[oslc-Reporting] OSLC Reporting - Paging

[Tack Tong]

Summarizing the Paging discussion in the Reporting WG call this morning. We
haven't arrive any conclusion. Thus, encourage further discussion via email
before next call.

There are potentially two ways to implement Paging at service end.
   Service does the query and caches complete resultset in memory/storage,
   then services one page at a time to the client. This approach would
   guarantee the validity of the resultset at time of query. However, the
   cache could potential expire before all pages are requested. Thus, need
   to specify how this exception situation should be handled. Also, there
   could be limitation on the server end on the size of the resultset it
   could handle due to resource limitation. (Note: Some Service may have a
   RDBMS underneath which would handle this via a DB cursor. I believe,
   from the end user perspective, this is similar to an application caching
   the resultset.)
   Service does query for a page at a time (i.e. different queries for
   different pages) based on certain parameters. Note: It does not
   necessarily has to be based on record offset, though this could be one
   of the approach. Since records could potentially be changed in-between
   pages, there could be cases that the complete resultset aggregated from
   the pages could have duplicated, or missing, or changed records. This
   approach obviously would help the server side resource limitation.
   However, the client side would have to deal with duplicated, missing,
   and changed records.

>From the Reporting client's perspective,
1. In the use case of ETL, duplicates and changed records could potentially
be handled in ETL logic in pre-processing phase of data cleansing. Missing
records could be a challenge.
2. In the use case of live reporting and document generation, duplicated,
missing, or changed records would produce misleading reports.

Comments/discussions/suggestions are encouraged and welcome.,

Tack Tong
IBM Rational software
tacktong at ca.ibm.com
905-413-3232
tie line 313-3232
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