Introduction

The Envoy xDS APIs are defined as proto3 <https://developers.google.com/protocol-buffers/docs/proto3>_ Protocol Buffers <https://developers.google.com/protocol-buffers/>_ in the :repo:api tree <api/>. They support:

• Streaming delivery of :ref:xDS <xds_protocol> API updates via gRPC. This reduces resource requirements and can lower the update latency.
• A new REST-JSON API in which the JSON/YAML formats are derived mechanically via the proto3 canonical JSON mapping <https://developers.google.com/protocol-buffers/docs/proto3#json>_.
• Delivery of updates via the filesystem, REST-JSON or gRPC endpoints.
• Advanced load balancing through an extended endpoint assignment API and load and resource utilization reporting to management servers.
• :ref:Stronger consistency and ordering properties <xds_protocol_eventual_consistency_considerations> when needed. The APIs still maintain a baseline eventual consistency model.

See the :ref:xDS protocol description <xds_protocol> for further details on aspects of xDS message exchange between Envoy and the management server.