Re: StreamBuilder threshold
On Thu, Feb 23, 2012 at 12:58 PM, Feras Moussa wrote:
> This isn't clear from the spec (And I've made a note to clarify it) but
> URLs for
> streams should be one time use URLs (once used it should be automatically
> revoked).
Is it always possible to define that in a sane way?
For example, what if you write
var url = createObjectURL(stream);
element.innerHTML = "";
or
var url = createObjectURL(stream);
document.getElementsByTagName("style")[0].textContent =
"body, div { background:url(" + url + "); }";
Basically I don't think "the exact moment a URL is used" is a well-defined
concept in our current specs.
Rob
--
“You have heard that it was said, ‘Love your neighbor and hate your enemy.’
But I tell you, love your enemies and pray for those who persecute you,
that you may be children of your Father in heaven. ... If you love those
who love you, what reward will you get? Are not even the tax collectors
doing that? And if you greet only your own people, what are you doing more
than others?" [Matthew 5:43-47]
Re: StreamBuilder threshold
On 02/23/2012 12:58 AM, Feras Moussa wrote: -Original Message- From: Stefan Hakansson LK [mailto:stefan.lk.hakans...@ericsson.com] Sent: Sunday, February 05, 2012 4:50 AM To: Feras Moussa Cc: Travis Leithead; public-webapps@w3.org Subject: Re: StreamBuilder threshold On 01/26/2012 07:05 PM, Feras Moussa wrote: Can you please clarify what scenario you are looking at regarding multiple consumers? When designing the StreamBuilder API, we looked at it as a more primitive API which other abstractions (such as multiple consumers) can be built upon. (Please forgive me if I am making stupid input - I am in a learning phase). A very simple scenario would be the example in the draft that "demonstrates how to use StreamBuilder to load a stream into the audio tag". In this example the consumer is an audio tag, and new data is appended to the stream each time the buffer falls below 1024 bytes. Fine so far, but what happens if the same stream (via createObjectURL) is connected to one more audio tag, but at T ms later. In this case the first audio tag would have consumed down to the threshold (1024 bytes) T ms before the second. This isn't clear from the spec (And I've made a note to clarify it) but URLs for streams should be one time use URLs (once used it should be automatically revoked). Thus a scenario as you said below (connecting the same stream to multiple tags) isn't possible. There will only be one event to notify the threshold has been reached, thus there should not be multiple consumers 'racing' for this event. Would be great to clarify. But to my understanding you could always call "createObjectURL" again with the same Stream as input argument. Even if both "createObjectURL"'s generate one-time URLs, you could have a 'race' condition. Another example could be that one Stream is uploaded using two parallel xhr's; one of them could have a couple of pakcet losses and then consume slower than the other (and if WS could take send(stream) the same would apply). If you can please let me know what issue you're trying to address, I'm happy to discuss the possibilities. I hope the above input explained the issue. However, I'm still not clear on what the scenario you'd like to accomplish is - can you please explain it in more detail? If you're looking for a way to reuse data from a Stream, then you should use StreamReader to read the data as a Blob (or another type) which will then provide you with all the Blob semantics, including multiple reads on the data. Actually I am not trying to satisfy a specific scenario, but I've heard people thinking about sending a Stream (being generated at this device using StreamBuilder) to several remote ends. I think this would not really work since there would always be some differences in transmission speed and then the low buffer threshold would have several different triggers (as discussed above). I think it need to be clarified that you can't do this (or attach it to several tags), but it is not clear how to clarify it to me (as said above, even if you have one time URLs you can create several of them). Thanks, Stefan Thanks, Feras Also, For future reference, the latest draft is now located on the W3 site at http://dvcs.w3.org/hg/streams-api/raw-file/tip/Overview.htm Thanks for updating me! Stefan Thanks, Feras -Original Message- From: Stefan Hakansson LK [mailto:stefan.lk.hakans...@ericsson.com] Sent: Tuesday, January 17, 2012 12:28 AM To: Feras Moussa; Travis Leithead Cc: public-webapps@w3.org Subject: StreamBuilder threshold I'm looking at http://html5labs.interoperabilitybridges.com/streamsapi/, and specifically at the StreamBuilder. It has the possibility to generate an event if the data available falls below a threshold. How is this supposed to work if there is more than one consumer, and those consumers either don't start consuming at exactly the same time or consume at different rates, of the Stream? --Stefan
RE: StreamBuilder threshold
> -Original Message- > From: Stefan Hakansson LK [mailto:stefan.lk.hakans...@ericsson.com] > Sent: Sunday, February 05, 2012 4:50 AM > To: Feras Moussa > Cc: Travis Leithead; public-webapps@w3.org > Subject: Re: StreamBuilder threshold > > On 01/26/2012 07:05 PM, Feras Moussa wrote: > > Can you please clarify what scenario you are looking at regarding > > multiple consumers? When designing the StreamBuilder API, we looked at > > it as a more primitive API which other abstractions (such as multiple > > consumers) can be built upon. > > (Please forgive me if I am making stupid input - I am in a learning phase). A > very simple scenario would be the example in the draft that "demonstrates > how to use StreamBuilder to load a stream into the audio tag". In this > example the consumer is an audio tag, and new data is appended to the > stream each time the buffer falls below 1024 bytes. Fine so far, but what > happens if the same stream (via createObjectURL) is connected to one more > audio tag, but at T ms later. > > In this case the first audio tag would have consumed down to the threshold > (1024 bytes) T ms before the second. This isn't clear from the spec (And I've made a note to clarify it) but URLs for streams should be one time use URLs (once used it should be automatically revoked). Thus a scenario as you said below (connecting the same stream to multiple tags) isn't possible. There will only be one event to notify the threshold has been reached, thus there should not be multiple consumers 'racing' for this event. > Another example could be that one Stream is uploaded using two parallel > xhr's; one of them could have a couple of pakcet losses and then consume > slower than the other (and if WS could take send(stream) the same would > apply). > > > > If you can please let me know what issue you're trying to address, I'm > > happy to discuss the possibilities. > > I hope the above input explained the issue. However, I'm still not clear on what the scenario you'd like to accomplish is - can you please explain it in more detail? If you're looking for a way to reuse data from a Stream, then you should use StreamReader to read the data as a Blob (or another type) which will then provide you with all the Blob semantics, including multiple reads on the data. Thanks, Feras > > > > Also, For future reference, the latest draft is now located on the W3 > > site at http://dvcs.w3.org/hg/streams-api/raw-file/tip/Overview.htm > > Thanks for updating me! > > Stefan > > > > > Thanks, Feras > > > >> -Original Message- From: Stefan Hakansson LK > >> [mailto:stefan.lk.hakans...@ericsson.com] Sent: Tuesday, January 17, > >> 2012 12:28 AM To: Feras Moussa; Travis Leithead Cc: > >> public-webapps@w3.org Subject: StreamBuilder threshold > >> > >> I'm looking at > >> http://html5labs.interoperabilitybridges.com/streamsapi/, and > >> specifically at the StreamBuilder. > >> > >> It has the possibility to generate an event if the data available > >> falls below a threshold. How is this supposed to work if there is > >> more than one consumer, and those consumers either don't start > >> consuming at exactly the same time or consume at different rates, of > >> the Stream? > >> > >> --Stefan > > > > >
Re: StreamBuilder threshold
On 01/26/2012 07:05 PM, Feras Moussa wrote: Can you please clarify what scenario you are looking at regarding multiple consumers? When designing the StreamBuilder API, we looked at it as a more primitive API which other abstractions (such as multiple consumers) can be built upon. (Please forgive me if I am making stupid input - I am in a learning phase). A very simple scenario would be the example in the draft that "demonstrates how to use StreamBuilder to load a stream into the audio tag". In this example the consumer is an audio tag, and new data is appended to the stream each time the buffer falls below 1024 bytes. Fine so far, but what happens if the same stream (via createObjectURL) is connected to one more audio tag, but at T ms later. In this case the first audio tag would have consumed down to the threshold (1024 bytes) T ms before the second. Another example could be that one Stream is uploaded using two parallel xhr's; one of them could have a couple of pakcet losses and then consume slower than the other (and if WS could take send(stream) the same would apply). If you can please let me know what issue you're trying to address, I'm happy to discuss the possibilities. I hope the above input explained the issue. Also, For future reference, the latest draft is now located on the W3 site at http://dvcs.w3.org/hg/streams-api/raw-file/tip/Overview.htm Thanks for updating me! Stefan Thanks, Feras -Original Message- From: Stefan Hakansson LK [mailto:stefan.lk.hakans...@ericsson.com] Sent: Tuesday, January 17, 2012 12:28 AM To: Feras Moussa; Travis Leithead Cc: public-webapps@w3.org Subject: StreamBuilder threshold I'm looking at http://html5labs.interoperabilitybridges.com/streamsapi/, and specifically at the StreamBuilder. It has the possibility to generate an event if the data available falls below a threshold. How is this supposed to work if there is more than one consumer, and those consumers either don't start consuming at exactly the same time or consume at different rates, of the Stream? --Stefan
Re: StreamBuilder threshold
On Thu, 26 Jan 2012 19:05:05 +0100, Feras Moussa wrote: When designing the StreamBuilder API, we looked at it as a more primitive API which other abstractions (such as multiple consumers) can be built upon. We should not have a StreamBuilder API. We should have a Stream constructor, similar to how we should not have a BlobBuilder API, but a Blob constructor (and we do now, I believe). It's a lot cleaner and in line with best practices for platform API design (which are undocumented, unfortunately). -- Anne van Kesteren http://annevankesteren.nl/
RE: StreamBuilder threshold
Can you please clarify what scenario you are looking at regarding multiple consumers? When designing the StreamBuilder API, we looked at it as a more primitive API which other abstractions (such as multiple consumers) can be built upon. If you can please let me know what issue you're trying to address, I'm happy to discuss the possibilities. Also, For future reference, the latest draft is now located on the W3 site at http://dvcs.w3.org/hg/streams-api/raw-file/tip/Overview.htm Thanks, Feras > -Original Message- > From: Stefan Hakansson LK [mailto:stefan.lk.hakans...@ericsson.com] > Sent: Tuesday, January 17, 2012 12:28 AM > To: Feras Moussa; Travis Leithead > Cc: public-webapps@w3.org > Subject: StreamBuilder threshold > > I'm looking at http://html5labs.interoperabilitybridges.com/streamsapi/, > and specifically at the StreamBuilder. > > It has the possibility to generate an event if the data available falls below > a > threshold. How is this supposed to work if there is more than one consumer, > and those consumers either don't start consuming at exactly the same time > or consume at different rates, of the Stream? > > --Stefan
