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Proposal for an extension XMLHttpRequest to allow sending files

From: Sam Weinig <weinig@apple.com>
Date: Thu, 17 Jul 2008 13:14:23 -0700
Message-Id: <EB6D3B80-A67B-4CD3-94BE-751C518E29B9@apple.com>
To: Web Applications Working Group WG <public-webapps@w3.org>
We would like to propose standardizing a way of using XMLHttpRequest  
to send files to the server.  We propose using a similar (and  
compatible) API to the Blob based API proposed by Google Gears (http://code.google.com/p/gears/wiki/BlobWebAPIPropsal 
), but instead of sending Blob objects, the File objects would be  
sent.  This will allow the common act of uploading files, now  
relegated to form submissions with an <input type="file">, to have  
access to ProgressEvents and the ability to abort mid way through.

As with the Blob API, this is reuses the File and FileList interfaces  
exposed by Mozilla (see http://developer.mozilla.org/en/docs/ 
nsIDOMFile and http://developer.mozilla.org/en/docs/nsIDOMFileList) in  
a compatible.  We are not proposing a specific way to get the contents  
of the files, but that would be a natural future extension.  Other  
potential future extensions would be access to the icon associated  
with the file.

Objects implementing the HTMLInputElement interface must also  
implement the FileHTMLInputElement interface.
interface FileHTMLInputElement {
    readonly attribute FileList files;

The files attribute must return a FileList containing all the files  
currently selected.  This list is live, and therefore updates if  
contents of the input element change.

interface FileList {
    readonly attribute unsigned long length
    [IndexGetter] File item(in unsigned long index);

Each item in the FileList is File, which is a token representation of  
file on the system.  The fileName attribute returns just the name and  
not the complete path.  The fileSize attribute returns the size of the  
file in bytes.

interface File {
    readonly attribute DOMString fileName;
    readonly attribute unsigned long long fileSize;

Sending a File can be accomplished with an extension to XMLHttpRequest  
that overrides the existing send() method.

Objects implementing the XMLHttpRequest interface must also implement  
the FileXMLHttpRequest interface.
interface FileXMLHttpRequest {
    void send(File data);

-Sam Weinig
Received on Thursday, 17 July 2008 20:15:06 UTC

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