Accessing The History Data Cache - how do I do this? (noob here)

[bhahn1800]

HI there,

As you all know from ready the subject for this thread, I am new to the eSignal API. I have it setup where I request historical data and it gives it to me just fine. Now, I know that there is the isHistoryReady(handle) call to check if the historical data is in the cache. My questions is, if it is in eSignal cache, what do I need to do or call to get eSignal to feed me the cached data?

Thanks!
Brant

[StarrM]

Hi Brant,

You just need to process the OnBarsReceived and OnBarsChanged events.

[bhahn1800]

Hi Starr,

Ok, I get the data from onBarsReceived just fine, but if I make the same request again, it doesn't call it. If I check getIsHistoryReady after I make the second request that doesn't return the data, it returns 1 - meaning it is in cached somewhere. I have to call releaseAllHistoryData before the onBarsReceived callback works again.

So, basically, when I make 1 request, it returns me data via onBarsReceived. When I make the same request right after it, the onBarsReceived event this time doesn't trigger b/c the data is 'cached' somewhere.... HERE's MY QUESTION: since onBarsReceived doesn't get triggered when data is 'cached' what do I need to call to get the 'cached' data??? Or, do I need to store the returned data from the first request, and manually pull it out when eSignal tells me that it is 'cached'????

Thanks,
Brant

[StarrM]

Brant,

All returned data is stored in a message queue until you process it. OnBarsReceived handles the initial return. How are you processing the OnBarsChanged event?

[bhahn1800]

Right now I am just handling onBarsReceived and am not doing anything with onBarsChanged. I read the documentation that differentiates the two, but I don't quite follow... can you explain?

When I make a fresh request, onBarsReceived is called. Now if I make a historical data request that is the same a second time, will eSignal invoke onBarsChanged instead?

Thanks

[StarrM]

That's basically correct. OnBarsReceived will give you the initial return. You need to process OnBarsChanged to get subsequent updates.