What does setPhase() in the js client?

[robert1]

Hey,

I'm currently writing a python client for Lightstreamer 6.2.5 as part of a school project. My current goal is to get live prices of https://www.ls-tc.de/en/ into a python project, so that other students are able to "speculate" with these assets.

As Lightstreamer 6.2.5 is legacy and not supported anymore, I'm writing my own client. I've been diving a lot into the network requests, but after a lot of hours I still can't answer the following questions:

1. Before connecting via WebSocket, the js Client makes a request to "https://push.ls-tc.de/lightstreamer/create_session.js".
The request includes "LS_phase" as form data. What exactly is "LS_phase"? As far as I understood, it's just a random 4-digit number, which is later used when upgrading to the WebSocket.
2. When sending the request to /create_session.js, the server answers with js which includes the same phase number and (I think) a session identifier, like "S74535bee154ceeb1T3449099". Wenn connecting to the WebSocket afterwards, this session identifier is sent to the server too. What's the difference between LS_phase and this session identifier?


Please note that I can't switch to another language for this project, as it has to be implemented in python3.

[giuseppe.corti]

Hi Robert1,

The old web libraries used an undocumented private protocol specific to the javascript languages.
So it is not a good idea to try to reverse engineering that protocol in order to apply it to other languages.
For example the LS_Phase is a very specific element of the javascript protocol used to recognize possible duplicate replies but which do not make sense in other languages.

For your python client you should implement the TLCP protocol version 2.0.0: https://sdk.lightstreamer.com/ls-gen...ifications.pdf
Something like this example do: https://github.com/Lightstreamer/Lig...thon/tree/v1.1
Indeed there is a new ready made python client library but that requires a Lightstreamer server 7.x.

Please also note you should make sure if the server you are targeting is enabled to accept requests for the TLCP protocol.

Regards,
Giuseppe