25896 2014-05-27 19:00:32 +0000 Why is EME creating new DOMException subclasses? 2014-09-16 00:44:41 +0000 1 1 1 Unclassified HTML WG Encrypted Media Extensions unspecified PC All RESOLVED FIXED P2 normal --- 23367 1 bzbarsky ddorwin annevk cpearce ddorwin jdsmith mike public-html-media public-html-bugzilla oldest_to_newest 106850 0 bzbarsky 2014-05-27 19:00:32 +0000 I thought we were trying to avoid creating new types of exception objects in the platform. 106851 1 annevk 2014-05-27 19:51:02 +0000 Yes we are. Hopefully we can avoid implementing this. 106863 2 ddorwin 2014-05-27 22:45:51 +0000 As far as I know, there are no implementations of this yet. The discussion of this starts in https://www.w3.org/Bugs/Public/show_bug.cgi?id=23619#c6. In the 10th comment, Microsoft wanted systemCode to remain accessible. If subclassing is discouraged and the advice in the advice on using DOMException for all errors is still accurate, we should replace MediaKeyError with DOMException. Implementations could choose to report system error codes in the DOMException message. 106894 3 annevk 2014-05-28 07:43:42 +0000 That sounds acceptable, if it is indeed phrased as a hint towards UAs (with regards to exposing system error codes) and not a requirement as no normative requirements can be made on the contents of .message. 107865 4 jdsmith 2014-06-16 19:07:01 +0000 Providing a discrete systemCode for clarity still seems preferable. A DOMException message could get mingled with errors unrelated to EME. That could be resolved by adding a clear exception type to the WebIDL, but I've seen some language that appears to discourage doing that. If so, we could end up using an existing type (or types), like SyntaxError for these messages. If we do go in this direction, we should preserve the intent of this MediaKeyError text (though modify it to remove the obsolete attribute): The systemCode attribute of a MediaKeySession object is a Key System-specific value for the error that occurred. This allows a more granular status to be returned than the more general name. It should be 0 if there is no associated status code or such status codes are not supported by the Key System. 107917 5 annevk 2014-06-17 05:42:53 +0000 Jerry, if it's key-system specific it seems you should include such details in the message field. They consideration here is whether you would expect branching to happen based on the exception that is returned. Typically the only thing that happens with exceptions is that they are reported back to the server for debugging. 108711 6 jdsmith 2014-07-03 21:04:02 +0000 I've had more discussions on this. We prefer returning a numeric error code. It is correct that this is key-system specific. Is it possible to augment DOMString with an systemCode attribute on the MediaKeySession? The DOMException message might then identify the exception as Media Key related. 108716 7 annevk 2014-07-04 05:43:29 +0000 No, it seems it should just go in the exception message. What's the expected usage scenario where it makes sense for this to be exposed as a distinct field only useful for your key system? 108762 8 jdsmith 2014-07-07 16:56:10 +0000 The current MediaKeyError provides a numeric systemCode that is key system specific. This would retain that. The DOMException message returns string error descriptions. We prefer a numeric error code. 108853 9 annevk 2014-07-11 08:37:46 +0000 Yes I understand you want that, but you have not justified it. 108870 10 jdsmith 2014-07-11 19:02:52 +0000 The specific concern is that mixing numeric values with text in the DOMException message may make parsing and logging of the numeric value more difficult. There's potential for the message content to vary by CDM. The end goal is to be able to accurately parse and log numeric error values. If there's an existing approach for doing this without a separate numeric error code, please provide a reference to it. 108900 11 annevk 2014-07-14 07:43:36 +0000 There is no existing approach for proprietary exceptions. Leaking through details of the CDM like that seems bad. 109102 12 ddorwin 2014-07-19 01:33:06 +0000 https://dvcs.w3.org/hg/html-media/rev/3368787fe08e removes systemCode as part of a larger removal of definitions that seem likely to change once bug 26372 is resolved. I think we can close this bug and make sure that the solution to bug 26372 does not include subclassing DOMException. 109317 13 annevk 2014-07-27 11:28:36 +0000 Thanks David, sounds good. 111566 14 jdsmith 2014-09-16 00:44:41 +0000 This bug was closed because the underlying issue with extending DOMExceptions was resolved. The SystemCode discussion from this bug is continued on Bug 26776 - Diagnosing and resolving CDM errors needs a numeric systemCode (deleted with MediaKeyError).