Sure, of course you can.
If you would like to run a test now, see https://jsbin.ably.io/oganib/10/edit which will give you a quick head start to test latency.
That will also show you which Ably datacenter you are connecting to.
When testing please remember that:
- Publishing over a Realtime connection offers the lowest possible publish latencies. REST publishes will be significantly slower than realtime publishes for the first request as a TLS TCP/IP connection is established. Subsequent publishes will be faster as that connection will be reused, but they will still be somewhat slower than realtime publishes, as there is a certain amount of overhead for every REST request (see point 4 of debugging slow REST requests).
- Measuring how long a publish takes to call its callback is not a good way to measure message publish and receive latency; the design of the system means that the message is often delivered before being confirmed (and so called back). Instead, it's better to subscribe to the channel and do an end-to-end test of how long it takes for a message to actually be received after being published.
- Publishing messages on channels without any subscribers will add latency. However, read why this does not ever impact real-world performance.
- We continuously measure our latencies globally using real browsers. View our global latencies.
- Why are some REST publishes on a channel slow, and then typically faster on subsequent publishes?
- Low latency publishes with lower QoS using the quickAck option (scroll down to section titled Low latency...)