org.ikasan.framework.component.transformation
Class XsltTransformer

java.lang.Object
  org.ikasan.framework.component.transformation.XsltTransformer

All Implemented Interfaces:

Transformer, ConfiguredResource<XsltConfiguration>, FlowComponent, ManagedResource

public class XsltTransformer
extends Object
implements Transformer, ManagedResource, ConfiguredResource<XsltConfiguration>

This class is an XSLT Transformer component that acts on all an Event's Payloads, transforming them using the supplied style sheet. This implementation is notable for the following reasons:

1. It is intended to be threadsafe with respect to the underlying Transformer as a new instance is created for every payload. Each instance of this class will associate to one and only one style sheet during its life, and as such instances will be good for only one type of transformation only.



2. Is is intended to be capable of transforming non-xml Payloads through the configuration of a content specific XMLReader; e.g. an XMLReader implementation capable of reading fixed length flat files can be setter-injected thus allowing flat file (fixed length) payloads to be directly transformed with XSLT. See setXmlReader(XMLReader)



3. It is designed to allow a set of externally sourced (injected) java objects to be supplied scoped to the underlying transformer. This allows for such function as database calls from the XSLT to be supported indirectly through the injection of externally managed supporting beans. See setExternalResources(Map)



4. Rather than relying on the default ErrorListener this transformer supplies its own implementation designed to propagate the exceptions thrown for parse time errors and warnings. This can be overridden by using Setter setErrorListener(ErrorListener)
.


5. The ability to configure its properties at runtime through implementation of ConfiguredResource contract. The configuration object allows for configuring use of translets (compiling a stylesheet) and the stylesheet's location



6. Configured stylesheets can either be loaded off of application's classpath, file system, web server ..etc. However, mixing them is not possible.

Gotchas to be aware of...

• When loading stylehsheets off of classpath, if the stylesheet tries to embed other stylesheets via xsl:import and/or xsl:include elements, then a custom URIResolver implementation capable of loading resources from classpath must be set on constructor-injected TransformerFactory. Also, if any of stylesheets load files using document()function, the custome URIResolver must also be set on the Transformer object created. This dictated by javax.xml.transform API peculiar design!

Author:

Ikasan Development Team

See Also:

ClasspathURIResolver, XsltConfiguration, ExceptionThrowingErrorListener

Constructor Summary

XsltTransformer(TransformerFactory transformerFactory)
Constructor

Method Summary

XsltConfiguration	getConfiguration() Set configuration.
String	getConfiguredResourceId() Get the id for this configured resource
ErrorListener	getErrorListener() Accessor
Map<String,Object>	getExternalResources() Accessor
String	getPayloadName() Accessor
Map<String,String>	getTransformationParameters() Accessor
XMLReader	getXmlReader() Accessor
void	onEvent(Event event) Transforms or otherwise changes the passed in Event
void	setConfiguration(XsltConfiguration configuration) Set configuration.
void	setConfiguredResourceId(String id) Set the id for this configured resource
void	setErrorListener(ErrorListener errorListener) Mutator
void	setExternalResources(Map<String,Object> externalResources) Mutator
void	setPayloadName(String payloadName) Mutator for payloadName
protected void	setPayloadParameters(Transformer transformer) Creates a parameter list of known fields derived from the Payload and makes these available to the transformer
void	setTransformationParameters(Map<String,String> transformationParameters) Mutator
void	setURIResolver(URIResolver resolver) Override the default URIResolver provided by transformer library.
void	setXmlReader(XMLReader xmlReader) Mutator
void	startManagedResource() Provision for starting a managed resource.
void	stopManagedResource() Provision for stopping a managed resource.
protected void	transform(Payload payload) Transforms the payload content.

Methods inherited from class java.lang.Object

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

Constructor Detail

XsltTransformer

public XsltTransformer(TransformerFactory transformerFactory)

Constructor

Parameters:

transformerFactory - - Transformer Factory to use

Method Detail

getPayloadName

public String getPayloadName()

Accessor

Returns:

payloadName or null if it has not been set

setPayloadName

public void setPayloadName(String payloadName)

Mutator for payloadName

Parameters:

payloadName - - The payload name to set

setURIResolver

public void setURIResolver(URIResolver resolver)

Override the default URIResolver provided by transformer library.

Parameters:

resolver - custom URIResolver implementation

getXmlReader

public XMLReader getXmlReader()

Accessor

Returns:

the xmlReader

setXmlReader

public void setXmlReader(XMLReader xmlReader)

Mutator

Parameters:

xmlReader - the xmlReader to set

getTransformationParameters

public Map<String,String> getTransformationParameters()

Accessor

Returns:

the transformationParameters

setTransformationParameters

public void setTransformationParameters(Map<String,String> transformationParameters)

Mutator

Parameters:

transformationParameters - the transformationParameters to set

getExternalResources

public Map<String,Object> getExternalResources()

Accessor

Returns:

the externalDataBeans

setExternalResources

public void setExternalResources(Map<String,Object> externalResources)

Mutator

Parameters:

externalResources - the externalDataBeans to set

getErrorListener

public ErrorListener getErrorListener()

Accessor

Returns:

the errorListener

setErrorListener

public void setErrorListener(ErrorListener errorListener)

Mutator

Parameters:

errorListener - the errorListener to set

getConfiguredResourceId

public String getConfiguredResourceId()

Description copied from interface: ConfiguredResource

Get the id for this configured resource

Specified by:

getConfiguredResourceId in interface ConfiguredResource<XsltConfiguration>

Returns:

setConfiguredResourceId

public void setConfiguredResourceId(String id)

Description copied from interface: ConfiguredResource

Set the id for this configured resource

Specified by:

setConfiguredResourceId in interface ConfiguredResource<XsltConfiguration>

getConfiguration

public XsltConfiguration getConfiguration()

Description copied from interface: ConfiguredResource

Set configuration.

Specified by:

getConfiguration in interface ConfiguredResource<XsltConfiguration>

setConfiguration

public void setConfiguration(XsltConfiguration configuration)

Description copied from interface: ConfiguredResource

Set configuration.

Specified by:

setConfiguration in interface ConfiguredResource<XsltConfiguration>

onEvent

public void onEvent(Event event)
             throws TransformationException

Description copied from interface: Transformer

Transforms or otherwise changes the passed in Event

Specified by:

onEvent in interface Transformer

Parameters:

event - Event to transform

Throws:

TransformationException - Exception if we could not transform

setPayloadParameters

protected void setPayloadParameters(Transformer transformer)

Creates a parameter list of known fields derived from the Payload and makes these available to the transformer

Parameters:

transformer - - Transformer to set the parameters on

transform

protected void transform(Payload payload)
                  throws TransformerException

Transforms the payload content.

Parameters:

payload - The payload to be transformed

Throws:

TransformerException - if an error occurs while transforming.

startManagedResource

public void startManagedResource()

Description copied from interface: ManagedResource

Provision for starting a managed resource.

Specified by:

startManagedResource in interface ManagedResource

stopManagedResource

public void stopManagedResource()

Description copied from interface: ManagedResource

Provision for stopping a managed resource.

Specified by:

stopManagedResource in interface ManagedResource