org.jboss.as.controller.extension

Interface ExpressionResolverExtension

public interface ExpressionResolverExtension

Object that can be used to extend the functionality of an ExpressionResolver by handling expression strings in formats not understood by the expression resolver.

Extension expressions must be of the form ${extensionidentifier::someextensionspecificdetails}, where extensionidentifier is some string that identifies the desired extension. All resolver extensions in a process must have unique identifiers. Best practice is for subsystems that register extensions to allow end user configuration control over the identifier so they can provide non-conflicting identifiers. The someextensionspecificdetails part of the expression is an opaque string understood by the relevant resolver extension.

Field Summary

Fields

Modifier and Type	Field and Description
static Pattern	EXTENSION_EXPRESSION_PATTERN A Pattern that strings must match for any ExpressionResolverExtension to handle them.

Method Summary

Modifier and Type	Method and Description
void	initialize(OperationContext context) Initialize the extension using the given OperationContext.
String	resolveExpression(String expression, OperationContext context) Resolve a given simple expression string, returning null if the string is not of a form recognizable to the plugin.

Field Detail

EXTENSION_EXPRESSION_PATTERN

static final Pattern EXTENSION_EXPRESSION_PATTERN

A Pattern that strings must match for any ExpressionResolverExtension to handle them.

Method Detail

initialize

void initialize(OperationContext context)
         throws OperationFailedException

Initialize the extension using the given OperationContext. May be called multiple times for a given extension, so extensions should handle that appropriately. Note that this method may be invoked in OperationContext.Stage#MODEL. Implementations are not required to support initialization in [@code OperationContext.Stage.MODEL} but should throw ExpressionResolver.ExpressionResolutionServerException if they do not.

Parameters:

context - the OperationContext. Will not be null

Throws:

OperationFailedException - if a problem initializing occurs that indicates a user mistake (e.g. an improper configuration of a resource used by the extension.) Do not use for non-user-driven problems; use runtime exceptions for those. Throwing a runtime exception that implements OperationClientException is also a valid way to handle user mistakes.

ExpressionResolver.ExpressionResolutionServerException - if a non-user-driven problem occurs, including an invocation during OperationContext.Stage#MODEL if that is not supported.

resolveExpression

String resolveExpression(String expression,
                         OperationContext context)

Resolve a given simple expression string, returning null if the string is not of a form recognizable to the plugin.

Note: A thread invoking this method must immediately precede the invocation with a call to initialize(OperationContext).

Parameters:

expression - a string that matches EXTENSION_EXPRESSION_PATTERN and that does not have any substrings that match that pattern.

context - the current OperationContext to provide additional contextual information.

Returns:

a string representing the resolve expression, or null if expression is not of a form understood by the plugin.

Throws:

ExpressionResolver.ExpressionResolutionUserException - if expression is a form understood by the plugin but in some way is unacceptable. This should only be thrown due to flaws in the provided expression or the configuration of resources used by the resolver extension, which are 'user' problems. It should not be used for internal problems in the resolver extension.

ExpressionResolver.ExpressionResolutionServerException - if some other internal expression resolution failure occurs.