Started implementing session matchmaking. Session creation and update implemented.

Config/DefaultEngine.ini

@@ -31,3 +31,6 @@ AppliedDefaultGraphicsPerformance=Maximum
 +PropertyRedirects=(OldName="/Script/TurnBasedTutorial.Trooper.OnPlayersSide",NewName="/Script/TurnBasedTutorial.Trooper.bOnPlayersSide")
 +FunctionRedirects=(OldName="/Script/TurnBasedTutorial.MyPlayerController.MoveHero",NewName="/Script/TurnBasedTutorial.MyPlayerController.MoveTropper")
 +FunctionRedirects=(OldName="/Script/TurnBasedTutorial.MyPlayerController.MoveTropper",NewName="/Script/TurnBasedTutorial.MyPlayerController.MoveTrooper")
+
+[OnlineSubsystem]
+DefaultPlatformService=Null

Source/TurnBasedTutorial/MyGameInstanceSubsystem.cpp

@@ -0,0 +1,101 @@
+// Fill out your copyright notice in the Description page of Project Settings.
+
+#include "MyGameInstanceSubsystem.h"
+
+#include "OnlineSubsystemUtils.h"
+
+UMyGameInstanceSubsystem::UMyGameInstanceSubsystem() : CreateSessionCompleteDelegate(
+	FOnCreateSessionCompleteDelegate::CreateUObject(this, &ThisClass::OnCreateSessionCompleted))
+{
+}
+
+
+void UMyGameInstanceSubsystem::CreateSession(int32 NumPublicConnections, bool bIsLANMatch)
+{
+	const IOnlineSessionPtr SessionInterface = Online::GetSessionInterface(GetWorld());
+	if (!SessionInterface.IsValid())
+	{
+		OnCreateSessionCompleteEvent.Broadcast(false);
+		return;
+	}
+
+	LastSessionSettings = MakeShareable(new FOnlineSessionSettings());
+	LastSessionSettings->NumPrivateConnections = 0;
+	LastSessionSettings->NumPublicConnections = NumPublicConnections;
+	LastSessionSettings->bAllowInvites = true;
+	LastSessionSettings->bAllowJoinInProgress = true;
+	LastSessionSettings->bAllowJoinViaPresence = true;
+	LastSessionSettings->bAllowJoinViaPresenceFriendsOnly = true;
+	LastSessionSettings->bIsDedicated = false;
+	LastSessionSettings->bUsesPresence = true;
+	LastSessionSettings->bIsLANMatch = bIsLANMatch;
+	LastSessionSettings->bShouldAdvertise = true;
+
+	LastSessionSettings->Set(SETTING_MAPNAME, FString("Your Level Name"),
+	                         EOnlineDataAdvertisementType::ViaOnlineService);
+
+	CreateSessionCompleteDelegateHandle = SessionInterface->AddOnCreateSessionCompleteDelegate_Handle(
+		CreateSessionCompleteDelegate);
+
+	const ULocalPlayer* localPlayer = GetWorld()->GetFirstLocalPlayerFromController();
+	if (!SessionInterface->CreateSession(*localPlayer->GetPreferredUniqueNetId(), NAME_GameSession,
+	                                     *LastSessionSettings))
+	{
+		SessionInterface->ClearOnCreateSessionCompleteDelegate_Handle(CreateSessionCompleteDelegateHandle);
+
+		OnCreateSessionCompleteEvent.Broadcast(false);
+	}
+}
+
+void UMyGameInstanceSubsystem::OnCreateSessionCompleted(FName SessionName, bool bSuccessful)
+{
+	const IOnlineSessionPtr SessionInterface = Online::GetSessionInterface(GetWorld());
+	if (SessionInterface)
+	{
+		SessionInterface->ClearOnCreateSessionCompleteDelegate_Handle(CreateSessionCompleteDelegateHandle);
+	}
+
+	OnCreateSessionCompleteEvent.Broadcast(bSuccessful);
+}
+
+void UMyGameInstanceSubsystem::UpdateSession()
+{
+	const IOnlineSessionPtr SessionInterface = Online::GetSessionInterface(GetWorld());
+	if (!SessionInterface.IsValid())
+	{
+		OnCreateSessionCompleteEvent.Broadcast(false);
+		return;
+	}
+
+	const TSharedPtr<FOnlineSessionSettings> UpdatedSessionSettings = MakeShareable(
+		new FOnlineSessionSettings(*LastSessionSettings));
+
+	// Here we can insert any changes we want
+	UpdatedSessionSettings->Set(SETTING_MAPNAME, FString("Updated Level Name"),
+	                            EOnlineDataAdvertisementType::ViaOnlineService);
+
+	UpdateSessionCompleteDelegateHandle =
+		SessionInterface->AddOnUpdateSessionCompleteDelegate_Handle(UpdateSessionCompleteDelegate);
+
+	if (!SessionInterface->UpdateSession(NAME_GameSession, *UpdatedSessionSettings))
+	{
+		SessionInterface->ClearOnUpdateSessionCompleteDelegate_Handle(UpdateSessionCompleteDelegateHandle);
+
+		OnUpdateSessionCompleteEvent.Broadcast(false);
+	}
+	else
+	{
+		LastSessionSettings = UpdatedSessionSettings;
+	}
+}
+
+void UMyGameInstanceSubsystem::OnUpdateSessionCompleted(FName SessionName, bool bSuccessful)
+{
+	const IOnlineSessionPtr sessionInterface = Online::GetSessionInterface(GetWorld());
+	if (sessionInterface)
+	{
+		sessionInterface->ClearOnUpdateSessionCompleteDelegate_Handle(UpdateSessionCompleteDelegateHandle);
+	}
+
+	OnUpdateSessionCompleteEvent.Broadcast(bSuccessful);
+}

Source/TurnBasedTutorial/MyGameInstanceSubsystem.h

@@ -0,0 +1,44 @@
+// Fill out your copyright notice in the Description page of Project Settings.
+
+#pragma once
+
+#include "CoreMinimal.h"
+
+#include "Interfaces/OnlineSessionInterface.h"
+#include "Subsystems/GameInstanceSubsystem.h"
+#include "MyGameInstanceSubsystem.generated.h"
+
+DECLARE_DYNAMIC_MULTICAST_DELEGATE_OneParam(FMyOnCreateSessionComplete, bool, Successful);
+DECLARE_DYNAMIC_MULTICAST_DELEGATE_OneParam(FMyOnUpdateSessionComplete, bool, Successful);
+
+/**
+ * 
+ */
+UCLASS()
+class TURNBASEDTUTORIAL_API UMyGameInstanceSubsystem : public UGameInstanceSubsystem
+{
+	GENERATED_BODY()
+
+public:
+	UMyGameInstanceSubsystem();
+
+	void CreateSession(int32 NumPublicConnections, bool bIsLANMatch);
+
+	void UpdateSession();
+	
+	FMyOnCreateSessionComplete OnCreateSessionCompleteEvent;
+	FMyOnUpdateSessionComplete OnUpdateSessionCompleteEvent;
+	
+protected:
+	void OnCreateSessionCompleted(FName SessionName, bool bSuccessful);
+
+	void OnUpdateSessionCompleted(FName SessionName, bool bSuccessful);
+	
+private:
+	FOnCreateSessionCompleteDelegate CreateSessionCompleteDelegate;
+	FDelegateHandle CreateSessionCompleteDelegateHandle;
+	TSharedPtr<FOnlineSessionSettings> LastSessionSettings;
+
+	FOnUpdateSessionCompleteDelegate UpdateSessionCompleteDelegate;
+	FDelegateHandle UpdateSessionCompleteDelegateHandle;
+};

Source/TurnBasedTutorial/TurnBasedTutorial.Build.cs

@@ -16,7 +16,7 @@ public class TurnBasedTutorial : ModuleRules
 		// PrivateDependencyModuleNames.AddRange(new string[] { "Slate", "SlateCore" });
 		
 		// Uncomment if you are using online features
-		// PrivateDependencyModuleNames.Add("OnlineSubsystem");
+		PrivateDependencyModuleNames.AddRange(new string[] {"OnlineSubsystem", "OnlineSubsystemUtils"});
 
 		// To include OnlineSubsystemSteam, add it to the plugins section in your uproject file with the Enabled attribute set to true
 	}

TurnBased.uproject

@@ -1,6 +1,6 @@
 {
 	"FileVersion": 3,
-	"EngineAssociation": "{B4FE6467-4579-3D84-B22A-558A3D607596}",
+	"EngineAssociation": "4.27",
 	"Category": "",
 	"Description": "",
 	"Modules": [