[Openais] AIS layering..

Steven Dake sdake at mvista.com
Sat Sep 11 19:48:09 PDT 2004


On Sat, 2004-09-11 at 02:56, Lennert Buytenhek wrote:
> Hi,
> 
> Nobody seems to have asked the question yet, so here goes..
> 
> I would like to use the EVS APIs in a small app I wrote, but I don't
> see the point of running a separate daemon and creating a separate
> user and such.  (I might not even have root access on the machines
> that I intend to run the program on.)
> 
> Is this possible?  Or is there any reason why these things cannot be
> avoided?
> 

Lennert,
This is not possible today, although planned for the future.

If you want to avoid a daemon at all, it is possible today to use the
libgmi.a code.  This is located in exec and gmi.h and aispoll.h are the
header files.  This allows you to use the protocol without having to
have a daemon.  Your application must act as a daemon, and it imposes an
event driven programming style.  The API (evs) is also not directly
available, although the functionality is about equivalent.

But the nice EVS api is not available at this level (yet).  In the
future, I plan to unify these APIs and allow someone to use either the
IPC mechanism (when there is more then one application) or act directly
in the protocol itself with one API.

The only problem without using IPC is that the protocol consumes CPU
resources.  If two apps run the protocol at the same time, they consume
twice as many resources, not good.  Scale this to 20 applications, and
you see the problems :)

I understand your concerns around requiring root priveleges to use
openais.  In the future, we will remove this absolute requirement (at
the cost of security of the API).

If you need help on using libgmi after reading the header files, please
ask on the mailing list.  Atul has already used this in a project for
cluster-wide event logging.

Thanks!
-steve
> 
> cheers,
> Lennert
> 
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