BaseX-Talk

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4 participants
5268 discussions

Using "define function ...."
by johanna.vompras＠uni-bielefeld.de 13 Jul '10

13 Jul '10

Hi, I am relatively new to baseX and XQuery and just trying the funcionalities of BaseX. I have got some questions on the possibility of defining user-defined functions, which take a node (or a node set) as parameters and process them subsequently (e.g. format the results as an html table, or another numerical computations etc.). This might look like this: define function createTable($n as node) { for $c in $n/* return <some html-output>; } and I would like to use the defined function "createTable" in a xquery expression. For example : for $questionscheme in doc("database")//d:QuestionScheme return createTable($questionscheme/node()) That means I need to pass a whole node (not the query results as string), in order to process the node with further xquery expressions. Is this compatible with BaseX? And where should I define such functions? Defining a function through the XQuery-API does not work. The functions in class Query in the BaseXClient.php seem to only support a successive query processing (one result tuple after another). Or have I overseen something? If not, can this class be quickly modified to support this? Many thanks for your help on this!

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support for EventTarget appears to be missing
by Godmar Back 12 Jul '10

12 Jul '10

Hi, the Elements returned by XQResultItem.getNode() don't appear to support the EventTarget interface: org.basex.api.dom.BXElem cannot be cast to org.w3c.dom.events.EventTarget This means we need to serialize the node to an XML string, then parse that string to obtain a org.w3c.dom.Node instance that supports this interface. This is awkward and highly inefficient. Why doesn't BaseX support EventTarget (or use the existing DOM implementation provided with Java, which does support DOM events?) - Godmar

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XQST0049 error in BaseX 6.1 that did not occur in BaseX 6.0
by Godmar Back 11 Jul '10

11 Jul '10

Hi, I recently upgraded to BaseX 6.1. I now receive an error when running a query that run without complications in BaseX 6.0 The offending query has this prolog: declare namespace libx='http://libx.org/xml/libx2'; declare namespace atom='http://www.w3.org/2005/Atom'; declare variable $metadata as xs:anyAtomicType := doc('libx2_meta')/metadata; declare variable $feed as xs:anyAtomicType := doc('libx2_feed')/feed; which results in *declare variable $metadata as xs:anyAtomicType := doc('libx2_meta')/metadata;* ^ javax.xml.xquery.XQQueryException: Stopped at line 3, column 48: [XQST0049] Duplicate definition of $metadata as xs:anyAtomicType. at org.basex.api.xqj.BXQDynamicContext.execute(BXQDynamicContext.java:251) at org.basex.api.xqj.BXQPreparedExpression.executeQuery(BXQPreparedExpression.java:54) at org.libx.libappdatabase.Query.main(Query.java:100) Simply exchanging BaseX61.jar with BaseX6.jar makes this query work as expected. I note that if I switch lines 3 and 4 (so that the 'declare variable $feed' appears first), the error is flagged on this line. The query runs fine using the command-client in both BaseX 6 and 6.1 I'm using org.basex.api.xqj.BXQDataSource, following by prepareExpression, followed by executeQuery. This query has no external variables. Another point of information: out of curiosity, I printed information about the prepared expression after prepareExpression like so: System.out.println("external vars: " + Arrays.asList(pe.getAllExternalVariables())); System.out.println("unbound vars: " + Arrays.asList(pe.getAllUnboundExternalVariables())); this shows 'metadata' and 'feed' as external variables: external vars: [metadata, feed] unbound vars: [] Why are 'metadata' listed as external, even though they are not declared as such? I would appreciate any insight. If the problem is mysterious, I can prepare a self-contained test case or aid in debugging. Thanks. - Godmar [*] http://top.cs.vt.edu/~gback/bx/get_connected_tree.xq

3 7

setting the BaseX directory
by Godmar Back 11 Jul '10

11 Jul '10

Hi, we use BaseX in a Tomcat server on Linux. We run multiple instances of our application as different web applications in that server. A problem we encountered is that BaseX refers to the 'user.home' property when identifying the location of its .basex configuration file. This property is related to which (Linux) user started the Tomcat server, which is unrelated to the web application that needs to start a BaseX instance. We are now using a very awkward work-around: temporarily setting 'user.home' to the desired value, then touching a class in org.basex.core to force its initialization: oldUserHome = System.getProperty("user.home"); System.setProperty("user.home", basexdir); if (!org.basex.core.Prop.HOME.startsWith(basexdir)) throw new java.lang.Error("BaseX property initialization failed"); System.setProperty("user.home", oldUserHome); Could a programmatic way to initialize BaseX be provided that does depend on system properties? I understand that it will require a small amount of refactoring (given how deep this assumption is wired into the code), but it is absolutely necessary to facilitate the use of BaseX in shared environments such as Tomcat. Thanks. - Godmar

2 3

startjaxrx
by Andy Chambers 10 Jul '10

10 Jul '10

Hi All, The startjaxrx script doesn't add all the necessary jars to the classpath before starting BaseX. Changing it to the following worked for me.... #!/bin/bash # Script for running the JaxRx server # Path to this script PWD=`dirname $0` # Check: path to BaseX binary BXPATH=$PWD/BaseX61.jar # Classpath LIB=$PWD/lib CP=$PWD/BaseX61-jaxrx.jar:${BXPATH} for jar in ${LIB}/*.jar do CP=${CP}:${jar} done # Assign more memory VM=-Xmx1g # Run JaxRx java -cp "$CP:." $VM StartJaxRx -- ---- Andy Chambers Formedix Ltd

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Re: [basex-talk] PHP: How can I get the name of the xquery function where an error occurred?
by Christian Grün 09 Jul '10

09 Jul '10

Dear Nigel, line and column information is omitted in error messages returned by the server. One solution to get more feedback is to use the BaseX API or the command line of BaseX, or to directly test your query in the BaseX GUI Editor. Your request is a good hint, though; we might add extended server feedback in the next minor release. Christian On Fri, Jul 9, 2010 at 7:58 PM, Nigel Alderton <nigel.alderton(a)bigtooth.co.uk> wrote: > If I get an error message like this: > > [XPST0003] Incomplete 'let' expression. > > How can I find out more information regarding the error eg. the name of the > function that failed? The error message doesn’t give any clue about where > the error occurred. > > I’m using PHP. My code is based on the example code supplied with BaseX. > > <?php > > include("BaseXClient.php"); > $CMD_OPEN = "open cgd-dat"; // BaseX command to open the database. > $xq = "xquery ... a long xquery"; // BaseX xquery command. > > try { > $session = new Session("localhost", 1984, "admin", "admin"); > $session->execute($CMD_OPEN); > print $session->execute($xq); > $session->close(); > } catch (Exception $e) { > print $e->getMessage(); > }

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PHP: How can I get the name of the xquery function where an error occurred?
by Nigel Alderton 09 Jul '10

09 Jul '10

If I get an error message like this: [XPST0003] Incomplete 'let' expression. How can I find out more information regarding the error eg. the name of the function that failed? The error message doesn't give any clue about where the error occurred. I'm using PHP. My code is based on the example code supplied with BaseX. <?php include("BaseXClient.php"); $CMD_OPEN = "open cgd-dat"; // BaseX command to open the database. $xq = "xquery ... a long xquery"; // BaseX xquery command. try { $session = new Session("localhost", 1984, "admin", "admin"); $session->execute($CMD_OPEN); print $session->execute($xq); $session->close(); } catch (Exception $e) { print $e->getMessage(); } ?>

1 0

PHP and the QueryExample.php
by johanna.vompras＠uni-bielefeld.de 09 Jul '10

09 Jul '10

Hi all, I was testing the PHP examples on your website ( https://svn.uni-konstanz.de/dbis/basex/trunk/api/etc/php/ ), but I get the following results after executing the QueryExample.php (the query string is: $input = "for $i in 1 to 10 return <xml>Text { $i }</xml>";): This is the output: "instead of 1 commands received." The basex server is running, the access to the server seems to work. I can type the query in the basex-api and it works! Through PHP no query is executed and no results are returned. Can someone help me? Have I overseen something? Should I specify the database (e.g. factbook.xml, and how?)?

2 1

PHP and the QueryExample.php
by johanna.vompras＠uni-bielefeld.de 09 Jul '10

09 Jul '10

1 0

Re: [basex-talk] error importing one million documents using console
by Patrick Schäfer 09 Jul '10

09 Jul '10

Hi Christian, > * Console: > open tuscreen > xquery //*:molecule[@*:id="11178"] Wow, thank you. That gave a huge boost in performance: for $i in //*:molecule[@*:id="298038"]/*:identifier[@*:convention="iupac:smile"] return <smile>{$i/@value}</smile> Takes 80ms now. But unfortunately it doesn't work for a query like: let $ids := (1 to 10) for $i in //*:molecule[@*:id = $ids]/*:identifier[@*:convention="iupac:smile"] return <smile>{$i/@value}</smile> Query executed in 3688.12 ms. So it still takes >3500 ms The Query execution plan is quite different I noticed: First Query: Result: element { "smiles" } { for $i in IndexAccess("298038", ATV)/self::*:id/parent::*:molecule/*:identifier[@*:convention = "iupac:smile"] return element { "smile" } { $i/@value } } Second Query: Result: for $i in IndexAccess("iupac:smile", ATV)/self::*:convention/parent::*:identifier[parent::*:molecule[@*:id = (1, 2, 3, 4, 5, 6, 7, 8, 9, 10)]] return element { "smile" } { $i/@value } So the second plan doesn't make use of the attribute index for locating the id-attributes. > Sorry, zu spät gesehen… Jederzeit ;) Je mehr Mails allerdings an die > Liste gehen, desto besser; dann bleiben auch die anderen auf dem > Laufenden. Dann antworte ich besser an die Liste ;) Patrick

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