[erlang-questions] Access control framework and method for data versioning

Schneider <>
Thu Dec 22 14:40:12 CET 2016

On 12/21/2016 10:06 PM, Magnus Ottenklinger wrote:
>> For the same application, I need to implement versioning of data, i.e.
>> data should not be changed after it is recorded but superseded by a new
>> version offering a full history of the data. Data is stored in some
>> NoSQL database system.
>> I would love to hear some suggestions on implementing versioning of data.
> Some time ago, I did a lot of thinking on how I would implement something like this. A
> friend and I prototyped something like that over a day by using git as a backing storage.
> The pull/push model of git does not fit the problem perfectly, but storing documents in
> git is very straight forward to get started. On top of that, you only need a simple
> PUT/GET API (no other calls, as nothing committed to storage may ever change) and a call
> to traverse the tree. For calling git, we called the git executable directly after taking
> a look into erlgit[1], which offered more than we actually needed for the prototype.
> Now, to make it completely distributed, a simple KV-store seems very appropriate, although
> storing the meta data in an efficient manner comes down to maintaining your own secondary
> index (you want to represent a tree of objects, after all). Additionally, concurrent
> access to a shared tree representation is not trivial without support for transactions.
> As I did not find enough time to really implement this system, I also did not take the
> time to research into other fitting storage mechanisms. Maybe a graph database would be
> the simplest approach to implement this.
> Magnus
> [1] https://github.com/gleber/erlgit
Thanks Magnus, I will investigate the git-like approach. Might solve the 
issue of having data forked onto disjoint systems and merged back later 
as well.

Is anybody familiar with using XACML, Argus [1] or PolicyMachine [2] for 
access control?


[1] https://argus-documentation.readthedocs.io/en/latest/index.html
[2] http://csrc.nist.gov/pm/

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