I know there's a new html5 API called web storage, but it basically allows only up to 5MB of storage per domain, so how services like Deezer do to offer an offline mode ? It means that they have to store the musics on the computer, but it's all in the browser, so how do they do to bypass the 5MB of storage ?
http://www.deezer.com/en/features/everywhere.html
I can't speak for Deezer, but there are several new APIs in development for HTML5 including the FileSystem and FileWriter API.
In use cases it gives examples of large storage requirements the API will be able to fulfil such as storage of large media files and assets.
Offline video viewer
It downloads large files (>1GB) for later viewing.
It needs efficient seek + streaming.
It must be able to hand a URL to the video tag.
It should enable access to partly-downloaded files e.g. to let you watch the first episode of the DVD even if your download didn't complete before you got on the plane.
It should be able to pull a single episode out of the middle of a download and give just that to the video tag.
It's still a working draft and not very widely adopted.
I'm currently working on a web app with the request that selected pages be accessible offline after downloading. I'm aware of the HTML5 offline storage method and have no problem with it, but as far as I can tell, it's developer specified.
Question is, is there a way in which I can set it up with a function that will write to the .manifest file when, for example, the user clicks a button on the page they'd like cached locally for offline viewing?
The app in its entirety would be far too large to cache locally (not only due to the restrictions of the HTML5 local storage method, but the sheer amount of time it would take).
Suggestions of alternate methods not relying on HTML5 local storage would also be welcome.
Any help would be greatly appreciated. Thanks.
I need an offline caching system where my app can store about 0.5 MB of data. It is preferred that there is no interaction required by the user, but small amount of user interaction might be acceptable
Currently, Microsoft's Silverlight is being used to store data offline. It is a large download for the plugin, and not installed as standard on most machines.
I have been considering cookies - but they are far too volatile. I can imagine numerous reasons someone might clear their browser cache and lose all their data.
I am not sure about HTML 5 storage, and how volatile it is in practice.
I have been looking into flash, which is installed on over 97% of windows computers. It seems I can load data from a user selected file, and save data to a user selected file.
My questions...
How big is the microsoft silverlight plugin download (in MB) for windows? (I think about 8mb, but did not get clear answer from the internet)
How can users accidentally (or deliberately without realizing the consequence) clear their HTML 5 storage on common browsers?
Is there a way to get flash to store or load data from local files without user interaction?
Is there another alternative I have not considered?
Well you could use Flash shared Object storage, which will allow between 0 and unlimited space. Check this settings panel for details of your own settings to get a better idea of what I mean.
http://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager03.html
Of course this does mean that the user will have to allow third party flash content to be stored locally, which is the default. Also the default storage space is 100KB, with the user being prompted to allow for a larger amount unless they have previously increased the default themselves. So that's a small draw back, but still workable.
I am not sure how you would access the shared object from within a silverlight app, as I have only used it via a Flash swf. I will do some digging around using javascript and get back to you on that.
Also there is another post that may help you:
Javascript bridge to Flash to store SO "cookies" within flash
It sounds like what you need is isolated storage.
I use it with all my silverlight apps and it couldn't be easier to use. With only a few calls you can store and retrieve data programatically.
Edit: I was thinking that your app is already programmed in Silverlight. What is your app programmed in? Is it simply HTML/CSS at the moment?
HI!
I have searched a lot, but I didn't find the answer to this question: Is there any possibility to save or set the html5 local storage on SD card or locally on device? Can anybody help me?
Thanks!
I don’t think the Local Storage API lets you decide the physical location of the data being stored. It just lets you store key/value pairs in the user’s browser via JavaScript, like a cookie except that it stays local and isn’t transmitted to the server.
The browser might choose to put its local storage data onto an SD card, or the device that it’s running on, but you don’t get to inspect the physical location of the data.
See http://diveintohtml5.ep.io/storage.html#localstorage for a good guide on what local storage can do, and how to use it.
http://www.w3.org/TR/file-writer-api
I do belive this is what you would need. Read support is done and there are some chrome extensions that take advantage of it (write space), however the apps don't have write support because chrome dosen't have the api, because its still wip. The chrome folks are doing a nice job with it and I think its mostly done. I've been searching around for examples.
For storing data offline WebApp can use:
session storage, "advanced version of cookies"
key/value based Web Storage (AKA local/global/offline/DOM storage)
sql-based Web SQL Database (deprecated) and Indexed Database API
FileReader and FileWriter API (requires user to select files each time the application loads)
But apparently there is no File Storage. Of course, there is a manifest-based caching, but it's just a cache and is not supposed to be used as a user data storage.
Does it mean that the user of WebApp is forced to use some sort of a cloud file storage?
Is there any way to save large files on user's local machine? Or maybe some way to select a local folder web application can use to store user data?
Edit. Security. HTML5 already has the ability to write big portions of data to user's local machine. I don't see any security issues if a browser will provide another, file-based abstraction to store data. It can be some virtual machine, virtual filesystem, whatever.
Hm, I think, it is possible to write JS filesystem and store it as a blob in SQL...
Similar questions.
Update:
Hm... recently I've found this and this. Maybe it is what I'm looking for... Yes, it is! See the answer below.
At last, I've found it! Here's the answer:
I’ll have the DOMFileSystem with a side of read/write access please wrote:
Eric Uhrhane of Google has been
working on the working draft of the
File API: Directories and System specification which defines a set of
APIs to create a sandboxed filesystem
where a web app can read and write
data to.
Wow! I'm so excited!
Why not use localStorage while the user is editing a document and the FileWriter API when they want to save it to disk? Most people are used to seeing a save dialog pop up when saving a document.
The only scenario I can think of that warrants userless access to the FileWriter API is an autosave feature, but autosaving to localStorage can be just as good.
There is a way to save relatively large files to a users hard drive if you are willing to use Flash. Look into Downloadify:
http://www.bitrepository.com/downloadify-client-side-file-generation.html
Downloadify allows you to send data to a SWF and have that SWF create a file on the users machine. My recommendation would be to store the data via one of the methods you listed, Webstorage, sqlite database, etc. Put all your assets, including the SWF in the manifest file so everything is cached locally to the browser. You can then pull information from your db or webstorage and use the SWF to create the files you need.
I'm not sure if you will be able to read these files back into your web application.
Another option to save data is by using link tags with the data URI scheme. However, I'm not sure if it is supported in all the major browsers at the moment.
For security reasons you can't write files to a user's local filesystem in case it gets used for nefarious purposes by evil people.
That's not likely to change, and that's a good thing.
The HTML5 FileSystem API started landing in Chrome 8 and is fairly complete as of now (Chrome 11).
There's a nice tutorial on it here: http://www.html5rocks.com/tutorials/file/filesystem/
http://fsojs.com wraps the FileSystem API effectively, if you want an easy solution
As mentioned by others here, the FileWriter and FileSystem APIs can be used to store files on a client's machine from the context of a browser tab/window.
However, there are several things pertaining to these APIs which you should be aware of:
Implementations of the APIs currently exist only in Chromium-based browsers (Chrome & Opera)
Both of the APIs were taken off of the W3C standards track on April 24, 2014, and as of now are proprietary
Removal of the (now proprietary) APIs from implementing browsers in the future is a possibility
A sandbox (a location on disk outside of which files can produce no effect) is used to store the files created with the APIs
A virtual file system (a directory structure which does not necessarily exist on disk in the same form that it does when accessed from within the browser) is used represent the files created with the APIs
IsolatedStorage, which hasn't been mentioned as of yet, also allows for file i/o from a tab/window context, but it is made available through solely through Silverlight and requires the use of managed code to access. It, like FileSystem, also exists in a sandbox and makes use of a virtual file system.
Given the high market penetration of both Chromium-based browsers and Silverlight (support for which, interestingly enough has been dropped by such browsers), you may find a solution which uses the first of the above approaches available on a client machine satisfactory.
BakedGoods, a Javascript library that establishes a uniform interface that can be used to conduct common storage operations in all native (including FileSystem), and some non-native (including IsolatedStorage) storage facilities, is an example of such a solution:
//Write file to first of either FileSystem or IsolatedStorage
bakedGoods.set({
data: [{key: "testFile", value: "Hello world!", dataFormat: "text/plain"}],
storageTypes: ["fileSystem", "silverlight"],
options: {fileSystem:{storageType: Window.PERSISTENT}},
complete: function(byStorageTypeStoredItemRangeDataObj, byStorageTypeErrorObj){}
});
Just for the sake of complete transparency, BakedGoods is maintained by this guy right here :) .