[jBoss-Dev] Externalizing the container interceptors

[Scott M Stark]

As far as I can tell the current container architecture does not support the
externalization of the container interceptors. This is based on looking at the
interaction between the J2eeDeployer and the ContainerFactory code.

Here is a proposal to allow for this.

1. Add a 'Element containerInterceptorsConf' to the 
org.jboss.metadata.ConfigurationMetaData
class. The DTD for this element would be:
<!ELEMENT container-interceptors (interceptor+)>

<!ELEMENT interceptor (#PCDATA)>

<!ATTLIST interceptor
    type  (BMT | CMT | Log | Security | Other)  #REQUIRED
    metricsEnabled  (true | false )  'false' >

a sample element for a message driven bean container:
<container-configuration>
...
  <container-interceptors>
    <interceptor type="Log">org.jboss.ejb.plugins.LogInterceptor</interceptor>
    <interceptor 
type="Security">org.jboss.ejb.plugins.SecurityInterceptor</interceptor>
    <interceptor type="CMT">org.jboss.ejb.plugins.TxInterceptorCMT</interceptor>
    <interceptor type="CMT" 
metricsEnabled="true">org.jboss.ejb.plugins.MetricsInterceptor</interceptor>
    <interceptor 
type="CMT">org.jboss.ejb.plugins.MessageDrivenInstanceInterceptor</interceptor>
    <interceptor 
type="BMT">org.jboss.ejb.plugins.MessageDrivenInstanceInterceptor</interceptor>
    <interceptor 
type="BMT">org.jboss.ejb.plugins.MessageDrivenTxInterceptorBMT</interceptor>
    <interceptor type="BMT" 
metricsEnabled="true">org.jboss.ejb.plugins.MetricsInterceptor</interceptor>
  </container-interceptors>
</container-configuration>

2. Introduce a ContainersInterceptor utility class:
public class ContainersInterceptors implements XmlLoadable
{
    Interceptor getLogInterceptor();
    Interceptor getSecurityInterceptor();
    Interceptor getMetricsInterceptor();
    Interceptor[] getCMTInterceptors(boolean metricsEnabled);
    Interceptor[] getBMTInterceptors(boolean metricsEnabled);
    Interceptor[] getOtherInterceptors();
}

3. The current interceptor code in the ContainerFactory class would be updated to use 
the
new element and utility class. As an example, the current MDB container setup would 
change
from:

   ConfigurationMetaData conf = bean.getContainerConfiguration();
    ...
   container.addInterceptor(new LogInterceptor());
   container.addInterceptor(new SecurityInterceptor());

   if (((MessageDrivenMetaData)bean).isContainerManagedTx())
   {
      // CMT
      container.addInterceptor(new TxInterceptorCMT());
      if (metricsEnabled)
        container.addInterceptor(new MetricsInterceptor());
      container.addInterceptor(new MessageDrivenInstanceInterceptor());
   }
   else
   {
      // BMT
      container.addInterceptor(new MessageDrivenInstanceInterceptor());
      // FIXME. should we have a special BMT tx interceptor
      // to place ACK there???
      container.addInterceptor(new MessageDrivenTxInterceptorBMT());
      if (metricsEnabled)
        container.addInterceptor(new MetricsInterceptor());
   }
   // Finally we add the last interceptor from the container
   container.addInterceptor(container.createContainerInterceptor());

to:

    ConfigurationMetaData conf = bean.getContainerConfiguration();
    ...
    ContainersInterceptors cis = new ContainersInterceptors();
    cis.importXml(conf.getContainerInterceptorsConf());
   container.addInterceptor(cis.getLogInterceptor());
   container.addInterceptor(cis.getSecurityInterceptor());

   Interceptor[] txInterceptors = {};
   if (((MessageDrivenMetaData)bean).isContainerManagedTx())
   {
      // CMT
      txInterceptors = cis.getCMTInterceptors(metricsEnabled);
   }
   else
   {
      txInterceptors = cis.getBMTInterceptors(metricsEnabled);
   }
   for(int i = 0; i < txInterceptors.length; i ++)
      container.addInterceptor(txInterceptors[i]);

   Interceptor[] others = cis.getOtherInterceptors();
   for(int i = 0; i < others.length; i ++)
      container.addInterceptor(others[i]);

   // Finally we add the last interceptor from the container
   container.addInterceptor(container.createContainerInterceptor());

How does this sound?