BaseX-Talk February 2017

basex-talk@mailman.uni-konstanz.de

38 participants
39 discussions

A suggestion (json:doc, etc.)
by Hans-Juergen Rennau 26 Feb '17

26 Feb '17

Dear BaseX team, if you are interested in further boosting the power of BaseX as a resource monitoring tool, you might consider the tiny, yet useful extension described below. Currently we have various functions for parsing non-XML formats into node trees: json:parse($text ...) csv:parse($text ...) html:parse($text ,,, These functions expect as input the text to be parsed, not the URI from which to retrieve the text. Of course, it is trivial to combine retrieval and parsing, using fn:unparsed-text(), like so: unparsed-text('foo.json') ! json:parse(.) However, the resulting document does not have a document URI, and it would be cumbersome to associate it with one. So how about adding three functions json:doc($uri ...) csv:doc($uri ...) html:doc($uri ...) Two advantages: first the document URI is available, second - sheer elegance. As an example of this elegance, consider the task to create a list of all .csv files found in a directory tree which have inconsistent record lengths. Using csv:doc, the solution is a simple expression, rather than a program: file:list($dir, true(), "*.csv") ! concat($dir, '/', .) ! csv:doc(.) [1 eq count(//record/count(*) => distinct-values())] /document-uri(.) Alaaf!Hans-Jürgen

1 0

Somewhat unusual question
by Marco Lettere 25 Feb '17

25 Feb '17

Hi to everyone, probably this is not the right place for such a discussion but the BaseX communitiy is the one I'm better introduced to and the one I trust the most. So I hope that this somewhat unusual excursus will anyway be of interest to some of you. As for myself I fell in love with XQuery and its power in terms of data manipulation many years ago. I wouldn't change it with anything else and BTW we're using it (thanks to the incredible BaseX runtime) much beyond data-processing being it the backbone of all our micro-service oriented architectures. Now, to the point, in the near future I probably will be called to face a somewhat skeptical customer who will argue about the technological choice of XQuery. My point will be to make a comparison with the technologies they're currently using and I would like to demonstrate that for a rather XML- (and in general data-) intensive workflow XQuery is perfectly suitable and probably better than many other alternatives. I would tend to exclude XSLT because it would face similar opposition. I would also exclude languages at a lower level of abstraction like Java, Python, Javascript, C/C++ and so on for obvious architectural reasons. But then only templating languages/engines come to my mind. Those would still be probably novel technologies to learn and wouldn't offer the structural, syntactic and semantic power of XQuery anyway. So I ask you kindly, in order to complete my preparation on these matters, is there anyone that has experience with other tools or languages that can be compared with XQuery when used for XML querying, generation, transformation, templating, composition and so on? Thanks a lot! Marco.

14 26

Improper use? Potential bug?
by Rob Stapper 25 Feb '17

25 Feb '17

Hi Christian, I encountered this error-message. I have a strong feeling that this error is related to previous reports, see . my email dd 13-05-2013 and 03-12-2014 My program is heavily recursive so it is hard to create a running snippet but I will try. Hopefully in the mean time you can have a look at the error. TIA, Rob Stapper ===================================== Error: Improper use? Potential bug? Your feedback is welcome: Contact: basex-talk(a)mailman.uni-konstanz.de Version: BaseX 8.6.1 beta 855f949 Java: Oracle Corporation, 1.8.0_31 OS: Windows Vista, x86 Stack Trace: java.lang.RuntimeException: $seq_1644 as (function(*))? index: 87, slot: 9 at org.basex.util.Util.notExpected(Util.java:62) at org.basex.query.var.QueryStack.pos(QueryStack.java:101) at org.basex.query.var.QueryStack.set(QueryStack.java:123) at org.basex.query.QueryContext.set(QueryContext.java:756) at org.basex.query.expr.gflwor.Let$LetEval.next(Let.java:184) at org.basex.query.expr.gflwor.GFLWOR.item(GFLWOR.java:58) at org.basex.query.expr.ParseExpr.toItem(ParseExpr.java:488) at org.basex.query.expr.ParseExpr.toArray(ParseExpr.java:663) at org.basex.query.func.fn.FnApply.value(FnApply.java:32) at org.basex.query.func.Closure.item(Closure.java:288) at org.basex.query.func.Closure.value(Closure.java:321) at org.basex.query.expr.gflwor.GFLWOR.value(GFLWOR.java:72) at org.basex.query.QueryContext.value(QueryContext.java:405) at org.basex.query.value.item.FuncItem.invValue(FuncItem.java:117) at org.basex.query.func.FuncCall.invoke(FuncCall.java:87) at org.basex.query.func.FuncCall.value(FuncCall.java:159) at org.basex.query.value.item.FItem.invokeValue(FItem.java:44) at org.basex.query.func.fn.FnApply.value(FnApply.java:38) at org.basex.query.expr.gflwor.GFLWOR.value(GFLWOR.java:72) at org.basex.query.QueryContext.value(QueryContext.java:405) at org.basex.query.value.item.FuncItem.invValue(FuncItem.java:117) at org.basex.query.func.FuncCall.invoke(FuncCall.java:87) at org.basex.query.func.FuncCall.value(FuncCall.java:159) at org.basex.query.value.item.FItem.invokeValue(FItem.java:44) at org.basex.query.func.fn.FnApply.value(FnApply.java:38) at org.basex.query.QueryContext.value(QueryContext.java:405) at org.basex.query.expr.If.value(If.java:128) at org.basex.query.expr.gflwor.GFLWOR.value(GFLWOR.java:72) at org.basex.query.QueryContext.value(QueryContext.java:405) at org.basex.query.value.item.FuncItem.invValue(FuncItem.java:117) at org.basex.query.func.FuncCall.invokeTail(FuncCall.java:123) at org.basex.query.func.FuncCall.value(FuncCall.java:60) at org.basex.query.expr.gflwor.GFLWOR.value(GFLWOR.java:72) at org.basex.query.QueryContext.value(QueryContext.java:405) at org.basex.query.value.item.FuncItem.invValue(FuncItem.java:117) at org.basex.query.func.FuncCall.invokeTail(FuncCall.java:123) at org.basex.query.func.FuncCall.value(FuncCall.java:60) at org.basex.query.QueryContext.value(QueryContext.java:405) at org.basex.query.expr.If.value(If.java:128) at org.basex.query.expr.gflwor.GFLWOR.value(GFLWOR.java:72) at org.basex.query.QueryContext.value(QueryContext.java:405) at org.basex.query.value.item.FuncItem.invValue(FuncItem.java:117) at org.basex.query.func.FuncCall.invokeTail(FuncCall.java:123) at org.basex.query.func.FuncCall.value(FuncCall.java:60) at org.basex.query.QueryContext.value(QueryContext.java:405) at org.basex.query.expr.If.value(If.java:128) at org.basex.query.expr.gflwor.GFLWOR.value(GFLWOR.java:72) at org.basex.query.QueryContext.value(QueryContext.java:405) at org.basex.query.value.item.FuncItem.invValue(FuncItem.java:117) at org.basex.query.func.FuncCall.invokeTail(FuncCall.java:123) at org.basex.query.func.FuncCall.value(FuncCall.java:60) at org.basex.query.expr.gflwor.GFLWOR.value(GFLWOR.java:72) at org.basex.query.QueryContext.value(QueryContext.java:405) at org.basex.query.value.item.FuncItem.invValue(FuncItem.java:117) at org.basex.query.func.FuncCall.invokeTail(FuncCall.java:123) at org.basex.query.func.FuncCall.value(FuncCall.java:60) at org.basex.query.QueryContext.value(QueryContext.java:405) at org.basex.query.expr.If.value(If.java:128) at org.basex.query.expr.gflwor.GFLWOR.value(GFLWOR.java:72) at org.basex.query.QueryContext.value(QueryContext.java:405) at org.basex.query.value.item.FuncItem.invValue(FuncItem.java:117) at org.basex.query.func.FuncCall.invokeTail(FuncCall.java:123) at org.basex.query.func.FuncCall.value(FuncCall.java:60) at org.basex.query.expr.gflwor.GFLWOR.value(GFLWOR.java:72) at org.basex.query.QueryContext.value(QueryContext.java:405) at org.basex.query.func.StaticFunc.invValue(StaticFunc.java:182) at org.basex.query.func.FuncCall.invoke(FuncCall.java:87) at org.basex.query.func.FuncCall.value(FuncCall.java:61) at org.basex.query.expr.TypeCheck.value(TypeCheck.java:131) at org.basex.query.func.Closure.item(Closure.java:288) at org.basex.query.func.Closure.value(Closure.java:321) at org.basex.query.expr.gflwor.GFLWOR.value(GFLWOR.java:72) at org.basex.query.expr.gflwor.GFLWOR.value(GFLWOR.java:72) at org.basex.query.QueryContext.value(QueryContext.java:405) at org.basex.query.value.item.FuncItem.invValue(FuncItem.java:117) at org.basex.query.func.FuncCall.invoke(FuncCall.java:87) at org.basex.query.func.FuncCall.value(FuncCall.java:159) at org.basex.query.value.item.FItem.invokeValue(FItem.java:44) at org.basex.query.func.fn.FnApply.value(FnApply.java:38) at org.basex.query.expr.gflwor.GFLWOR.value(GFLWOR.java:72) at org.basex.query.QueryContext.value(QueryContext.java:405) at org.basex.query.value.item.FuncItem.invValue(FuncItem.java:117) at org.basex.query.func.FuncCall.invoke(FuncCall.java:87) at org.basex.query.func.FuncCall.value(FuncCall.java:159) at org.basex.query.value.item.FItem.invokeValue(FItem.java:44) at org.basex.query.func.fn.FnApply.value(FnApply.java:38) at org.basex.query.QueryContext.value(QueryContext.java:405) at org.basex.query.expr.gflwor.Let$LetEval.next(Let.java:182) at org.basex.query.expr.gflwor.GFLWOR$1.next(GFLWOR.java:95) at org.basex.query.expr.ParseExpr.item(ParseExpr.java:51) at org.basex.query.expr.ParseExpr.value(ParseExpr.java:65) at org.basex.query.QueryContext.value(QueryContext.java:405) at org.basex.query.value.item.FuncItem.invValue(FuncItem.java:117) at org.basex.query.func.FuncCall.invoke(FuncCall.java:87) at org.basex.query.func.FuncCall.value(FuncCall.java:159) at org.basex.query.value.item.FItem.invokeValue(FItem.java:44) at org.basex.query.func.fn.FnFoldLeft.value(FnFoldLeft.java:22) at org.basex.query.QueryContext.value(QueryContext.java:405) at org.basex.query.expr.gflwor.Let$LetEval.next(Let.java:182) at org.basex.query.expr.gflwor.GFLWOR$1.next(GFLWOR.java:95) at org.basex.query.scope.MainModule$1.next(MainModule.java:121) at org.basex.query.QueryContext.cache(QueryContext.java:635) at org.basex.query.QueryProcessor.cache(QueryProcessor.java:113) at org.basex.core.cmd.AQuery.query(AQuery.java:86) at org.basex.core.cmd.XQuery.run(XQuery.java:22) at org.basex.core.Command.run(Command.java:257) at org.basex.core.Command.execute(Command.java:95) at org.basex.gui.GUI.exec(GUI.java:471) at org.basex.gui.GUI.access$3(GUI.java:425) at org.basex.gui.GUI$6.run(GUI.java:413)

2 7

Cross-Origin Resource Sharing ( CORS) not available in jetty version 8
by Rob Stapper 25 Feb '17

25 Feb '17

Hi Christian, I'm trying to build a web based frontend with Angular(2) with Basex as backend. Since Angular uses localhost:3000 and basex uses localhost:8984 I need CORS to be activated in the bachend's jetty-service. If I try to activate this by editing the web.xml file I get the message from the jetty that this service is not available. Obviously version 8 of jetty does not support CORS. According to the documentation Jetty 9 should support CORS. Is replacing jett 8 with version 9 somewere on the agenda? Or can I do this myself? (new area for me) I wouldn't mind testrunning it. TIA, Rob Stapper PS. I see the request the request being handled and send back by the backend (basex) but it misses the necessary header. Debugging my Angular app in the browser say that CORS-header is missing.

4 4

BaseX 8.6.1
by Christian Grün 24 Feb '17

24 Feb '17

Dear all, A new minor update of BaseX is available (version 8.6.1, see [1] for more details). If you use BaseX with many users in parallel, we recommend you to switch to this version, which provides an improved locking strategy for excessive parallelism. Have fun, and (just in case) a nice weekend, Christian PS: Thanks everyone for the interesting mailing list discussion on XQuery in commercial environments. The good thing: Once you convince your customers or CTOs that XQuery is an attractive alternative, and once your project is a success, they usually want to realize everything with XQuery, no matter if it makes sense... Keep on going, don't give up too early! [1] https://github.com/BaseXdb/basex/blob/master/CHANGELOG

2 1

Gzip/RESTXQ
by meumapple 23 Feb '17

23 Feb '17

Hi All, I am wondering whether for RESTXQ one should enable gzip encoding to improve data transmission: if the database is used for storage (where the data are in binary form), is the gzip option still useful? Best, Joseph

4 6

BaseX schema aware
by Leo Studer 23 Feb '17

23 Feb '17

Hello I am wondering whether there are plans to make BaseX schema aware? Thanks for considering Always Leo

2 1

base-uri() changed answer around v8.5
by Amanda Galtman 23 Feb '17

23 Feb '17

Hi, I'm seeing different results from base-uri() in BaseX 8.4 vs. 8.5.2. I believe the 8.4 answer is correct and the 8.5.2 answer is incorrect. Here is an example, and there is nothing special about the particular folder or XML file I used. base-uri(collection("file:///C:/Program%20Files%20(x86)/BaseX8.4/webapp/WEB-INF")/*[*:display-name]) BaseX 8.4 result: file:///C:/Program%20Files%20(x86)/BaseX8.4/webapp/WEB-INF/web.xml BaseX 8.5.2 and 8.6 result (notice "WEB-INF/" is missing): file:///C:/Program%20Files%20(x86)/BaseX8.4/webapp/web.xml Saxon agrees with BaseX 8.4. Thanks, Amanda

2 4

count(//elem) not optimized, even though `elem` is in the index
by Gioele Barabucci 22 Feb '17

22 Feb '17

Hello, I was stressing the BaseX 8.6 planner/optimizer when I noticed that expressions like `count(//elem)` are not optimized at all, even though they are correctly indexed, as demonstrated by `index:element-names()`. The current database is a 300 MB TEI document. All the elements are in the `http://www.tei-c.org/ns/1.0` namespace. The following test case will report the correct number, but it will take a couple of seconds to run, instead of a few milliseconds. ``` declare namespace tei="http://www.tei-c.org/ns/1.0"; let $n := index:element-names("monier")[. = 're']/@count let $c := count(//tei:re) return <res><in-index>{$n}</in-index><in-doc>{$c}</in-doc></res> ``` I wonder if the presence of the namespace somehow confuses the optimizer. The same problem can be observed running the same test case with ``` declare default element namespace "http://www.tei-c.org/ns/1.0"; [...] let $c := count(//re) ``` Regards, -- Gioele Barabucci <gioele.barabucci(a)uni-koeln.de>

3 5

XSLT caching
by Tom De Herdt 19 Feb '17

19 Feb '17

Hi all, I'm evaluating BaseX as an alternative (and very attractive) platform for an XML/XSLT-based website that needs to be migrated from ASP.NET. The website relies heavily on XSLT. Each page is generated on-the-fly with Saxon.NET, using a complex set of stylesheets. To get reasonable performance, stylesheets are compiled on first use and cached for subsequent requests. This is crucial, as XSLT compilation is typically orders of magnitude slower than execution; without caching, the server would spend most of the time compiling the same stylesheets over and over again. I was happy to find that BaseX can use Saxon, but as far as I can see, xslt:transform() does not cache compiled stylesheets. Can anyone confirm this? If not, are there any plans to support stylesheet caching in the future? Or is there a way to reuse compiled stylesheets manually? Thanks, Tom De Herdt

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BaseX-Talk February 2017