Facet

Some element can have facets that constrain the data they contain.

The facet element has a attribute as follows:

• name

The name attribute specifies a name of constraint.

The facet element has a constraint value as element contents.

Example

List 19.4.1.1[grammarFacet.rcdl] is a sample RCDL definition and List 19.4.1.2[grammarFacet.rng] is a sample RELAX NG schema to be used in the sample RCDL definition.

<component xmlns="http://www.relaxer.org/xmlns/cdl"
           namespace="http://example.com/account"
           name="backOffice">
  <interface namespace="http://example.com/account" name="accountManager">
<grammar namespace="http://example.com/account" \
    location="grammarFacet.rng"/>
    <operation name="findAccount">
      <in name="accountNo" type="token">
        <facet name="length">5</facet>
      </in>
      <out label="account"/>
    </operation>
  </interface>
</component>

<grammar xmlns="http://relaxng.org/ns/structure/1.0"
         datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">
  <start>
    <ref name="account"/>
  </start>
  <define name="account">
    <element name="account">
      <attribute name="accountNo">
        <data type="token"/>
      </attribute>
      <element name="balance">
        <data type="int"/>
      </element>
      <element name="owner">
        <data type="token"/>
      </element>
      <ref name="address"/>
      <zeroOrMore>
        <ref name="phone"/>
      </zeroOrMore>
    </element>
  </define>
  <define name="address">
    <element name="address">
      <attribute name="zip">
        <data type="token"/>
      </attribute>
      <text/>
    </element>
  </define>
  <define name="phone">
    <element name="phone">
      <attribute name="area">
        <data type="token"/>
      </attribute>
      <data type="token"/>
    </element>
  </define>
</grammar>

When you use relaxer with -cdl.filer.assert switch, a filter for assertion, AccountManagerAssertionFilter shown in List 19.4.1.3[AccountManagerAssertionFilter.java], is generated. This filter checks the condition defined by the postCondition element before and after method execution.

import java.rmi.RemoteException;
import org.relaxer.runtime.*;

public class AccountManagerAssertionFilter extends \
    AbstractAccountManagerFilter {

    /**
     * @param master
     */
    public AccountManagerAssertionFilter(Object master) {
        super(master);
    }

    /**
     * Asserts against operation findAccount$AccountManager.
     *
     * @param accountNo
     * @exception RemoteException
     * @return Account
     */
public Account findAccount$AccountManager(String accountNo) throws \
    RemoteException {
        IAccountManagerFilter $reference$ = rGetReference$AccountManager();
        RVerifyReport $report$ = new RVerifyReport();
        RVerifyContext $context$ = new RVerifyContext();
        String $message$;
        try {
            rAssertInvariants();
            $message$ = $context$.isValid(accountNo, "token", "length:5");
            if ($message$ != null) {
$report$.addError("accountNo", RVerifyReport.INVALID_VALUE, accountNo, \
    "token{length:5}", $message$);
            }
            if (!$report$.isValid()) {
                throw (new IllegalArgumentException());
            }
Account $result$ = $reference$.findAccount$AccountManager(accountNo);
            rAssertInvariants();
            $report$.addError($result$.verify());
            if (!$report$.isValid()) {
                throw (new RAssertionException($report$));
            }
            return ($result$);
        } catch (RemoteException e) {
            throw (e);
        } catch (Exception e) {
            if (e instanceof RAssertionException) {
                throw ((RAssertionException)e);
            } else {
                throw (new RemoteException(e.getMessage(), e));
            }
        }
    }

    /**
     * Invariant
     *
     * @exception RemoteException
     * @return boolean
     */
    public boolean rIsValidInvariants() throws RemoteException {
        IAccountManagerFilter $reference$ = rGetReference$AccountManager();
        return (true);
    }

    /**
     * Invariant
     *
     * @exception RemoteException
     */
    public void rAssertInvariants() throws RemoteException {
        if (!(rIsValidInvariants())) {
            throw (new RAssertionException("invariant"));
        }
    }
}