Online Services

The Online Services plugin is some of the new hotness in UE 5.1+. Though it’s still in beta as of UE 5.5, if your new game intends to upgrade to subsequent UE 5 versions, Epic recommends using Online Services (OSSv2) rather than the old soon-to-be-deprecated Online Subsystem (OSSv1).

LyraStarterGame is the example Epic has published that intends to demonstrate how to use the new Online Services plugin. It does so via the Common User plugin that ships with Lyra.

The information in this document is based on Lyra’s implementation of Online Services and Common User, given a Lyra project that has been configured to use OSSv2 (NOT the default configuration as of UE 5.5). To upgrade your Lyra config for OSSv2 see this official Epic documentation.

EOS Configuration

In general the Epic docs for how to configure EOS are good, but when I initially set this up in my project, I found the INI a bit confusing. To make it more clear, here is the diff you will need to make to Config/Custom/EOS/DefaultEngine.ini:

Default Config/Custom/EOS/DefaultEngine.ini	Modified Config/Custom/EOS/DefaultEngine.ini
;+[OnlineServices.EOS] ;+ProductId=PRODUCTID ;+SandboxId=SANDBOXID ;+DeploymentId=DEPLOYTMENTID ;+ClientId=CLIENTID ;+ClientSecret=CLIENTSECRET	[OnlineServices.EOS] ProductId=PRODUCTID SandboxId=SANDBOXID DeploymentId=DEPLOYTMENTID ClientId=CLIENTID ClientSecret=CLIENTSECRET

In other words, don’t just uncomment the default settings, as Epic says, but also remove the leading + character from each of the lines.

Though a leading + is required in some cases in INI files, they are NOT wanted here.

Obviously, you also want to populate PRODUCTID, SANDBOXID and the other ALLCAPS values with your project info as described in the Epic docs.

5.6 INI change

In UE 5.5 they made another change here, with a deprecation notice to take effect in 5.6. After following the Epic docs, you may get a warning like this every time you start UEditor:

LogOnlineEngine: Warning: bUseOnlineServicesV2 is deprecated, please instead configure [/Script/Engine.OnlineEngineInterface]:ClassName=/Script/OnlineSubsystemUtils.OnlineServicesEngineInterfaceImpl

To fix it, just comment out bUseOnlineServicesV2 and add the line they told you to add in the warning. The appropriate config for [/Script/Engine.OnlineEngineInterface] looks like this:

[/Script/Engine.OnlineEngineInterface]
;bUseOnlineServicesV2=true
ClassName=/Script/OnlineSubsystemUtils.OnlineServicesEngineInterfaceImpl

You don’t have to leave the commented-out bUseOnlineServicesV2=true, I just did so to make it clear that we’re replacing that line with the ClassName=... line.

Game Initialization

The Common User plugin defines the CommonUserBasicPresence Game Instance Subsystem, which declares CommonSessionSubsystem as a dependency.

When the GameInstance initializes, these subsystems are initialized as well.

During init, the CommonSessionSubsystem grabs a reference to the game’s default Online Services interface and to that service’s Lobbies interface.

Notice: If you’re getting an exception here where OnlineServices->GetLobbiesInterface() is returning nullptr, that means your EOS config is not correct!

Interesting Initialization Methods

FOnlineServicesEOSGS::Init

FOnlineServicesEOS is derived from FOnlineServicesEOSGS, so this is executed during EOS Init.

This loads the EOSShared module if needed and verifies the EOS SDK has initialized successfully.

It then loads the platform-specific config from Config files, looking in the [OnlineServices.EOS] section, which you must have correctly configured for your project.

FOnlineServicesRegistry::CreateServices

This is the method that actually instantiates an Online Service (such as Epic for EOS). If you want to understand what exactly goes into constructing and initializing an Online Service, breakpoint this method in your debugger.

In the case of the Epic Online Service (EOS), the FOnlineServicesFactoryEOS class is the factory that creates new Online Service instances, with its Create method instantiating a shared pointer to a new FOnlineServicesEOS class.

FOnlineServicesEOSModule::StartupModule

This method is run when the FOnlineServicesEOSModule loads. It registers EOnlineServices::Epic with the FOnlineServicesRegistry.

This is why later calls to FOnlineServicesRegistry::CreateServices are able to create new Epic Online Services insteances.

Debugging Tips

To make it easier to debug and test Online Services code, I recommend disabling code optimization in a few Engine Target.cs build scripts, including:

• Engine/Plugins/Online/OnlineServices/Source/OnlineServicesCommon/OnlineServicesCommon.Build.cs
• Engine/Plugins/Online/OnlineServices/Source/OnlineServicesCommonEngineUtils/OnlineServicesCommonEngineUtils.Build.cs
• Engine/Plugins/Online/OnlineServices/Source/OnlineServicesInterface/OnlineServicesInterface.Build.cs
• Engine/Plugins/Online/OnlineServicesNull/Source/OnlineServicesNull.Build.cs

Code snippet

// [BEGIN xist debug hack]
// Allow debugger stepping in this Engine module when built as DebugGame
if (Target.Configuration == UnrealTargetConfiguration.DebugGame)
{
    OptimizeCode = CodeOptimization.Never;
}
// [END xist debug hack]

Example Diff for OnlineServicesInterface.Build.cs

Recommended Reading

• Using Lyra With Epic Online Services
• Common User Plugin