That's great info Phil thank you, exactly what I'm looking for.
Do you mind if I run an application implementation idea past you? This is just my experiment platform, I may end up pushing these applications down to the field mangos but I'll see how it goes, just experimenting with what I can do.
I have some Mango ES devices in the field. They poll local MODBUS devices for pulse counts (electric meter, water meter, gas meter) every minute. Currently I am goofing around with a cloud based Mango platform running on EC2. From the mangos on site, I push data to my central one using HTTP POST. The point updates are just an accumulated pulse count, so the number gets bigger and bigger all the time, and they are pushed every minute.
On the cloud Mango instance I have told the equivalent points to perform instant logs every 5 minutes. I then have a meta point which attempts to calculate the last five minute interval delta (it also applies a meter factor and does a couple other quick maths to the number). My initial implementation was to try and use
var.value - var.lastValue(1).value triggered at a 5 min interval, initially using CRON
This was causing some issues and what I just figured out is that lastValue(1) seems to return just any last value, so cached values are returned. I thought that lastValue(1) would return the last logged value.
I have now moved on to trying to use the following
var.past(MINUTE, 5) triggered update type logged
Since I am logging the context point at an interval of 5 minutes I would expect that the script is triggered only every 5 minutes and the delta should give me the difference in counts between now and 5 minutes ago. Do I understand this correctly?