Core Concepts
Understanding the fundamental architecture and design principles of EOS Integration Kit
Before diving into features, it helps to understand how EOS Integration Kit is structured and the key concepts behind Epic Online Services.
What is EOS?
Epic Online Services (EOS) is a free, cross-platform service from Epic Games that provides:
- Authentication - Login with Epic, Steam, PlayStation, Xbox, and more
- Multiplayer - Lobbies, sessions, matchmaking, and P2P networking
- Social - Friends, presence, and party systems
- Progression - Achievements, stats, and leaderboards
- Storage - Cloud saves and title data
- Voice Chat - Built-in voice communication
- Anti-Cheat - Easy Anti-Cheat integration
What is EIK?
EOS Integration Kit (EIK) is a plugin that brings all EOS features to Unreal Engine through:
- Blueprint nodes for visual scripting
- C++ APIs for programmers
- Online Subsystem integration for seamless Unreal networking
Key Concepts
Two Authentication Paths
EOS has two ways to authenticate users, each with different capabilities:
| Connect Interface | Auth Interface | |
|---|---|---|
| Account Type | Product User ID | Epic Account |
| Features | Game services only | Full EOS features |
| Overlay | No | Yes |
| Epic Friends | No | Yes |
Learn more: Auth vs Connect
Two Online Subsystems
Unreal Engine has two networking frameworks, and EIK supports both:
| Online Subsystem (v1) | Online Services (v2) | |
|---|---|---|
| Status | Legacy but stable | Modern, recommended |
| UE Version | All versions | UE 5.2+ |
| API Style | Interfaces | Services |
Learn more: Online Services
Artifacts
Artifacts are configuration profiles containing your EOS credentials. You can have multiple artifacts for:
- Development - Dev sandbox for testing
- Staging - QA and staging environment
- Production - Live game deployment
Architecture Overview
┌─────────────────────────────────────────────────┐
│ Your Game │
├─────────────────────────────────────────────────┤
│ EIK Blueprints │
│ (Easy-to-use BP nodes) │
├─────────────────────────────────────────────────┤
│ EIK Core │
│ (Abstraction layer for OSS v1/v2) │
├──────────────────────┬──────────────────────────┤
│ OnlineSubsystemEIK │ OnlineServicesEIK │
│ (OSS v1) │ (OSS v2) │
├──────────────────────┴──────────────────────────┤
│ EOS SDK │
│ (Epic Online Services) │
└─────────────────────────────────────────────────┘Next Steps
- Auth vs Connect - Choose your authentication approach
- Online Services - Understand the networking layer
- Quick Start - Start building