Using VB2008 to acccess the Betfair API: A tutorial

[antonello273]

Update bets

Thanks I solved it by myself, found the solution.

[antonello273]

updatebet

Hello everyone, first of all I CuSO for my English, I state that programming vb.net are a beginner, having said that you tell me how I can open the "UpdateBet" du times consecutively? I tried using the function call, but I noticed that the first time is the second tells me there are a pricing error, ie the value of nudprice back to 1000 instead of changing the value 10.
Thanks and I apologize again for my English.

I post my code:

Private Sub bPlaceBet_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles bPlaceBet.Click
Dim quota As Decimal
Dim stake As Decimal
Print("*** PlaceBet ***")


If stake < 2.0 Then
If rbBack.Checked Then BetType = bfuk.BetTypeEnum.B Else BetType = bfuk.BetTypeEnum.L 'Select Back or Lay bet
PlaceBet(IdMercato.Text, IdSelezione.Text, bfuk.BetTypeEnum.B, 1000, 2) 'The call to place the bet
Call UpdateBet(TheBetId, 1000, 1000, 2 + nudSize.Value, 2)
quota = InputBox("Iserisci la nuova quota")
nudPrice.Value = quota
Call UpdateBet(TheBetId, nudPrice.Value, 1000, nudSize.Value, 2 + nudSize.Value)
Else

BetPrice = nudPrice.Value 'The selected price
BetSize = nudSize.Value 'The selected bet size

PlaceBet(IdMercato.Text, IdSelezione.Text, bfuk.BetTypeEnum.B, BetPrice, BetSize) 'The call to place the bet
End If

End Sub

[valentroch]

Thank you for the response Mumbles0.

I will try and I tell you back if it works.

[Mumbles0]

valentroch,

It’s possible that your problem is caused by the API’s use of type Double to hold price values. This can cause rounding errors.

Try using a rounding function like this:

odds = 1.54 'Your odds value
.price = Decimal.Round(CDec(odds), 2)

This is not guaranteed to work, but it might improve the problem.

[valentroch]

Invalid_Price error

Hi,

Thank you for this topic. It very helped me to make a automatic exchange program.

But I have a little problem. I place a lot of bet with my program and mostly it works but sometimes I have an INVALID_PRICE error (bet's Result Code). I have this problem even with totally normal odds (like 1.36, 1.54, 1.81, 1.33, 1.07, 1.06)... I don't understand. Can anybody help me?

Thank you
valentroch

[Ferbar11]

What is the best value for the purpose timer function with TabControl?

1000 ms?

[Ferbar11]

How can I place a bet with less than 2€?

[monkeymagix]

Throttle_limit

Cheers for replying Mumbles and BigSprout

I am already looking into compressed version of market prices but I would like to solve this issue as it is troubling me why my code loses all it's references after a call to my beat method.

My code is built as a windows service and is already using timers to initiate calls to my Bot at 30 second periods using a Timer object.

I will amend my code to check for the bestPrices length before accessing them to see if that fixes the problem but it does seem to happen ONLY after a THROTTLE LIMIT error so I am 99.99% sure the issue is down to that and I am wondering if there is some method I can call after a "Beat Throttle Limit" check to ensure all references are still available and if not re-gain them.

As for server time difference issues I have most certainly run into issues with this before. It would be nice to know how out of sync my server is with Betfair's so that I can add/subtract this to my calculations.

I know from my day job that our DEV and PRODUCTION servers are up to a minute out of sync and even on the PRODUCTION server our web and DB server are 10+ seconds out of sync which makes scanning log files looking for errors logged in the DB a right pain the XXX.

Thanks for your help!

[Mumbles0]

Beating the throttle limit.

Monkeymagix,

Beating the throttle limit.

You have a scheme which attempts to deal with the call rate limits imposed by the free API. This scheme requires your computer’s clock to be synchronized to Betfair‘s.

It assumes that Betfair count the calls during a one minute time window and reset the counter at the end of each minute. I experimented with this, but my observations were inconsistent with this assumption. Exactly how Betfair determine the EXCEEDED_THROTTLE condition remains a mystery to me.

Sleeping the thread could freeze your app until the next minute commences. This may be OK for an unattended bot, but, in general, it may not be a sensible thing to do.

A more conservative strategy is to simply restrict your call rate using, say, a timer control, rather than firing off a barrage of calls and taking corrective action when the calls ultimately fail.

The contents of the program’s variables (including object references) should not be affected by the Thread.Sleep call. I don’t know what could be causing your problems here.

AFIK, the call count is done on a “user” basis, so you can’t “beat the throttle” by using multiple computers concurrently with the same Username.

BTW, as BigSprout has pointed out, getMarketPrices has a call limit of only 10/min, If you are running into throttle problems you would be better off calling getMarketPricesCompressed. This returns the same data but has a much higher call limit (60/min). See step 14.


Error: Index was outside the bounds of the array.

Sometime there is no money for a runner. In this case the .bestPricesToBack array (or .bestPricesToLay) will be empty. So you should always test the length of these arrays before you access any element. Do something like this (if you’ll pardon the VB):

  With MpriceResp.marketPrices.runnerPrices(i)
    If .bestPricesToBack.Length > 0 Then backPrice = .bestPricesToBack(0).price
    If .bestPricesToLay.Length > 0 Then layPrice = .bestPricesToLay(0).price
 End With

If you don’t do this you will get the error.

[Ferbar11]

oHeaderUK() is a function, described in Step 5.

Thanks for help me.

[Mumbles0]

oHeaderUK() is a function, described in Step 5.

[Ferbar11]

Ferbar11,

Whenever you cal the API it is always a good idea to check for errors in case the call doesn't work properly. Do something like this:

  Dim Req As New BFUK.GetAccountFundsReq
  Dim Resp As BFUK.GetAccountFundsResp

  Req.header = oHeaderUK()
  Resp = BetFairUK.getAccountFunds(Req)

  With Resp
    CheckHeader(.header)   'Check the header for API error
    If .errorCode = BFUK.GetAccountFundsErrorEnum.OK Then

      lShowSaldo.Text = .availBalance  'OK, show balance in the textbox

    Else
      Print(.errorCode.ToString)  'If getAccountFunds error
    End If
  End With

The code shown here does full error checking and will only update the textbox if the call worked OK. Otherwise it will tell you what the problem is.

What is it; oHeaderUK() ? Method? Variable?

[BigSprout]

...My bot only runs once every 30 seconds. So I should not be running into issues related to calling the same market more than once every 30 seconds and can only presume the fault lies when I am trying to get prices for multiple markets (e.g all markets for a day) or something else.

Any ideas?

Hmmm, seems I did misinterpret what you wrote

What I now understand is that you are calling multiple markets every 30 seconds using GetMarketPrices...if this is the case then I refer to my original post

You can only call GetMarketPrices 10/minute, any more than that and an "Exceeded_Throttle" error is sent, the 10/minute limit is for all markets - not for just one market.

You appear to be calling multiple markets twice/minute, if at any time the accumulative number of the markets exceed 10, then the error will occur.

Please advise if I am correct this time and we can then look at an alternative - as this is a tutorial on VB2008 it may be best if another thread was started

...or...I could be wrong once again

cheers

[Mumbles0]

GetAccountFunds

Ferbar11,

Whenever you cal the API it is always a good idea to check for errors in case the call doesn't work properly. Do something like this:

  Dim Req As New BFUK.GetAccountFundsReq
  Dim Resp As BFUK.GetAccountFundsResp

  Req.header = oHeaderUK()
  Resp = BetFairUK.getAccountFunds(Req)

  With Resp
    CheckHeader(.header)   'Check the header for API error
    If .errorCode = BFUK.GetAccountFundsErrorEnum.OK Then

      lShowSaldo.Text = .availBalance  'OK, show balance in the textbox

    Else
      Print(.errorCode.ToString)  'If getAccountFunds error
    End If
  End With

The code shown here does full error checking and will only update the textbox if the call worked OK. Otherwise it will tell you what the problem is.

[monkeymagix]

Beating Throttle Limit

Thanks for replying Big Sprout but if you actually read what I said and look at the code I posted:

a) I said the following "I thought that rather than get a single horse at one time I would just loop through all the selections in the market and return a list object of a custom struct (bet selection) that could then be saved to the DB."

So I am not getting the price of a single horse at one time BUT rather I am doing it the way you suggested and getting all the selection prices for a market in one go.

b) I am using BetfairUK.getMarketPrices to get all the prices for one market.

I am looking into the compressed version but I would still like to solve this problem with the null object reference after a wait if possible.

My bot only runs once every 30 seconds. So I should not be running into issues related to calling the same market more than once every 30 seconds and can only presume the fault lies when I am trying to get prices for multiple markets (e.g all markets for a day) or something else.

Any ideas?