Hi All, I am trying to create a prototype for supporting XQuery-DAS. Below are some points I have gathered so far. Please give your comments, add to the points.
1) Basic Features that can be supported:-
Need to support associating path expression to xml data source.
Parameter passing in path expression
Support for FLWOR expressions - use of parameters, data source name
JOIN operation will involve multiple data sources and multiple expressions
- need to support association for same.
Support for XQuery update facility
2) Places where current das config/code needs to be modified:-
Provide flexibility in config to support RDB/XQUery/xyz...Can have
expansion to current config.xsd to support multiple connections of multiple types? like RDB/XQuery...
Command - needs to take care of associating multiple data sources with
multiple expressions say, in RDB - its select from t1, t2... in XQuery - the FLWOR - we can say books.xml <-> expr1, stores.xml <-> expr2 and have a JOIN.
Getting connection to data store - should be in Interface-Impl , not
directly in impl- like it is currently there in DASImpl not in DAS, to keep it generic.
graph building related classes should also have separation of interface
and implementation. 3) What can be kept for in-future and what is MUST for the first cut:- Need comments from you all. 4) Questions:-
In RDB-DAS we do not support connection to multiple databases. Even
JIRA-952 talks only about multiple schemas. Is there any requirement for this/ constraint due to which we need to stick to single database?
Also, in future, there can be mix of data stores, RDB, XQuery, .... What
are the pros/cons for supporting connection to multiple different types of datastores (like one RDB compliant, one XQuery compliant) 5) Link from ML - [DAS] Refactoring DAS to allow multiple implementatons http://www.mail-archive.com/[email protected]/msg14428.html During the attempt to separate APIs from Impl, we can now decide on the approach and structure the design. Regards, Amita
