Implement VIA_MBS_5 Service Announcement Mode

[devbbc]

MBS User Service defines three service announcement modes namely: VIA_MBS_5, VIA_MBS_DISTRIBUTION_SESSION and PASSED_BACK.

The reference implementation currently implements VIA_MBS_DISTRIBUTION_SESSION and PASSED_BACK announcement mode.

This issue is to implement the announcement mode VIA_MBS_5 specified in clause 9 of TS 26.517.

For VIA_MBS_DISTRIBUTION_SESSION announcement mode, we implemented a co-located MBS AF to serve the User Service Descriptions bundle. The MBS AF library implements a class DocrootHTTPRequestHandler to handle the requests and serve the bundle.

According to TS 26.517, the User Service Description retrieval API for VIA_MBS_5 announcement mode at reference point MBS-5 is through the URL base path: {apiRoot}/3gpp-mbs-user-service-discovery/{apiVersion}/.

Table 9.2.2 1 of TS25.517 specifies two operations supported by User Service Description retrieval API. The MBSF populates the User Service Descriptions Bundle depending on the operation based on either the query parameter or externalServiceId. The current MBSF implementation needs to enhanced to populate the User Service Descriptions Bundle:

• Discover User Service Descriptions: The base URL path is followed by a sub-resource path and query parameters namely user-service-descriptions?‌service-class=.
  • The co-located MBS AF needs to be enhanced with a HTTP Request Handler to handle query parameters.
• Retrieve User Service Description based on externalServiceId, which uniquely identifies a single User Service Description resource in the MBS AF.
  • The current MBS AF may be able to handle this with minor modifications.