BaseX-Talk

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4 participants
5268 discussions

the implicit context of position
by Graydon Saunders 30 Jun '22

30 Jun '22

Hello -- I've got an element node that's part of a document. I need its position among the element children of its parent. $step/position() will (correctly!) always return 1, there's one thing in $step, of course it does. replace($step/path(),'^.*\[(\p{Nd}+)\]$','$1') => xs:integer() gets me the implicit position but is something of a horror. for $e at $in in $step/../* where $e is $step return $in works, too, but any notion of elegance and clarity have fled screaming into the night. I keep thinking there must be a better way; anyone got any suggestions? Thanks! Graydon

4 4

Sym links in BaseX 9.7.2
by Maud Ingarao 30 Jun '22

30 Jun '22

Hi everybody ! As we had problems getting our formatDateTime() outputs in french, we followed Christian's advice and updated to BaseX 9.7.2. Now it works and we get our outputs in French, thanks a lot ! But we face a new problem : symbolic links inside the webapp are no longer followed. We tried to had the following to jetty.xml : | <Call name="addAliasCheck"> <Arg><New class="org.eclipse.jetty.server.handler.AllowSymLinkAliasChecker"/></Arg> </Call> | But this doesn't seem to be the answer. I can't remember configuring anything in particular in the previous versions of BaseX and our webapp was just running fine. Thanks for your help. Maud || -- Maud Ingarao IHRIM - UMR 5317 Institut d’histoire des représentations et des idées dans les modernités École Normale Supérieure de Lyon 15 Parvis René Descartes - BP7000 - 69342 Lyon CEDEX 07 +33 4 37 37 65 79 - maud.ingarao(a)ens-lyon.fr */Présente les lundi - mardi - mercredi/* */At the office on mondays - tuesdays - wednesdays/* http://ihrim.ens-lyon.fr/ http://ahn.ens-lyon.fr/ https://cahier.hypotheses.org/

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How To Determine if You're In Daylight Saving Time?
by Eliot Kimber 28 Jun '22

28 Jun '22

I’m showing times on RESTXQ generated pages that need to be adjusted for a particular time zone. Doing the time zone adjustment is easy enough but I realized that knowing whether or not a given time zone should be standard or daylight time is a challenge not directly addressed by the XQuery time functions. So my question: does anyone have a technique for determining if a given time zone or region is using DST? Of course I can hard-code some sort of DST calendar for the time zones I know I need (U.S. time zones, European Central Time, India Standard Time) but it seemed like there ought to be a more general solution somewhere. My server is running on Linux but is developed and tested on macOS. Thanks, Eliot _____________________________________________ Eliot Kimber Sr Staff Content Engineer O: 512 554 9368 M: 512 554 9368 servicenow.com<https://www.servicenow.com> LinkedIn<https://www.linkedin.com/company/servicenow> | Twitter<https://twitter.com/servicenow> | YouTube<https://www.youtube.com/user/servicenowinc> | Facebook<https://www.facebook.com/servicenow>

2 1

Fonts problem with database list and system dialogs
by Jonathan Robie 28 Jun '22

28 Jun '22

I can't read the names of databases in my UI now - the font is tiny. And the systems dialogs I might otherwise be able to use to find and fix the problem also use tiny fonts. Other windows are fine. [image: image.png] Jonathan

2 7

XPATH injection / escaping
by trichel 26 Jun '22

26 Jun '22

Hello, How to write secure queries when the queried text nodes contain ampersands? For instance: declare variable $publisher external; (: $pub == 'Faber & Faber' :) declare variable $db := db:open('db'); let $records := $db/record/publisher[. = $publisher] (: publisher == 'Faber & Faber' :) The external variable is unsafe input, escaped by the sending application. Escaping the ampersand in the external variable with & (& a m p ;) doesn't work, Basex stops finding hits. Just letting the ampersand pass might expose the code to injection attacks? I could switch to a full-text query and remove the ampersand from the external variable, but that's a bit hackish. The expression is exact. How to proceed in a secure way?

2 4

Link Graph Construction: Anything I Can Crib or Learn From?
by Eliot Kimber 26 Jun '22

26 Jun '22

In the context of our Project Mirabel system that manages DITA content, I need to be able answer the question “for topic X, what other topics link to it directly or indirectly?” That is, say Topic A links to Topic B that Links to Topic C. Asking the question “What topics ultimately link to topic C?” I would like to get the answer “Topic A, Topic B”. Getting the answer for direct references is easy—I already build a where-used index that captures, for each DITA map or topic, what other maps and topics link directly to it. But to get the Topic A part of the answer I need some kind of link graph index and I’m not sure how best to go about calculating this or capturing it in some index or set of indexes. In our content the fan out from a single Topic C to the set of topics that ultimately reference it could be 10s of 1000s of topics. We have about 45K topics in the content for each version of the ServiceNow Platform and a number of topics that are used by a large number of other topics, so the explosion can be quite large. That suggests that a simple topic-to-ultimately-referenced-topics index would be very inefficient in that the entry for any given topic could potentially have 45K – 1 entries (we don’t care that a topic references itself). On the other hand, working backwards through chains of direct references can also be expensive and is probably too slow, so maybe the brute-force index is the best option? At the same time, I would like to be able to quickly visualize the link graph extending from or ending in any given topic or simply the link graph for the entire information set, which requires capturing the nodes and edges. My question: does anyone either have experience or insight into this kind of link graph challenge or know of relevant papers or general discussion of graph processing I might look at? Thanks, Eliot _____________________________________________ Eliot Kimber Sr Staff Content Engineer O: 512 554 9368 M: 512 554 9368 servicenow.com<https://www.servicenow.com> LinkedIn<https://www.linkedin.com/company/servicenow> | Twitter<https://twitter.com/servicenow> | YouTube<https://www.youtube.com/user/servicenowinc> | Facebook<https://www.facebook.com/servicenow>

4 3

Construct URL-Friendly Base64 Strings
by Eliot Kimber 22 Jun '22

22 Jun '22

I’m trying to replicate a call to a remote REST API that uses hmac encoding to construct an authentication string. I’m working from existing Python code that does the same thing. What I’m seeing is that the crypto:hmac() function can return Base64 strings that include characters that must be escaped in URIs, i.e.: mTA76dRZkiCf84WUKM/PWySydamj3dMZ6Tm26s9QGNI (Note the “/”) Python’s base64 support includes the method urlsafe_b64encode(), which avoids the characters “+” and “/”. Unfortunately the handler of the API call fails if I escape the “/” or “+”—I’m not sure why. So I need to construct the same URI-friendly base64 string that the Python method is generating. I don’t see an obvious way to do this with the BaseX conversion package. Is there a way short of implementing my own Base64 encoding algorithm to get a URI-friendly base64 string? I’m using 9.6.4 at the moment but could upgrade if necessary. Thanks, E. _____________________________________________ Eliot Kimber Sr Staff Content Engineer O: 512 554 9368 M: 512 554 9368 servicenow.com<https://www.servicenow.com> LinkedIn<https://www.linkedin.com/company/servicenow> | Twitter<https://twitter.com/servicenow> | YouTube<https://www.youtube.com/user/servicenowinc> | Facebook<https://www.facebook.com/servicenow>

2 2

I can’t use character maps with RESTXQ
by Imsieke, Gerrit, le-tex 22 Jun '22

22 Jun '22

For HTML with embedded Javascript, I need to output > as > rather than as > In XSLT I’m doing <xsl:character-map name="a">  <xsl:output-character character=">" string=">"/> </xsl:character-map> and <xsl:output method="xhtml" indent="no" encoding="UTF-8" use-character-maps="a" omit-xml-declaration="no" html-version="5.0" doctype-public="" doctype-system=""/> In RESTXQ I tried the following: I created a document called html-charmap.xml with the following content: <?xml version="1.0" encoding="UTF-8"?> <serialization-parameters xmlns="http://www.w3.org/2010/xslt-xquery-serialization"> <use-character-maps> <character-map character=">" map-string=">"/> </use-character-maps> </serialization-parameters> It resides in the directory where the xqm is located. The xqm contains this function: module namespace my = 'my'; declare %rest:GET %rest:path("/charmap/test") %output:method("xhtml") %output:html-version("5.0") %output:parameter-document("html-charmap.xml") %rest:produces("text/html") function my:html() { <html> <head> <title>Charmap Test</title> <meta charset="UTF-8"/> <script> alert('You are in ' + (document.compatMode==='CSS1Compat'?'Standards':'Quirks') + ' mode and 1 > 0 is ' + (1 > 0)</script> </head> <body> <h1>Charmap Test</h1> <p>></p> <p>></p> </body> </html> }; When I retrieve /charmap/test, all > characters are still escaped as > When I change %output:parameter-document to %output:parameter-document("tml-charmap.xml"), BaseX doesn’t complain about the missing parameter document. What am I doing wrong? In XSLT 3 with Saxon, I can also do <xsl:output method="xhtml" indent="yes" include-content-type="no" encoding="UTF-8" parameter-document="html-charmap.xml" omit-xml-declaration="no" html-version="5.0" doctype-public="" doctype-system=""/> and this will use html-charmap.xml and it will complain when it’s the wrong file name. Gerrit

2 3

Something is off with db:enforceindex in 9.7.2.
by Omar Siam 20 Jun '22

20 Jun '22

Consider this XQuery: declare namespace _="urn:_"; declare function _:query-index___($dict as xs:string, $ind as xs:string, $str as xs:string) { let $rs := (# db:enforceindex #) { switch ($ind) case "any" return collection($dict)//index/w[text() contains text { $str } using wildcards] default return if ($str = '*') then collection($dict)//index[@id = $ind]/w else collection($dict)//index[@id = $ind]/w[text() contains text { $str } using wildcards] } return $rs }; _:query-index___('dc_arz_eng_publ__ind', 'any', 'beer.*') where dc_arz_eng_publ__ind contians a single XML which looks like (probably irrelevant): <indices> <index id="lem"> <w>-</w> <w>mafṛama</w> <w>without</w> </index> <index id="other"> </index> </indices> There is a java.lang.ArrayIndexOutOfBoundsException: Version: BaseX 9.7.2 Java: Azul Systems, Inc., 11.0.14.1 OS: Windows 10, amd64 Stack Trace: java.lang.ArrayIndexOutOfBoundsException: Index -1 out of bounds for length 8 at org.basex.query.var.QueryStack.get(QueryStack.java:99) at org.basex.query.QueryContext.get(QueryContext.java:553) at org.basex.query.var.VarRef.value(VarRef.java:46) at org.basex.query.expr.ParseExpr.atomValue(ParseExpr.java:61) at org.basex.query.expr.Expr.atomItem(Expr.java:116) at org.basex.query.func.fn.Docs.collection(Docs.java:36) at org.basex.query.func.fn.FnCollection.value(FnCollection.java:15) at org.basex.query.expr.index.IndexDynDb.data(IndexDynDb.java:86) at org.basex.query.expr.index.IndexDb.data(IndexDb.java:35) at org.basex.query.expr.ft.FTWords.iter(FTWords.java:153) at org.basex.query.expr.ft.FTIndexAccess.iter(FTIndexAccess.java:43) at org.basex.query.expr.ft.FTIndexAccess.value(FTIndexAccess.java:63) at org.basex.query.expr.path.CachedPath.nodes(CachedPath.java:43) at org.basex.query.expr.path.AxisPath.value(AxisPath.java:41) at org.basex.query.expr.Extension.value(Extension.java:59) at org.basex.query.expr.ParseExpr.iter(ParseExpr.java:46) at org.basex.query.expr.gflwor.For$1.next(For.java:112) at org.basex.query.expr.gflwor.Let$LetEval.next(Let.java:144) at org.basex.query.expr.gflwor.OrderBy$1.sort(OrderBy.java:73) at org.basex.query.expr.gflwor.OrderBy$1.next(OrderBy.java:54) at org.basex.query.expr.gflwor.GFLWOR$1.next(GFLWOR.java:68) at org.basex.query.QueryContext.next(QueryContext.java:359) at org.basex.query.expr.constr.Constr.add(Constr.java:73) at org.basex.query.expr.constr.CElem.item(CElem.java:149) at org.basex.query.expr.constr.CElem.item(CElem.java:1) at org.basex.query.expr.ItemMap.item(ItemMap.java:29) at org.basex.query.expr.ParseExpr.value(ParseExpr.java:51) at org.basex.query.expr.ParseExpr.iter(ParseExpr.java:46) at org.basex.query.scope.MainModule.iter(MainModule.java:60) at org.basex.query.QueryContext.iter(QueryContext.java:338) at org.basex.http.restxq.RestXqResponse.serialize(RestXqResponse.java:85) at org.basex.http.web.WebResponse.create(WebResponse.java:58) at org.basex.http.restxq.RestXqServlet.run(RestXqServlet.java:72) at org.basex.http.BaseXServlet.service(BaseXServlet.java:69) at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) at org.eclipse.jetty.servlet.ServletHolder$NotAsync.service(ServletHolder.java:1450) at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:799) at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:550) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143) at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:600) at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127) at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:235) at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1624) at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:233) at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1440) at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:188) at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:501) at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1594) at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:186) at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1355) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141) at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127) at org.eclipse.jetty.server.Server.handle(Server.java:516) at org.eclipse.jetty.server.HttpChannel.lambda$handle$1(HttpChannel.java:487) at org.eclipse.jetty.server.HttpChannel.dispatch(HttpChannel.java:732) at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:479) at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:277) at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:311) at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:105) at org.eclipse.jetty.io.ChannelEndPoint$1.run(ChannelEndPoint.java:104) at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.runTask(EatWhatYouKill.java:338) at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:315) at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.tryProduce(EatWhatYouKill.java:173) at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:131) at org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:409) at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:883) at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:1034) at java.base/java.lang.Thread.run(Thread.java:829) If I don't use (# db:enforceindex #) {} it works as expected Best regards -- Mag. Ing. Omar Siam Austrian Center for Digital Humanities and Cultural Heritage Österreichische Akademie der Wissenschaften | Austrian Academy of Sciences Stellvertretende Behindertenvertrauensperson | Deputy representative for disabled persons Wohllebengasse 12-14, 1040 Wien, Österreich | Vienna, Austria T: +43 1 51581-7295 omar.siam(a)oeaw.ac.at | www.oeaw.ac.at/acdh

2 2

unexpected behavior from prof:track()
by C. M. Sperberg-McQueen 20 Jun '22

20 Jun '22

Short version: When I call prof:track(...) with an expression as argument, I get the results I would expect. When I assign prof:track#1 to a variable and then call it with an expression by referring to that variable, the time shown is always 0. Is this the expected behavior? Details: Consider the following XQuery module: let $f := function($s as xs:string) { trace('hi'), prof:sleep(2000), trace($s) }, $pt := (function-lookup( QName('http://basex.org/modules/prof', 'track'), 1), function($item) { map {'time':'?', 'value': $item} } )[1] return (prof:track($f('world')), $pt($f('friends!')) ) It defines two variables: - $f, a function that produces output (so I can see that it ran) and calls prof:sleep (so it takes more than a couple of ms), and - $pt, which will be the prof:track() function if it exists (as it will in BaseX) or a substitute function which just evaluates the expression but does not provide any timing information. It then calls function $f twice, once wrapped in prof:track() and once wrapped in $pt(). The output follows: map { "memory": 0, "time": 2.00069e3, "value": ("hi", "world") } map { "memory": 0, "time": 0.0e0, "value": ("hi", "friends!") } As may be seen, the 'time' value in the map is 0. Conjecture: I suspect that this has to do with the fact that prof:track() is not a normal function -- in Lisp or Scheme, it would have to be implemented as a macro or 'special form', meaning that the arguments to the call are not evaluated before calling the function. I wonder whether what is happening here is that when the call to $pt($f('friends')) is handled, the argument is being evaluated (producing the sequence ('hi', 'friends!')) and then prof:track() is being called. Since it has no work to do, prof:track() then just returns the result, accurately showing a time cost of 0. Background: In a test harness I use to run tests for an XQuery program I am writing, I initially used prof:track() to keep track of how long each test takes to run. Recently, as part of an effort to ensure that the program is implementation-neutral, I rewrote the test harness so that it could run under other XQuery engines as well -- hence the indirection and the definition of $pt. I realize that I could get the BaseX version to work by saying something like let $prof-track := function-lookup(...) let $fall-back := function(...) if (exists($prof-track)) then prof:track(...) else $fall-back(...) but my recollection is that I tried this first and it provoked fatal errors in other engines, since prof:track() is not available in the static context in those engines. Is there any way to write a single module so that prof:track() is used (and produces useful information) if available, and the fallback function is used otherwise? I would really like to avoid generating different versions of the test harness for different XQuery engines. Many thanks for any thoughts or advice anyone on this list can provide. Michael Sperberg-McQueen -- C. M. Sperberg-McQueen Black Mesa Technologies LLC http://blackmesatech.com

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