2011/6/21 Peter Tröger <peter@troeger.eu>:
Hi,
The bigger ones are likely caused by my limited understanding of the background which led to the design, so please bear with me - I don't want to reopen any discussions which have been closed for good...
I like your attitude ;-) ...
;-) Thanks for the answers, that helps. Some comments inlined below. Cheers, Andre.
- I think the following is asymmetric. There is likely a reason, but I am not sure I understand it:
- job session: create (name, contact), open (name), close (session), destroy (name) - reserv. session: create (name, contact), open (name), close (session), destroy (name) - monit. session: create ( contact), close (session)
From the above, it seems like create/close are pairs? I would naively expect the following pairs: open/close and create/destroy, as usual - what is the rationale?
I don't get your point. Creation returns a new persistent XXXsession instance. Open allows you to re-access the persistent existing session. Close is for cleanup after both create and open. Destroy throws away the persistent information, and therefore does not demand an open session instance.
Why not close(name), so that all ops work with name as arg? Would be more symmetric.
Why is the Monitoring session handled differently, i.e. has no name/open/destroy?
Monitoring session have no persistency, so they need no name for opening, and no destruction.
If something has a create, I would expect it to have a destroy, too. That might just be me, but semantically those two go together... Anyway, your explanation helps!
- JobWaitStarted/Terminated: The function returns always a Job object, in order to allow chaining, e.g. job.wait(JobStatus.RUNNING).hold(). The session-level functions
I find that strange and inconsistent - chaining is not supported elsewhere AFAICS, why here? What is the advantage over 'job.wait(JobStatus.RUNNING); job.hold();'? this has exactly the same race conditions...
Chaining was raised as important thing only for the wait functions. I am too lazy to search the minutes for this, but it is handy in OO languages. We didn't spend deeper thoughts on supporting this elsewhere.
You may want to make sure that chaining was *not* introduced to prevent race conditions - because it does not.
Proposals welcome.
Proposal: don't do chaining, it makes error handling a nightmare - for almost all languages really, but in particular so for exception-less languages.
- sessionManager.drmaaVersion: this seems to return the implementation version, not the DRMAA spec version (i.e. 2.0). I think this is useless without also reporting the drmaaName, i.e. the implementation name. Otherwise the user may report to you that she is using version 4.5, but what implementation?? ;-)
You get the DRMS type, this is your DRMAA implementation. I propose that there will be no two DRMAA implementations for the same DRM system in the same language.
Woah - you MAY be able to ensure that for the current WG constituency, but you are writing a *standard*! You expect there will only *one* implementation using fork, for example? Only one implementation for PBS? You can never ensure this, and that contradicts the idea of an standard, really... The potentially missing API call is a minor point really, but your argument does not hold water ;-)
- what is the use of the sessionManager interface? It cannot be created/destroyed, so is likely a singleton? This however is not explicit in the spec. A sessionManager does not seem to have state (apart from the new addition of a monitoring callback), but a stateless singleton is rather useless? All methods can easily be provided as free functions - is a language binding allowed to do that?
Yes, it's a singleton.
This should be noted in the spec (unless I missed it).
Yes, you can do free functions in the language binding. IDL does not support that.
Ok, thanks. Cheers, Andre. -- Nothing is ever easy...