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From Amila Jayasekara <>
Subject Re: Orchestration Component implementation review
Date Fri, 17 Jan 2014 18:29:44 GMT
On Fri, Jan 17, 2014 at 10:32 AM, Saminda Wijeratne <>wrote:

> Following are few thoughts I had during my review of the component,
> *Multi-threaded vs single threaded*
> If we are going to have multi-threaded job submission the implementation
> should work on handling race conditions. Essentially JobSubmitter should be
> able to "lock" an experiment request before continuing processing that
> request so that other JobSubmitters accessing the experiment requests a the
> same time would skip it.

+1. These are implementation details.

> *Orchestrator service*
> We might want to think of the possibility in future where we will be
> having multiple deployments of an Airavata service. This could particularly
> be true for SciGaP. We may have to think how some of the internal data
> structures/SPIs should be updated to accomodate such requirements in future.


> *Orchestrator Component configurations*
> I see alot of places where the orchestrator can have configurations. I
> think its too early finalize them, but I think we can start refactoring
> them out perhaps to the I'm also seeing the
> orchestrator is now hardcoded to use default/admin gateway and username. I
> think it should come from the request itself.

+1. But in overall we may need to change the way we handle configurations
within Airavata. Currently we have multiple configuration files and
multiple places where we read configurations. IMO we should have a separate
module to handle configurations. Only this module should be aware how to
intepret configurations in the file and provide a component interface to
access those configuration values.

> *Visibility of API functions*
> I think initialize(), shutdown() and startJobSubmitter() functions should
> not be part of the API because I don't see a scenario where the gateway
> developer would be responsible for using them. They serve a more internal
> purpose of managing the orchestrator component IMO. As Amila pointed out so
> long ago (wink) functions that do not concern outside parties should not be
> used as part of the API.


> *Return values of Orchestrator API*
> IMO unless it is specifically required to do so I think the functions does
> not necessarily need to return anything other than throw exceptions when
> needed. For example the launchExperiment can simply return void if all is
> succesful and return an exception if something fails. Handling issues with
> a try catch is not only simpler but also the explanations are readily
> available for the user.

+1. Also try to have different exception for different scenarios. For
example if persistence (hypothetical) fails, DatabasePersistenceException,
if validation fails, ValidationFailedException etc ... Then the developer
who uses the API can catch these different exceptions and act on them

> *Data persisted in registry*
> ExperimentRequest.getUsername() : I think we should clarify what this
> username denotes. In current API, in experiment submission we consider two
> types of users. Submission user (the user who submits the experiment to the
> Airavata Server - this is inferred by the request itself) and the execution
> user (the user who corelates to the application executions of the gateway -
> thus this user can be a different user for different gateway, eg: community
> user, gateway user).
> I think we should persist the date/time of the experiment request as well.

> Also when retrying of API functions in the case of a failure in an
> previous attempt there should be a way to not to repeat already performed
> steps or gracefully roleback and redo those required steps as necessary.
> While such actions could be transparent to the user sometimes it might make
> sense to allow user to be notified of success/failure of a retry. However
> this might mean keeping additional records at the registry level.

In addition we should also have a way of cleaning up unsubmitted experiment
ids. (But not sure whether you want to address this right now). The way I
see this is to have a periodic thread which goes through the table and
clear up experiments which are not submitted for a defined time.

BTW, nice review notes, Saminda.


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