org.apache.taverna.reference

Interface ExternalReferenceTranslatorSPI<SourceType extends ExternalReferenceSPI,TargetType extends ExternalReferenceSPI>

All Known Implementing Classes:

GreenToRed, InlineByteToInlineStringTranslator, InlineStringToInlineByteTranslator

public interface ExternalReferenceTranslatorSPI<SourceType extends ExternalReferenceSPI,TargetType extends ExternalReferenceSPI>

Constructs an ExternalReference instance from an existing ExternalReference, most usually of a different type. Used by the ReferenceSetAugmentor. This SPI should not be used for cases where an ExternalReferenceSPI is constructed from a stream of bytes, this is intended for direct reference to reference translation with the assumption that this is more efficient for whatever reason. For cases where the reference is constructed from a byte stream you should implement ExternalReferenceBuilder instead.

For SPI purposes implementations should be java beans with default constructors, any required state such as the location of remote repositories to which data can be staged will be passed in in the ReferenceContext.

Author:

Tom Oinn

Method Summary

Modifier and Type	Method and Description
TargetType	createReference(SourceType sourceReference, ReferenceContext context) Given an existing ExternalReferenceSPI, build the appropriate target ExternalReferenceSPI implementation and return it.
Class<SourceType>	getSourceReferenceType() Return the type of external reference that this translator consumes.
Class<TargetType>	getTargetReferenceType() Return the type of external reference this translator constructs.
float	getTranslationCost() Return an approximate complexity cost of the translation.
boolean	isEnabled(ReferenceContext context) Because the reference translator may rely on facilities provided to it through the context this method is available to check whether these facilities are sufficient.

Method Detail

createReference

TargetType createReference(SourceType sourceReference,
                           ReferenceContext context)

Given an existing ExternalReferenceSPI, build the appropriate target ExternalReferenceSPI implementation and return it.

Parameters:

sourceReference - the reference to be used as source for the translation.

context - a reference resolution context, needed potentially to access the existing external references or to construct the new one, especially in cases where the context contains security agents giving access to a remote data staging system

Returns:

the newly constructed ExternalReferenceSPI instance.

Throws:

ExternalReferenceConstructionException - if an error occurs instantiating the new reference.

getSourceReferenceType

Class<SourceType> getSourceReferenceType()

Return the type of external reference that this translator consumes.

Returns:

ExternalReferenceSPI class corresponding to the reference type used as a source by this translator.

getTargetReferenceType

Class<TargetType> getTargetReferenceType()

Return the type of external reference this translator constructs.

Returns:

ExternalReferenceSPI class corresponding to the reference type emitted by this translator.

isEnabled

boolean isEnabled(ReferenceContext context)

Because the reference translator may rely on facilities provided to it through the context this method is available to check whether these facilities are sufficient.

Parameters:

context - the reference context that will be used to construct new references during the translation process

Returns:

whether the context contains necessary resources for the reference construction process

getTranslationCost

float getTranslationCost()

Return an approximate complexity cost of the translation. In general we can't make any guarantees about this because the complexity of the translation depends on more than just the types involved - it can depend on local configuration, network location relative to the data stores referenced and in some cases on the data themselves. For now though we assign an approximation, the default value is 1.0f and lower values represent less costly operations.