Hi,
I have been thinking about one of the use cases that we been advocating for VOSpace- that of using it for temporary storage of results between steps in a workflow. This has been a principal use of MySpace within Astrogrid for instance. The UWS pattern allows for each service to be the temporary storage for the data that is to be the input to the next step in the workflow i.e. the second application can read data from the (jobs)/(jobid)/results uri of the first step. This is both easier to implement and more efficient in data transport terms than moving the data into a scratch VOSpace. UWS provides all of the data management facilities needed for this simple scenario.
The above conclusion holds for a set of distributed UWS services an a centralized VOSpace - if services are co-located then the conclusions become more complex. Imagine that there is a UWS data processing service and a co-located VOSpace service, where the two services actually share the same backend storage - i.e. in VOSpace terms the file: protocol could be used by the UWS to retrieve the data. In this case there could be some benefit to having a co-located VOSpace because the data could be retrieved and put to the VOSpace very efficiently and it allows for long term storage, so that the combined UWS/VOSpace service could gradually accumulate raw and processed data products that perhaps with the addition of a colocated Querying service could provide a valuable dataset.
Cheers,
Paul.
.
Dr. Paul Harrison
JBCA, Manchester University
http://www.manchester.ac.uk/jodrellbank
Received on 2007-10-12Z12:20:52