Each instance of TransformService
supports a specific transform or canonicalization algorithm and XML mechanism type. To create a TransformService
, call one of the static {@link #getInstance 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 {@link java.security.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, "org.example.XPath2TransformService"); 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 section of the API overview. See the Service Providers section of the API overview for a list of standard 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 {@link #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 {@link #init(TransformParameterSpec)} methodis called to initialize the transform with parameters and the {@link #marshalParams marshalParams} method is called to marshal the parameters to XML and provide the transform with document context. Finally, the {@link #transform 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.
@author Sean Mullan
@author JSR 105 Expert Group
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