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Re: HTML5 File

From: Jonas Sicking <jonas@sicking.cc>
Date: Wed, 2 Jun 2010 13:14:02 -0700
Message-ID: <AANLkTinwe5KPf4sfrmFVlx2kmsbKIucgZXElCNBngfkg@mail.gmail.com>
To: ifette@google.com
Cc: Cristiano Sumariva <sumariva@gmail.com>, public-webapps@w3.org
It keeps seeming to me that moving the file-writer spec to WebApps
would make much more sense...

/ Jonas

2010/6/2 Ian Fette (イアンフェッティ) <ifette@google.com>:
> http://www.w3.org/TR/file-writer-api/
>
> On Tue, Jun 1, 2010 at 8:18 AM, Cristiano Sumariva <sumariva@gmail.com>
> wrote:
>>
>> I have been reading the specification on file section.
>> I would like to ask why not propose that File interface allow a create
>> method to let user save data for his use?
>>
>> Resume:
>>
>> Interface File extends Blob
>> {
>>     attribute unsigned long long currentPosition;
>>     readonly attribute signed long long deviceSpaceLeft;
>>     readonly attribute unsigned short machineEndian;
>>     const unsigned short BIG_ENDIAN = 1;
>>     const unsigned short LITTLE_ENDIAN = 0;
>>     const unsigned short UNKNOW_SIZE = -1;
>>     File create( );
>>     File createBynary();
>>     signed long write( in DOMString text, optional in unsigned long long
>> position,  optional DOMString fromCharset )
>>     signed long writeBinary( in DOMString blob, optional in unsgined long
>> long position )
>> }
>>
>> An web application in this way could for example create a list of computed
>> values and allow the user to save the contents to a file without need send
>> data for the server to pack contents and issue a file download request to
>> client.
>> Or implement an image editor in javascript code using the new canvas
>> element and allow read, create, store to be done without server assistance.
>> Work on offline mode too.
>>
>> About security on file creation:
>> When the web application request this operation File.create() the browser
>> could launch a confirm( save file) dialog so the user only could grant the
>> rights for a file creation.
>> This dialog( modal? ) would manage file overwrite and more stuff related
>> to file access( user may write at selected folder ) so that returned file
>> reference could be overwritten by client script without trouble.
>> The return type for that function could be string or a File object.
>> An empty name value or Exception signal that user denied the request.
>>
>> If there is concerns about absolute file paths been exposed to javascript
>> code
>> then the File.create method could return a boolean status indicating that
>> the object is ready to write( true ) and no file paths would be exposed at
>> all. Or only the basename of file without path information.
>>
>> For differences between binary and text modes a second method call could
>> signal File object that the new file should be used on binary mode:
>> File.createBinary() - same behavior like File.create above but in binary
>> mode.
>>
>> The file object could have some read only properties for device space
>> control:
>> For example:
>> readonly File.deviceSpaceLeft  - so when script is making write calls to
>> file if would know in advance if space still available for writing. Or
>> application could launch a warn that no space left to save data. If the
>> implementer do not know how to tell the space left then a File.UNKNOWSIZE
>> value should be returned.
>>
>> double File.currentPosition - traditional File pointer to know where in
>> the file the client is writing to. Since size is readonly changing this
>> property move the current position in file cursor. Negative values are
>> invalid and ignored. A positive value greater then current value increase
>> the file size to the new size( doing this at begin could be a way to reserve
>> space needed on disk at once since the file would grow to this current size,
>> and help filesystem reduce fragmentation ). Changing this attribute on a
>> file opened for read does nothing and is ignored. The size atrribute should
>> reflect the new size confirming that file size increased.
>>
>> May cause UI hangs on large move requests.
>> User agents may show on the create dialog a max file size allowed to be
>> created making impossible to script consume all space left on device.
>>
>> readonly boolean File.machineEndian - binary files on target machine could
>> have data stored in different formats then the script reading would expect.
>> This flag would tell the script how to pack unpack data to be used on client
>> machine.
>>
>> Cristiano
>>
>>
>
>
Received on Wednesday, 2 June 2010 20:15:12 GMT

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