org.osgi.util.xml
Class XMLParserActivator

java.lang.Object
  org.osgi.util.xml.XMLParserActivator

All Implemented Interfaces:

BundleActivator, ServiceFactory

public class XMLParserActivator

extends java.lang.Object

implements BundleActivator, ServiceFactory

A BundleActivator class that allows any JAXP compliant XML Parser to register itself as an OSGi parser service. Multiple JAXP compliant parsers can concurrently register by using this BundleActivator class. Bundles who wish to use an XML parser can then use the framework's service registry to locate available XML Parsers with the desired characteristics such as validating and namespace-aware.

The services that this bundle activator enables a bundle to provide are:

• javax.xml.parsers.SAXParserFactory (SAXFACTORYNAME)
• javax.xml.parsers.DocumentBuilderFactory(DOMFACTORYNAME)

The algorithm to find the implementations of the abstract parsers is derived from the JAR file specifications, specifically the Services API.

An XMLParserActivator assumes that it can find the class file names of the factory classes in the following files:

• /META-INF/services/javax.xml.parsers.SAXParserFactory is a file contained in a jar available to the runtime which contains the implementation class name(s) of the SAXParserFactory.
• /META-INF/services/javax.xml.parsers.DocumentBuilderFactory is a file contained in a jar available to the runtime which contains the implementation class name(s) of the DocumentBuilderFactory

If either of the files does not exist, XMLParserActivator assumes that the parser does not support that parser type.

XMLParserActivator attempts to instantiate both the SAXParserFactory and the DocumentBuilderFactory. It registers each factory with the framework along with service properties:

• PARSER_VALIDATING - indicates if this factory supports validating parsers. It's value is a Boolean.
• PARSER_NAMESPACEAWARE - indicates if this factory supports namespace aware parsers It's value is a Boolean.

Individual parser implementations may have additional features, properties, or attributes which could be used to select a parser with a filter. These can be added by extending this class and overriding the setSAXProperties and setDOMProperties methods.

Field Summary

static java.lang.String	DOMCLASSFILE Fully qualified path name of DOM Parser Factory Class Name file
static java.lang.String	DOMFACTORYNAME Filename containing the DOM Parser Factory Class name.
static java.lang.String	PARSER_NAMESPACEAWARE Service property specifying if factory is configured to support namespace aware parsers.
static java.lang.String	PARSER_VALIDATING Service property specifying if factory is configured to support validating parsers.
static java.lang.String	SAXCLASSFILE Fully qualified path name of SAX Parser Factory Class Name file
static java.lang.String	SAXFACTORYNAME Filename containing the SAX Parser Factory Class name.

Constructor Summary

XMLParserActivator()

Method Summary

java.lang.Object	getService(Bundle bundle, ServiceRegistration registration) Creates a new XML Parser Factory object.
void	setDOMProperties(javax.xml.parsers.DocumentBuilderFactory factory, java.util.Hashtable props) Set the customizable DOM Parser Service Properties.
void	setSAXProperties(javax.xml.parsers.SAXParserFactory factory, java.util.Hashtable properties) Set the customizable SAX Parser Service Properties.
void	start(BundleContext context) Called when this bundle is started so the Framework can perform the bundle-specific activities necessary to start this bundle.
void	stop(BundleContext context) This method has nothing to do as all open service registrations will automatically get unregistered when the bundle stops.
void	ungetService(Bundle bundle, ServiceRegistration registration, java.lang.Object service) Releases a XML Parser Factory object.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

SAXFACTORYNAME

public static final java.lang.String SAXFACTORYNAME

Filename containing the SAX Parser Factory Class name. Also used as the basis for the SERVICE_PID registration property.

See Also:

Constant Field Values

DOMFACTORYNAME

public static final java.lang.String DOMFACTORYNAME

Filename containing the DOM Parser Factory Class name. Also used as the basis for the SERVICE_PID registration property.

See Also:

Constant Field Values

SAXCLASSFILE

public static final java.lang.String SAXCLASSFILE

Fully qualified path name of SAX Parser Factory Class Name file

See Also:

Constant Field Values

DOMCLASSFILE

public static final java.lang.String DOMCLASSFILE

Fully qualified path name of DOM Parser Factory Class Name file

See Also:

Constant Field Values

PARSER_VALIDATING

public static final java.lang.String PARSER_VALIDATING

Service property specifying if factory is configured to support validating parsers. The value is of type Boolean.

See Also:

Constant Field Values

PARSER_NAMESPACEAWARE

public static final java.lang.String PARSER_NAMESPACEAWARE

Service property specifying if factory is configured to support namespace aware parsers. The value is of type Boolean.

See Also:

Constant Field Values

Constructor Detail

XMLParserActivator

public XMLParserActivator()

Method Detail

start

public void start(BundleContext context)
           throws java.lang.Exception

Called when this bundle is started so the Framework can perform the bundle-specific activities necessary to start this bundle. This method can be used to register services or to allocate any resources that this bundle needs.

This method must complete and return to its caller in a timely manner.

This method attempts to register a SAX and DOM parser with the Framework's service registry.

Specified by:

start in interface BundleActivator

Parameters:

context - The execution context of the bundle being started.

Throws:

java.lang.Exception - If this method throws an exception, this bundle is marked as stopped and the Framework will remove this bundle's listeners, unregister all services registered by this bundle, and release all services used by this bundle.

See Also:

Bundle.start()

stop

public void stop(BundleContext context)
          throws java.lang.Exception

This method has nothing to do as all open service registrations will automatically get unregistered when the bundle stops.

Specified by:

stop in interface BundleActivator

Parameters:

context - The execution context of the bundle being stopped.

Throws:

java.lang.Exception - If this method throws an exception, the bundle is still marked as stopped, and the Framework will remove the bundle's listeners, unregister all services registered by the bundle, and release all services used by the bundle.

See Also:

Bundle.stop()

setSAXProperties

public void setSAXProperties(javax.xml.parsers.SAXParserFactory factory,
                             java.util.Hashtable properties)

Set the customizable SAX Parser Service Properties.

This method attempts to instantiate a validating parser and a namespaceaware parser to determine if the parser can support those features. The appropriate properties are then set in the specified properties object.

This method can be overridden to add additional SAX2 features and properties. If you want to be able to filter searches of the OSGi service registry, this method must put a key, value pair into the properties object for each feature or property. For example, properties.put("http://www.acme.com/features/foo", Boolean.TRUE);

Parameters:

factory - - the SAXParserFactory object

properties - - the properties object for the service

setDOMProperties

public void setDOMProperties(javax.xml.parsers.DocumentBuilderFactory factory,
                             java.util.Hashtable props)

Set the customizable DOM Parser Service Properties.

This method attempts to instantiate a validating parser and a namespaceaware parser to determine if the parser can support those features. The appropriate properties are then set in the specified props object.

This method can be overridden to add additional DOM2 features and properties. If you want to be able to filter searches of the OSGi service registry, this method must put a key, value pair into the properties object for each feature or property. For example, properties.put("http://www.acme.com/features/foo", Boolean.TRUE);

Parameters:

factory - - the DocumentBuilderFactory object

props - - Hashtable of service properties.

getService

public java.lang.Object getService(Bundle bundle,
                                   ServiceRegistration registration)

Creates a new XML Parser Factory object.

A unique XML Parser Factory object is returned for each call to this method.

The returned XML Parser Factory object will be configured for validating and namespace aware support as specified in the service properties of the specified ServiceRegistration object. This method can be overridden to configure additional features in the returned XML Parser Factory object.

Specified by:

getService in interface ServiceFactory

Parameters:

bundle - The bundle using the service.

registration - The ServiceRegistration object for the service.

Returns:

A new, configured XML Parser Factory object or null if a configuration error was encountered

See Also:

BundleContext.getService(org.osgi.framework.ServiceReference)

ungetService

public void ungetService(Bundle bundle,
                         ServiceRegistration registration,
                         java.lang.Object service)

Releases a XML Parser Factory object.

Specified by:

ungetService in interface ServiceFactory

Parameters:

bundle - The bundle releasing the service.

registration - The ServiceRegistration object for the service.

service - The XML Parser Factory object returned by a previous call to the getService method.

See Also:

BundleContext.ungetService(org.osgi.framework.ServiceReference)