Synchronous calls to another serverless function

Hi,

I love serverless, but I’m not sure how to architect the following:
Occasionally I have a function in one service that needs to call a function in another service.
Normally if there is no time sensitivity, and I don’t need a response from that other function - I just use events / AWS SNS to subscribe the other function to an event that I trigger.

But what options do I have for synchronous calls to another function, where I need a response in < 500ms?
I don’t want to have to use the REST API that serverless will provide… as that feels inefficient.

Any ideas? Something like RPC?

thanks

The simplest solution is to invoke the Lambda directly.