Python client for lightstreamer

Mamoa

epep You're right !

It seems that IG changed something about the persistence of authentication tokens, my script get stuck trying to reconnect with invalid password … I need more intelligence here. I'll let you know as soon as I have done something good.

Hello epep, I'm trying to get the IG Streaming API up and running but I'm having the same problem as you. Did you finally manage to solve the problem? Thanks!

Mamoa

Hi Gianluca,

First of all, thank you very much for the code, it has been really useful for me. I'm also using it to connect to the IG Streaming API and it has work just fine, the only problem that I'm having is the reconnect issue as stated by IG:

The Lightstreamer client should also have the ability to reconnect in the event of a connection failure or if instructed by the Lightstreamer server (e.g. due to a LOOP rebind message). A re-connection attempt can fail if the CST and X-SECURITY-TOKEN tokens have expired in which case it will be necessary to re-authenticate to obtain new security tokens.

I was thinking on adding a Timer to the LSClient class, connecting the timeout (after 2 seconds for example) to a new method that unsubscribes, disconnects and reconnects and resubscribe. Obviously I will have to end the session with the rest api and start a new one to get new session tokens.
What do you think of this approach?

Thanks in advance!

Gianluca Finocchiaro

Hi Mamoa,
it can certainly work, but the LSClient should be left as a general purpose Lightstreamer Client, hence I believe that your proposed logic should be put somewhere else, because it catches a specific use case.

Reconnection is a feature handled by other official Lightstreamer Client, by it is supposed that credentials do not change or, if they do, you have to write some custom logic to provide updated values.

Please let me know if your reconnection proposal also involves handling of new session tokens.

Thanks, Gianluca

Mamoa

Gianluca Finocchiaro Hi Mamoa,
it can certainly work, but the LSClient should be left as a general purpose Lightstreamer Client, hence I believe that your proposed logic should be put somewhere else, because it catches a specific use case.

Reconnection is a feature handled by other official Lightstreamer Client, by it is supposed that credentials do not change or, if they do, you have to write some custom logic to provide updated values.

Please let me know if your reconnection proposal also involves handling of new session tokens.

Thanks, Gianluca

Hi Gianluca,

Thanks for the reply. I have been very busy lately and I'm sorry that I didn't get back to you sooner. As you said, my case is really specific to my situation so it shouldn't be added to your lightstreamer client.
To answer your question, yes, my logic requires handling new session tokens so actually I had to use another api client (Rest API from IG) to get reconnected and getting new sessions tokens.
Finally I got it running (with a few custom modifications) but I'm having problems with a special case.

IG Streaming API (https://labs.ig.com/streaming-api-reference) has a special case where you have a DISTINCT Mode subscription , with 1 Item (TRADE) and 1 Field (OPU) but within that field you have various elements. When I subscribe to this trade I see the following message printed by the LightStreamer Client:

Received update message ---> <1,1|{"stopLevel":1.74014,"trailingStopDistance":0,"limitLevel":null,"trailingStep":0,"currency":"CAD","expiry":"-",
"guaranteedStop":false,"dealIdOrigin":"DIAAAABBHRQJLBA","direction":"SELL","epic":"CS.D.GBPCAD.MINI.IP",
"dealId":"DIAAAABBHRQJLBA","dealReference":"GCMJXRBVSFD44TD","level":1.73414,"status":"OPEN","size":1,
"channel":"PublicRestOTC","timestamp":"2017-05-26T07:23:21.000","dealStatus":"ACCEPTED"}>

but in the table listener I get this message:

{'values': {'OPU': u'{"stopLevel":1.74014'}, 'pos': 1, 'name': 'TRADE:MCMVD'}

As you can see, I only received the first element of the dict in the listener. I could make an adaptation for this case but I thought it could be positive to add this feature (multiple elements within the field) to your lightstreamer client. What do you think?

Thanks again,
Mamoa

Gianluca Finocchiaro

Hi Mamoa,

thank you very much for this post, as you helped me find out a bug in the demo.
Actually, the 'values' dict should have been looked like the following:

{'values': {'OPU':u'{"stopLevel":1.74014,"trailingStopDistance":0,"limitLevel":null,"trailingStep":0,"currency":"CAD","expiry":"-","guaranteedStop":false,"dealIdOrigin":"DIAAAABBHRQJLBA","direction":"SELL","epic":"CS.D.GBPCAD.MINI.IP","dealId":"DIAAAABBHRQJLBA","dealReference":"GCMJXRBVSFD44TD","level":1.73414,"status":"OPEN","size":1,"channel":"PublicRestOC","timestamp":"2017-05-26T07:23:21.000","dealStatus":"ACCEPTED"}', 'pos': 1, 'name': 'TRADE:MCMVD'}

where the value associated with the 'OPU' key is a json string to be processed by your custom logic.
I've just fixed the client on our github repository.

Please let me know wheter it helps.

Thanks and Regards.
Gianluca

Bostom

Gianluca Finocchiaro

{'values': {'OPU':u'{"stopLevel":1.74014,"trailingStopDistance":0,"limitLevel":null,"trailingStep":0,"currency":"CAD","expiry":"-","guaranteedStop":false,"dealIdOrigin":"DIAAAABBHRQJLBA","direction":"SELL","epic":"CS.D.GBPCAD.MINI.IP","dealId":"DIAAAABBHRQJLBA","dealReference":"GCMJXRBVSFD44TD","level":1.73414,"status":"OPEN","size":1,"channel":"PublicRestOC","timestamp":"2017-05-26T07:23:21.000","dealStatus":"ACCEPTED"}', 'pos': 1, 'name': 'TRADE:MCMVD'}

This works like the magic for me as well. Thank you!

Mamoa

Hi GianLuca,

I tested the fixed client and now is working perfectly. Thank you very much!

Regards,
Mamoa

majestrooo

Hello guys

I have the following issue reoccurring somewhat randomly, like after 4, 10, 24 hours etc.

All of the sudden the streamer just stops receiving messages and this is the last one:

Waiting for a new message
Received message ---> <1,1||||||||||||||1|>
Received update message ---> <1,1||||||||||||||1|>

I've downloaded the python LSClient from your Github examples, so the rebind = True function is available. Previously I was using an old version from the pip repository and that always closed the connection after around one hour. Where the rebinding didn't even occur!

Please advise on how to debug this.

Gianluca Finocchiaro

Hi majestrooo,

let me first clarify that the Lightstreamer Client Python package actually available from the pip repository is not provided by our company.

Could you provide us with a server side log excerpt of the issue?

Thanks,
Gianluca

majestrooo

Gianluca Finocchiaro Hi majestrooo,

let me first clarify that the Lightstreamer Client Python package actually available from the pip repository is not provided by our company.

Could you provide us with a server side log excerpt of the issue?

Thanks,
Gianluca

Hello Gianluca

I am using the lightstreamer code from this URL https://github.com/Lightstreamer/Lightstreamer-example-StockList-client-python/blob/master/src/stock_list_demo.py

The only part I removed is the stuff in the end for the demo.

What server side log do you need? I only have those of the ls_streamer. Otherwise please advise if there's a way to turn on more logging.

Gianluca Finocchiaro

Hi Majestrooo,

we need the log files produced by your Lightstreamer Server installation, under <ls_home>/logs.

Thanks
Gianluca

majestrooo

Gianluca Finocchiaro Hi Majestrooo,

we need the log files produced by your Lightstreamer Server installation, under <ls_home>/logs.

Thanks
Gianluca

Hi Gianluca

I'm afraid I don't have those, I'm only using the client towards IG.

Gianluca Finocchiaro

Ok,

it was not clear to me that you were testing against IG. In this case, we can only inspect your client log files, provided that you have configured logging at DEBUG level.

Please send files to support@lightstreamer.com.

Thanks
Gianluca

fab

epep You're right !

It seems that IG changed something about the persistence of authentication tokens, my script get stuck trying to reconnect with invalid password … I need more intelligence here. I'll let you know as soon as I have done something good.

Hi guys, did you work this issue out? I am getting a SYNC ERROR and would like to re-bind the session but then an IOERROR() is raised on the rebind.
Thanks a lot for your help in advance.

Mickael

Hi,
I'm having trouble maintaining the streaming connection with IG as well.
It cuts automatically after roughly an hour or so, and I don't know how to test if the connection is active or not.
Any help with that would be greatly appreciated.

Thanks in advance.

Gianluca Finocchiaro

Hi Mickael,

could you please send us the client side log snippet that puts in evidence the cut?

Thanks, Gianluca

femi

Hi,

I am trying to connect to IG streaming api with lightstreamer with Python. I am using the the light streamer stock list demo implementation on Github with the parameters modified for IG index. I appear to be getting a server error, When i use the same details on IG streaming companion, i was able to connect to the server successfully, which makes me suspect that this is not a server issue.

see my debug logs below

urllib3.connectionpool - DEBUG - Starting new HTTPS connection (1): demo-api.ig.com
urllib3.connectionpool - DEBUG - https://demo-api.ig.com:443 "POST /gateway/deal/session HTTP/1.1" 200 359

root - DEBUG - Opening a new session to <https://demo-apd.marketdatasystems.com>

root - DEBUG - Making a request to <https://demo-apd.marketdatasystems.com/lightstreamer/create_session.txt> with body <b'LS_op2=create&LS_cid=mgQkwtwdysogQz2BJ4Ji+kOj2Bg&LS_user=*****&LS_password=CST-*****XST-*****'>
root - ERROR - -2

Server response error:
%sA system error occurred.

Any assistance would be appreciated

Gianluca Finocchiaro

Hi Femi,

consider that the Python demo is just an example of how to implement the Network Protocol, so it is possible that some corner case has not been taken into consideration.

Anyway, we'll be going into a debug session to check what goes wrong when connecting with IG and get back to you with more information.

Thanks,
Gianluca

Gianluca Finocchiaro

Thank you very much Femi for your cooperation in analyzing this issue.

After having fixed a bug in the demo source code on a logging instruction, and tried to establish a session with IG by using similar JavaScript code, we have concluded that something unexpected is happing to your account.

In fact, the negative code error sent back by the server (-2) indicates that the specific Metadata Adapter implementation has refused the user connection, as you can see from the documentation.

Please let us know if your issue will be resolved.

Thanks and Regards,
Gianluca

femi

Thanks a lot Gialunca. I found out the issue was a bug in my own code that generated the tokens for the request. really appreciate your help.

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