[RUS-WG] RUS IDL Comments (extractUsageRecordIds operation)

[Gilbert Netzer]

Dear Xiaoyu and RUS-WG members,

I split up the reply into two separate mails to keep the threads apart. So
this is concerning comment 1 below only!

See also the tracker at https://forge.gridforum.org/sf/go/artf6015

I am a little bit confused about the presented use-case. If a client does
not know what query, how should it be able to query the recordIds, both
need the same query?

The user needs in no case to be exposed to any XPath, the client which is
software can have any interface towards the user and is the only part that
actually has to handle the XPath language (or any other query dialect for
that matter).

So we should instead consider if XPath is good as the only option for use
by the client, though I would advocate for keeping the number of mandatory
query dialects very small, preferably 1.

The extractSpecificUsageRecords could in the new specification be best
modelled using a query dialect for the extractUsageRecords operation since
this was exactly the use case I had in mind for having query dialects.
However if this is only to shield the user from XPath I would strongly
suggest that it is the clients job to wrap the user query into a suitable
XPath statement which can be easily constructed by the client.

However I can see the following use-case for a more limited query operation:
First a client wants to get a limited amount of information for a large
number of usage records to present a overview list to the user. Later on it
can request detailed information on specific records selected by the user.

In this case it could be interesting to not transfer all information
up-front but only return the parts that the client is interested in.

For continuing the discussion on this thread, I want to suggest comments on
the following questions:

- Do you think the use-cases presented for the more limited
extractUsageRecordIds (or similar generalized operation) are relevant, e.g.
is this something your actually use in an application or plan to use?

- If yes, should this be part of the RUS Core specification or should this
be offered in the RUS Advanced specification, e.g. is this a "showstopper"
for using the RUS interface or is it merely a nice to have feature that you
can live without (that does not mean that it is not valuable and should be
considered)?

- Do you only need a very limited set of results from this operation (e.g.
only the record ID value) or do you need a more general operation that can
return arbitrary parts of usage records selectable by the client (e.g. give
me the recordId, the JobId and the startTime)?

- Should this be implemented as a separate opertion or is it better to
generalize the extractUsageRecords operation to be able to return partial
usage records?


Thanks in advance for you comments!

Best Regards
Gilbert Netzer


Xiaoyu Chen wrote:
> Dear RUS chairs and members:
>  
>         Here are my comments on RUS IDL spec (https://forge.gridforum.org/sf/go/artf6015?nav=1)  submitted by Glibert recently:
>  
>         1). The service interface description should be clarified in a consistent way as defined in IDL spec especially in following particular points:
>  
>          RUS:extractUsageRecords need to re-defined as IDL spec. How about RUS:extractUsageRecordIds? This is an important operation as I can see. An example usage scenario would be query specific usage record using urf:UsageRecord/urf:RecordIdentity/@recordId as a context node within xpath statement. The client won't know the recordId value before querying. An auxiliary operation, RUS:extractUsageRecordIds would be helpful. For users unfamilar with xpath statement, would it be better to have RUS:extractSpecificUsageRecords with a set of recordId values as parameters?
> 
>         2). Most of modification operations (updates and deletions) defined within RUS v1.7 specs are reduntant. I totally agree to remove most of them, except RUS:replaceUsageRecords. It is difficult to replace existing usage records using a single RUS:modifyUsageRecords operation.
> 
>        kind regards!
> 
>  
> School of Engineering and Design
> Mobile: Mobile: ++44(0)7871876894
> X. Chen
> --
>   rus-wg mailing list
>   rus-wg at ogf.org
>   http://www.ogf.org/mailman/listinfo/rus-wg