XQJ status

> Is it right that the current XQJ driver for BaseX doesn't support > XQuery 3 syntax? Everytime I try to use a query that includes some of > the newer features it barks at me with Invalid XQuery syntax, syntax > does not pass static validation. Is there way to get around that, say, > when the result would not use these XQuery 3 data types? > > I'm wondering what the fate is of XQJ in general. Will it remain relevant?

> Also I am confused why files.basex /maven repo has XQJ driver 1.6.0 > and xqj.net has 1.4.0 as the latest or what the difference is.

> The reason I was looking into XQJ was that it provides ways to get XDM > type info with the result. I would like to be able to deal with the > result from a query at a higher level than just strings. I've briefly > looked into BaseXClient.java which seems to be able to return XDM > metadata but then I saw that XQJ could do this out of the box.

> In general I would be interested to hear what the best way would be to > get a client to deal with query responses as native (client-side) > types (including hashmaps and arrays) instead of strings. Would it be > better to focus on using BaseXClient and forget about XQJ?

On Tue, Apr 5, 2016 at 11:58 AM, Christian Grün <christian.gruen at gmail.com> wrote: > Hi Marc, > >> Is it right that the current XQJ driver for BaseX doesn't support >> XQuery 3 syntax? Everytime I try to use a query that includes some of >> the newer features it barks at me with Invalid XQuery syntax, syntax >> does not pass static validation. Is there way to get around that, say, >> when the result would not use these XQuery 3 data types? >> >> I'm wondering what the fate is of XQJ in general. Will it remain relevant? > > I decided to pass on your question directly to Charles Foster; he > might be able to give you some outlook! > >> Also I am confused why files.basex /maven repo has XQJ driver 1.6.0 >> and xqj.net has 1.4.0 as the latest or what the difference is. > > I have sent a pull request to Charles’ repo; it may be included in the > next version there. > >> The reason I was looking into XQJ was that it provides ways to get XDM >> type info with the result. I would like to be able to deal with the >> result from a query at a higher level than just strings. I've briefly >> looked into BaseXClient.java which seems to be able to return XDM >> metadata but then I saw that XQJ could do this out of the box. > > Right, that’s only possible with XQJ. > >> In general I would be interested to hear what the best way would be to >> get a client to deal with query responses as native (client-side) >> types (including hashmaps and arrays) instead of strings. Would it be >> better to focus on using BaseXClient and forget about XQJ? > > From my perspective, it’s good to use XQuery whenever possible and use > our Client Module to address BaseX server instances [1] ;) > > Cheers, > Christian > > [1] http://docs.basex.org/wiki/Client_Module

On Tue, Apr 5, 2016 at 5:22 PM, Hans-Juergen Rennau <hrennau at yahoo.de> wrote: > Hi Marc, > > like you, I find the integration of XQuery results into other languages a > most interesting topic, and I think it is a topic deserving more attention > from the XML-community than it receives. > > I feel that the integration should completely hide the fact that XQuery is a > different language than the host language, that is, the query results should > be delivered in *exactly* that format which the host language programmer > desires. From this perspective, XQuery plays the role of an information > service to the host language application. The XQuery programmer is > responsible for writing queries which deliver information as an XDM > representation of the information desired by the, say, Java programmer. The > query is designed to produce a result XDM which the host language > infrastructure (high-level API) transforms into the desired "final" format > without the application programmer ever being aware of the XDM origin. To > achieve an unambiguous correspondance between XDM and non-XDM, the query may > augment the result with additional XDM items ("meta items") providing meta > data about how to transform the (primary) XDM items into host language items > (e.g. meta items defining the mapping of an XML fragment to a host language > map via XPath expressions, or segmenting the XDM sequence into subsequences > corresponding to distinct host language items.) > > The key to all this is a high-level API which completely hides the > conversions between host language types and the XDM. Such an infrastructure > must be built upon a low-level API like XQJ or the equivalent s9api of Saxon > - which bridges the host language type system and the XDM type systems. The > higher level API is responsible for *all* conversions between host language > type system and XDM. I suggest a long series of XQuery execution functions > with known result types, like > execQuery2string > execQuery2strings (: returns String[] :) > execQuery2int > execQuery2ints (: returns int[] :) > ... > execQuery2map_string_string > execQuery2map_string_int > ... > etcera! > > from which the host language programmer chooses. The choice is dictated by > the actual query to be launched: each published query has a known signature > described in terms of host language types like integer arrays and > string-to-boolean maps. So any given query has to be launched with a > particular variant of execQuery, and this query delivers the desired data > type. > > The approach can be extended in various way, for example by supporting the > delivery of complex containers of information ("info trays") consisting of > named entries each one of which has its own and independent type ( [1] ). > > So in summary I believe there are very interesting possibilities of > integrating XQuery seamlessly into other languages, and the foundation is a > low-level API preserving XDM type information. All else can be built on > that. > > Cheers, > Hans-Jürgen > > > [1] > http://www.balisage.net/Proceedings/vol5/html/Rennau01/BalisageVol5-Rennau01.html#d64477e307 > > >

On Tue, Apr 5, 2016 at 9:04 PM, Charles Foster <charles at cfoster.net> wrote: > Hi Marc, > > I plan to open source all the XQJ drivers I’ve written, (in the long-run). > > The XQJ specification was designed to support XQuery 1.0 only, however I don’t see why it can’t be made to support XQuery 3.0 and 3.1 syntax to some extent. > > Regarding XDM Maps and Arrays being bound to external variables and returned in result sequences along with the conversion between XDM and Java types wouldn’t be too difficult to achieve in practice. > > Java’s List and Map classes spring to mind, along with XQItemAccessor getObject(...) [1] to retrieve and XQDynamicContext.bindObject(...) [2] to bind where you would of course have to do manual casting. The datatypes of Java's Map and Array entries and conversions between their XDM counterparts could be determined by following the rules already laid out in the XQJ spec itself [3]. > > One would of course be going above and beyond the original XQJ specification here, but I think technically it would still be within the rules and providing it was well documented I’m sure user’s could cope. I would love Oracle to update their existing XQJ specification to cater for XQuery 3.1 properly, I would even help them get there if they wished, but I don’t know if they would be up for something like this. > > I think once the drivers are open sourced, the world of XQJ will be in healthier place for the community to update going forward. > > Specifically regarding BaseX XQJ - for the moment, please assume that any of the driver’s provided by BaseX themselves are the latest and greatest. > > Kind Regards, > > Charles > > P.S. Please come to XML London in June - it will be great! > > [1] http://xqj.net/javadoc/javax/xml/xquery/XQItemAccessor.html > [2] http://xqj.net/javadoc/javax/xml/xquery/XQDynamicContext.html > [3] https://en.wikipedia.org/wiki/XQuery_API_for_Java#Default_data_type_mapping > > > On 5 Apr 2016, at 14:41, Marc van Grootel <marc.van.grootel at gmail.com> wrote: > >> Hi Christian, >> >> Thanks. Very curious to hear about XQJ's fate. >> >> I am currently using BaseX for data integration which got me thinking >> about integration of XQuery in other web applications >> (node/python/clojure etc.). I was triggered by the recent thread about >> node-basex[1] and Hans Jürgen and your Balisage paper [2]. I was >> considering what the most performant way would be to return XQuery >> results as native types. Eg. function returns an array with maps or >> XML nodes and it gets converted to the host application's native data >> types so the application can use the results as if they were native >> data types. >> >> Maybe the only viable way to tackle this *is* via HTTP and a smart >> serialization (EDN[3] for example is such a, non-JSON, serialization >> that includes type info) but I was thinking if there was an existing >> lower-level way (without the BaseX HTTP layer). XQJ would enable this >> (at least for XQuery < 3) but I have doubts if it would deserialize >> non-atomic XDM values (like nested maps/arrays) as this is new to >> XQuery 3, I didn't check but I figure that the BaseXClient on which it >> is based also doesn't provide the XDM metadata for each nested item. >> >> Just pondering how to bridge from XQuery to other languages. >> >> [1]: http://www.mail-archive.com/basex-talk%40mailman.uni-konstanz.de/msg07882.html >> [2]: http://www.balisage.net/Proceedings/vol15/html/Rennau01/BalisageVol15-Rennau01.html >> [3]: https://github.com/edn-format/edn >> >> >> On Tue, Apr 5, 2016 at 11:58 AM, Christian Grün >> <christian.gruen at gmail.com> wrote: >>> Hi Marc, >>> >>>> Is it right that the current XQJ driver for BaseX doesn't support >>>> XQuery 3 syntax? Everytime I try to use a query that includes some of >>>> the newer features it barks at me with Invalid XQuery syntax, syntax >>>> does not pass static validation. Is there way to get around that, say, >>>> when the result would not use these XQuery 3 data types? >>>> >>>> I'm wondering what the fate is of XQJ in general. Will it remain relevant? >>> >>> I decided to pass on your question directly to Charles Foster; he >>> might be able to give you some outlook! >>> >>>> Also I am confused why files.basex /maven repo has XQJ driver 1.6.0 >>>> and xqj.net has 1.4.0 as the latest or what the difference is. >>> >>> I have sent a pull request to Charles’ repo; it may be included in the >>> next version there. >>> >>>> The reason I was looking into XQJ was that it provides ways to get XDM >>>> type info with the result. I would like to be able to deal with the >>>> result from a query at a higher level than just strings. I've briefly >>>> looked into BaseXClient.java which seems to be able to return XDM >>>> metadata but then I saw that XQJ could do this out of the box. >>> >>> Right, that’s only possible with XQJ. >>> >>>> In general I would be interested to hear what the best way would be to >>>> get a client to deal with query responses as native (client-side) >>>> types (including hashmaps and arrays) instead of strings. Would it be >>>> better to focus on using BaseXClient and forget about XQJ? >>> >>> From my perspective, it’s good to use XQuery whenever possible and use >>> our Client Module to address BaseX server instances [1] ;) >>> >>> Cheers, >>> Christian >>> >>> [1] http://docs.basex.org/wiki/Client_Module >> >> >> >> -- >> --Marc >> >