Limited frequency RAW and DISTINCT modes

[Dejan Milosevic]

Hi,

I'd like to know how RAW and DISTINCT modes behave in case of limited frequency, imposed by LS edition param "Update per Second for Each Item". If we have 1 update allowed only, and 5 new ItemEvents come from data provider within few ms, what happens in these modes? Is some data discarded or just delayed and sent in consecutive 4 seconds?

On a similar note, the docs say for DISTINCT mode: "Not all the itemEvents need to be sent to the client". How is this decided, which itemEvent is discarded and which is sent? Is it affected only by this frequency limit?

Tnx

[marco.testa]

Hi Dejan,

In RAW mode and in DISTINCT mode with unfiltered dispatching the bufferSize is unlimited, thus all itemEvents supplied by the Data Adapter are kept in the itemEventBuffer, allowing event bursts to be absorbed, in order to send them to the Client with a delay compatible with the assigned maximum frequency.
Instead, if for example the item is subscribes in DISTINCT mode and with filtered dispatching, and the bufferSize is limited, the itemEvents may exceed the buffer size limits. In this case, when the buffer is full and a new itemEvent arrives from the supplier Data Adapter, the new itemEvent will still enter the buffer, forcing the rejection of the oldest element (the first element that entered) at the top of the buffer.
Be aware that in all cases where the bufferSize is unlimited, the Kernel is free at runtime to leverage a “robustness mechanism” which puts a limit on the maximum dimension of the buffer. This means that the Kernel can block a further growth of buffer size to protect itself. If the mode is RAW or unfiltered dispatching has been requested, the Kernel must also signal to the Client that one or more events were lost;
You may find more details at section 3.3 of Lightstreamer General Concepts.

regards,
Marco