BaseX-Talk

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5244 discussions

Re: [basex-talk] Navigating a DOM
by Charles Foster 21 Oct '12

21 Oct '12

Hi Rainer, May I suggest XOM? [1]. Also, navigating a DOM tree is quite irksome in comparison to using XQuery/XPath. Perhaps you could consider slicing up your large document into "manageable chunks" (e.g. smaller documents) then inserting the smaller documents into BaseX with a view to then running XQuery to get specific parts of the logical large document when and as required. This approach would use less memory and may well be more efficient. May I also suggest checking out the BaseX XQJ API [2], where retrieved XML can be obtained as a Java DOM Node (e.g. Element / Document), StaX XMLStreamReader and SAX ContentHandler. Regards, Charles [1] http://www.xom.nu/ [2] http://xqj.net/basex > Hi, > > I did some first steps with BaseX, but unfortunately I was not very > successful. > > I have a really large XML file which does not fit into memory, and I > would like to navigate it as a DOM. My hope was that I could store it as > a BaseX database, retrieve the root element as a org.w3c.dom.Node, and > then start navigating down and up the DOM as needed without having to > have the whole stuff in memory. > > I tried something like this: > > QueryProcessor processor = new QueryProcessor("doc('catalog')/*", > context); > Iter iter = processor.iter(); > Item item = iter.next(); > Object node = item.toJava(); > > According to the debugger the item variable indeed denoted my root > element. However, when calling item.toJava() not only that very node was > returned. Instead BaseX obviously tried to retrieve the whole DOM > which was just the very thing I wanted to avoid. > > Am I doing something wrong here? Or is this an unforeseen use case? > > By the way, I also had trouble getting any result at all. Only with > "doc('catalog')/*" I got an item that was not null. When I tried to > retrieve all elements named "article" using "doc('catalog')//article" > the item was null. I also tried the item.iter() in order to find a > node's children. However, it turned out that item().iter().next() == item. > > And I had quite a tough time fiddling around with the documentation and > with the JavaDoc. While the documentation puts a lot of effort into > XQuery, it remains unclear to some extend how to do some basic stuff > with BaseX programmatically. This is a hurdle for the BaseX beginner. > Some more Java examples and explanations would be nice showing how to > connect to the database, submit a query and process the result. > Currently the examples show only how to dump a query result to > System.out. It would be interesting to learn about processing it further > see my troubles with Iter. > > -- > > Best regards > Rainer Klute

6 13

BaseX performance
by Christopher Harper 21 Oct '12

21 Oct '12

Hi @ll, I'm working on an CM/DM solution that uses BaseX as the metadata repository. This isn't my first stab at a DM/CM system just that the XML database portion is new to me Now when trying to scale the system up I find that I have created at least one offending query: count( distinct-values( let $item := doc('db')/repository/items/*//object for $path in $item/paths/path where starts-with($path/@name, '/Root/Temp/Import/') return $item/@uuid ) ) The '*/' could be replaced with 'documents/document' and 'folders', but that would be two separate queries and their individual times would still be offending. The goal of the query is to list items placed into a certain folder structure represented by items in the database. This seems like a straight forward query but I'm stumped at trying to get it to perform adequately. Any suggestions? / Chris

2 2

Using full Java regular expressions
by The Trainspotter 21 Oct '12

21 Oct '12

Hi, I'm currently converting my project to use BaseX instead of Saxon. One thing you can do in Saxon is provide a flag (an exclamation mark) to your regular expression to tell the matches function to use the Java regular expression processor, rather than the rather cut down expressions available in the XQuery spec. Is there anything similar in BaseX? If not what do you recommend to define a Java regular expression based function for XQuery? Thanks in advance, Gary

4 7

Need help on Xquery create Collection using java
by riyaz 18 Oct '12

18 Oct '12

Dear Team, This is Riyaz from Hyderabad , India. I have been using X query since one and half year. I need help on the following query. When I add xmls of 199 MB to create collection using " new Add(xmlfilepath).execute(context)" (JAVA), it is taking 440 MB on hard disk and 3 mins to complete the process. Is there any other way to reduce the size and time? Thanks a ton in advance and would appreciate the earliest response. Please help me on this. -- Thanks & Regards, Riyaz Shaik, In10^s Technologies Ltd. /"What you risk reveals what you value."/

2 2

running xquery scripts in REST server
by pw＠themail.co.uk 16 Oct '12

16 Oct '12

Hello List this is a noob question: I have BaseX 7.3 set up using httpserver. I can add a script to HTTPPATH and run it using http://{server:port}/rest?run=myScript.xq However, if I add myScript.xq to a database and try to run it then [http://{server:port}/rest/DB/myScript.xq ] then all I get returned is the XQuery script itself as a text file, the query doesn't run. >From the examples e.g. http://docs.basex.org/wiki/REST#GET_Requests_2 I thought that I am doing the same type of call, e,g, http://localhost:8984/rest/DB/mult.xq?a=21&b=2 What should I be doing? Many thanks Peter

1 0

Clusters
by Raymond Meester 16 Oct '12

16 Oct '12

Is it possible to set up a BaseX server as a clustered database (where data is synchronized over the servers by BaseX)? For example on two servers where a client session can be set up with "host1,host2". If one of the hosts fails then there is immediate fault tolerant failover to the second host (url). If this is possible is there an example available (couldn't find anything in this direction on GitHub)?

2 1

Add files to the database
by Raymond Meester 16 Oct '12

16 Oct '12

Charles, thanks for the examples. I first thought using the core API, like "new Add(doc).execute(context); ", but to get working you need conversions and ToString methods and loose the direct manipulation options. I needed a concurrent set up anyway. What I also didn't get from the core library; when using multiple instances I got a FileLockException in the stack trace (as expected), but then the general message "org.basex.core.BaseXException: Improper use? Potential bug?" was shown. Maybe an error message about the filelock and concurrency would be clearer as its not a bug. There are some databases like SQLite that support concurrency (to some extend) while directly using a OS file system, but that lead often to unexpected results (locking on network shares for example).

1 0

Upload a file to baseX server
by nestor vb 16 Oct '12

16 Oct '12

Hi everyone: I have a question, is there a way to upload a file to a baseX server? I have a c# application and I would like to upload a whole xml file to the server, is this possible? any pinpoints or recommendations? Thanks Regasts, Nestor

2 1

Replication
by David Sargeant 11 Oct '12

11 Oct '12

Does BaseX have any replication features? This would be really nice. David

2 1

Re: [basex-talk] Add files to the database
by Charles Foster 11 Oct '12

11 Oct '12

Hi Raymond, Here are some examples using the BaseX XQJ API if that helps. // ---------------------------------------------------- // Inserting a DOM Document item // ---------------------------------------------------- import javax.xml.xquery.*; import javax.xml.namespace.QName; import net.xqj.basex.BaseXXQDataSource; import javax.xml.parsers.*; import org.w3c.dom.*; import org.xml.sax.*; import java.io.*; import com.xqj2.*; public class Test { public static final Document getDocument() throws Exception { return DocumentBuilderFactory.newInstance().newDocumentBuilder(). parse(new InputSource(new StringReader("<e>Hello World</e>"))); }; public static void main(String[] args) throws Exception { XQDataSource xqs = new BaseXXQDataSource(); xqs.setProperty("serverName", "localhost"); xqs.setProperty("port", "1984"); xqs.setProperty("databaseName", "TEST"); // DATABASE NAME: TEST XQConnection2 conn = (XQConnection2)xqs.getConnection("admin", "admin"); Document doc = getDocument(); conn.insertItem( "my-document-uri.xml", conn.createItemFromNode(doc, null), null ); XQPreparedExpression px = // have to state DATEBASE NAME, in URI: conn.prepareExpression("fn:doc('TEST/my-document-uri.xml')"); XQResultSequence rs = px.executeQuery(); System.out.println(rs.getSequenceAsString(null)); conn.close(); } } // ---------------------------------------------------- // ---------------------------------------------------- // Inserting an XML Document from a File object // ---------------------------------------------------- import javax.xml.xquery.*; import javax.xml.namespace.QName; import net.xqj.basex.BaseXXQDataSource; import java.io.*; import com.xqj2.*; public class Test { public static void main(String[] args) throws Exception { XQDataSource xqs = new BaseXXQDataSource(); xqs.setProperty("serverName", "localhost"); xqs.setProperty("port", "1984"); xqs.setProperty("databaseName", "TEST"); // DATABASE NAME: TEST XQConnection2 conn = (XQConnection2)xqs.getConnection("admin", "admin"); conn.insertItem( "test.xml", conn.createItemFromDocument( new FileInputStream(new File("test.xml")), null, null ), null ); XQPreparedExpression px = // have to state DATEBASE NAME, in URI: conn.prepareExpression("fn:doc('TEST/test.xml')"); XQResultSequence rs = px.executeQuery(); System.out.println(rs.getSequenceAsString(null)); conn.close(); } } // ---------------------------------------------------- > Is it possible to add Document objects (org.w3c.dom) directly to the > database without using TransformerFactory to convert it first to > string? > > And what if you have a File object? >

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