Parsing First Message from Lightstreamer Server

Yousef2006

Currently, I am using the Python client to connect to Lightstreamer, and for every update we receive from the server, we get three messages.

Based on my understanding, the onItemUpdate(self, update) function works for the third message in the sequence. Below are the three messages that we receive:

2025-02-16 11:09:20.249100|DEBUG|lightstreamer.stream|LS_IO|HTTP event: text(U,1,1,18.24|280|.14|.774792|538711|⁸|U|2025/
2025-02-16 11:09:20.260871|DEBUG|lightstreamer.protocol|Thread-2 (hx_local_0)|U,1,1,18.24|280|.14|.774792|538711|⁸|U|202
2025-02-16 11:09:20.296087|DEBUG|lightstreamer.subscriptions|Thread-2 (hx_local_0)|Subscription 1:1 update: [1:StringVal(1020
I would like to parse the first message as soon as it arrives, without waiting for the third message.

Do you have any suggestions or ideas on how I can achieve this?

Yousef2006

I will add this logic once I'm able to get the frist message on ( onItemUpdate )

if message.startswith("U,1,1,"):
parts = message.split('|')
print(f"Message starts with 'U,1,1,': {message}")
last_price = float(parts[2])
print(f"Extracted last price: {last_price}")

Yousef2006

if the frist message not allowed i want to parse secound msg

Alessandro.Carioni

You don't need to parse the update argument of onItemUpdate, as this argument is of type ItemUpdate and the ItemUpdate class provides methods to access the data coming from the server, such as getValue.

For more examples on how to use the Python SDK, please refer to the Quickstart guide and the StockList demo.

Yousef2006

"Due to the delay between the first message and the third one, I want to do it this way: Is it possible to parse it by knowing the function, or can I use a logger?

Alessandro.Carioni

I don't believe your approach is worth the effort just to save a mere 50 milliseconds of delay: parsing the server updates requires a deep knowledge of the protocol used by the server.
However, you can try installing a custom logger through the Lightstreamer.setLoggerProvider method and scan the messages (see also LoggerProvider and Logger).