Thanks you your response very much,
@magnificent-energy-493.
I want the backend system to call Ory Hydra, passing in information such as the user ID ( from your existing system,) and then receive a JWT token in return. This token will be used subsequently for purposes like authenticating requests or maintaining user sessions.
It's is the same flow at
https://www.ory.sh/docs/oauth2-oidc/resource-owner-password-grant, but i don't know Ory Hydra Opensource can support me resolve this problem?