BaseX-Talk

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6 participants
5269 discussions

meaningless numbers print out to std out
by Erdal Karaca 28 Sep '10

28 Sep '10

When running basex in XQJ mode and using copy... modify..., some numeric sequences are print out to std.out in the eclipse debug console, e.g.:0 / 0 1 / 0 ...

2 1

BaseXClient.java ignores EOF from server
by Godmar Back 27 Sep '10

27 Sep '10

BaseXClient.receive ignores EOF if the connection is severed: /** * Receives a string and writes it to the specified output stream. * @param o output stream * @throws IOException I/O exception */ private void receive(final OutputStream o) throws IOException { while(true) { final int b = in.read(); if(b == 0) break; o.write(b); } } The result is an out of memory error because you're trying to stuff infinitely many -1 values into the ByteArrayOutputStream backing o. - Godmar

1 0

Using the options
by Maximilian Gärber 27 Sep '10

27 Sep '10

Hi, from the FAQ ( http://www.inf.uni-konstanz.de/dbis/basex/faq#5.4 ), I read that there are several options available. However, I could not figure out how to set those options from jax-rx or any other client than Java (I found in Java there's something like CONTEXT.props("key", "value") ). Regards, Max

2 1

XPTY0019 error in basex 6.2.7 that did not appear in 6.2.3
by Godmar Back 25 Sep '10

25 Sep '10

This query: declare variable $metadata as xs:anyAtomicType := doc('libx2_meta')/metadata; let $roots := $metadata/roots[@document="libx2_feed"]/id return ... produces [XPTY0019] Context node required for roots[@document = "libx2_feed"]; xs:untypedAtomic found. in BaseX 6.2.7, but it works in 6.2.3 Is this correct? Substituting the declare variable with a let $metadata := ... works, so no showstopper here. On a related note, declaring a function "as xs:anyAtomicType()*" behaves differently in 6.2.7 than in 6.2.3. I suppose the correct semantics for this is to cast the result to an anyAtomicType; 6.2.3 did not do that but 6.2.7 does. - Godmar

2 3

explicit use of namespace prefixes in xquery expressions does not appear to work
by Godmar Back 25 Sep '10

25 Sep '10

I'm trying to create snapshots for the problems we're having with namespaces. Here's the first one (this is not a showstopper, just something I believe is wrong). In http://top.cs.vt.edu/~gback/bx/nsbug1/ you can find http://top.cs.vt.edu/~gback/bx/nsbug1/BaseXData.bug1.zip which contains a zipped BaseX folder. The script 'test.sh' demonstrates what I believe to be a problem with 6.2.7. Notably, the following query: declare namespace libx='http://libx.org/xml/libx2'; doc("libx2_feed")//libx:entry[@src="34"] returns: <libx:entry xmlns:libx="http://libx.org/xml/libx2" xmlns=" http://www.w3.org/2005/Atom" src="34"/> (the inherited default name space for the libx:entry element is 2005/Atom. But explicitly asking for atom:src in the query: declare namespace libx='http://libx.org/xml/libx2'; declare namespace atom='http://www.w3.org/2005/Atom'; doc("libx2_feed")//libx:entry[@atom:src="34"] returns an empty sequence when in my opinion it should provide the same result. Am I wrong? (As an aside, using libx:src also doesn't return anything:) Run test.sh to reproduce. - Godmar

2 1

namespace problems nehmen kein Ende
by Godmar Back 25 Sep '10

25 Sep '10

Hi, BaseX's server sends illegal XML to the client, see below. This should never happen, correct? - Godmar > java -cp "../../../../WEB-INF/lib/*" org.basex.BaseXClient -p 1985 Username: admin Password: BaseX 6.2.3 [Client] Try "help" to get some information. > *xquery declare namespace atom='http://www.w3.org/2005/Atom'; doc("libx2_feed")/atom:feed/atom:entry[atom:id="49"]* <entry xmlns="http://libx.org/xml/libx2" xmlns:libx=" http://libx.org/xml/libx2" xmlns="http://www.w3.org/2005/Atom"> <id>49</id> <title>Package 2</title> <updated>2010-09-23T19:17:06.183Z</updated> <author> <name>LibX Team</name> <uri>http://libx.org</uri> <email>libx.org(a)gmail.com</email> </author> <content type="html">Content created by LibX Libapp Builder</content> <libx:package> <libx:entry xmlns="http://libx.org/xml/libx2" src="50"/> </libx:package> </entry> Query executed in 2.19 ms. >

2 1

request: please don't use java.io.Console when -P is given
by Godmar Back 24 Sep '10

24 Sep '10

The current version of BaseXClient uses java.io.Console, which makes redirecting input from stdin impossible. That makes it difficult to create any type of script that interacts with the database (essentially, it would require using 'expect' or equivalent). As far as I can see, the only thing you need java.io.Console for is reading the password. Please do not use console if the user provides the password on the command line with -P. Alternatively, or in addition, consider supporting a "source" command that reads commands from a file and sends them to the server. - Godmar

2 2

possible bug
by Godmar Back 24 Sep '10

24 Sep '10

I received this stacktrace: Error: Possible bug? Feedback is welcome: basex-talk(a)mailman.uni-konstanz.de BaseX 6.2.3: java.lang.ArrayIndexOutOfBoundsException: 0 org.basex.io.TableDiskAccess.readBlock(TableDiskAccess.java:344) org.basex.io.TableDiskAccess.<init>(TableDiskAccess.java:67) org.basex.data.DiskData.init(DiskData.java:92) org.basex.data.DiskData.<init>(DiskData.java:56) org.basex.core.cmd.Open.open(Open.java:61) org.basex.core.cmd.Check.check(Check.java:53) org.basex.query.QueryContext.check(QueryContext.java:473) org.basex.query.QueryContext.doc(QueryContext.java:436) org.basex.query.func.FNGen.doc(FNGen.java:155) org.basex.query.func.FNGen.atomic(FNGen.java:60) org.basex.query.func.FNGen.c(FNGen.java:74) org.basex.query.func.Fun.comp(Fun.java:49) org.basex.query.expr.Arr.comp(Arr.java:34) org.basex.query.QueryContext.compile(QueryContext.java:245) org.basex.query.QueryProcessor.compile(QueryProcessor.java:74) org.basex.core.cmd.AQuery.query(AQuery.java:83) org.basex.core.cmd.XQuery.run(XQuery.java:22) org.basex.core.Command.run(Command.java:234) org.basex.core.Command.exec(Command.java:217) org.basex.core.Command.execute(Command.java:65) org.basex.server.ServerProcess.run(ServerProcess.java:158) This happens intermittently (not reproducibly) when executing: BX="java -cp ../WEB-INF/lib/basex-6.2.3.jar org.basex.BaseXClient -p 1985 -U admin -P admin" $BX -c 'create db test' $BX -q 'insert node <root /> into doc("test")' $BX -q 'doc("test")/root'

2 1

Using Updates in XQJ
by Erdal Karaca 23 Sep '10

23 Sep '10

I do not seem to be able to update/modify a DOM and return it using the same query. BaseX complains about update not being possible at that context... let $x := <root/> return (insert node <x/> into $x, $x) Is there a way to update and return the DOM using one query or is that not handled by xquery in general? -- 1 + 1 = 10

3 2

a note on client/server interface
by Godmar Back 23 Sep '10

23 Sep '10

Should the client/server interface support the declaration of external variables? Right now, consider an XQuery such as this one (simplified form shown) declare variable *$entry* as xs:anyAtomicType external; return insert node <entry> <title>Copy of { *$entry*//atom:title/text() }</title> { *$entry*/libx:module | *$entry*/libx:package | *$entry*/libx:libapp } </entry> into $feed Suppose "entry" is an element rendered into a blob of XML of 1000 characters and markup. Before we can send above XQuery to the BaseX server, we have to replace all instances of '$entry' with the actual XML (as per the previous discussion that XQJ is deprecated and the client/server interface is the preferred way to communicate with BaseX). This means that we're sending roughly 4x the amount of data (note that $entry is used four times above), just to be able to say "$entry//atom:title/text()". This can easily lead to unexpected performance as queries become more complicated; in addition and more importantly, it makes it really tough to debug the expanded XQuery if there is a need. Why not extend the protocol so that a client can define the external variables in an XQuery first? - Godmar ps: I understand that I could work around this by introducing additional variables with let, as in let $dummy = $entry ... and then using $dummy//atom:title/text() etc. Awkward.

2 1

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