ORM is not a problem with current tools. In fact frameworks like Hibernate and Grails make Object-Relational Mapping something enjoyable to work with. I think the problem with the described approach is the growth of the relational schema when your knowledge base grows. But there are design challenges, ORM doesn't solve all the problems itself. IMHO, the object model that should be mapped to relational, if relational is chosen as DBMS, is not the raw openEHR IM. Simplifications over the IM are needed in order to prevent excessive JOINs and huge hierarchies. In fact I teach this in one of my courses and this was part of the tutorial we did on MEDINFO. For example, the OBJECT_REFs can be designed as simple relationships, because plays the role of a FK in the object model. There are many simplifications that can be done to reach an object model that is compatible with the openEHR model but more "relational friendly".
-- Kind regards, Eng. Pablo Pazos Gutiérrez http://cabolabs.com Date: Mon, 25 Jan 2016 18:42:01 +0100 Subject: Re: Archetype relational mapping - a practical openEHR persistence solution From: bert.verh...@rosa.nl To: openehr-technical@lists.openehr.org Another problem is you have to convert your object oriented model (which RM is) to a relational model, which becomes complex in converting templates/aql to SQL. I have been that way. More then five years ago I left it. It is difficult doable, if you want a full featured openehr kernel. I would never recommend going this way, unless someone has a really smart idea. It can work for a light featured openehr light derived application model. Best regards Bert Op 25 jan. 2016 15:26 schreef "pazospa...@hotmail.com" <pazospa...@hotmail.com>: I talked about this approach with a colleague from China during MEDINFO. The problem is your schema grows with your archetypes. Also, that storing data from many templates that don't use all the fields in the archetype, will generate sparse tables (lots of null columns). I told him it was easier to do an ORM from the IM, because the schema doesn't change and allows to store data from any archetype/template. But they already have a system working this way. Sent from my LG Mobile ------ Original message------From: Ian McNicollDate: Mon, Jan 25, 2016 10:06To: For openEHR technical discussions;Subject:Archetype relational mapping - a practical openEHR persistence solutionInteresting paper from China http://bmcmedinformdecismak.biomedcentral.com/articles/10.1186/s12911-015-0212-0 IanDr Ian McNicoll mobile +44 (0)775 209 7859 office +44 (0)1536 414994 skype: ianmcnicoll email: i...@freshehr.com twitter: @ianmcnicoll Co-Chair, openEHR Foundation ian.mcnicoll@openehr.orgDirector, freshEHR Clinical Informatics Ltd. Director, HANDIHealth CIC Hon. Senior Research Associate, CHIME, UCL _______________________________________________ openEHR-technical mailing list openEHR-technical@lists.openehr.org http://lists.openehr.org/mailman/listinfo/openehr-technical_lists.openehr.org _______________________________________________ openEHR-technical mailing list openEHR-technical@lists.openehr.org http://lists.openehr.org/mailman/listinfo/openehr-technical_lists.openehr.org
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