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Thread: Meaning of _definst_ in links to media files

  1. #1

    Default Meaning of _definst_ in links to media files

    Dear wowza community,

    I am not shure about the meaning of the "_definst_" in links to media files and I hope you can help me:

    I set up a video on demand application called "vod". If I open a media file, e.g:
    the file will be played.

    If I change the link to e.g.:
    the file will also be played. If I remove "_definst_", the file will not be played, e.g.:
    My questions are:
    What happens if I use "video123", "audio123" or any other string instead of "_definst_? Is there any side effect (eg video could not be played in some players or on some devices?) Are there any limitations to the name of the string?

    Is der any possibility to remove "_definst_"?
    So, the link will be
    thank you & best regards,


  2. #2


    Hello Anton.

    An Application.xml file defines the configuration that you set up in Wowza Streaming Engine Manager for a given application. An application instance is an instantiation of an application and provides a namespace and context for streaming. An application instance is started dynamically and a single application can have multiple named application instances running simultaneously. If no name is specified for an application instance, then the default name (_definst_) is used. In many streaming scenarios, a single application instance is used per- application and the name is never referenced and defaults to _definst_. It's more common to use multiple application instances in video chat and video conferencing scenarios where you must create multiple rooms for streaming. In this case, application instances are used to separate streaming into rooms. Each room is a separate application instance, which provides separation and a namespace for each room.
    You define application instances in the playback URL like you have done in this example:
    You can also define the application instance when publishing a live stream:
    You don't create application instances anywhere else in configuration files.

    When using a subfolder for content, or a folder other then the /content folder, you will need to name an application instance, or use _definst_ to access the files.

    I hope this answers your question.


    Last edited by salvadore; 08-13-2015 at 04:10 AM.

  3. #3


    Dear Salvadore,

    now I understand, thanks for your help and explaining.

    best regards, Anton

  4. #4


    Anton, you are most welcome. I am glad I could help.
    I did update my response however.
    When using a subfolder for content, or a folder other then the /content folder, you will need to name an application instance, or use _definst_ to access the files.


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