I have a 6MB binary file in my AppEngine backed app. I need to get this file to my GWT client to do many computations. I'm trying to avoid doing the computations on the server to save my instance hours quota. But this means I have to get the file to my client somehow.
I also don't want to download it to the app each time the app is opened, that would hurt my appengine outgoing bandwidth quota.
It would be nice to download it once, then have the client somehow store it for use the next time the app is opened.
How to best do this?
A ClientBundle? Use HTML5 Storage? Is this sort of thing just not done, and should I just do the computations on the server and send the result to the client?
The most easiest way to permanently cache the file is using application cache.
Another ways is HTML5 Storage (localStorage), but there is 2.5 MB limit. To use more than that amount, you have use IndexedDB (Chrome, Firefox, IE10) and WebSQL (Safari, Opera). A wrapper library like YDN-DB help in this case.
You can use DataResource:
https://developers.google.com/web-toolkit/doc/latest/DevGuideClientBundle#DataResource
The only problem you face is the file size. Different browsers have different limits - I've seen 5MB and 8MB numbers. If you can compress your file to be under 5MB, you should be fine with most browsers. (By the way, it's an enormous amount of data if it can't be compressed any further.)
Also, you can detect a mobile browser (or offer a different URL for mobile version), and do computations on the server for mobile users.
Related
I have a web application that uses a lot of offline storage. It was running good until the data increased and reached around 8MB. Whenever storing that much data to the WebSQL, I received error stating "The inspeted target has crashed." I assume that it has to do with the storage capacity, although I am not sure. Since everything was working fine until the data increased, I would like to check after increasing the WebSQL capacity. There is a post I read that talk about creating a manifest.json file. My question is
Does this work for web applications?
Where is this file placed?
What are the furhter steps to take after creating this file?
What about other browsers? Does this solve problem for only Chrome?
I think this has something to do with the implementation of your WebSQL. I have offline databases in WebSQL that are well over 100MB and load in Chrome without a hitch.
I am just researching and playing around with HTML5 FileSystem API. I am downloading a video from the server and saving it to the local sandbox filesystem. Say a user comes to the sites, hits download on the video, it saves to the filesystem, then the user happens to go offline.
My question is, what is the best practice for checking if video is already in the filesystem and loading it from there?
Thanks
You're asking about persistent, client-side storage of video, specifically using the Directories and System API, sometimes called "File System API." I believe this is currently only supported on Chrome 28 and Opera 16 or higher – i.e., slightly less than 1 in 3 web users right now.
Per the API spec, the users will be prompted to allow the quota for the on-client storage allotment because you're requesting persistent, not transient, storage. While the persistent client storage may be handy, it's not entirely transparent to the user.
As for determining if the Chrome or Opera user has the video stored locally, simply calling getFile() file will do it; if the file doesn't exist, it simply throws an error that you can then handle to go ahead and pull down the video. That's the standard / best practice way of determining if a file has been stored locally.
PS: Yes, I see that Blackberry mobile supports the API, too. I just don't know if either of the remaining Blackberry users will have the device storage quota available for video :-)
I had a doubt regarding HTML5 storage technologies like WebSQL, WebStorage/LocalStorage, and indexedDB and to a lesser extent appCache.
Considering the case of chrome (my default browser), these stores are maintained in chrome browser's own directory. Do they impact the starting-up time of the browser?
A colleague has said to experience browser slowing down or behaving in sluggish manner when a larger amount of data is stored.
Couldn't find references to how these technologies impact the browser working, so would love if any fellow-stacker could guide me.
Be careful : the WebSQL API is dead (it was based on sqlite instead of a generic API and so was judged not desirable by the Mozilla team, the Indexed Database API will be used instead but you should probably wait for it to be more supported).
LocalStorage is fine, I use it in all my web applications without problems nor measurable boot time. But keep it for parameters, preferences, and so on, as the only reliable storage is always server side. The local storage can be removed, lost, modified, not readable for many reasons (user uses another browser or computer for example). And it seems to me that a big local storage is a burden to the user and thus not very correct (which is probably the reason why this size is limited).
BTW, there is no reason a reasonnable local storage could slow in a measurable manner the launching of a browser.
I agree with dystroy; Normally the local storing is harmless if done the right way. Storing MASSIVE amounts of data in the browser on the other hand is quite discouraged. It won't slow down the browser performance overall but will slow down the web app using it (as far as I know, Chrome fetches the local storage values dynamically when the 'owner app' is called).
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?
I am building a mobile app that must work in Blackberry, iPhone and Android phones. I am building this mobile app in HTML5, CSS and JQuery Mobile. Then I will use PhoneGap to allow the code to run as a native mobile app for the phone. The mobile app must be able to work without connection to the internet. The only time the app must require an internet connection is when it loads for the first time, because that's when the app will download over 50 MB worth of data. Next time the app has internet connectivity, it will poll the server for more recent data to consume.
My problem lies in where do I store 50 mb worth of data which can be updated when internet connectivity exists?
Additional Notes
I've been discouraged by others to use Web SQL Database because the specification is no longer in active maintenance. I've read that localStorage and cache manifest has a storage limit of about 3-5 mb depending on the browser. From experience, I've encountered a lot of challenges working with the PhoneGap API to create one set of code that will reliably write to all of the following file systems: ios, bb, android.
Based on your needs: (store 10,000 images, 10,000 pdfs, +videos etc.) I don't think a "lightweight" HTML5 application is going to suit your needs.
I think that a native application is likely going to work much better where you have proper filesystem access to store the files on the device as needed (and even structure them better).
The HTML5 localStorage (5mb) and the WebSQL (SQLLite) (5mb-~50mb) database options really won't give you what you need as far as I can tell.
WebApp "wrappers" like PhoneGap and WebWorks (for BlackBerry) will give you the filesystem access you need, but I'm not sure if either of them have limitations that you'll hit size/quantity wise... hopefully someone with experience in these wrapper frameworks can indicate any size limits they've encountered.