Hi Bert, Xquery wasn't stable in 2006 when we needed a query language. AQL was implemented by Ocean by 2007 and has been working since then, and something similar implemented by companies in Brazil. Later on, Marand implemented it, and I suspect someone else.
I don't know anyone who has done a serious analysis to show if Xquery could do the job. At the very least archetype identifiers and pathing would need to be catered for, but the rest might be made to work. I would welcome any kind of analysis like this. - thomas On 20/04/2013 23:00, Bert Verhees wrote: >> I don't think there is an AQL engine open source yet, but in any case it >> only makes sense when there is an open source openEHR EHR service, which >> there currently is not. > > I don't think it is possible to write an AQL engine right now, because it is > not defined well yet. One can only anticipate on what one thinks it will be. > > So, my guess is it will be something between XPath and SQL. Instead of > fieldnames, using paths replacing fields. I think the specification takes too > long to arrive. It seems to me quite obvious what it will be. > > But writing an engine, from scratch, for it will cost, more then one year for > a very experienced developer, and even then..... > Companies like Oracle spend a substantial part of their developer-investment > in good query-engines. > > Storing data is peanuts, queriyng them is the hard part. > > But there is a way around, use what others did, and that is, using path-based > query-engines. There are quite some, also open source, good ones too. > > It is just a matter of storing your OpenEHR datasets path-based, and query > them path-based. For example, using an XML-database. Maybe there are other > possibilities too. > > And then you have a full featured AQL engine, as I think it will look like in > the future, when the specs will be finally written. Maybe some > syntax-translation is needed. > > What could the AQL-specification hold for promises, which are not already > delivered by XPath/XQuery right now? I cannot think of anything. > > I think it would be wise for the OpenEHR community to look very well on what > is already done by commercial companies and open source communities for years > now, instead of reinventing the wheel, unless of course, when there are good > reasons. > It would make introduction of many OpenEHR implementations much more easy, > and that would be good for worldwide success for the OpenEHR specifications. > > Ok, these are my two cents. I am very anxious to learn why the current > XPath/XQuery-specifications are not good enough. > > Have a nice sunday. > > Bert. > > Verstuurd vanaf mijn iPad > > Op 20 apr. 2013 om 18:29 heeft Thomas Beale <thomas.beale at > oceaninformatics.com> het volgende geschreven: > >> I don't think there is an AQL engine open source yet, but in any case it >> only makes sense when there is an open source openEHR EHR service, which >> there currently is not. > _______________________________________________ > openEHR-technical mailing list > openEHR-technical at lists.openehr.org > http://lists.openehr.org/mailman/listinfo/openehr-technical_lists.openehr.org > -- Ocean Informatics *Thomas Beale Chief Technology Officer, Ocean Informatics <http://www.oceaninformatics.com/>* Chair Architectural Review Board, /open/EHR Foundation <http://www.openehr.org/> Honorary Research Fellow, University College London <http://www.chime.ucl.ac.uk/> Chartered IT Professional Fellow, BCS, British Computer Society <http://www.bcs.org.uk/> Health IT blog <http://www.wolandscat.net/> * * -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.openehr.org/pipermail/openehr-technical_lists.openehr.org/attachments/20130422/96d75f9e/attachment-0001.html> -------------- next part -------------- A non-text attachment was scrubbed... Name: ocean_full_small.jpg Type: image/jpeg Size: 5828 bytes Desc: not available URL: <http://lists.openehr.org/pipermail/openehr-technical_lists.openehr.org/attachments/20130422/96d75f9e/attachment-0001.jpg>
