Building Bridges from Java to XQuery

XQJ

XQuery API for Java

Java Standard

Create XQuery

Submit to an

XQuery Engine

Process the results

module namespace e = "http://www.example.com";

declare function e:contains-any-of

($arg as xs:string?,

$searchStrings as xs:string*) as xs:boolean

{ ... code ... };

declare function e:word-count($arg as xs:string?) as xs:integer

{ ... code ... };

declare function e:multiply($a as xs:float, $b as xs:float) as xs:float

{ $a * $b };

public interface Example

{

public boolean containsAnyOf(String arg, String... searchStrings);

public int wordCount(String arg);

public float multiply(float a, float b);

}

public boolean containsAnyOf(String arg, String[] searchStrings);

public boolean containsAnyOf(String arg, List<String> searchStrings);

public boolean containsAnyOf(String arg, Iterator<String> searchStrings);

Overriding default behavior

with Annotations

public interface MyXMLStore

{

@XQFunctionName("insert-xml-content")

public void insertXMLContent(String uri, Source xmlSource);

}

public interface MyXMLStore

{

@XQFunctionName("insert-xml-content")

public void insertXMLContent(String uri,

@XQCastAs("document-node(element())") String value);

}

Plain Old Java Objects Mapping

XQJ Spec never defined how POJOs should be mapped to XDM types

PersonStore personStore = conn.createModuleProxy(

"http://person-store.com",

"/modules/person-store.xqy",

PersonStore.class);

Person john = new Person();

john.firstName = "John";

john.lastName = "Smith";

john.dateOfBirth =

DatatypeFactoryImpl.newXMLGregorianCalendar("1970-04-12");

john.phoneNumbers = new PhoneNumbers(

new String[] { "123-789", "789-123" }

);

personStore.insertPerson("/john-smith.xml", john);

john = null; // John is gone!

john = personStore.getPerson("/john-smith.xml"); // Welcome back John!

(:~ FunctX XQuery Function Library. Copyright (C) 2007 Datypic. :)

module namespace functx = "http://www.functx.com" ;

declare default function namespace "http://www.w3.org/2005/xpath-functions";

declare function functx:add-attributes(

$elements as element()*,

$attrNames as xs:QName*,

$attrValues as xs:anyAtomicType*) as element()?

{

... code ...

};

declare function functx:add-months(

$date as xs:date?,

$months as xs:integer) as xs:date?

{

... code ...

};

declare function functx:add-or-update-attributes(

$elements as element()*,

$attrNames as xs:QName*,

$attrValues as xs:anyAtomicType*) as element()?

{

... code ...

};

// Generated from functx-module.xqy

import javax.xml.xquery.XQException;

import javax.xml.namespace.QName;

import org.w3c.dom.Element;

import javax.xml.datatype.XMLGregorianCalendar;

public interface FunctxModule

{

public Element addAttributes(

Element[] elements,

QName[] attrNames,

String[] attrValues) throws XQException;

public XMLGregorianCalendar addMonths(

XMLGregorianCalendar date,

int months) throws XQException;

public Element addOrUpdateAttributes(

Element[] elements,

QName[] attrNames,

String[] attrValues) throws XQException;

}

CustomerDAO.java

import javax.xml.xquery.XQException;

public interface CustomerDAO

{

public void insertCustomer(Customer pojo) throws XQException;

public void deleteCustomer(Customer pojo) throws XQException;

public Customer findCustomer(String uri) throws XQException;

public void updateCustomer(Customer pojo) throws XQException;

public Iterator<Customer> getAllCustomers() throws XQException;

}

class Customer {

String uri;

String collection;

/** other details **/

}

customer-dao.xqy

(: Generated from CustomerDAO.java :)

module namespace c = "http://example.org";

declare function c:insert-customer($pojo as node()) as empty-sequence()

{

()

};

declare function c:delete-customer($pojo as node()) as empty-sequence()

{

()

};

declare function c:find-customer($uri as xs:string) as node()

{

<?stub?>

};

declare function c:update-customer($pojo as node()) as empty-sequence()

{

()

};

declare function c:get-all-customers() as node()*

{

<?stub?>

};

Thank you!

Questions?

Charles Foster

xquery2java

functx-module.xqy

FunctxModule.java

Code Generation

charles@xqj.net

@fostercharles

java2xquery

JCP 225

Supported by:

DataDirect Technologies

X-Hive (now EMC XDB)

Software AG

IPEDO

Oracle

IBM

BEA Systems

Sun

Sybase

XQuery aware

No XML Parsing

SQL/Relational Database

Stored Procedures

• Reduce compilation overhead
• Reduce network traffic
• Embed business logic in DB
• Invokable from JDBC 2.0 onwards

XQuery/XML Database

XQuery Modules (Main and Library)

• Reduce compilation overhead
• Reduce network traffic
• Embed business logic in DB
• No support in XQJ 1.0!

Desiging an API to invoke

stored XQuery code

New Approach to invoke

XQuery code from Java

• XML is a second class citizen in Java.
• Java APIs for XML have been inelegant.

• Invoke XQuery functions as if they were regular Java methods.
• Introducing an RPC/Service like model to Java's approach to XQuery.
• Extensions to the XQJ interfaces.

(Off-the-wall - definitely an option).

Key Thought

Initial Implementations

Java methods bare similarity with XQuery functions.

MarkLogic, eXist and Sedna

Client code

Final Notes

Relational Database

POJO

Implementation-defined

class Person

{

String firstName;

String lastName;

XMLGregorianCalendar dateOfBirth;

PhoneNumbers phoneNumbers;

}

class PhoneNumbers

{

public PhoneNumbers(String[] number) {

this.number = number;

}

String[] number;

}

This doesn't have to be Java

This concept could be

applied else where,

e.g. XSLT functions.

Example example =

XQConnection2.createModuleProxy(

"http://www.example.com",

"/modules/example.xqy",

Example.class

);

boolean contains =

example.containsAnyOf("abc", "bc", "xy");

int totalWords =

example.wordCount("The quick brown fox jumps over the lazy dog");

float product =

example.multiply(3f, 4f);

XML Document in a

XML Database

POJO

<person>

<first-name>John</first-name>

<last-name>Smith</last-name>

<date-of-birth>1970-04-12</date-of-birth>

<phone-numbers>

<number>123-789</number>

<number>789-123</number>

</phone-numbers>

</person>

XQuery Library Module

What's the difference?

Java to XQuery name

translation.

(Default Behaviour)

public interface PersonStore

{

public Person getPerson(

String uri);

public void insertPerson(

String uri,

Person person);

}

Java method

XQuery function

insertXmlContent

insert-xml-content

declare function do-work(

$a as xs:int,

$b as xs:double,

$c as xs:string,

$d as document-node()

) as xs:string*

insertXMLContent

insert-x-m-l-content

public String[] doWork(

int a,

double b,

String c,

Document d

);

module namespace ps="http://person-store.com";

declare function ps:get-person(

$uri as xs:string) as element(person)?

{

fn:doc($uri)/element()

};

declare function ps:insert-person(

$uri as xs:string,

$person as element(person))

{

xdmp:document-insert($uri, $person)

};

Java Facade

• Java Interfaces as Facades for XQuery Library Modules.
• Java values are mapped to XDM values according to the XQJ Specification.

Building Bridges from Java to XQuery

A new approach to invoke XQuery functions from Java as if they were Java methods.