post abstract method
Sends an HTTP POST request to the specified url
with the given body
.
Optionally, you can provide additional header
parameters for the request.
Returns a Future that completes with the response body as a String.
Note: This method is intended for use in RPC services that might need additional HTTP interactions beyond the standard RPC calls.
Implementation
Future<String> post(String url, String body, {Map<String, String>? header});