Hi fimmu,

1) In the implementation proposed in that example the class StockListDemoAdapter acts as a listener for the ExternalFeed. This one simulates the component that interfaces with the broker, or any other supplier of prices, and each time it is generated a fresh data calls the OnEvent method of StockListDemoAdapter.

2) Assuming that you keep the data logic with one Item for each symbol, the updates are passed from the Adapter to the Lighstreamer server via a call to Update method for each symbol.
How implementing the event handling depends on how you receive the updates from your broker, for example if they are received asynchronously or for example through synchronous requests.

3) Do you mean you want the updates for all the 300 symbols in the same message? I confirm that if each symbol is a different Item the updates for each of them are independently managed by the server and therefore can reach the client at different times.
You might consider grouping all the symbols in the same Item but this is not a practice generally recommended.

Please let me know if you need further clarifications.

Regards,
Giuseppe