Content for  TS 23.558  Word version:  19.0.0

This clause describes the functional entities of the architecture for enabling edge applications.

EES provides supporting functions needed for EASs and EEC. Functionalities of EES are:

1. provisioning of configuration information to EEC, enabling exchange of application data traffic with the EAS;
2. providing API invoker and API exposing functions as specified in TS 23.222. To support deployments specified in clause A.5, providing CAPIF core functions as specified in TS 23.222;
3. interacting with 3GPP Core Network for accessing the capabilities of network functions either directly (e.g. via PCF) or indirectly (i.e. SCEF/NEF/SCEF+NEF);
4. exposing events related to ACT;
5. EEC context transfer between EESs;
6. supporting external exposure of 3GPP network and service capabilities to the EAS(s) over EDGE-3;
7. registration functions (i.e., registration, update, and de-registration) for the EEC(s) and the EAS(s);
8. triggering the EAS instantiation on demand; and
9. supporting ACR related operations (e.g. ACR launching, ACR information notification, EELManagedACR).

EEC provides supporting functions needed for AC(s). Functionalities of EEC are:

1. retrieval of configuration information to enable the exchange of Application Data Traffic with the EAS;
2. discovery of EASs available in the EDN;
3. detecting UE mobility events;
4. exposure of events of interest to AC; and
5. retrieval of UE ID and/or Edge UE ID.

ECS provides supporting functions needed for the EEC to connect with an EES. Functionalities of ECS are:

1. provisioning of Edge configuration information to the EEC. The Edge configuration information includes the following:
   1. the information for the EEC to distinguish amongst the EESs (e.g. EDN service area); and
   2. the information for establishing a connection with EESs (such as URI);
2. providing the T-EES information to the S-EES;
3. supporting the functionalities of registration (i.e., registration, update, and de-registration) for the EES(s);
4. supporting the functionalities of API invoker and API exposing function as specified in TS 23.222;
5. interacting with 3GPP Core Network for accessing the capabilities of network functions either directly (e.g. via PCF) or indirectly (i.e. SCEF/NEF/SCEF+NEF).
6. providing service provisioning information to a partner ECS; and
7. retrieving service provisioning information from a partner ECS.

If the ECSP is required to support service provisioning for a certain EAS whose information is not within the pre-configuration or OAM configuration, the ECS can use Edge repository functions to support ECS discovery via ECS-ER. To support functions of the edge repository the ECS supports the following functionality(ies):

1. registering and providing edge deployment information to ECS-ER.

To support the federation and discovery of a common EAS for a set of UEs the functionalities of the enhanced ECS i.e. ECS-ER, in addition to ECS functionalities, are:

1. Federation
   1. supporting the functionalities of registration (i.e., registration, update, and de-registration) for the ECS(s);
   2. receiving and storing information about edge computing resources from the ECS(s);
   3. receiving and storing information about edge computing resources from other ECS-ER(s); and
   4. providing information about Edge computing resources to other ECS-ER(s) of the federation.
2. Common EAS discovery
   1. storing and providing common EES and common EAS information.
3. Common EAS bundle discovery
   1. storing and providing common EAS bundle information and its associated EES information.

AC is the application resident in the UE performing the client function. Depending on how ACR is implemented, the AC might be required to decide whether to initiate ACR. Other details of the AC are out of scope of this specification.

EAS is the application server resident in the EDN, performing the server functions. The AC connects to the EAS in order to avail the services of the application with the benefits of Edge Computing. It is possible that the server functions of an application are available only as an EAS. However, it is also possible that certain server functions are available both at the edge and in the cloud, as an EAS and an Application Server resident in the cloud respectively. The server functions offered by an EAS and its cloud Application Server counterpart may be the same or may differ; if they differ, the Application Data Traffic exchanged with the AC may also be different. The EAS can consume the 3GPP Core Network capabilities in the following ways, all of which are optional to support:

1. invoking 3GPP Core Network capabilities via the edge enabler layer through the EES
2. invoking 3GPP Core Network function (e.g. PCF) APIs directly, if it is an entity trusted by the 3GPP Core Network; and
3. invoking the 3GPP Core Network capabilities through the capability exposure functions i.e. SCEF/NEF/SCEF+NEF.

The EAS can support processing ACR related operations (e.g. ACR status update, selected target EAS declaration). The EAS can expose its Service API(s) (i.e., EAS Service API(s)) towards the other EASs by supporting API provider domain functions as specified in TS 23.222; and the EAS can consume the EAS Service API(s) exposed by the other EAS(s) by supporting API invoker functionalities as specified in TS 23.222.

Notification management client is as specified in TS 23.434.

Notification management server is as specified in TS 23.434.

CES provides supporting functions needed for CASs. The CES is part of the EEL and it does not have service area restriction. CES facilitates service continuity between EAS and CAS. Functionalities of the CES are:

1. providing access to network capability information (e.g. location information) to the CAS;
2. facilitating setup of a data session between AC and CAS with a specific QoS; and
3. supporting ACR related operations.

CAS is the application server resident in the cloud, performing the server functions. The AC connects to the CAS in order to avail the services of the application.