[tahoe-dev] several newbie questions

[Miles Fidelman]

Kevin Reid wrote:
>> 1. Tahoe seems to support multi-writer mutable files - but I can't 
>> seem to find any discussion of consistency management and conflict 
>> resolution mechanisms.  Are there any, and if so, can someone point 
>> me at some documentation?
>
> <http://tahoe-lafs.org/trac/tahoe-lafs/browser/trunk/docs/specifications/mutable.rst#the-prime-coordination-directive-don-t-do-that> 
>
>
> “The current rule for applications which run on top of Tahoe is "do 
> not perform simultaneous uncoordinated writes". That means you need 
> non-tahoe means to make sure that two parties are not trying to modify 
> the same mutable slot at the same time.”
>
> “If you do not follow this rule, Bad Things will happen. The 
> worst-case Bad Thing is that the entire file will be lost. A less-bad 
> Bad Thing is that one or more of the simultaneous writers will lose 
> their changes. An observer of the file may not see 
> monotonically-increasing changes to the file, i.e. they may see 
> version 1, then version 2, then 3, then 2 again.”
Thanks for the pointer - lots of details in that directory.

I was afraid that was the answer, and...
>> 2. Looking at the capability mechanisms, it's not clear to what 
>> extent capabilities are bound to individuals.  The standard problem 
>> with key-based capabilities mechanisms is that they can be copied.
>
> That's a feature, not a bug.

Not if you want any kind of access control.  All the security goes out 
the door if somebody gets their hands on a URL.

Thanks for the answers.

Miels


-- 
In theory, there is no difference between theory and practice.
In<fnord>  practice, there is.   .... Yogi Berra