BaseX-Talk June 2022

basex-talk@mailman.uni-konstanz.de

26 participants
24 discussions

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>

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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

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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

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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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Feature Preview: Caching Module
by Christian Grün 17 Jun '22

17 Jun '22

Hi there, BaseX 10 will come with a new Caching Module [1], which will allow you to store XQuery values (atomic items, nodes, sequences, maps, arrays, anything except function items) in a main-memory cache. Caches are persistent: Its contents will be written to disk at shutdown time and retrieved from disk in a new or restarted BaseX instance when accessed for the first time. The cache size is only limited by the available RAM. We started off with an XML format for representing caches in files, but we switched to a binary format to speed up the processing of large caches. It’s also possible to put large XML documents in the cache, but the classic database representation will give you better results in most cases. A first snapshot is available [2]. In addition, we’ll soon introduce new database functions, which will enable you to store XQuery values (…including maps) in a database. Have fun, Christian [1] https://docs.basex.org/wiki/Caching_Module [2] https://files.basex.org/releases/latest-10/

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BaseX performance with Apple M1 Max
by Tim Thompson 15 Jun '22

15 Jun '22

Hi, all, I just had my five-year workstation upgrade for my work laptop. Since BaseX is my main productivity tool, I was curious to test performance on the new hardware. Old machine: 2016 MacBook Pro 2.6 GHz Quad-Core Intel Core i7 16 GB 2133 MHz LPDDR3 New machine: 2021 MacBook Pro Apple M1 Max 32 GB unified memory With BaseX 9.7.3 beta, I tested a 4.11 GB XML document that has a series of *entry *elements, each representing a name from our library catalog. On the old machine, it took 9 minutes to create a database from this file, with text and full-text indexes. On the new machine, it took 3.5 minutes. I ran the following query on both machines: <data>{ for tumbling window $entry in /*/entry start $s next $sn when starts-with($sn/key, $s/key) end $e next $en when not(starts-with($en/key, $e/key)) return <group id="{$entry/@id}">{$entry/key}</group> }</data> On the old machine, execution time ranged from 40s to 47s. On the new machine, it ranged from 11.5s to 18s. In short, it looks as though I'll be a lot more productive now! :) Tim -- Tim A. Thompson (he, him) Librarian for Applied Metadata Research Yale University Library

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Term Frequency/inverse Document Frequency Calculation?
by Eliot Kimber 13 Jun '22

13 Jun '22

We’d like to report tf/idf for our DITA content set (https://en.wikipedia.org/wiki/Tf%E2%80%93idf) Of course this is possible using BaseX and basic full-text processing. My question: has anyone done this or is there somewhere I can look to at least get an idea of the level of effort? Having thought about it for not much time at all I’m thinking it’s an application of the basic “make an index over the words for each doc” technique that others have discussed recently. 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>

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random initialization vector (IV) - "As the IV has to be passed along with the encrypted message somehow"
by Patrick Durusau 13 Jun '22

13 Jun '22

Greetings! The recent noise from MongoDB about encrypted querying made me look at the encryption documentation, here: https://docs.basex.org/wiki/Cryptographic_Module The signatures seem straight forward enough: crypto:encrypt|($data as xs:anyAtomicType, $type as xs:string, $key as xs:anyAtomicType, $algorithm as xs:string) as xs:base64Binary||| ||||*crypto:decrypt*($data as xs:anyAtomicType, $type as xs:string, $key as xs:anyAtomicType, $algorithm as xs:string) as xs:string|| ||OK, but where is the random initialization vector (IV)?|| ||The documentation says:|| ||"As the IV has to be passed along with the encrypted message somehow, data which has been encrypted by the |crypto:encrypt| function in BaseX can only be decrypted by calling the |crypto:decrypt| function."|| ||I suppose as a standards editor it's the "somehow" that I find troubling. Exactly what "somehow?" || ||Asking because I would want to invoke a recorded IV to change:|| ||"The result of an encryption using the same message, algorithm and key looks different each time it is executed."|| ||to:|| ||The result of an encryption using the same message, algorithm, key and *IV looks the same* each time it is executed.|| ||Such that I can search by delivering an encrypted string in an XQuery statement, to be match against the same encrypted string in BaseX, with the results of the query being returned and the result being decrypted upon delivery to the user.|| ||That is the data in BaseX and the query, are never visible during the query or response to the query.|| ||Does that make sense?|| ||It's not an immediate need but I thought I should ask before it is.|| ||Thanks for all you do in this wonderful project!|| ||Patrick || -- Patrick Durusau patrick(a)durusau.net Technical Advisory Board, OASIS (TAB) Editor, OpenDocument Format TC (OASIS), Project Editor ISO/IEC 26300 Co-Editor, ISO/IEC 13250-1, 13250-5 (Topic Maps) Another Word For It (blog): http://tm.durusau.net Homepage: http://www.durusau.net Twitter: patrickDurusau

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Encoding hassle ....
by Marco Lettere 13 Jun '22

13 Jun '22

Dear all, after wrapping our heads around this for hours today, we don't know how to get rid of this inconsistency. Thus I ask for help ... SSCE: BaseX 9.6.4 [Standalone] Try 'help' to get more information. > xquery file:write-text("a1.txt", "°" || out:nl()) (: Same with codepoints-to-string(176) instead of "°" :) Query executed in 183.94 ms. > xquery file:read-text("a1.txt") ° Query executed in 1.49 ms. > xquery file:write-text("a2.txt", file:read-text("a1.txt")) Query executed in 3.4 ms. > xquery file:read-text("a2.txt") [file:io-error] Decoding error: xb0 Testing the files with linux command-line tool "file", this is the output: > file a1.txt a1.txt: Unicode text, UTF-8 text > file a2.txt a2.txt: ISO-8859 text Reading the file after "copying" it seems to change the encoding. How is this supposed to be handled? Regards, Marco.

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Lock avoidance using inspect:functions?
by Andy Bunce 13 Jun '22

13 Jun '22

Following Omar's message on lock management [1] I thought I would share a technique that I have tried. It makes use of the function inspect:functions [2]. The code below shows two versions of an eval-update function. After running each version the info.result view reports: - local:eval-update => a global write lock. - local:eval-update2 => no locks at all! I am pretty sure this is a bug/oversight in inspect:functions. I suspect running it risks data integrity, so it is not a good idea. However, I do make use of a non-updating version of this technique, as a way to do string evaluation without triggering a global read lock. If I know that no lockable resources are referenced then it seems safe to me? Note: inspect:functions is similar to the unimplemented standard XQuery 3.1 function fn:load-xquery-module[3] /Andy [1] https://mailman.uni-konstanz.de/pipermail/basex-talk/2022-May/017207.html [2] https://docs.basex.org/wiki/Inspection_Module#inspect:functions [3] https://www.w3.org/TR/xpath-functions-31/#func-load-xquery-module (:~ evaluate XQuery string, string is enriched with external variable definitions for convenience :) declare %updating function local:eval-update($exp as xs:string,$binds as map(*)){ let $decl:= map:keys($binds)!``[declare variable $`{ . }` external;]``=>string-join("") return xquery:eval-update($decl || $exp, $binds) }; declare %updating function local:eval-update2($exp as xs:string,$binds as map(*)){ let $decl:= map:keys($binds)!``[let $`{ . }` :=$binds("`{ . }`") ]``=>string-join("") let $mod:=("module namespace _='abuse'; declare %updating function _:foo($binds){" , $decl, "return " , $exp , "};")=>string-join("") let $p:=file:create-temp-file("APB", ".xqm") let$_:=file:write-text($p,$mod) return updating inspect:functions($p)($binds) }; (: note: the bind functionality is not used in this example) let $binds:=map{"p1":42} let $exp:="db:replace('factbook', 'abuse.xml', '<a/>')" return local:eval-update2($exp,$binds)

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BaseX-Talk June 2022