We are having a real time data upload application, that reads continuous streaming file. We developed this logic 2 year before.
In chrome 81, real time file upload stopped working because file BLOB read by chrome is not getting updated (If file data changed), it still shows old Blob. Whatever new data adding in file not showing. Further I see, all File API properties showing old data e.g. File.lastModifiedDate, File.Size.
In previous versions of chrome, all these properties got updated when file content got changed.
Uploaded file details. File grown upto 1000KB, FILE API still shows old details with size 49.2KB.
I believe this is a new bug in Chrome 81 has to be addressed. Please advice if their is an alternative.
Unfortunately this new behavior is working as intended. File objects on the web always were supposed to be immutable snapshots. Chrome in the past unfortunately had a number of exceptions where this behavior wasn't implemented properly (largely because the implementation predates the specification), and those inconsistencies were fixed in M81.
In Chrome we're also experimenting with the Native File System API (https://web.dev/native-file-system/), which explicitly does intend to support the use case of being able to read from files even after they are modified, so that might be an alternative.
I have a cesium viewer using a local imageryProvider. I have 8 levels available, but when I zoom in, Cesium takes longer than it should to call the next level. I zoom in, my map gets blurred, then it changes the level.
This is my viewer code:
var viewer = new Cesium.Viewer(mapID, {
imageryProvider: new Cesium.UrlTemplateImageryProvider({
url: '../../app/CesiumUnminified/Assets/Textures/myTiles/{z}/{x}/{y}.png',
maximumLevel: 8
})
});
Is there any way to call the next level faster so my map doesn't get blurred?
Thank you!
The next level is blurred while waiting for a response from your server. In this case it looks like you're serving the images locally, so the server could be a development or stripped-down server that might not have the performance of a production server.
Most browsers these days have a "Developer tools" type section with a network tab, that shows traffic between the client and server. For example, here's an article explaining how to interpret this display in Google Chrome, although similar tools exist in Firefox, IE, and Edge. Take a look at the timing of tile responses, and see if there's anything that can be done to the server to speed things up.
I have Disable cache tick removed and still request is made on each video loop iteration(Only on chrome).
What Initiator: Other mean in chrome inspector network section? First time the video is loaded from the host, but after that all requests are loaded from Other.
Each iteration video size is the same, not (from cache). Is that mean the browser download it every time?
Can it be avoided somehow without saving the video in localStorage(I saw it in similar question), because this solution will not work in private browser mode and localStorage have size limit?
UPDATE
With Disable cache checked
Without Disable cache checked
UPDATE
Bug report: https://bugs.chromium.org/p/chromium/issues/detail?id=680063
The meaning of this is that another process than Chrome initiated the request:
Some other process or action initiated the request, such as the user
navigating to a page via a link, or by entering a URL in the address
bar.
In the case of Chrome, video is decoded using ffmpeg which likely is this other process. The process is likely reopening the file from the cache which is why the request is initiated, or, the cache only holds the latter part (or max content length in sum) of the file in case the file is large and has to re-stream parts of the content over again - though, you state that when cache is disabled this doesn't happen.
localStorage has a very limited size and is not very suitable for storing video data (it can only hold strings so video must be encoded as mime-64 which increases the size 33% + each char takes up two bytes due to unicode).
A better alternative would be to use IndexedDB - this can hold much larger data as well as store the data in binary format (Blob). But it comes with an initial limit as with localStorage but contrary to the latter method you can request a larger size which the user need to confirm. I haven't tested, but I would assume you will run into the same limitations with private mode as with any other storage mechanism.
Yesterday I had the same issue. I found that Chrome's tab crashes after a couple of minutes. It looks it happens only when Disable cache is checked, but if this still bugs you, you can store the video into the local storage. More code in this answer.
I'm trying to debug some JavaScript for a Rails project and its incredibly frustrating to go line by line when the source code is compressed in the Sources developer tab.
I know this compression is done by Chrome through the body variable. What I want to know is if there is any way to stop Chrome from compressing files in source view, i.e:
\application.js?body=1 --> \application.js
Thank you for your time.
Compression is being done by Rails. Disable it in your configuration:
# config/production.rb (or whatever environment you're in)
config.assets.compress = false
You might want to investigate a new feature in Chrome called Source Maps.
Source Maps allows Chrome to map the compressed source code it receives to the uncompressed original, which in turn means that you can debug the code, even though it's been compressed.
This feature should help you get around this kind of problem without having to change the compression settings on your server.
You can read more about it here: http://blog.mascaraengine.com/news/2012/4/16/sourcemap-support-in-chrome-greatly-improves-debugging.html
I believe this feature is still in test and not yet in the final release version of Chrome. I'm sure it will arrive in due course, but for the time being you may need to install the "Canary" version of Chrome, ie the pre-release version that includes all the forthcoming features that they're still working on.
I'm writing a web app to be used offline on iOS. I've created a manifest, am serving it up as text/cache-manifest, and it usually works fine, when running inside Safari.
If I add it as an app to my home screen, then turn on Airplane mode, it can't open the app at all -- I get an error and it offers to close the app. (I thought this was the entire purpose of an offline app!)
When I load the app a first time when online, I can see in my logs that it's requesting every page listed in the manifest.
If I turn off Airplane mode, and load the app, I can see the first file it's requesting is my main.html file (which is both listed in the manifest, and has the manifest=... attribute). It then requests the manifest, and all my other files, getting 200's for all (and 304's for anything requested a second time during this load).
When I load the page in Chrome, and click around, the logs show the only thing it's trying to reach on the server is "/favicon.ico" (which is a 404, and which I don't think iOS Safari tries to load, anyway). All of the files listed in the manifest are valid and served without error.
The Chrome inspector lists, under "APPLICATION CACHE", all the cached files I've listed which I expect. The entire set of files is about 50 KB, way under any limit on offline resources that I've found.
Is this supposed to work, i.e., am I supposed to be able to create an offline iOS app using only HTML/CSS/JS? And where do I go about figuring out why it's failing to work offline?
(Related but doesn't sound quite the same to me, since it's about Safari and not a standalone app: "Can't get a web app to work offline on iPod")
I confirm that name 'cache.manifest' solved the offline caching problem in IOS 4.3. Other name simply did not work.
I found debugging HTML5 offline apps to be a pain. I found the code from this article helped me figure out what was wrong with my app:
http://jonathanstark.com/blog/2009/09/27/debugging-html-5-offline-application-cache/
Debugging HTML 5 Offline Application Cache
by Jonathan Stark
If you are looking to provide offline access to your web app, the Offline Application Cache available in HTML5 is killer. However, it’s a giant PITA to debug, especially if you’re still trying to get your head around it.
If you are struggling with the cache manifest, add the following JavaScript to your main HTML page and view the output in the console using Firebug in Firefox or Debug > Show Error Console in Safari.
If you have any questions, PLMK in the comments.
HTH,
j
var cacheStatusValues = [];
cacheStatusValues[0] = 'uncached';
cacheStatusValues[1] = 'idle';
cacheStatusValues[2] = 'checking';
cacheStatusValues[3] = 'downloading';
cacheStatusValues[4] = 'updateready';
cacheStatusValues[5] = 'obsolete';
var cache = window.applicationCache;
cache.addEventListener('cached', logEvent, false);
cache.addEventListener('checking', logEvent, false);
cache.addEventListener('downloading', logEvent, false);
cache.addEventListener('error', logEvent, false);
cache.addEventListener('noupdate', logEvent, false);
cache.addEventListener('obsolete', logEvent, false);
cache.addEventListener('progress', logEvent, false);
cache.addEventListener('updateready', logEvent, false);
function logEvent(e) {
var online, status, type, message;
online = (navigator.onLine) ? 'yes' : 'no';
status = cacheStatusValues[cache.status];
type = e.type;
message = 'online: ' + online;
message+= ', event: ' + type;
message+= ', status: ' + status;
if (type == 'error' && navigator.onLine) {
message+= ' (prolly a syntax error in manifest)';
}
console.log(message);
}
window.applicationCache.addEventListener(
'updateready',
function(){
window.applicationCache.swapCache();
console.log('swap cache has been called');
},
false
);
setInterval(function(){cache.update()}, 10000);
Sometimes an application cache group gets into a bad state in MobileSafari — it downloads every item in the cache and then fires a generic cache error event at the end. An application cache group, as per the spec, is based on the absolute URL of the manifest. I've found that when this error occurs, changing the path to the manifest (eg, cache2.manifest, etc) gives you a fresh cache group and circumvents the problem. I can vouch that all of our web apps work offline in full-screen with 4.2 and 4.3.
No offline web app (as of iOS 4.2) can run without an internet connection (which means Airplane mode, too) when using <meta name="apple-mobile-web-app-capable" content="yes" /> in the html head section. I have verified this with every example I've seen and the ones that use Safari to render the site work fine, but when you throw in that meta tag, it won't work. Try your app without it and you'll see what I mean.
I have found that clearing the Safari cache after enabling Airplane mode to be an effective way of testing whether the app is really functioning offline.
I have sometimes been fooled into thinking that the application cache was working when it wasn't.
I had struggled with this iOS 4.3 "no offline cache" problem since I updated my iPad to 4.3.1 from 4.2. I saw in another post in this site that it was working again in 4.3.2. So I updated by iPad again, now to iOS 4.3.3. But still couldn't get the offline caching to work until I renamed my manifest file to "cache.manifest". Then the caching started working again and I could run my HTML5 offline app from the Home Screen. I did not need to put the favicon.ico in to the cache manifest. And I also had full screen going (setting the "apple-mobile-web-app-capable" to "yes").
I have several working offline and on/offline web apps.
When I turn off airport mode, I get a request for the manifest and some other files.
I don't get requests for images, JavaScript, CSS or cached AJAX files.
If you see requests for your resources, IOS doesn't have them cached.
Safari in general is more picky with manifests.
I suggest you try Safari on your computer.
I have run into the same problem today on iOS 4.3. I was able to fix the problem by adding a favicon.ico file and also adding it to the manifest.
I've written an offline app that still seems to work in 4.2 and 4.2.1; the post is a little dusty, but the code still runs:
http://kentbrewster.com/backchannel/
Remy Sharp has a newer post with code that also works, here:
http://remysharp.com/2011/01/31/simple-offline-application/
His app:
http://rem.im/boggle/
After days of messing with getting offline web apps to work on an iPhone/iPod Touch using the Webserver's HTTP authentication, I discovered these useful nuggets:
Make sure Safari is at the URL root of the web app when tapping "Add to Home Screen". I used jQuery Mobile and was sometimes adding the link with"/#pageId". Caused trouble.
Run your Ajax calls in serial. This might only be important if your web app is using HTTP authentication, but my app was firing a whole slew of Ajax calls on page load in parallel and it caused the app to hang on the "apple-touch-startup-image".
Ajax calls are "successful" when offline (at least using Prototype.js). Test for an actual piece of data in the Ajax response, not just on the HTTP status. I used this to test for displaying cached (SQL) or live data.
In the manifest use "NETWORK:\n*\n". From what I could muster, this is a catch-all statement for anything not explicit in the "CACHE:" section. Use Chrome to make sure your manifest is correct. Look at Chrome's console for errors.
Not directly related, but tripped me up for a bit, openDatabase.transaction() calls are ASYNCHRONOUS! Meaning, the line of JS code after transaction (execute(), error(), success()) will execute BEFORE the success() function.
Good luck!
I found this solution that seemed to work for me, since I also ran into this problem during my development. This fix has worked fine for me so far and also for other people that I've asked to test it with, and I'm able to get it running offline (in airplane mode) and off the home screen after caching and whatnot. I've written a post about it on my site:
http://www.offlinewebapp.com/solved-apple-mobile-web-app-capable-manifest-error/
Delete your current web app icon on the home screen.
Go to settings and clear your Safari browser cache.
Double tap your home button to open the multitasking bar. Find the Safari one, hold your
finger down on it, and exit it.
Please let me know if this works for you also! Good luck!
I've written an app and it works fine through the mobile browser, but when adding the desktop... Doesnt work. I guess apple have given up on IOS4 and all efforts are now on OS5. Shame :(
I have one potential workaround for this - it seems a bit crazy, but here goes... I work with the cache.manifest and full screen apps a lot (here's a test if you need: http://www.mrspeaker.net/2010/07/12/argy-bargy/ - add to home screen then turn on flight mode and it launches - at least, as of iOS 4.2.1)
One weird thing I found is that sometimes it seems that some kind of "meta" information in files can mess them up from being cached - Have you ever noticed that in bash that if you do a "ls" some files (depending on your colour settings) are highlighted for no apparent reason? Files can have meta data that the operating system (I think) adds automagically - and there are ways to remove it... I can't remember why but here's some more details: Strip metadata from files in Snow Leopard
After tearing my hair out one day - and refusing to give up because I knew it SHOULD have worked... Chrome was saying it loaded all the files, but ended with a generic error. In the end I recreated the project structure with blank files and copy/pasted the contents over. It worked - started caching as it was supposed to!
When I looked at the files I noticed there was some meta info. I tried scrubbing this info and the original project worked again. I'm not sure this was the reason it worked again - perhaps it was just a coincidence.
Because it worked, I didn't think too much about it. The same problem happened again some months later and the copy/paste trick worked again. I was busy, so I didn't investigate further - but vowed I would get to the bottom of it the next time it happened.... but I haven't had to yet.
Phew. Anyway, glad I got to write that down somewhere...
[UPDATE: months and months later - I've not been able to reproduce this, so I don't think it's the metadata]