BaseX-Talk January 2010

basex-talk@mailman.uni-konstanz.de

14 participants
24 discussions

BaseX 6 GUI does not start properly
by Rares Vernica 02 Feb '10

02 Feb '10

Hello, I used BaseX GUI before version 6 successfully. Version 6 GUI does not start properly and throws a lot of exceptions. Here is the first one: Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at sun.java2d.SunGraphics2D.addRenderingHints(SunGraphics2D.java:1295) at org.basex.gui.layout.BaseXBack.paintComponent(BaseXBack.java:62) at org.basex.gui.view.ViewContainer.paintComponent(ViewContainer.java:114) at javax.swing.JComponent.paint(JComponent.java:1029) at org.basex.gui.view.ViewContainer.paint(ViewContainer.java:269) at javax.swing.JComponent.paintToOffscreen(JComponent.java:5124) at javax.swing.BufferStrategyPaintManager.paint(BufferStrategyPaintManager.java:278) at javax.swing.RepaintManager.paint(RepaintManager.java:1220) at javax.swing.JComponent._paintImmediately(JComponent.java:5072) at javax.swing.JComponent.paintImmediately(JComponent.java:4882) at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:803) at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:714) at javax.swing.RepaintManager.seqPaintDirtyRegions(RepaintManager.java:694) at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(SystemEventQueueUtilities.java:128) at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209) at java.awt.EventQueue.dispatchEvent(EventQueue.java:597) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161) at java.awt.EventDispatchThread.run(EventDispatchThread.java:122) The main window loads but it is empty. If I hover over the window with my mouse, the buttons start appearing. Anyway, it is unusable. I do not have this issue with 5.7. Here is the Java version that I use: > java -version java version "1.6.0_16" Java(TM) SE Runtime Environment (build 1.6.0_16-b01) Java HotSpot(TM) Client VM (build 14.2-b01, mixed mode, sharing) The computer is a 32bit PC with the latest Ubuntu OS. Thank you for BaseX. Keep up the good work! Cheers, Rares Vernica

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xpath expressions vs xquery select
by Travis Webb 31 Jan '10

31 Jan '10

I'm trying to figure out which is more efficient (xpath or xquery select), so if someone has knowledge on this I'd appreciate any input. This may or may not be specific to the implementation of BaseX. For example, the following queries return the same thing, but which one is faster? Does basex treat them the same way? 1 uses xquery select, 2 uses xpath 1. for $x in doc('test')/* where $x/node="value" return $x OR 2. for $x in doc('test')/*[node="value"] return $x Thanks. -tjw

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Certificate for BaseX - Works with Vista
by FreeVistaFiles.com 29 Jan '10

29 Jan '10

January 29, 2010 ************************** Hello DBIS Group, University of Konstanz, We are glad to let you know that your software "BaseX" have received a "Works with Vista" certificate. You must know, no more than 20% of all software titles from our site will receive this award. ----------------------------------------------------------------------------------------------------- You should use this certificate by displaying it on your website or inside your product: CERTIFY IMAGE URL: http://www.freevistafiles.com/images/vista_certificate.png URL: http://www.freevistafiles.com/ TITLE: Windows Vista Downloads Best Regards, Free Vista Files team http://www.freevistafiles.com/

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Re: [basex-talk] BaseX questions
by Christian Grün 28 Jan '10

28 Jan '10

Dear Swaminathan, On Thu, Jan 28, 2010 at 8:48 AM, Swaminathan S <swami2(a)gmail.com> wrote: > Hi Christian, > > I am will be using BaseX for multiple xml files that are about 1GB size > (few million lines of in the file). I will be doing transactions on these > BaseX databases in any sequence (For example: an update on databaseA, an > update on databaseB, few Queries on databaseC, few updates on databaseB > ...). > > Could you please give your reply on the following questions: > > My questions: > > Question 1) Does creating a Collection object (see example below) a > costly operation in terms of memory utilization? Also, let > Collection collection = > database_.getCollection("basex://localhost:1984/databaseName", null, null) I guess you are using the XML:DB API? Creating a collection should be very cheap (i.e., not take longer than some milliseconds). > Question 2) Suppose I do the following steps in the order given below: > > a) create a Collection on the database > b) create a XPathQueryService object as below: > service = (XPathQueryService) collection.getService( "XPathQueryService", > "1.0" ); > c) Run Xquery Updates on the database using "Xquery" object of BaseX. > d) query the collection created in step a) as follows: > ResourceSet resourceSet = service.query("< my query>") > > Will my "query" in step d) be able to see the "updates" made in step c) ? > Could you please let me know briefly if there are some concept of > "Collection" I need to know. All database updates will be reflected by subsequent queries. I'm not 100% sure, however, what you refer to with the "Xquery" object? The usual approach to perform queries with the XML:DB API is to call the query() method: XPathQueryService.query(query); ..see also http://basex.org/code.php?code=XMLDBQuery > Question 3) When I do an Xquery on an invalid xpath (or do > xPathQueryService.query() on an invalid xpath), BaseX is not throwing an > exception. Our application would need this functionality. Could you please > give your comments on this? Well, it depends on what you call "invalid". As long as an XPath query is correct, according to the language specification, no errors will be thrown. If you use tag names in your location path that do not occur in the original XML document, the query processor cannot guess that this was done by mistake. > Question 4) I have two choices to run queries on BaseX database a) using > Xquery object b) using XPathQueryService on a Collection. Could you please > let me know which is better and in which scenarios? So you talk about using our own API vs. the XML:DB API? In general, I would recommend to stick to one single API and not mix them up. Next, we observe that most users end up using our own API and discard XQJ and XML:DB, as these APIs do not come up to all expectations – at least in their current stage. Hope this helps, Christian fyi: I've forwarded your e-mail to the basex-talk mailing list.

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Re: [basex-talk] BaseX db questions
by Christian Grün 28 Jan '10

28 Jan '10

Dear Aleks, > Adding a flag would be great , this will helps out so that we can sync database changes into xml file in one call. I've added the flag which allows updates files to be written back to disk. Note that, currently, all files of a modified database will be written back to disk after an update operation has been completed. Note that this is experimental; you're invited to test the latest version of the sources, which you find in our Subversion repository. The flag can be activated via the SET command in BaseX: Command Line: set writeback on; create db input.xml; xquery delete node //text() BaseX API: Context ctx = new Context(); new Set("WRITEBACK", true).execute(ctx); new CreateDB("input.xml").execute(ctx); new XQuery("xquery delete node //text()").execute(ctx); > We are getting the following exception while performing query against database : > Main.notexpected(Object...) line: 205 > TableDiskAccess.cursor(int) line: 326 > [...] > Can you shade some light why would this happen ? this problem happens randomly. This exception might (but need not) indicate an inconsistency in the data storage. It would be great if you could try to create a reproducible example – although I guess this might not be easy if the issue occurs only randomly. > We currently create a single Context object for every open database and keep passing this context for every call, do you think this will cause the problem ? That should be fine. Do you close the database/context – data.close() / context.close() – after all updates have been processed? All the best, Christian

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Issue with Add using XML string
by J Gager 28 Jan '10

28 Jan '10

Sorry for the repeat posts on my last question. I was expecting a confirmation from the web page that the mail was sent - I should know better than to keep clicking :) As stated in my previous question (subject: Issues with XQuery insert), we have tried different methods to add new XML documents to a collection using the Java API. One such approach is to use the Add command, supplying the document content as the XML string. When doing so, the process will fail when there are double quotes used in the attribute values. For example, the following string; <s:test xmlns:s="abc" xmlns:x="def">hello</s:test> yields this error; (Line 1): Open quote is expected for attribute "{1}" associated with an element type "xmlns:s". Alternatively this string; <s:test xmlns:s='abc' xmlns:x='def'>hello</s:test> is not an issue. The double quotes are also not an issue when the argument to the Add command points to a file. Has anyone else encountered this issue? We could of course replace the double quotes with single quotes - however this is not desirable since some of the content of our XML file may contain double quotes that we would not want to change. Thanks, J Gager

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Issues with XQuery insert
by j.gager＠metadatatechnology.com 28 Jan '10

28 Jan '10

Hello We are using BaseX6 to manage a local repository of XML artifacts in a Java based application. We initially start with an empty collection, and add documents as they are needed. We have tried a number of approaches to this (more to come on this in a separate email). One such approach is to insert the documents as nodes into the container using XQuery. Example: insert nodes document {<t:test xmlns:t='xyz' xmlns:s='def'>good <s:test>bye</s:test></t:test>} into collection('MyCollection') It seems to me that only the first namespace declaration is retrained. If I follow this insertion with the following query: declare namespace x ="xyz"; declare namespace y ="def"; collection('MyCollection')/x:test I get the following result: <t:test xmlns:t="xyz">good <s:test xmlns:s="">bye</s:test></t:test> Notice that the namespace for the prefix s is now empty. Further, if I reverse the order of the namespace declarations in the insert query: <t:test xmlns:s='def' xmlns:t='xyz'>good <s:test>bye</s:test></t:test> The query used above will not return a result (presumably because the xyz namespace has been dropped). Has anyone else encountered such issues? Currently we are working around this by saving the XML content to a file and using the Add process - which seems to work as expected. If possible, we would prefer to avoid this extra step of saving the XML to a temporary file before adding it to our BaseX database. Thanks, J Gager

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BaseX db questions
by aleks＠narus.com 27 Jan '10

27 Jan '10

Hello, I'm evaluating baseX database and trying to figure out few details: 1) What is the concept of the Context ? Do I need to create a new context for every database operation or same context should be used within open database ? 2) Is it true that I have to open and close database every time I run query or I can keep database open. 3) How does commit occur, with basex6 it seems like data being committed to disk with some delay? Thanks a lot in advance!! --Aleks

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Issues with XQuery insert
by J Gager 27 Jan '10

27 Jan '10

1 0

Issues with XQuery insert
by j.gager＠metadatatechnology.com 27 Jan '10

27 Jan '10

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BaseX-Talk January 2010