How is backward compatibility implemented in the gRPC protocol?

Backward compatibility in gRPC is achieved through the use of Protocol Buffers, which support the evolution of message schemas without breaking existing clients and servers.

Main principles:

• Do not delete fields — instead of deleting a field, it can be marked as deprecated.
• Do not change field numbers — field numbers (tags) should remain constant, as they are used for data identification.
• Add new fields with new numbers — new fields can be added, and old clients simply ignore them.

Thus, old clients can work with new servers by ignoring new fields, and new clients can process old messages by having default values for missing fields.