess,
    const TArray<FCrimsonSessionSearchResult>& Results)
{
    if (bSuccess && Results.Num() > 0)
    {
        UCrimsonOnlineSubsystemGI::Get(this)->GetSessionService()->JoinSession(Results[0]);
    }
}

void UMyMatchmaking::HandleSessionJoined(bool bSuccess, const FString& TravelURL)
{
    if (bSuccess && !TravelURL.IsEmpty())
    {
        if (APlayerController* PC = GetWorld()->GetFirstPlayerController())
        {
            PC->ClientTravel(TravelURL, TRAVEL_Absolute);
        }
    }
}