[kepler-users] About the string constant component in the Ecogrid workflow example.

[ben leinfelder]

Hi Bina,
The actor will have all values available on its input ports from upstream actors that are connected when the fire method is called. With the SDF director the sequence of firing is predictable and follows what you'd expect in terms of linear workflow execution. Downstream actors wait for upstream actors to "finish" whatever they are doing before they can do whatever it is they do. So in the case of your example, the data file should have been created by the time you pass off the fileName to the metadata source actor.
Hope that helps.
-ben

On Apr 1, 2012, at 11:09 AM, Bina Philip wrote:

> Hi Ben,
> 
> I think that makes sense. What I was trying to understand was that, if any special configuration would have to be made to the output port of the upstream actor that might be producing this file in order to pass this output file as an input to the metadata source component. But guessing from your answer it seems like there is no such configuration needed, and that an actors output port can be connected to another actors input port without making any special configurations. Please correct my understanding if I am stating otherwise.
> 
> Moving on to my next question which I mentioned above 
> 
> " In addition to this I would like to know how the fire method of the (any) actor is triggered in the workflow. Does the actor get triggered after the necessary parameters are found or does it get triggered once the control shifts to the actor? (More of a data v/s control flow question)"
> 
> Please let me know.
> 
> Best
> 
> 
> On Fri, Mar 30, 2012 at 5:18 PM, ben leinfelder <leinfelder at nceas.ucsb.edu> wrote:
> Hi Bina,
> I believe Jing is out today (UC holiday), but I looked at your workflow and you're only using a string constant to pass the data file name to the Metadata Source actor. You can provide the data file name to this actor in many other ways. An upstream actor might create the data file, for example, and one of that actor's output ports could be the file name that it created. The Metadata Source actor would then use that value when it received it on the 'dataFileNameIn' port.
> Hope that helps,
> -ben
> 
> On Mar 30, 2012, at 12:31 PM, Bina Philip wrote:
> 
> > Hello Jing,
> >
> > In a previous email exchange you had given an example workflow which demonstrated the usage of EcogridWriter workflow. In this workflow the "string constant" was used to send the data file to the metadata source component.
> >
> > I had one question about the "string constant" component -- Is this also capable of receiving a data file from a previous actor (which possibly generates this file) and supplies the same data file to the next actor which in the example case is the metadata source component. Basically I am trying to find out if the same string constant component can also receive as an input from another actor the data file? Kindly let me know.
> >
> > Please find attached the workflow I am referring to.
> >
> > In addition to this I would like to know how the fire method of the actor is triggered in the workflow. Does the actor get triggered after the necessary parameters are found or does it get triggered once the control shifts to the actor? (More of a data v/s control flow question)
> >
> > Best
> >
> > --
> > Regards,
> > Bina
> > Indiana University Bloomington
> > Dept Of Computer Science (Master's).
> > Contact:- 812-327-4780
> >
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> 
> 
> 
> 
> -- 
> Regards,
> Bina
> Indiana University Bloomington
> Dept Of Computer Science (Master's).
> Contact:- 812-327-4780
>