How to throttle WCF service per client

Question

I'm developing a service that will be exposed on the internet to only a few select clients. However I don't want one client to be able to call the service so often that they prevent another client calling the service, or being responded to within a reasonable time. I realise that WCF has a number of throttling configuration settings built in, but I understand that these are only for the service as a whole.

Is there any built in mechanism that will enable me to configure the service such that a single client can only carry out (eg.) 10 concurrent calls or similar?

This question is related to another question here:

Best way to secure a WCF service on the internet with few clients

where I'm still trying to determine if I need to, and how I will identify individual clients.

Answer 1

The phrase you're looking for here is Rate limiting. And, no, there's no built-in way to rate-limit a WCF service. As you said, you can play with the WCF feature set around service throttling, but this is a service-level setting and not per-client.

In order to implement rate limiting the general guidance seems to be to use an in-memory collection (or something like redis for scale-out scenarios) to perform fast look-ups against the incoming user string or IP address. Then you can define some limiting algorithm around that information.

More info here and here.