term.java

一个完整的XACML工程,学习XACML技术的好例子!

/*
* Copyright (c) 2000-2005, University of Salford
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package issrg.pba.rbac.xmlpolicy.ifstatement;

/**
 * This interface defines the functionality necessary to deliver results. The
 * IF-statement consists of terms, some of them being unary and binary 
 * operators,
 * others being sources of data (Constants, Arguments, Environment).
 *
 * @author A.Otenko
 * @version 1.0
 */

public interface Term {
  /**
   * This method returns the type of the value this term returns. The
   * types are defined by convention of the developers and RBAC policy
   * administrators.
   *
   * @return a case-sensitive type name as calculated at run-time
   */
  public String getType();

  /**
   * This method returns the evaluated result at run-time. The actual type
   * of the object depends on the term and is guaranteed to be of the type
   * returned by getType().
   *
   * @param env is the execution environment
   *
   * @return an object representing the result
   * @throws EvaluationException if the term cannot be evaluated
   */
  public Object evaluate(Environment env) throws EvaluationException;
}