Raw mode subscription, missing snapshot

PradeepChahal

Hello,

We are facing an issue in RAW mode subscription, below is the description of scenario:-

Client1 and Client2 subscribing same item in different mode RAW and MERZE (snapshot flag as true) respectively. Our DataAdapter return true for the function call isSnapshotAvailable() to lightstreamer for this item.

Since RAW mode does not support snapshot, LS never push snapshot update to Client1 while Client2 receive snapshot update. Please correct me if I am wrong.

In this case Client1 is missing first update (snapshot).

For us update with snapshot flag true is as important as update with snapshot flag is false. We want to make sure that Client1 also get snapshot update.

DataAdapter get informed about an item subscription only not about subscription mode and even if we get the information of subscription mode then we have to restrict all the clients to subscribe in same mode, as LS ask isSnapshotAvilable() for first client only, so that we can decide should we return true or false for isSnapshotAvilable() call.

We want that client subscribing in RAW mode also get snapshot update.

Would you like to suggest a way so that client subscribing in RAW mode don’t miss snapshot update?

Dario Crivelli

You may never need to subscribe to your item in RAW mode.
In fact, if some clients need that no updates are filtered, they could subscribe to the item in MERGE mode with the "unfiltered" flag set,
that is, by issuing table.setRequestedMaxFrequency("unfiltered") on your table.
This differs from RAW mode in two ways:

The snapshot is included in the update flow; this holds regardless that the subscription is the first one (and the snapshot comes from the Data Adapter) or it is not the first one (and the snapshot is generated by Lightstreamer).
If any field is missing in an update coming from the Data Adapter, it is considered as an unchanged field (whereas in RAW mode it is forwarded as a null). This is the same behavior as MERGE mode.