It's been a number of months since I started porting from Betfair's old SOAP-based API-6 to the new JSON-based API-NG. In some ways it has been pleasurable and in other ways not.
The new API has permitted me to see Betfair's data in a new way. I have been able to quickly develop applications and get on with the task of analysing data for building new trading strategies. JSON permits easy collection and manipulation of data.
On the other hand Betfair itself has been none too helpful. Often, it's left to the users of the API to report bugs so that Betfair can improve the API. It seems to me that Betfair's developers have little knowledge of betting markets and don't appreciate the problems simple bugs create. The developers are just looking to solve the problem of disseminating data with a top down approach. They have no understanding of a trader's requirements for clean data.
I have discovered that often there are duplicate horses in the listMarketCatalogue method. An easy bug to get around as you can handle the exception when building a database quite easily. However, it's the way that Betfair handled my bug report that left me far from impressed. First they denied the bug. After I sent them evidence in a JSON string containing duplicates they said they would fix the bug. That was many months ago and the bug has still not been sorted out.
Then I found that overseas races were being added to Betfiar's database of UK races causing races from the United States, Hong Kong and Dubai to be added to my bot. Again a crude work-around was needed.
Now I find that the totalMatched volume count for runners never equals the actual colume for each price traded and often the totalMatched increases with no apparent volume increase for any price.
These bugs leave one disconcerted as to whether the data is accurate or not. A trader lives by the accuaracy of their data. If Betfair is not feeding the right data then a trader could end up in a lot of bother.
All in all, I feel that the new API is very promising indeed. It allows me to do so much more than I was able to do in the past. My productivity rate has increased greatly but I still have a suspicion in the back of mind that something could go wrong at any moment.
