TransformService (Java(TM) XML Security API Specification)

java.lang.Object
- javax.xml.crypto.dsig.TransformService

All Implemented Interfaces:

AlgorithmMethod, Transform, XMLStructure
```
public abstract class TransformService
extends java.lang.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,
         "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 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.

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

private static class TransformService.MechanismMapEntry

Nested Classes
Modifier and Type	Class and Description
`private static class`	`TransformService.MechanismMapEntry`

Field Summary

Fields
Modifier and Type	Field and Description
`private java.lang.String`	`algorithm`
`private static java.lang.Class`	`cl`
`private static java.lang.reflect.Method`	`getImplMethod`
`private static java.lang.Class[]`	`getImplParams`
`private java.lang.String`	`mechanism`
`private java.security.Provider`	`provider`

Fields inherited from interface javax.xml.crypto.dsig.Transform
BASE64, ENVELOPED, XPATH, XPATH2, XSLT

Constructor Summary

Constructors
Modifier Constructor and Description

protected TransformService()
Default constructor, for invocation by subclasses.

Constructors
Modifier	Constructor and Description
`protected`	`TransformService()` Default constructor, for invocation by subclasses.

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`private static TransformService`	`findInstance(java.lang.String algorithm, java.lang.String mechanismType, java.security.Provider provider)`
`java.lang.String`	`getAlgorithm()` Returns the URI of the algorithm supported by this `TransformService`.
`static TransformService`	`getInstance(java.lang.String algorithm, java.lang.String mechanismType)` Returns a `TransformService` that supports the specified algorithm URI (ex: `Transform.XPATH2`) and mechanism type (ex: DOM).
`static TransformService`	`getInstance(java.lang.String algorithm, java.lang.String mechanismType, java.security.Provider provider)` Returns a `TransformService` that supports the specified algorithm URI (ex: `Transform.XPATH2`) and mechanism type (ex: DOM) as supplied by the specified provider.
`static TransformService`	`getInstance(java.lang.String algorithm, java.lang.String mechanismType, java.lang.String provider)` Returns a `TransformService` that supports the specified algorithm URI (ex: `Transform.XPATH2`) and mechanism type (ex: DOM) as supplied by the specified provider.
`java.lang.String`	`getMechanismType()` Returns the mechanism type supported by this `TransformService`.
`java.security.Provider`	`getProvider()` Returns the provider of this `TransformService`.
`abstract void`	`init(TransformParameterSpec params)` Initializes this `TransformService` with the specified parameters.
`abstract void`	`init(XMLStructure parent, XMLCryptoContext context)` Initializes this `TransformService` with the specified parameters and document context.
`abstract void`	`marshalParams(XMLStructure parent, XMLCryptoContext context)` Marshals the algorithm-specific parameters.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface javax.xml.crypto.dsig.Transform
getParameterSpec, transform, transform

Methods inherited from interface javax.xml.crypto.XMLStructure
isFeatureSupported

- Field Detail
  - algorithm
```
private java.lang.String algorithm
```
  - mechanism
```
private java.lang.String mechanism
```
  - provider
```
private java.security.Provider provider
```
  - cl
```
private static java.lang.Class cl
```
  - getImplParams
```
private static final java.lang.Class[] getImplParams
```
  - getImplMethod
```
private static java.lang.reflect.Method getImplMethod
```
- Constructor Detail
  - TransformService
```
protected TransformService()
```
    Default constructor, for invocation by subclasses.
- Method Detail
  - getInstance
```
public static TransformService getInstance(java.lang.String algorithm,
                                           java.lang.String mechanismType)
                                    throws java.security.NoSuchAlgorithmException
```
    Returns a TransformService that supports the specified algorithm URI (ex: Transform.XPATH2) and mechanism type (ex: DOM).
    This method uses the standard JCA provider lookup mechanism to locate and instantiate a TransformService implementation of the desired algorithm and MechanismType service attribute. It traverses the list of registered security Providers, starting with the most preferred Provider. A new TransformService object from the first Provider that supports the specified algorithm and mechanism type is returned.
    Note that the list of registered providers may be retrieved via the Security.getProviders() method.
    
    Parameters:
    
    algorithm - the URI of the algorithm
    
    mechanismType - the type of the XML processing mechanism and representation
    
    Returns:
    
    a new TransformService
    
    Throws:
    
    java.lang.NullPointerException - if algorithm or mechanismType is null
    
    java.security.NoSuchAlgorithmException - if no Provider supports a TransformService implementation for the specified algorithm and mechanism type
    
    See Also:
    
    Provider
  - getInstance
```
public static TransformService getInstance(java.lang.String algorithm,
                                           java.lang.String mechanismType,
                                           java.security.Provider provider)
                                    throws java.security.NoSuchAlgorithmException
```
    Returns a TransformService that supports the specified algorithm URI (ex: Transform.XPATH2) and mechanism type (ex: DOM) as supplied by the specified provider. Note that the specified Provider object does not have to be registered in the provider list.
    
    Parameters:
    
    algorithm - the URI of the algorithm
    
    mechanismType - the type of the XML processing mechanism and representation
    
    provider - the Provider object
    
    Returns:
    
    a new TransformService
    
    Throws:
    
    java.lang.NullPointerException - if provider, algorithm, or mechanismType is null
    
    java.security.NoSuchAlgorithmException - if a TransformService implementation for the specified algorithm and mechanism type is not available from the specified Provider object
    
    See Also:
    
    Provider
  - getInstance
```
public static TransformService getInstance(java.lang.String algorithm,
                                           java.lang.String mechanismType,
                                           java.lang.String provider)
                                    throws java.security.NoSuchAlgorithmException,
                                           java.security.NoSuchProviderException
```
    Returns a TransformService that supports the specified algorithm URI (ex: Transform.XPATH2) and mechanism type (ex: DOM) as supplied by the specified provider. The specified provider must be registered in the security provider list.
    Note that the list of registered providers may be retrieved via the Security.getProviders() method.
    
    Parameters:
    
    algorithm - the URI of the algorithm
    
    mechanismType - the type of the XML processing mechanism and representation
    
    provider - the string name of the provider
    
    Returns:
    
    a new TransformService
    
    Throws:
    
    java.security.NoSuchProviderException - if the specified provider is not registered in the security provider list
    
    java.lang.NullPointerException - if provider, mechanismType, or algorithm is null
    
    java.security.NoSuchAlgorithmException - if a TransformService implementation for the specified algorithm and mechanism type is not available from the specified provider
    
    See Also:
    
    Provider
  - findInstance
```
private static TransformService findInstance(java.lang.String algorithm,
                                             java.lang.String mechanismType,
                                             java.security.Provider provider)
                                      throws java.security.NoSuchAlgorithmException
```
    Throws:
    
    java.security.NoSuchAlgorithmException
  - getMechanismType
```
public final java.lang.String getMechanismType()
```
    Returns the mechanism type supported by this TransformService.
    
    Returns:
    
    the mechanism type
  - getAlgorithm
```
public final java.lang.String getAlgorithm()
```
    Returns the URI of the algorithm supported by this TransformService.
    
    Specified by:
    
    getAlgorithm in interface AlgorithmMethod
    
    Returns:
    
    the algorithm URI
  - getProvider
```
public final java.security.Provider getProvider()
```
    Returns the provider of this TransformService.
    
    Returns:
    
    the provider
  - init
```
public abstract void init(TransformParameterSpec params)
                   throws java.security.InvalidAlgorithmParameterException
```
    Initializes this TransformService with the specified parameters.
    If the parameters exist in XML form, the init(XMLStructure, XMLCryptoContext) method should be used to initialize the TransformService.
    
    Parameters:
    
    params - the algorithm parameters (may be null if not required or optional)
    
    Throws:
    
    java.security.InvalidAlgorithmParameterException - if the specified parameters are invalid for this algorithm
  - marshalParams
```
public abstract void marshalParams(XMLStructure parent,
                                   XMLCryptoContext context)
                            throws MarshalException
```
    Marshals the algorithm-specific parameters. If there are no parameters to be marshalled, this method returns without throwing an exception.
    
    Parameters:
    
    parent - a mechanism-specific structure containing the parent node that the marshalled parameters should be appended to
    
    context - the XMLCryptoContext containing additional context (may be null if not applicable)
    
    Throws:
    
    java.lang.ClassCastException - if the type of parent or context is not compatible with this TransformService
    
    java.lang.NullPointerException - if parent is null
    
    MarshalException - if the parameters cannot be marshalled
  - init
```
public abstract void init(XMLStructure parent,
                          XMLCryptoContext context)
                   throws java.security.InvalidAlgorithmParameterException
```
    Initializes this TransformService with the specified parameters and document context.
    
    Parameters:
    
    parent - a mechanism-specific structure containing the parent structure
    
    context - the XMLCryptoContext containing additional context (may be null if not applicable)
    
    Throws:
    
    java.lang.ClassCastException - if the type of parent or context is not compatible with this TransformService
    
    java.lang.NullPointerException - if parent is null
    
    java.security.InvalidAlgorithmParameterException - if the specified parameters are invalid for this algorithm

Fields inherited from interface javax.xml.crypto.dsig.Transform

Methods inherited from class java.lang.Object

Methods inherited from interface javax.xml.crypto.dsig.Transform

Methods inherited from interface javax.xml.crypto.XMLStructure

algorithm

mechanism

provider

cl

getImplParams

getImplMethod

TransformService

getInstance

getInstance

getInstance

findInstance

getMechanismType

getAlgorithm

getProvider

init

marshalParams

init