Python client for lightstreamer

[gianluca.finocchiaro]

Ok William,

I've misinterpreted MYLSSESSIONID (very similar to MYSESSIONID), sorry...

The commands seem right, but with no direct access to the system is very hard to understand what goes wrong.
If it is ok for you, send me via private mail your credentials in order to reproduce the case.

Regards,
Gianluca.

[gianluca.finocchiaro]

Hi William,

issues are involved in LS_id and LS_schema parameters. It's not clear to me how many different items and related field schemas are available from Cityindex, but reading through their forum, it seems the following should work:

LS_id=PRICE.400616114
LS_schema=MarketId%20TickDate%20Bid%20Offer%20Pric e

Here the Python version:

<br /> subscription = Subscription( <br /> adapter="PRICES", <br /> mode="MERGE", <br /> items=["PRICE.400616114"],<br /> fields=["MarketId", "TickDate", "Bid", "Offer", "Price"] <br /> ) <br /> <br /> # A simple function acting as a Subscription listener <br /> def on_item_update(item_update): <br /> print("{MarketId}, {TickDate}, {Bid}, {Offer}, {Price}".format(**item_update["values"]))

Let me know.
Gianluca

[Colombao]

Hi Gianluca, sorry to trouble you again

After the login and the subscriptions, after about 20-40 minutes I correctly receive push updates from IG, I don't receive any push update anymore, like if the connection is lost.
This behavior is sistematic and reproducible with others PC or internet connections.

The workaround I adopted is to setup a timer that if he see e.g. 20 seconds of silence, re-login and make subscriptions again but...this happen each 20 minutes, it is too frequent...

Do you have any other solution / advice ? Could it be caused by the program that doesn't elaborate push updates enough quick?

Thanks again!

Colombao

[socalwill]

Hello Gianluca - this is excellent! With your help I got both the plain curl commands working as well as the python script, which I will use for my purposes down the line. Thanks so much! I will continue with the implementation with other parts, that are more broker-specific, and I will post a working code soon. Thanks again,

William

[gianluca.finocchiaro]

Hi Dario,

this is a known problem but thank you for reporting it. I'm going to fix the demo and I'll let you know once done.

Thanks and Regards,
Gianluca

[gianluca.finocchiaro]

Hi Dario,

I've just released on Github a new version of the Basic StockList-Demo with support for bind operation, which allows a "fluent" streaming with no need of workarounds.
If you are interested at the protocol details, here you can find an exhaustive explanation [Par. 4.2].

Let me know.
Regards,

Gianluca

[socalwill]

This is great, thanks, Gianluca. I notice that reproducible interruption as well and I just started simple workaround with a ten minute duration for the streaming and a ten min periodic restart via cronjob, but your fix will be much better. (This may be intentional, but I noticed you kept the debug mode in line 397.)

[gianluca.finocchiaro]

Hi William,

I confirm that such workarounds go against the "session binding" as designed inside the Lightstreamer Server, so it is better to avoid them and to use the right features the Lightstreamer Network Protocol offers to leverage the power of the server.

Keeping the debug mode was a misprint, now I've fixed it and the source code is available on Github.

Thanks and Regards,
Gianluca

[Colombao]

Gianluca, with your last update the number of interruptions decreased dramatically. Gianluca the best!

[gianluca.finocchiaro]

Hi Dario,

thanks to your precious feedback I was finally able to fix last minor bugs. Now the implementation seems stable even when connected to several Lightstreamer instances deployed in a cluster.

Thank You!
Gianluca