Class TransformService

All Implemented Interfaces:
AlgorithmMethod, Transform, XMLStructure

public abstract class TransformService
extends Object
implements Transform
A Service Provider Interface for transform and canonicalization algorithms.

Each instance of TransformService supports a specific transform or canonicalization algorithm and XML mechanism type. To create a TransformService, call one of the static getInstance methods, passing in the algorithm URI and XML mechanism type desired, for example:

TransformService ts = TransformService.getInstance(Transform.XPATH2, "DOM");

TransformService implementations are registered and loaded using the Provider mechanism. Each TransformService service provider implementation should include a MechanismType service attribute that identifies the XML mechanism type that it supports. If the attribute is not specified, "DOM" is assumed. For example, a service provider that supports the XPath Filter 2 Transform and DOM mechanism would be specified in the Provider subclass as:

     put("TransformService." + Transform.XPATH2,
     put("TransformService." + Transform.XPATH2 + " MechanismType", "DOM");
TransformService implementations that support the DOM mechanism type must abide by the DOM interoperability requirements defined in the DOM Mechanism Requirements. See the TransformService section in the Java Security Standard Algorithm Names Specification for a list of standard algorithm URIs and mechanism types.

Once a TransformService has been created, it can be used to process Transform or CanonicalizationMethod objects. If the Transform or CanonicalizationMethod exists in XML form (for example, when validating an existing XMLSignature), the init(XMLStructure, XMLCryptoContext) method must be first called to initialize the transform and provide document context (even if there are no parameters). Alternatively, if the Transform or CanonicalizationMethod is being created from scratch, the init(TransformParameterSpec) method is called to initialize the transform with parameters and the marshalParams method is called to marshal the parameters to XML and provide the transform with document context. Finally, the transform method is called to perform the transformation.

Concurrent Access

The static methods of this class are guaranteed to be thread-safe. Multiple threads may concurrently invoke the static methods defined in this class with no ill effects.

However, this is not true for the non-static methods defined by this class. Unless otherwise documented by a specific provider, threads that need to access a single TransformService instance concurrently should synchronize amongst themselves and provide the necessary locking. Multiple threads each manipulating a different TransformService instance need not synchronize.