Re: multiple changes to resources

On 18 September 2013 22:58, Steve Speicher <sspeiche@gmail.com> wrote:

> Hi Melvin,
>
>
> On Wed, Sep 18, 2013 at 4:47 PM, Melvin Carvalho <melvincarvalho@gmail.com
> > wrote:
>
>> Hi All
>>
>> Has anyone thought about what happens when 2 or more people want to
>> access a resource or container at the same time.
>>
>> Could we develop a race condition here?  Is there a basic strategy (such
>> as in unix locking) that could be used to prevent such things.
>>
>> Has anyone considered this case at all?
>>
>
> The closest thing I think is where we detect that a change has happened
> and prevent overwriting someone else's changes as we have in 4.5.2
>    http://www.w3.org/TR/2013/WD-ldp-20130730/#ldpr-4_5_2
>

This is great, thanks for pointing it out.  I guess it makes quite a lot of
sense.


>
> If this isn't what you were thinking, are you saying it is like WebDAV's
> LOCK mechanism?
>    http://www.ics.uci.edu/~ejw/authoring/protocol/rfc2518.html#METHOD_LOCK
>

So when timbl was explaining this whole concept a while back he was making
an analogy to the UNIX file system which is quite robust and has stood the
test of time.

It struck me that UNIX system V IPC has 3 elements iirc

1. Shared memory

This could be thought of as shared resources where the URL is the pointer

2. Messaging

I think this is handled by AWW, by sending triples or quads from one
resource to another

3. Semaphores

If I remember correctly this is related to locking.  So I suppose we're
good with if-match and ETags.

I didnt know about WebDAV LOCK, I'll dig a bit deeper on that one, thanks!
:)


>
> - Steve Speicher
>
>
>
>