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Work around for Html5 Local File Access

We are currently looking at porting a enterprise silverlight application over to html5. The major roadblock that we have hit is the ability to open files from the user's local disk. Currently they have a document library which just links to files on their computer that they can open from within the app and view or print out. All that I read is that you can only access the local sandbox of the web app with the html5 file api's. We want to load these files from code.
Does anyone know of any workarounds to this?
Thanks

There is no way for html5 to access local file without user selection. But FSO: FileSystemObject works for IE and MAYBE could be regarded as a work around. But still there are some requirements to meet.

It is possible to use chrome's filesystem API to access files on a users local filesytem. So you'd have to be willing to make this a chrome only application.

Using java you can create a "Signed" applet which has access to the local filesystem. (if the applet is signed you can request filesystm permissions)
then there is a tutorial for accessing methods of your java code directly from javascript here: http://docs.oracle.com/javase/tutorial/deployment/applet/invokingAppletMethodsFromJavaScript.html
you should be able to perform something similar from silverlight.

There is no workaround in pure HTML5/Javascript. You need the use of plugins, such as Java or Silverlight (maybe you shouldn't port it after all). As for workarounds, HTML5 gives you an easy way drag and drop multiple files that you could transfer on the server and then display back to your users. Another workaround would be to install a custom agent (a software with only a tray icon) that would send the information about the current user "document library" to server and then again, you could display it back to the user.
Note: I've heard somewhere that browsers will eventually stop supporting plugins. http://www.howtogeek.com/179213/why-browser-plug-ins-are-going-away-and-whats-replacing-them/

Ya, I agree with Markain. However, if you were to limit your audience solely to chrome users, I daresay, you would most likely use some of your users. If Huazhihao is right, then your number of leaving customers should decrease but users who regularly use firefox won't be happy. Overall, I think that this will not work. Otherwise, there would be too many websites that trashed your hard driver (or at least wherever you have the rights to edit/delete files). I think it would be best if your product was setup to synchronize the file whenever an internet connection was detected and a change was made to the file. That way the user would not need to visit the website whenever the file was uploaded. If this is some kind of an error file, then it would be most beneficial if you were to make a link in the application that when clicked, would upload the file to the website and the website were to do whatever was necessary. If this is a purely online thing, then I don't see what business you would have looking through other peoples' files =-). Hope I helped!

Can I pass a file into the browser then manipulate it with javascript?

I understand that javascript running in the browser would not be allowed to access a local file system directly, it make sense and I am not looking for a way to violate that.
However are there any safe and kosher ways to grab files from the local system for the browser to use? Would these methods be platform specific? Would I be limited it what kinds of files and would access have to be granted on a per file basis?
What I am thinking about is when you upload photos, it will open a system level dialog and then eventually present that file to the browser for the browser to send to a remote server via http. Would it then be possible to pass a file in to the browers local memory/ give the browser permission to read it as it were to be upload but instead of uploading it somehow pass over to java script and allow it to manipulate it client side much in the way you can manipulate files with server side javascript?
The reason I am asking is because I have recently become interested in browser-based file manipulation programs, their feasibility and what could be done with them in a Chrome OS type environment. Just out of curiosity then any idea of it being practical any time soon.
edit: attempted to clarify and make my question more direct.

Use the File API (MDN has a tutorial) but be aware that it is a new specification and has limited browser support.
It allows files selected in an <input type="file"> to be accessed with client side JS.

Solutions to allowing intranet/local file access in an HTML5 application?

I am all too aware of the fact that even with the new FileAPI it's not possible to access the local path of a file added using a file input field or drag-and-drop. Whether or not this is good, bad or ugly is not the issue here. According to the FileAPI specs local file access is not to be implemented, and so I'm not holding my breath.
But let's just pretend I'm in a situation with the following fixed parameters:
Developing an HTML5 application only to be used internally at a company
.NET used for backend (needed due to interop with APIs)
Can specify/control exactly which browser and version should be used with the application
Need to access files that are usually located on a network share, but possibly also locally at a user's workstation
And by access I don't mean access file data, but rather be able to relay a file drag-and-drop/select event to some other API by feeding the third party the file's local path, so that the third party can pick up the file and do some sort of work on it. This can be likened to using an input[type=file] field as you would an OpenFileDialog in .NET - i.e. the point is to feed the application a file path, not an actual file.
I realise that out of the box this is probably not possible. But I also think that there must be some sort of solution to the problem.
Some ideas I've been toying with are:
Using browser specific methods for allowing "secure features"
Not sure if possible - tired using some of these features to no avail
Would limit the app to a specific version of a browser as the functionality could potentially be removed in the future
Something like a Chrome extension could possibly do the trick
Using some sort of companion application installed locally on a clients computer that takes care of all on-disk file handling, possibly communicating with the HTML5 client using websockets or the like.
A potentially pretty messy solution
Would probably confuse the users a bit at first
Submitting the selected file data to the server, storing it at specific path and sending this new path to the third party.
Would constitute a lot of sending files over the company network, some 100+ MB in size
Would not be able to do any in-place changes to a file a user has selected
... and that's about it.
Any snazzy suggestions? Wise words? Helpful links? Snarky comments?
Thanks.
Edit: For anyone curious about it, this was very simple using Silverlight as per jgauffin's suggestion below.
From the Silverlight codebehind (using elevated privileges):
private void fileBtn_Click(object sender, RoutedEventArgs e)
{
//prompt file select dialog in Silverlight:
var dlg = new OpenFileDialog();
dlg.ShowDialog();
//call JavaScript method and feed it the file path:
HtmlPage.Window.Invoke("onFileSelected", dlg.File.FullName);
}

You'll probably have to use something that runs in the browser like flash or silverlight.
Since it's an internal app I would use silverlight as everything else is in .NET. It should be enought to only make the file access part in the plugin.
Here is an article about local file access: https://www.wintellect.com/silverlight-4-s-new-local-file-system-support/

does the server hosting the site have access to the network of pc's?
you could just list all the files that way.. build a small ajax script like a file dialog that will have php or whatever sending back the structure
no plugins needed, works on all browsers... :)

Remote site, local file redirection

As a followup on this answer:
Specified javascript does work in case of a local website, but fails in case of a remote site. The firefox extension locallink helps in case of links, but is useless in case of the javascript solution provided by the linked answer. Please provide possible workarounds for redirecting to local files (unc) in firefox.

The only way I can think to do this would involve a signed, Java applet running on your page. Essentially what you'd do is provide the file to the applet and have it open up a new browser window with the file's URL. Since the applet is trusted by the local system it should have access to the local hard drive and should be able to start up a new application.
Note: I've not tried this, I'm just speculating on how I would do it. I have used a signed, Java applet to get at some local networking parameters for use in a Wake on LAN application so I know that signed applets are allowed to interact with the system in ways that browsers can't.

Write to local disk from web page

I'm working on a Silverlight control that will allow multi-file downloading. At the moment I'm trying to get my mind around the permission model of the browser.
Let's say, on a web page, a user enters a local folder (c:\temp) in a text box. The user then clicks a button.
Is it possible in JavaScript or Silverlight, to write a collection of files (that are stored on the server) to that folder on the user's drive?

From Javascript - NO. It would be way too easy from some scumbag to install a virus on your PC if that were possible.
Silverlight I don't know about, but I would assume writing to the users hard drive would be very limited and tightly controlled.

Only if the browser has a security hole that you can exploit.
Since the capability you describe would allow any webpage to do whatever it damn well pleases to the visitor's system, there is no way anyone would implement arbitrary access to the local disk deliberately in this day and age.
The next best thing you can to is to have the user download a ZIP archive and tell him to decompress him wherever he likes.

You cannot from Silverlight. The only thing you have access to is the Isolated Storage.
http://blog.paranoidferret.com/index.php/2007/10/12/silverlight-tutorial-using-isolated-storage/
http://msdn.microsoft.com/en-us/library/bdts8hk0.aspx

Warning: most of these answers are incorrect.
You can so write to a file via Javascript in both MSIE (using ActiveX FileSystemObject) and Firefox (using nsIFileOutputStream). In both cases the user will be presented with a security dialogue, which can be allow or deny the read or write.

I have used the Scripting.FileSystemObject to do this. Only works in IE, and only with very relaxed and unsafe security settings, but it might work for intranet sites in an enterprise, at least it worked for me.

Google Gears has a method to do client-side storage.
http://gears.google.com/
That said, I doubt it will do what you are attempting. I think you would be better off having a server-side thing download files and put them into a .zip file for the client before passing it on to them.

As it was answered earlier, this would have to be done via server-side, Silverlight and JavaScript are sandboxed to disable this type of security hole. I would suggest packing the files into a zip archive on the server and then downloading the zip archive.

You can do this via an ActiveX control or Java applet. Either way you do this the project has to be signed with a code signing certificate. You can use a self-signed certificate but the warning dialogs will be louder and brighter.
You can then use Javascript to call into the signed control and save files. Be very careful about creating an applet like this. You don't want to allow any other website to use this control so the control must implement some of the following:
Only work on a certain website.
Save files only in a specific location.
Prompt the user where to save the files so that they know that this is happening and it doesn't happen silently in the background.
You can probably find a control or applet somewhere that can be controlled with Javascript.

I don't believe this is possible as it create countless security problems. The only way I can see this being secure is a mix of user permissions and some way of verifying (on the client side) the authenticity of the website and the files they want to download to my computer.
One method you could do is triggering the "FileSaveDialog" but I don't think that is what your looking for. Maybe packaging the collection of files first and then triggering is the way to achieve your goals. Silverlight only allows for 1mb of isolated storage per domain and will absolutely not give sites access to the clients hard drive.

This doesn't directly answer the question, but Adobe Flex 4 allows doing it with FileReference class.

Silverlight 4 OOB allows access to the user's document directory.