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Glossary term · Services

S-EES

Source Edge Enabler Server

Services →

S-EES is a functional entity in 3GPP's Edge Computing Enabler Layer that acts as a trusted intermediary for clients to discover and access edge application servers and their services.

Introduced
Rel-17
Where
Services
Specifications
3 specs
S-EES Description Purpose What changed Neighbours Detected Changes Specifications

Description

The Source Edge Enabler Server (S-EES) is a core component of the 3GPP Edge Computing Enabler Layer (ECEL) architecture defined from Release 17. It functions as a service discovery and access gateway for application clients (ACs) seeking to utilize edge computing resources. The S-EES is typically deployed within the operator's network or a trusted third-party domain. Its primary role is to act as a trusted intermediary that an AC first contacts. The AC provides the S-EES with a service description or identifier for the edge application it wishes to consume. The S-EES then consults with other ECEL entities, primarily the Edge Configuration Server (ECS), to discover the appropriate Edge Application Server (EAS) instances that can fulfill the request. This discovery process considers factors like the client's location, network conditions, and EAS capabilities to select an optimal endpoint. Once a suitable EAS is identified, the S-EES provides the AC with the necessary information, such as an IP address or FQDN, and often a secure access token, to establish a direct or proxied connection to the EAS. This architecture abstracts the complexity of the edge deployment from the application, enabling dynamic service discovery and seamless mobility as clients move between different edge service areas. The S-EES also plays a crucial role in security, enforcing authentication and authorization policies for ACs before revealing EAS details, thereby protecting the edge infrastructure from unauthorized access. It interfaces with the ECS using the En-1 reference point and with ACs via the En-2 reference point, as specified in TS 23.558.

Purpose & Motivation

The S-EES was created to address the challenges of service discovery and access in distributed edge computing environments. Prior to its standardization, accessing edge applications often required static configuration or proprietary discovery mechanisms, which were not scalable, secure, or interoperable across different operators and vendors. The proliferation of latency-sensitive and bandwidth-intensive applications, such as augmented reality, industrial automation, and video analytics, necessitated a standardized way to dynamically find and connect to the closest or most suitable compute instance. The S-EES solves this by providing a centralized, trusted point of contact for clients. It decouples the client application from the physical and logical topology of the edge network, enabling operators to deploy, manage, and scale their edge resources independently. This standardization, initiated in Release 17, was motivated by the need to foster an ecosystem of interoperable edge services, reduce integration complexity for application providers, and ensure secure and efficient utilization of edge computing infrastructure as a key enabler for 5G and beyond networks.

What changed in its specifications

The latest release-to-release comparison of specifications that define S-EES. Each summary describes the whole specification, not only this term.

TS 23.558Rel-18 → Rel-19

Rel-19 adds common EAS removal and update procedures, ACR event subscription, bundle EAS discovery, and federation and roaming to TS 23.558. It also adds application group handling with group-level EAS discovery and ACR for UE groups, plus ADAE edge load analytics for EES selection.

Full comparison in TS 23.558 →
TS 29.558Rel-18 → Rel-19

Added an ACR Events service with subscriptions, InOutArea enumeration, new data types, and an Eecs_ACREvents API with consent checks and registration updates. Also added associated devices and MetaverseApp representation in EASProfile.

Full comparison in TS 29.558 →

Release Timeline

Detected Changes Across Releases

from 3GPP Change Requests

Specific changes extracted from the „Change history“ tables of 3GPP specifications (10 CRs across 2 releases). Complements the general historical overview above with the evidence-based evolution of this function.

Studied in Rel-17, normative work from Rel-18.

Rel-18 7 changes
  • ACR with CAS - EEC executed ACR via S-EES TS 23.558CR0334
  • ACR with CAS - S-EES executed ACR TS 23.558CR0338
  • Bundle EAS ACR within the same DNAI for S-EES executed ACR TS 23.558CR0376
  • CAS decided ACR scenario via old S-EES for CESless architecture TS 23.558CR0401
  • Cleanup on CAS decided ACR scenario via the last S-EES TS 23.558CR0464
  • Solving EN on CAS - S-EES executed ACR TS 23.558CR0485

+ 1 more changes

Rel-19 3 changes
  • Service continuity for common EAS (overload situation) – S-EES detected scenario. TS 23.558CR0608
  • Solve EN in S-EES executed ACR TS 23.558CR0681
  • Correction in S-EES executed ACR to CAS TS 23.558CR0554

Defining Specifications

3GPP specifications that define or reference S-EES, with the latest known release. Sourced from the 3GPP document catalog — see methodology.

SpecificationTitleRelease
TS 23.558 vk30 Enabling Edge Applications Rel-20 read
TS 29.558 vk00 Edge Application Enablement APIs Rel-20 read
TR 33.739 vi10 Study on security enhancement of support for Rel-18 read