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  1. #1
    Join Date
    Feb 2008

    Client alert with error 120

    Hello! We get the 120 error occasionally and we suppose it is a network connectivity issue.

    We don't even hit the onSimilarEngineFound as we don't have a case where the same application name is used from the same host in a single browser instance more than once.

    So my question is what are the possible reasons for this error to occur?

  2. #2
    Power Member
    Join Date
    Jul 2006
    Cesano Maderno, Italy
    It's difficult to know what's the reason you've seen such message, but I can explain when the alert is shown so that maybe we can understand it together:

    When a client tries to connect to a server (or tries to subscribe to a table) and fails it checks if there are other clients connected to the same server on the same browser instance. If it finds that maybe there are other engines connected to such server it guess that the reason it failed to connect is that the limit of concurrent connections per server was exhausted.
    Such limit should be 2 by HTTP specs, but it vary from browser to browser.

    Which browser were you using?
    After the alert was the client able to connect?
    Was it true that others clients were open on the same browser (the onSimilarEngineFound is by default NEW_SESSION so that if you don't set it and open 2 tabs with the same application than both will create their engine and connect to the server)

    Note that you can avoid the alert from being shown reimplementing onClientAlert methods:

    about the 2 connections limit check http specs on [Page 46]:


  3. #3
    Join Date
    Jan 2008

    I'm able to reproduce this error in IE with two browsers.
    Steps to reproduce:
    1. Browser1 will establish lightstreamer connection.
    2. Use Cntrl+N to open browser2.
    Browser2 is throwing 'Error 120'.

    Any idea which property is common between these two, causing this error?


  4. #4
    Join Date
    Jul 2006
    Milan, Italy
    Hi DK,

    Make sure you use "SHARE_SESSION" as the third parameter of your createEngine() call. The explanation is that opening multiple IE windows with CTRL+N, you still have one process instance, not multiple. So you should avoind saturating the browser's connection pool. The trick is to use one single shared stream connection for all the windows and you can achieve that by using the "SHARE_SESSION" parameter.



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