BaseX-Talk February 2019

basex-talk@mailman.uni-konstanz.de

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geo:distance() return units
by Jacob Borisov 26 Feb '19

26 Feb '19

Hello. Could anybody explain how to get a result from geo:distance() in kilometers or miles? Thanks.

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Re: [basex-talk] BaseX-Talk Digest, Vol 110, Issue 29
by Shaun Flynn 25 Feb '19

25 Feb '19

Hello there Marco, This might be down to the choice of regex. Assume $path = "path" app/{$path=.+} Will match "app/path=1234" And "app/path=1234/input" Which I think would be matched by ".+" part of the expression, as "/input" would match ".+". Kind regards On Sat, 23 Feb 2019, 11:00 , <basex-talk-request(a)mailman.uni-konstanz.de> wrote: > Send BaseX-Talk mailing list submissions to > basex-talk(a)mailman.uni-konstanz.de > > To subscribe or unsubscribe via the World Wide Web, visit > https://mailman.uni-konstanz.de/mailman/listinfo/basex-talk > or, via email, send a message with subject or body 'help' to > basex-talk-request(a)mailman.uni-konstanz.de > > You can reach the person managing the list at > basex-talk-owner(a)mailman.uni-konstanz.de > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of BaseX-Talk digest..." > > > Today's Topics: > > 1. RESTXQ and regexp (Marco Lettere) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Fri, 22 Feb 2019 12:05:29 +0100 > From: Marco Lettere <m.lettere(a)gmail.com> > To: BaseX <basex-talk(a)mailman.uni-konstanz.de> > Subject: [basex-talk] RESTXQ and regexp > Message-ID: <3f71e0bc-e16d-6c4d-6ee8-246a7cc7595c(a)gmail.com> > Content-Type: text/plain; charset=utf-8; format=flowed > > Hello all, > > according to the docs this should be possible: > > (: Matches all paths with "app" as first, a number as second, and > "order" as third segment :) > declare %rest:path("app/{$code=[0-9]+}/order") > ? function page:order($full-path) { ... }; > > (: Matches all other all paths starting with "app/" :) > declare %rest:path("app/{$path=.+}") > ? function page:others($path) { ... }; > > And it actually is... We are currently in the very unfortunate situation > where we need the following: > > (: Matches anything followed by /input :) > declare %rest:path("app/{$path=.+}/input") > ? function page:inputs($path) { ... }; > > (: Matches all other all paths starting with "app/" :) > declare %rest:path("app/{$path=.+}") > ? function page:others($path) { ... }; > > Unfortunately this makes all the calls to be redirected to the > page:others function ... is there a motivation behind it or could it be > possible to work around that? > > Thanks, > > Marco. > > > > End of BaseX-Talk Digest, Vol 110, Issue 29 > ******************************************* >

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read/write database locks
by Johannes Bauer 21 Feb '19

21 Feb '19

Hi, I need some input on how best to implement an updating database operation. I use BaseX within a Web Application and have RESTXQ service endpoints. One such service collects information from multiple databases and creates a new document (with the collected infos) in another database. The list of affected databases is dynamic and will be determined by the RESTXQ module. I'm afraid that, due to the missing static database information in the query, the service will lock *all* databases and because I have an updating operation the locks will be write locks. Depending on the amount of databases and their size, the operation might take some time (maybe even up to some minutes). And I don't want to have write locks for such a long period of time. I've also tried another approach: I use a non updating service that collects the data and then calls another RESTXQ service per HTTP request that makes the db update. This way I only have read locks on *all* databases and then a short single write lock on the modified db. But this did not work. The write call deadlocked. The first service probably has not released the read locks yet when the second service is called. I also tried to set the QUERYINFO option to see some lock information for my module, but I didn't get any output. Do you have any best practice on how to approach such a task? Best regards Johannes

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Stack Overflow: Try tail recursion
by Giuseppe G. A. Celano 20 Feb '19

20 Feb '19

I am writing a recursive function which is similar to the one here: https://stackoverflow.com/questions/27702718/to-add-values-in-cumulative-fo… Interestingly, local:sum() works if there are not many <book/>. However with 38000 book element I get the error "Stack Overflow: Try tail recursion". Any idea? Ciao, Giuseppe

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Release client libraries as packages?
by Jakub Pavlík 20 Feb '19

20 Feb '19

Hi, as a programmer occasionally working with BaseX I find the current "way of life" of the client libraries rather inconvenient: 1. nowadays most programming languages have some sort of packaging system (PHP's composer, Ruby's gems, Python's pip etc.), but the official BaseX client libraries are not released to these and I have to copy the files "manually" to each project using them 2. the libraries are rather minimal, lacking proper documentation and test suite. (Yes, they are arguably small, but still.) Have you considered releasing them as packages (which would, at least for PHP, require a separate git repository)? Or do you prefer to have individuals who have use for such packages to create and maintain them themselves? Regards, Jakub

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Docker Volumes Permission denied
by Marie Starck 19 Feb '19

19 Feb '19

Hello everyone, So I am looking to add Docker to a BaseX webapp that is currently running properly on my local. In order to do that, I ran docker run -ti -d --publish 1984:1984 --publish 8984:8984 --volume ~/Projects/Architextus/basex-xquery-server/data:/srv/BaseXData --volume ~/Projects/Architextus/basex-xquery-server/webapp:/srv/BaseXWeb --volume ~/Projects/Architextus/basex-xquery-server/repo:/srv/BaseXRepo basex/basexhttp:8.6.4 And while localhost:8984 shows me the regular BaseX introduction page, none of the rest endpoints work and I get this error when I try to access the webapp from my localhost: Stopped at /srv/BaseXWeb/xqm/g-holismo.xqm, 136/24: [bxerr:BXDB0002] Resource "/srv/BaseXData/DITA-AppResources/tbl.basex (Permission denied)" not found. Stack Trace: - /srv/BaseXWeb/xqm/g-holismo.xqm, 11/10 I checked the permissions on my docker container and it seems that the basex user only has permissions on WEB-INF but none of the volumes, BaseXData, BaseXRepo and BaseXWeb, those are shown as belonging to user 1000. Has anyone experienced this before? Thank you for any help or tip you could provide, Marie

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Schema 1.1 validation and Xerces cta-full-xpath-checking?
by Zimmel, Daniel 15 Feb '19

15 Feb '19

Hi, is there any chance BaseX will support the cta-full-xpath-checking option (see https://xerces.apache.org/xerces2-j/features.html)? Without it, schema 1.1 validation is limited. I could not find any switches to configure Xerces features, but did find someone mentioning it from two years ago: https://www.mail-archive.com/basex-talk@mailman.uni-konstanz.de/msg08446.ht… Or have I missed something in the documentation? Regards, Daniel

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Nullpointer exception using http:send-mail with authentication details, no send-authorization attribute
by Markus Wittenberg 15 Feb '19

15 Feb '19

Hi there, I get a Nullpointer exception (see below) using the http:send-mail method with authentication details (Basic Auth), but without the send-authorization attribute in the http:request element. According to the EXPath HTTP Client Module spec (http://expath.org/spec/http-client#d2e430) the send-authorization attribute is not mandatory, default value false should be used if it is missing. Unexpected error: Improper use? Potential bug? Your feedback is welcome: Contact: basex-talk(a)mailman.uni-konstanz.de Version: BaseX 9.1.1 Java: Oracle Corporation, 1.8.0_92 OS: Windows 7, amd64 Stack Trace: java.lang.NullPointerException at org.basex.util.http.HttpClient.setContentType(HttpClient.java:259) at org.basex.util.http.HttpClient.sendRequest(HttpClient.java:83) at org.basex.query.func.http.HttpSendRequest.iter(HttpSendRequest.java:34) at org.basex.query.expr.ParseExpr.value(ParseExpr.java:74) at org.basex.query.expr.gflwor.GFLWOR.value(GFLWOR.java:73) at org.basex.query.func.StaticFunc.invValue(StaticFunc.java:181) at org.basex.query.func.FuncCall.invoke(FuncCall.java:89) at org.basex.query.func.FuncCall.value(FuncCall.java:62) at org.basex.query.func.FuncCall.iter(FuncCall.java:67) at org.basex.query.scope.MainModule.iter(MainModule.java:118) at org.basex.query.QueryContext.iter(QueryContext.java:335) at org.basex.http.restxq.RestXqResponse.serialize(RestXqResponse.java:73) at org.basex.http.web.WebResponse.create(WebResponse.java:56) at org.basex.http.restxq.RestXqServlet.run(RestXqServlet.java:54) at org.basex.http.BaseXServlet.service(BaseXServlet.java:59) at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:857) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1655) at org.eclipse.jetty.websocket.server.WebSocketUpgradeFilter.doFilter(WebSocketUpgradeFilter.java:215) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1642) at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:533) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:146) at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:548) at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132) at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:257) at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1595) at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:255) at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1340) at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:203) at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:473) at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1564) at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:201) at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1242) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:144) at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:220) at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:126) at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132) at org.eclipse.jetty.server.Server.handle(Server.java:503) at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:364) at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:260) at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:305) at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:103) at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:118) at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:765) at org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:683) at java.lang.Thread.run(Thread.java:745) Best regards -- Markus Wittenberg Tel +49 (0)8382 911 07 24 Mail wittenberg(a)axxepta.de ---- axxepta solutions GmbH Lehmgrubenweg 17, 88131 Lindau Amtsgericht Berlin HRB 97544B Geschäftsführer: Karsten Becke, Maximilian Gärber

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proc:execute
by Giuseppe G. A. Celano 14 Feb '19

14 Feb '19

Hi, I am trying to run a parser via proc:execute/system. While if I run it from the command line, it works, it does not, if I run it via BaseX. More precisely, I get the following error: Traceback (most recent call last): File "main.py", line 325, in <module> test_data = loader.load(params.test) File "/Users/mycomputer/Desktop/Basex9.1beta 2/utils.py", line 57, in load for line in f: File "/Users/mycomputer/anaconda/lib/python3.6/encodings/ascii.py", line 26, in decode return codecs.ascii_decode(input, self.errors)[0] UnicodeDecodeError: 'ascii' codec can't decode byte 0xe2 in position 5390: ordinal not in range(128) Is there a way to avoid that? Thanks. Best, Giuseppe

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Re: [basex-talk] Global locks
by James Ball 14 Feb '19

14 Feb '19

I think I’m probably doing something similar on a current project with but with some careful query writes and use of jobs I’ve been able to keep everything running within acceptable time. However while optimising my code it did get me thinking about possible improvements. Clearly it’s difficult (or even impossible) to determine all the databases that will be used ahead of running the query. But I wonder how many times the calling function already knows? Then I thought of the (# db:enforceindex #) that was introduced for cases where the query writer knows that the databases will have indexes. I wondered if something similar might be possible for databases. A pragma or a function wrapper that would allow the name of a database (or databases) to be supplied and that would restrict access only to that database for the rest of the query. Returning an error if the query tries to address another. I’m sure this wouldn’t be simple - but might be easier and more reliable than trying to find more optimisations to the locking algorithm. Just thinking aloud… Kindest regards, James > From: Christian Grün <christian.gruen(a)gmail.com> > Subject: Re: [basex-talk] Global locks > Date: 11 February 2019 at 12:27:37 GMT > To: Andy Bunce <bunce.andy(a)gmail.com> > Cc: "basex-talk(a)mailman.uni-konstanz.de" <basex-talk(a)mailman.uni-konstanz.de> > > > Hi Andy, > > The current behavior is correct indeed – but it might not be what one > expects. Currently, we are… > > a) collecting all static database references in the query and > b) assigning either read or write locks to these databases, depending > if the overall query is updating or not. > > The reason is that it’s often tricky to determine statically (i.e., > while parsing the query and before compiling and optimizing it) which > databases will be accessed for read or write operations without > analyzing the query in more detail. An arbitrary example: > > let $db := db:open('db1') > return insert node <new/> into $db/* > > We would need to follow the variable reference in order to find out if > db1 will be updated. In simple queries such as yours, however, this > might be possible; I’ll have some more thoughts on that. > > Cheers > Christian

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BaseX-Talk February 2019