CDS 10, HCQL and MCP

CAP's June 2026 release (cds 10) adds two capabilities that compose with cds-data without any change to your annotations or pipeline configuration. Both build on the same fact: queries reach the plugins only when dispatched through the application service.

All three cds-data packages run on both CDS 9 and CDS 10 (@sap/cds >= 9). The behavior below only activates on CDS 10 with a CAP-to-CAP hop or the MCP adapter installed.

HCQL — a faster wire protocol for delegate and replicate

HCQL (CQL over HTTP) is a new CAP protocol adapter that carries a CQN SELECT as an HTTP request instead of translating it to OData $filter / $select. For CAP-to-CAP integration, CAP's remote client auto-selects HCQL over OData when the provider serves @hcql. CAP describes HCQL as "best suited, and thus chosen automatically for data federation scenarios."

The plugins never serialize the wire protocol themselves — they forward CQN via remote.run(query). So both federation strategies benefit transparently:

Strategy	Read path	HCQL benefit
@federation.delegate	remote.run(req.query) on the application service	Richer path expressions (flattened associations like customer.name) that OData-only remotes cannot express
@federation.replicate	Pipeline READ phase via the engine's remote adapter	Same adapter handles OData V2/V4 and HCQL; delta paging is unchanged

There is no @federation.hcql strategy and no adapter to pick — HCQL is a CAP-runtime choice. Annotate the CAP provider @hcql @odata and bind the consumer as usual. See:

• Federation → Service query execution — the dispatch story.
• Pipeline → Remote CQN sources (OData & HCQL) — adapter details and flattened-column behavior.

MCP — exposing data to AI agents

CAP's @cap-js/mcp protocol adapter exposes a service to AI agents over the Model Context Protocol. Annotate a service @mcp: 'agent' and its entities become MCP tools (describe, query, call_action).

Because MCP query calls run CQN on the application service, they hit the same @federation.delegate / @federation.replicate handlers that OData and srv.run do — MCP never calls remote providers directly:

AI agent ──tools/call query──▶ @mcp service ──srv.run(CQN)──▶ federation handler
                                                              ├─ delegate → remote provider
                                                              └─ replicate → local synced table

An MCP agent transparently gets live-proxied remote data (delegate), locally synced data (replicate), or cached responses — with no MCP-specific federation code. See Federation → MCP integration for a runnable demo.