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December 8th, 2006, 06:14 PM
#1
near loss-less update notification for trade transactions
Hi all,
I hope asking these many questions is not too much...
Question 1)
In the stock streaming demo we are trying to do, we need to push to selected users the real-time trade transactions executed for a particular stock item. I realize this requires important bandwidth and update frequency and my assumption for the demo is that there is no restrictive limitation in this regard.
However, I have some problems. The frequency was set to 20, bandwith to 40 and bufferSize to 100 but I can still see that the lightstreamer client is not receiving "enough" transaction updates and a lot many of them get dropped.
For instance, the feed can deliver 5 new transactions for a specific item in the same millisecond, but in total, it only delivers 100 new transactions in 1 second then it calms down. So technically, if lightstreamer can keep 100 updates in the buffer/history, it should be able to deliver the 100 updates to the client using the assigned client/server frequency, right ? So I should be able to receive the 100 updates in the client within the 100/20 = 5 seconds ? But in reality, I receive only few of them.
Any help in this regard ?
For info, the subscription is "MERGE" because of the issue discussed below.
Question 2)
For the trade transactions, I first used DISTINCT to get the updates, but this caused receiving a lot of NULL/UNCHANGED updates instead. For instance:
- The data adapter generates 100 "different" transaction events to lightstreamer (most of the fields are different, including the timestamp)
- Client subscribing to this item in DISTINCT mode receives:
[=====>TRADE] update for 1: [0001, null, 07:00:00:051, 77.500000, 120, 12780, 5186]
[=====>TRADE] update for 1: [UNCHANGED, UNCHANGED, 07:00:00:057, UNCHANGED, 38, 12808, 6860]
[=====>TRADE] update for 1: [UNCHANGED, UNCHANGED, 07:00:00:062, UNCHANGED, 20, 12837, 9005]
[=====>TRADE] update for 1: [UNCHANGED, UNCHANGED, 07:00:00:068, UNCHANGED, 50, 12865, 10453]
[=====>TRADE] update for 1: [UNCHANGED, UNCHANGED, 07:00:00:074, UNCHANGED, 10, 12896, 12126]
[=====>TRADE] update for 1: [UNCHANGED, UNCHANGED, 07:00:00:079, UNCHANGED, 65, 12922, 13299]
[=====>TRADE] update for 1: [UNCHANGED, UNCHANGED, 07:00:00:081, UNCHANGED, 20, 12929, 13659]
[=====>TRADE] update for 1: [UNCHANGED, UNCHANGED, UNCHANGED, UNCHANGED, UNCHANGED, UNCHANGED, UNCHANGED]
[=====>TRADE] update for 1: [UNCHANGED, UNCHANGED, UNCHANGED, UNCHANGED, UNCHANGED, UNCHANGED, UNCHANGED]
[=====>TRADE] update for 1: [UNCHANGED, UNCHANGED, UNCHANGED, UNCHANGED, UNCHANGED, UNCHANGED, UNCHANGED]
[=====>TRADE] update for 1: [UNCHANGED, UNCHANGED, UNCHANGED, UNCHANGED, UNCHANGED, UNCHANGED, UNCHANGED]
... more items in the same form, all UNCHANGED
[=====>TRADE] update for 1: [UNCHANGED, UNCHANGED, UNCHANGED, UNCHANGED, UNCHANGED, UNCHANGED, UNCHANGED]
- Client subscribing to this item in MERGE mode receives:
[=====>TRADE] update for 1: [0001, null, 07:00:00:051, 77.500000, 190, 12782, 5390]
[=====>TRADE] update for 1: [UNCHANGED, UNCHANGED, 07:00:00:057, UNCHANGED, 17, 12811, 6977]
[=====>TRADE] update for 1: [UNCHANGED, UNCHANGED, 07:00:00:063, UNCHANGED, 65, 12840, 9250]
[=====>TRADE] update for 1: [UNCHANGED, UNCHANGED, 07:00:00:069, UNCHANGED, 25, 12869, 10648]
[=====>TRADE] update for 1: [UNCHANGED, UNCHANGED, 07:00:00:075, UNCHANGED, 20, 12900, 12286]
[=====>TRADE] update for 1: [UNCHANGED, UNCHANGED, 07:00:00:081, UNCHANGED, UNCHANGED, 12929, 13659]
The problem is that MERGE makes a lot of updates disapear. DISTINCT makes some disapear and many contain nothing (NULL/UNCHANGED)
The idea was to receive most of the updates, how can I achieve this ?
Question 3)
I need to deliver news feed thru the same stock streaming demo in the following way:
- Any time a user subscribes to the news, he should receive all the news item of the current day
- Then the user needs to receive the news updates in real-time.
How can I achieve this ?
Question 4)
Performance wise, which one is better ?
- Data adapter to filtrate all the redundant data (unchanged fields) and only send real updates to lightstreamer
- Data adapter to send everything to lightstreamer which will handle the unchanged data
Thanks in advance,
R
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