jOOX and XSLT. An XML love story, continued

jOOX - a jQuery port to Java The somewhat functional way of thinking involved with jOOX’s XML manipulation cries for an additional API enhancement simply supporting XSLT. XSL transformation has become quite a standard way of transforming large amounts of XML into other structures, where normal DOM manipulation (or jOOX manipulation) becomes too tedious. Let’s have a look at how things are done in standard Java

Example input:

<books>
  <book id="1"/>
  <book id="2"/>
</books>

Example XSL:

<?xml version="1.0" encoding="ISO-8859-1"?>
<xsl:stylesheet version="1.0"
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

    <!-- Match all books and increment their IDs -->
    <xsl:template match="book">
        <book id="{@id + 1}">
            <xsl:apply-templates/>
        </book>
    </xsl:template>

    <!-- Identity-transform all the other elements and attributes -->
    <xsl:template match="@*|*">
        <xsl:copy>
            <xsl:apply-templates select="*|@*"/>
        </xsl:copy>
    </xsl:template>
</xsl:stylesheet>

Verboseness of XSL transformation in Java

The standard way of doing XSL transformation in Java is pretty verbose – as just about anything XML-related in standard Java. See an example of how to apply the above transformation:

Source source = new StreamSource(new File("increment.xsl"));
TransformerFactory factory = TransformerFactory.newInstance();
Transformer transformer = factory.newTransformer(source);
DOMResult result = new DOMResult();
transformer.transform(new DOMSource(document), result);

Node output = result.getNode();

Drastically decrease verbosity with jOOX

With jOOX, you can write exactly the same in much less code:

Apply transformation:
// Applies transformation to the document element:
$(document).transform("increment.xsl");

// Applies transformation to every book element:
$(document).find("book").transform("increment.xsl");

The result in both cases is:

<books>
  <book id="2"/>
  <book id="3"/>
</books>

CSS selectors in Java

CSS selectors are a nice and intuitive alternative to XPath for DOM navigation. While XPath is more complete and has more functionality, CSS selectors were tailored for HTML DOM, where the document content is usually less structured than in XML.

Here are some examples of CSS selector and equivalent XPath expressions:

CSS:   document > library > books > book
XPath: //document/library/books/book

CSS:   document book
XPath: //document//book

CSS:   document book#id3
XPath: //document//book[@id='3']

CSS:   document book[title='CSS for dummies']
XPath: //document//book[@title='CSS for dummies']

 

This becomes more interesting when implementing pseudo-selectors in XPath:

CSS:   book:first-child
XPath: //book[not(preceding-sibling::*)]

CSS:   book:empty
XPath: //book[not(*|@*|node())]

 

A very nice library that allows for parsing selector expressions according to the w3c specification is this “css-selectors” by Christer Sandberg:

https://github.com/chrsan/css-selectors

The next version of jOOX will include css-selector’s parser for simpler DOM navigation. The following two expressions will hold the same result:

Match match1 = $(document).find("book:empty");
Match match2 = $(document).xpath("//book[not(*|@*|node())]");

Use Xalan’s extension functions natively in jOOX

jOOX - a jQuery port to Java jOOX aims at increased ease of use when dealing with Java’s rather complex XML API’s. One example of such a complex API is Xalan, which has a lot of nice functionality, such as its extension namespaces. When you use Xalan, you may have heard of those extensions as documented here:

http://exslt.org

These extensions can typically be used in XSLT. An example is the math:max function:

<!-- Source -->
<values>
   <value>7</value>
   <value>11</value>
   <value>8</value>
   <value>4</value>
</values>

<!-- Stylesheet -->
<xsl:template match="values">
   <result>
      <xsl:text>Maximum: </xsl:text>
      <xsl:value-of select="math:max(value)" />
   </result>
</xsl:template>

<!-- Result -->
<result>Maximum: 11</result>

But in fact, math:max can be used in any type of XPath expression, also the ones that are directly created in Java. Here’s how you can do this:

Document document = // ... this is the DOM document

// Create an XPath object
XPathFactory factory = XPathFactory.newInstance();
XPath xpath = factory.newXPath();

// Initialise Xalan extensions on the XPath object
xpath.setNamespaceContext(
  new org.apache.xalan.extensions.ExtensionNamespaceContext());
xpath.setXPathFunctionResolver(
  new org.apache.xalan.extensions.XPathFunctionResolverImpl());

// Evaluate an expression using an extension function
XPathExpression expression = xpath.compile(
  "//value[number(.) = math:max(//value)]");
NodeList result = (NodeList) expression.evaluate(
  document, XPathConstants.NODESET);

// Iterate over results
for (int i = 0; i < result.getLength(); i++) {
  System.out.println(result.item(i).getTextContent());
}

jOOX is much more convenient

The above is pretty verbose. With jOOX, you can do exactly the same, but with a lot less code:

Document document = // ... this is the DOM document

// jOOX's xpath method already supports Xalan extensions
for (Match value : $(document).xpath(
    "//value[number(.) = math:max(//value)]").each()) {
  System.out.println(value.text());
}

jOOX answers many Stack Overflow questions

jOOX - a jQuery port to Java When you search for Stack Overflow questions regarding XML, DOM, XPath, JAXB, etc, you could very often answer them simply with an example involving jOOX. Take this question extract for example:

Goal

My goal is to achieve following from this ex xml file :

<root>
    <elemA>one</elemA>
    <elemA attribute1='first' attribute2='second'>two</elemA>
    <elemB>three</elemB>
    <elemA>four</elemA>
    <elemC>
        <elemB>five</elemB>
    </elemC>
</root>

to produce the following :

//root[1]/elemA[1]='one'
//root[1]/elemA[2]='two'
//root[1]/elemA[2][@attribute1='first']
//root[1]/elemA[2][@attribute2='second']
//root[1]/elemB[1]='three'
//root[1]/elemA[3]='four'
//root[1]/elemC[1]/elemB[1]='five'

jOOX answer

The above can be achieved quite simply with jOOX (compared to the other answers to the question involving XSLT, SAX, DOM, etc):

List<String> list = $(document).xpath("//*[not(*)]").map(new Mapper<String>() {
  public String map(Context context) {
    return $(context).xpath() + "='" + $(context).text() + "'";
  }
}});

This will produce

/root[1]/elemA[1]='one'
/root[1]/elemA[2]='two'
/root[1]/elemB[1]='three'
/root[1]/elemA[3]='four'
/root[1]/elemC[1]/elemB[1]='five'

It is an “almost” solution to the OP’s problem, jOOX does not (yet) support matching/mapping attributes. Hence, attributes will not produce any output. This will be implemented in the near future, though.

See the full answer and question here:

http://stackoverflow.com/questions/4746299/generate-get-xpath-from-xml-node-java/8943144#8943144

jOOX and JAXB

jOOX - a jQuery port to Java jOOX has been awfully quiet lately due to increased development focus in jOOQ. Nevertheless, the jOOX feature roadmap is full of promising new features. Unlike its inspiration jquery, jOOX is positioning itself in the Java world, where many XML API’s already exist. One of the most important XML APIs in Java is JAXB, a very simple means of mapping XML to Java through annotations (see also my blog stream on the subject of Annotatiomania™).

Let’s have a look at this small XML document

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<customer id="13">
    <age>30</age>
    <name>Lukas</name>
</customer>

Typically, we would write a Java class like this to map to the above XML document:

@XmlRootElement
public class Customer {
    String name;
    int age;
    int id;

    public String getName() {
        return name;
    }

    @XmlElement
    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    @XmlElement
    public void setAge(int age) {
        this.age = age;
    }

    public int getId() {
        return id;
    }

    @XmlAttribute
    public void setId(int id) {
        this.id = id;
    }
}

And then, we would marshal / unmarshal the above using the following code snippet:

JAXB.marshal(new Customer(), System.out);
Customer c = JAXB.unmarshal(xml, Customer.class);

JAXB and jOOX

This is very neat and convenient. But it gets even better when JAXB is used along with jOOX. Have a look at the following piece of code:

// Use the $ method to wrap a JAXB-annotated object:
$(new Customer());

// Navigate to customer elements in XML:
String id   = $(new Customer()).id();
String name = $(new Customer()).find("name").text();

// Modify the XML structure, and unmarshal it again into 
// a JAXB-annotated object:
Match match = $(new Customer());
match.find("name").text("Peter");
Customer modified = match.unmarshalOne(Customer.class);

Check back soon on jOOX for new features!

Loading CSV data with jOOQ

After the recent efforts made in jOOX, developments of jOOQ have been continued. The main new feature of the upcoming release 1.6.5 is the support for loading of CSV data. The jOOQ Factory will now provide access to a dedicated fluent API for loading CSV files into generated tables, specifying a field mapping and various other parameters related to the batch-processing of bulk loads. Some sample code of what the API might look like:

// The typical jOOQ factory
Factory create = new Factory(connection, SQLDialect.ORACLE);

// Configure and execute a Loader object
Loader<TAuthor> loader =
create.loadInto(AUTHOR)
      .onDuplicateKeyError()
      .onErrorAbort()
      .commitAll()
      .loadCSV("1;'Kafka'\n" +
               "2;Frisch")
      .fields(Author.ID, Author.LAST_NAME)
      .quote('\'')
      .separator(';')
      .ignoreRows(0)
      .execute();

// The resulting Loader object then holds various
// information about the loading process:

// The number of processed rows
int processed = loader.processed();

// The number of stored rows (INSERT or UPDATE)
int stored = loader.stored();

// The number of ignored rows (due to errors, or duplicate rule)
int ignored = loader.ignored();

// The errors that may have occurred during loading
List<LoaderError> errors = loader.errors();
LoaderError error = errors.get(0);

// The exception that caused the error
SQLException exception = error.exception();

// The row that caused the error
int rowIndex = error.rowIndex();
String[] row = error.row();

// The query that caused the error
Query query = error.query();

Along with the previously implemented export API, it is easy to export results from org.jooq.Result into CSV, let users modify them in Excel or any other office software, and upload the CSV again. Other ideas for future versions of jOOQ will also include loading data from XML and JSON data sources, “merging” data (i.e. including DELETE operations), etc.

Feedback is very welcome.

FluentDOM, another mimick of jQuery DOM manipulation, in PHP

The triumph of jQuery over any other XML API seems prominent, in many languages. Here is another example of a nice jQuery-port to PHP: FluentDOM.

http://fluentdom.github.com/

Similar to jOOX, FluentDOM aims to combine a jQuery-like fluent API with XPath and general DOM XML manipulation. Here are some simple examples taken from the FluentDOM documentation:

// read a file and set the message tag's content
echo FluentDOM($xmlFile)
  ->find('/message')
  ->text('Hello World!');

// Find the <root> first then the second element in it
var_dump($fd->find('/root')->find('*[2]')->item(0)->textContent);

// Append elements to an object
$menu
  ->append('<li/>')
  ->append('<a/>')
  ->attr('href', '/sample.php')
  ->text('Sample');

I’m in contact with the developers of FluentDOM. As always with OSS, there is great potential for synergy, which in the end will make both products better. For jOOX, this means that loading of files/streams is going to be a nice plus. XPath is already implemented in the upcoming release 0.9.2. On the other hand, maybe FluentDOM can get inspiration from jOOQ’s document creation syntax (which isn’t part of jQuery):

$("root",
  $("element",
    $("child", "text"),
    $("child", "more text")));

… which will create

<root>
  <element>
    <child>text</child>
    <child>more text</child>
  </element>
</root>

Excited as always, let’s get back to hacking! :-)

See the latest progress here: http://code.google.com/p/joox/