Why are ticker messages in the MtGox PubNub API repeated?

Question

I'm using MtGox's PubNub API to fetch ticker data. I've subscribed to the BTC/EUR ticker with id 0bb6da8b-f6c6-4ecf-8f0d-a544ad948c15 . In more than half the cases when I receive a new ticker message, the data is just the same as that of the previous message, except for the timestamp of course. I expected ticker messages only when there is new data available, so I do not understand why the ticker messages get repeated. Examples:

diff_to_previous  instant_________      last_all        last_local      last_orig       buy_____        sell____        vwap____        vol_____________    item  avg_____      high____        low_____
n/a               2013-12-12 16:31:46   EUR 628.31408   EUR 620.22000   USD 865.00000   EUR 620.22000   EUR 629.00000   EUR 647.91649   BTC 1365.61335998   BTC   EUR 649.27938 EUR 680.00000   EUR 615.00000
none              2013-12-12 16:31:50   EUR 628.31408   EUR 620.22000   USD 865.00000   EUR 620.22000   EUR 629.00000   EUR 647.91649   BTC 1365.61335998   BTC   EUR 649.27938 EUR 680.00000   EUR 615.00000
none              2013-12-12 16:31:53   EUR 628.31408   EUR 620.22000   USD 865.00000   EUR 620.22000   EUR 629.00000   EUR 647.91649   BTC 1365.61335998   BTC   EUR 649.27938 EUR 680.00000   EUR 615.00000
last_all          2013-12-12 16:32:05   EUR 617.41846   EUR 620.22000   USD 850.00000   EUR 620.23000   EUR 629.00000   EUR 647.91649   BTC 1365.61335998   BTC   EUR 649.27938 EUR 680.00000   EUR 615.00000

What kind of events trigger a ticker message to be broadcast?

Answer 1

PubNub MtGox API Ticker Repeat Messages

The Ticker Events are Updates that are streamed directly to you which may or may not represent a price change. However the ticker updates are typically tied to a trade event which occur on the trade channel.

You can find the trade stream here: http://www.pubnub.com/console/?sub=sub-c-50d56e1e-2fd9-11e3-a041-02ee2ddab7fe&pub=demo&channel=dbf1dee9-4f2e-4a08-8cb7-748919a71b21&origin=pubsub.pubnub.com&ssl=true

So in regards to the updates you may receive unchanging value updates. You may also consider looking at historical values by using the History API: http://www.pubnub.com/how-it-works/storage-and-playback/

Also check out the related Stackoverflow article: https://stackoverflow.com/questions/20547815/convenient-way-to-extract-data-from-the-mtgox-pubnub-json-api/20553315#20553315

or

https://stackoverflow.com/questions/20495713/are-there-ready-made-java-classes-for-the-mtgox-pubnub-json-api/20500700#20500700