Re: [MirageOS-devel] Mirage and External Data Storage

[Richard Mortier <Richard.Mortier@xxxxxxxxxxxxxxxx>]

On 10 Dec 2014, at 19:58, Brian Brietzke <bbrietzke@xxxxxxxxx> wrote:

I think I may have my own answer, but I thought I would ask anyways.  

I would like to be able to interface the Mirage images ( either running on xen or just through unix ) to be able to contact external data storage systems ( i.e. postgresql, mysql, redis, mongodb ) so that it can some data processing.  

I tried using sqlite3 with the bindings for OCaml, and it gave me an error that it can't load then extensions, which makes perfect sense.  The files the library is looking don't exist inside the tiny world of the Mirage virtual machine.  

That means that we would have to use a client library which is totally written in OCaml, no linkages to external dependencies.  That severally limits the number of client libraries available, which could or could not be a bad thing.  

Is this assumption correct?  

yes, that sound right to me. you can depend on mirage libs but not on external libraries that pull in OS dependencies via the filesystem, threading, processes, whatever.

I'm assuming that it would be a very difficult ( if not an impossible ) task to make the C libraries available from postgresql or sqlite into the Mirage OS.  

tricky but technically not impossible i think. the trick is to remove all external (POSIX) dependencies... :)

another option might be to interface using a network protocol-- i'm not particularly familiar with those storage systems directly, but if any support (e.g.) an http or other network protocol api, implementing that for mirage (ie., in pure ocaml) *might* be a more straightforward option...

-- 

Cheers,

R.

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