We have a few changes coming in the next month or two with respect to our real-time price APIs, so answering your question is an opportune time to highlight a couple of things.
At present our real-time APIs do not receive any data between 11:00pm (I think) and 7:00am New Zealand time, so obviously the APIs won't be pushing out anything during that time window. Throughout the rest of the day, all SPD case files, including the RTP and RTD case files are sent to us by the system operator in batches, at intervals of about 10 minutes. By the time we load the real-time data and get it pushed out via the API, it might be up to about 15 minutes behind real time.There are several potential points of failure in this process so from time to time we do observe unplanned outages with the real-time price APIs. I haven't checked the logs but I'm guessing that's what occurred on 24 July.
In the coming months, we plan to change the real-time APIs from a data 'push to all subscribers' operation to notification/pull pattern. This will require users to modify the way in which they interact with the API and we will give plenty of advanced notice before making this change. In addition we will most likely do 'price-only' APIs as well as others that have price, load and generation data, as is the case at present. This split should mean that prices can be delivered closer to real time.
Hope this helps,
Phil