BaseX-Talk November 2013

basex-talk@mailman.uni-konstanz.de

38 participants
54 discussions

search into basex talk archive ?
by jean-marc Mercier 22 Nov '13

22 Nov '13

Hi, is there a (convenient) way to search into basex talk archives ? At present time, I downloaded some of the monthly archive to look at, but it is a little bit tedious... Cheers

2 2

Bug with Full Text functions ?
by Maud Ingarao 20 Nov '13

20 Nov '13

Hi everybody ! We are very excited that our BaseX kit for Digital Humanities Corpus is almost done and we look forward to presenting it to you ! We only have a last bug using the Full Text functions. The very same function call works fine through the rest api but generates a 500 Servor Internal Error through our restxq files. Example (you won't be able to access this private server) : http://ahn-basex.cbp.ens-lyon.fr:8984/rest/Desanti?query=count(collection('Desanti')/*[local-name() = 'ead']/*[local-name() = 'archdesc']/*[local-name() = 'dsc'] //*[local-name() = 'c']/*[local-name() = 'controlaccess']/*[local-name() = 'persname'][text() contains text 'Aristote']) works fine and returns the number of occurrences whereas let $occurrences := count(collection("Desanti")/*[local-name() = 'ead']/*[local-name() = 'archdesc']/*[local-name() = 'dsc']//*[local-name() = 'c'] /*[local-name() = 'controlaccess']/*[local-name() = 'persname'][text() contains text 'Aristote']) generates one of the two ERROR 500 below. PS : ft:count does't work and return 0 occurrences Thanks a lot und bis bald ! Maud and Nathalie HTTP ERROR 500 Problem accessing /desanti/catalogue. Reason: Unexpected error: Improper use? Potential bug? Your feedback is welcome: Contact: basex-talk(a)mailman.uni-konstanz.de Version: BaseX 7.7 Java: Sun Microsystems Inc., 1.6.0_27 OS: Linux, amd64 Stack Trace: java.lang.NullPointerException ------------------------------------------------------------------------ /Powered by Jetty:/// or HTTP ERROR 500 Problem accessing /brede/theme. Reason: Unexpected error: Improper use? Potential bug? Your feedback is welcome: Contact: basex-talk(a)mailman.uni-konstanz.de Version: BaseX 7.7 Java: Sun Microsystems Inc., 1.6.0_27 OS: Linux, amd64 Stack Trace: java.lang.NullPointerException at org.basex.query.ft.FTContainsExpr.item(FTContainsExpr.java:44) at org.basex.query.ft.FTContainsExpr.item(FTContainsExpr.java:24) at org.basex.query.expr.ParseExpr.ebv(ParseExpr.java:92) at org.basex.query.expr.ParseExpr.test(ParseExpr.java:106) at org.basex.query.expr.Preds.preds(Preds.java:133) at org.basex.query.path.IterStep$1.next(IterStep.java:42) at org.basex.query.path.CachedPath.iter(CachedPath.java:103) at org.basex.query.path.CachedPath.iter(CachedPath.java:106) at org.basex.query.path.CachedPath.iter(CachedPath.java:72) at org.basex.query.expr.ParseExpr.ebv(ParseExpr.java:94) at org.basex.query.expr.ParseExpr.test(ParseExpr.java:106) at org.basex.query.expr.Preds.preds(Preds.java:133) at org.basex.query.path.IterStep$1.next(IterStep.java:42) at org.basex.query.path.IterStep$1.next(IterStep.java:31) at org.basex.query.path.IterPath$1.next(IterPath.java:70) at org.basex.query.path.IterPath$1.next(IterPath.java:41) at org.basex.query.gflwor.For$1.next(For.java:71) at org.basex.query.gflwor.Let$1.next(Let.java:74) at org.basex.query.gflwor.GFLWOR$2.next(GFLWOR.java:72) at org.basex.query.expr.Constr.add(Constr.java:66) at org.basex.query.expr.CElem.item(CElem.java:91) at org.basex.query.expr.CElem.item(CElem.java:23) at org.basex.query.expr.ParseExpr.value(ParseExpr.java:68) at org.basex.query.QueryContext.value(QueryContext.java:339) at org.basex.query.gflwor.Let$1.next(Let.java:75) at org.basex.query.gflwor.GFLWOR$2.next(GFLWOR.java:72) at org.basex.query.iter.Iter.value(Iter.java:64) at org.basex.query.expr.ParseExpr.value(ParseExpr.java:71) at org.basex.query.QueryContext.value(QueryContext.java:339) at org.basex.query.func.StaticFunc.invValue(StaticFunc.java:199) at org.basex.query.func.BaseFuncCall.value(BaseFuncCall.java:62) at org.basex.query.func.StaticFuncCall.iter(StaticFuncCall.java:84) at org.basex.query.gflwor.GFLWOR$2.next(GFLWOR.java:76) at org.basex.query.expr.Constr.add(Constr.java:66) at org.basex.query.expr.CElem.item(CElem.java:91) at org.basex.query.expr.CElem.item(CElem.java:23) at org.basex.query.expr.ParseExpr.value(ParseExpr.java:68) at org.basex.query.QueryContext.value(QueryContext.java:339) at org.basex.query.gflwor.Let$1.next(Let.java:75) at org.basex.query.gflwor.GFLWOR$2.next(GFLWOR.java:72) at org.basex.query.expr.Constr.add(Constr.java:66) at org.basex.query.expr.CElem.item(CElem.java:91) at org.basex.query.expr.CElem.item(CElem.java:23) at org.basex.query.expr.ParseExpr.value(ParseExpr.java:68) at org.basex.query.QueryContext.value(QueryContext.java:339) at org.basex.query.expr.Switch.value(Switch.java:91) at org.basex.query.QueryContext.value(QueryContext.java:339) at org.basex.query.gflwor.Let$1.next(Let.java:75) at org.basex.query.gflwor.GFLWOR$2.next(GFLWOR.java:72) at org.basex.query.expr.Constr.add(Constr.java:66) at org.basex.query.expr.CElem.item(CElem.java:91) at org.basex.query.expr.CElem.item(CElem.java:23) at org.basex.query.expr.ParseExpr.iter(ParseExpr.java:46) at org.basex.query.gflwor.GFLWOR$2.next(GFLWOR.java:76) at org.basex.query.iter.Iter.value(Iter.java:64) at org.basex.query.expr.ParseExpr.value(ParseExpr.java:71) at org.basex.query.QueryContext.value(QueryContext.java:339) at org.basex.query.func.StaticFunc.invValue(StaticFunc.java:199) at org.basex.query.func.BaseFuncCall.value(BaseFuncCall.java:62) at org.basex.query.QueryContext.value(QueryContext.java:339) at org.basex.query.value.item.FuncItem.invValue(FuncItem.java:180) at org.basex.query.func.DynFuncCall.value(DynFuncCall.java:58) at org.basex.query.func.DynFuncCall.iter(DynFuncCall.java:63) at org.basex.query.QueryContext.iter(QueryContext.java:328) at org.basex.query.expr.Constr.add(Constr.java:65) at org.basex.query.expr.CElem.item(CElem.java:91) at org.basex.query.expr.CElem.item(CElem.java:23) at org.basex.query.expr.ParseExpr.iter(ParseExpr.java:46) at org.basex.query.QueryContext.iter(QueryContext.java:328) at org.basex.query.expr.Constr.add(Constr.java:65) at org.basex.query.expr.CElem.item(CElem.java:91) at org.basex.query.expr.CElem.item(CElem.java:23) at org.basex.query.expr.ParseExpr.iter(ParseExpr.java:46) at org.basex.query.QueryContext.iter(QueryContext.java:328) at org.basex.query.expr.Constr.add(Constr.java:65) at org.basex.query.expr.CElem.item(CElem.java:91) at org.basex.query.expr.CElem.item(CElem.java:23) at org.basex.query.expr.ParseExpr.value(ParseExpr.java:68) at org.basex.query.QueryContext.value(QueryContext.java:339) at org.basex.query.func.StaticFunc.invValue(StaticFunc.java:199) at org.basex.query.func.BaseFuncCall.value(BaseFuncCall.java:62) at org.basex.query.QueryContext.value(QueryContext.java:339) at org.basex.query.value.item.FuncItem.invValue(FuncItem.java:180) at org.basex.query.func.DynFuncCall.value(DynFuncCall.java:58) at org.basex.query.func.DynFuncCall.iter(DynFuncCall.java:63) at org.basex.query.QueryContext.iter(QueryContext.java:328) at org.basex.query.expr.List$1.next(List.java:120) at org.basex.query.expr.Constr.add(Constr.java:66) at org.basex.query.expr.CElem.item(CElem.java:91) at org.basex.query.expr.CElem.item(CElem.java:23) at org.basex.query.expr.ParseExpr.value(ParseExpr.java:68) at org.basex.query.QueryContext.value(QueryContext.java:339) at org.basex.query.func.StaticFunc.invValue(StaticFunc.java:199) at org.basex.query.func.BaseFuncCall.value(BaseFuncCall.java:62) at org.basex.query.QueryContext.value(QueryContext.java:339) at org.basex.query.value.item.FuncItem.invValue(FuncItem.java:180) at org.basex.query.func.DynFuncCall.value(DynFuncCall.java:58) at org.basex.query.func.DynFuncCall.iter(DynFuncCall.java:63) at org.basex.query.QueryContext.iter(QueryContext.java:328) at org.basex.query.expr.List$1.next(List.java:120) at org.basex.query.expr.Constr.add(Constr.java:66) at org.basex.query.expr.CElem.item(CElem.java:91) at org.basex.query.expr.CElem.item(CElem.java:23) at org.basex.query.expr.ParseExpr.value(ParseExpr.java:68) at org.basex.query.QueryContext.value(QueryContext.java:339) at org.basex.query.func.StaticFunc.invValue(StaticFunc.java:199) at org.basex.query.func.TailFuncCall.value(TailFuncCall.java:47) at org.basex.query.QueryContext.value(QueryContext.java:339) at org.basex.query.func.StaticFunc.invValue(StaticFunc.java:199) at org.basex.query.func.BaseFuncCall.value(BaseFuncCall.java:62) at org.basex.query.func.StaticFuncCall.iter(StaticFuncCall.java:84) at org.basex.query.MainModule.iter(MainModule.java:93) at org.basex.query.QueryContext.iter(QueryContext.java:282) at org.basex.http.restxq.RestXqResponse.create(RestXqResponse.java:73) at org.basex.http.restxq.RestXqModule.process(RestXqModule.java:108) at org.basex.http.restxq.RestXqFunction.process(RestXqFunction.java:100) at org.basex.http.restxq.RestXqServlet.run(RestXqServlet.java:31) at org.basex.http.BaseXServlet.service(BaseXServlet.java:58) at javax.servlet.http.HttpServlet.service(HttpServlet.java:848) at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:684) at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:457) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:137) at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:557) at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:231) at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1075) at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:384) at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:193) at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1009) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:135) at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116) at org.eclipse.jetty.server.Server.handle(Server.java:370) at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:489) at org.eclipse.jetty.server.AbstractHttpConnection.headerComplete(AbstractHttpConnection.java:949) at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.headerComplete(AbstractHttpConnection.java:1011) at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:644) at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:235) at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:82) at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:668) at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:52) at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:608) at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:543) at java.lang.Thread.run(Thread.java:679) -- /« Ne travaillez jamais »/ *Maud Ingarao* IHPC (UMR 5037) Institut d'histoire de la pensée classique, de l'Humanisme aux Lumières Ecole Normale Supérieure de Lyon - Site Descartes - Bureau R322 15 Parvis René Descartes - BP7000 - 69342 Lyon CEDEX 07 +33 4 37 37 65 79 - maud.ingarao(a)ens-lyon.fr /Je suis absente le vendredi | Out of office on Fridays/ http://pensee-classique.ens-lyon.fr http://institutdesanti.ens-lyon.fr http://ahn.ens-lyon.fr http://www.mutec-shs.fr http://www.projet-plume.org http://www.cahier.paris-sorbonne.fr/

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Bugreport V7.7 java.lang.ArrayIndexOutOfBoundsException
by Bodo Hüsemann 20 Nov '13

20 Nov '13

Hi BaseX team, Using BaseX 7.7 in an embedded Java Application Server Ive encountered the following reproducible error. The error occurs if the same query is issued the second time after the first has been successfully executed (after restarting the server the query will run again the first time ok and the second time with this error). This indicates a potential concurrency or non-closed cursor bug to me, but I dont see the problem and surely we shouldnt get an java.lang.ArrayIndexOutOfBoundsException even if with my bad code quality. Could you please have a look and advise to improve my code, or fix a potential bug? Many thanks in advance, Bodo Error stack trace: WARNING 2013.11.19 23:00:36 Error while loading document: sqlQuery_ora_F30929C659D0CED7525C61A7D149E7D4C0301A18 org.basex.core.BaseXException: Improper use? Potential bug? Your feedback is welcome: Contact: basex-talk(a)mailman.uni-konstanz.de Version: BaseX 7.7 Java: Oracle Corporation, 1.7.0_15 OS: Windows 7, amd64 Stack Trace: java.lang.ArrayIndexOutOfBoundsException: 2 at org.basex.io.random.TableDiskAccess.flush(TableDiskAccess.java:124) at org.basex.data.DiskData.finishUpdate(DiskData.java:212) at org.basex.core.cmd.Add.run(Add.java:109) at org.basex.core.Command.run(Command.java:345) at org.basex.core.Command.exec(Command.java:321) at org.basex.core.Command.execute(Command.java:78) at org.basex.core.Command.execute(Command.java:90) at org.basex.server.ClientListener.execute(ClientListener.java:386) at org.basex.server.ClientListener.add(ClientListener.java:357) at org.basex.server.ClientListener.run(ClientListener.java:100) at org.basex.server.ClientSession.receive(ClientSession.java:259) at org.basex.server.ClientSession.send(ClientSession.java:246) at org.basex.server.ClientSession.send(ClientSession.java:284) at org.basex.server.ClientSession.add(ClientSession.java:134) at de.infabswissarmy.control.XMLDBManagerBaseX.putDoc(XMLDBManagerBaseX.java:25 2) at de.infabswissarmy.control.XMLDBManagerBaseX.putDoc(XMLDBManagerBaseX.java:56 ) at de.infabswissarmy.control.QueryTask.sqlQuery(QueryTask.java:258) at de.infabswissarmy.control.QueryTask.query(QueryTask.java:138) at de.infabswissarmy.control.QueryTask.run(QueryTask.java:283) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) org.basex.core.BaseXException: java.nio.channels.OverlappingFileLockException at org.basex.server.ClientQuery.cache(ClientQuery.java:81) at org.basex.server.Query.more(Query.java:74) at de.infabswissarmy.control.XMLDBManagerBaseX.query(XMLDBManagerBaseX.java:86) at de.infabswissarmy.control.XMLDBManagerBaseX.queryDoc(XMLDBManagerBaseX.java: 131) at de.infabswissarmy.control.QueryTask.query(QueryTask.java:192) at de.infabswissarmy.control.QueryTask.run(QueryTask.java:283) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) Relevant source extract: private static void putDoc(String inContainerName, String inDocumentRef, byte[] inDocument){ ClientSession mySession = null; try { mySession = getClientSession(); // document already exists? if(existsDoc(inContainerName, inDocumentRef)){ // delete old document mySession.execute(new Open(inContainerName)); mySession.execute(new Delete(inDocumentRef)); } mySession.execute(new Open(inContainerName)); // add new document mySession.add(inDocumentRef, new ByteArrayInputStream(inDocument)); } catch (IOException e) { logger.warning("Error while loading document: " + inDocumentRef); e.printStackTrace(); }finally { if (mySession != null){ try { mySession.close(); } catch (IOException e) {} } } } public ArrayList<String> query(String inQuery, String[][] inArgs){ ClientSession mySession = null; ClientQuery myQuery = null; ArrayList<String> tmpString = new ArrayList<String>(); try { mySession = getClientSession(); myQuery = mySession.query(inQuery); // bind variable if (inArgs != null){ for (int i=0; i < inArgs.length; i++){ myQuery.bind("$" + inArgs[i][0], inArgs[i][1]); } } while (myQuery.more()){ tmpString.add(myQuery.next()); } } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { if (myQuery != null){ try { myQuery.close(); } catch (BaseXException e) { // ignore } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } if (mySession != null){ try { mySession.close(); } catch (BaseXException e){ //ignore } catch (IOException e){ // TODO Auto-generated catch block e.printStackTrace(); } } } return tmpString; }

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Re: [basex-talk] Is it right query using ft:search ?
by John Best 20 Nov '13

20 Nov '13

Hi Dirk, Thanks for your reply.. What will be the query for the following structure - I tried your yesterday's query it achieved the result as required. My structure was not exactly the same as mentioned yesterday. I thought, I would modify it as per my structure. But, I was not successful. Below is my complete structure. I want to search the MainDesc, which have 2 child nodes viz; shortDesc and longDesc. <Docs> <Doc> <DocTitle C="1"></DocTitle> <MainDesc> <shortDesc></shortDesc> <longDesc> some text to make the word(s) bold Optional some text to make the word(s) italic Optional some text to have an underline Optional some text some text </longDesc> </MainDesc> <FullDesc></FullDesc> </Doc> </Docs> ------------------------------------------------------------------------- Hello John, I guess your second query isn't really doing what you intend it to do. Actually, it will yield the same output as your first query (the child step /MainDesc will only have the effect that fragments without MainDesc as a child will be filtered out). I guess the following query should work (at least if I understood correctly what you are trying to achieve): for $x in ft:search("docMaster", ("emf","waves"), map{'mode':='all words'})/parent::*:MainDesc/ parent::*:Doc return $x/DocTitle/text() Thereby, you using the parent step you assure that the found text node was actually inside a MainDesc node. Please also note that there is a difference between an ancestor step and a parent step and as you seem to know your structure it might be easier and faster to simply use parent. Cheers, Dirk -- Have a nice day JBest

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Schema Validation Error
by Paul Fancher 19 Nov '13

19 Nov '13

I am trying to get a working schema validation, and I'm hitting a hangup: Context: db:open("Test","NewXMLSchema.xsd") <schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:tns=" http://www.example.org/NewXMLSchema" targetNamespace=" http://www.example.org/NewXMLSchema" elementFormDefault="qualified"> <element name="test" type="tns:test"/> <complexType name="test"> <sequence> <element name="item" type="string" maxOccurs="unbounded" minOccurs="1"/> </sequence> </complexType> </schema> db:open("Test","NewFile1.xml") <tns:test xmlns:tns="http://www.example.org/NewXMLSchema" xmlns:xsi=" http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation=" http://www.example.org/NewXMLSchema NewXMLSchema.xsd "> <tns:item>Poke</tns:item> <tns:item>Poke</tns:item> <tns:item>Poke</tns:item> </tns:test> Test Code: declare namespace tns = "http://www.example.org/NewXMLSchema"; validate:xsd-info("/tns:test", db:open("Test","NewXMLSchema.xsd")) The error message I get back is "Fatal: Content is not allowed in prolog." Any ideas what's going on? Paul shoutout to the the people behind eclipse and the Eclipse XML Editors and Tools for some really awesome development software!

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Blocking threads on updating calls
by Joe Templeman 19 Nov '13

19 Nov '13

Hi, I've e-mailed before about this issue, but that was a while ago so I wanted to start a new thread. I'm currently experiencing a situation where all calls (updating or otherwise) are being blocked by any updating call within the same database, even when GLOBALLOCK is set to false. The setup is that we have a restxq endpoint which is checks if the requested content is loaded and if it isn't, we use a java library to fetch the content and then add it to the database. We return a restxq:forward, to the requested endpoint which thens processes the request, assuming the content exists. For some reason however, even with GLOBALLOCK set to false,

3 9

GUI Editor, Code Completions
by Christian Grün 19 Nov '13

19 Nov '13

Dear followers, we are interested to get your opinion on the code completions that we’ve just added to the text editor of our BaseX GUI [1]. You are invited to propose templates that you are missing here! Many of you would probably love to have context-based code completions (such as all functions in the current context, etc.). All I can say is that this is indeed planned for a future version of BaseX. Beside that, we’ve just added an implementation of the upcoming EXPath Binary Module [2]. As usual, a new stable snapshot is available, which contains the new features [3]. Thanks all, Christian [1] http://docs.basex.org/wiki/Shortcuts#Code_Completions [2] http://docs.basex.org/wiki/Binary_Module [3] http://files.basex.org/releases/latest/

2 1

Is it right query using ft:search ?
by John Best 19 Nov '13

19 Nov '13

Hi Team, Below is my XML Structure - <Docs> <Doc> <DocTitle C="1"></DocTitle> <MainDesc></MainDesc> <FullDesc></FullDesc> </Doc> <Doc> <DocTitle C="2"></DocTitle> <MainDesc></MainDesc> <FullDesc></FullDesc> </Doc> ............ ............ </Docs> I have to search the Full Text DB of above documents with 3 different options - 1. Complete Document 2. Only in MainDesc (Main Description) 3. Only in FullDesc (Full Description) Below is the query, using ft:search, for the first options, mentioned above for $x in ft:search("docMaster", ("emf","waves"), map{'mode':='all words'})/ancestor::*:Doc return $x/DocTitle/text() Now, this is for the 2nd options, i.e; for MainDesc - for $x in ft:search("docMaster", ("emf","waves"), map{'mode':='all words'})/ancestor::*:Doc/MainDesc return $x/DocTitle/text() Is it right ? I am little bit confused.. -- Have a nice day JBest

2 1

Reg : Group By In Xquery
by ChandraSekhar 19 Nov '13

19 Nov '13

Dear Basex Team, I am running XQuery using group by clause with large collection ,But I am getting out of main memory , it is taking huge memory to execute,our requirement should use the group by clause,Is their any alternate to group by.Please do the needful Thanks & regards Chandra Sekhar -- This message is for the intended recipient only. If you are not the intended recipient you are notified that disclosing, copying, distributing or taking any action in reliance on the contents of the information is strictly prohibited. __

2 1

Linear Algebra module in XQUERY ?
by jean-marc Mercier 18 Nov '13

18 Nov '13

Hi all, I was thinking about the opportunity of writing a basic linear algebra module in XQUERY (matrix / vector elementary computations, maybe up to cholesky decomposition), since I did not find any at present time. However, there are some little things that seems difficult to me. That could be nice to have opinions of more experimented XQUERY developers before starting trying to write it. Indeed, XQUERY might provide the two basics needs to write a good linear algebra modulus : - The first one is template programming. template programming is straightforward with XQUERY. - The second one is template expressions (see http://en.wikipedia.org/wiki/Expression_templates for a definition). I guess that such patterns are not too difficult to implement with XQUERY. However, the bad points seems to be the following ones. Maybe someone have some insight over these questions ? - I don't know how to allocate and address directly contiguous memory blocks in XQUERY. That is not a good point for performance issues, as working directly with such memory blocks drastically improves basic operations in copying objects (in linear algebra implementation, this is a key point to performance). - Immutability might result in a big overload in memory? This might not be true, see a recent thread over this topic (XQUERY for noobs). - I don't know how to overload the basic operators (*,+,-) with XQUERY. This may result in quite heavy notations like alg:prod($mat1,alg:minus($mat2,$mat3)) instead of $mat1*($mat2-$mat3). Notice however that there are alternatives to XQUERY, since some very good linear algebra modules exists, but written in imperative languages. I list some alternatives, however, it might not be a good idea to wrap a functional language like XQUERY to an imperative, not thread safe, external module (this point has been noticed to me by BaseX teams members). At my knowledge, UBLAS is very performant, flexible, and almost standardized one, but written in C++ http://www.boost.org/doc/libs/1_54_0/libs/numeric/ublas/doc/index.htm. I don't know how to bind C++ to JAVA, but it is certainly possible. However, I am wondering if this could be a good idea. Eigen is another quite interesting C++ implementation (less performant, but more complete). Indeed, it provides a JAVA wrapper, named JEIGEN. Thus it could suit most of my needs. Any suggestions welcome Regards, Jean-Marc

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BaseX-Talk November 2013