console/servlets/src/main/java/org/apache/edgent/console/servlets/StreamScopeUtil.java

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regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
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  http://www.apache.org/licenses/LICENSE-2.0

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package org.apache.edgent.console.servlets;

import java.lang.management.ManagementFactory;

import javax.management.JMX;
import javax.management.MBeanServer;
import javax.management.MalformedObjectNameException;
import javax.management.ObjectName;

import org.apache.edgent.streamscope.mbeans.StreamScopeMXBean;
import org.apache.edgent.streamscope.mbeans.StreamScopeRegistryMXBean;

public class StreamScopeUtil {
  
  /**
   * Get the StreamScope for the specified stream.
   * <P>
   * N.B. until certain runtime issues are worked out, the stream that a
   * StreamScopeMXBean is registered for is NOT the "origin stream" (opletId/oport)
   * that the StreamScope was created for.  Rather the registration is for
   * the actual StreamScope oplet's opletId and oport 0, so that's what must be
   * supplied as the parameters.
   * <BR>
   * See the commentary in StreamScope oplet code.
   * <BR>
   * Once that is addressed, opletId/oport of the "origin stream" will
   * need to be supplied as parameters.
   * </P>
   * 
   * @param jobId the job id (e.g., "JOB_0")
   * @param opletId the oplet id (e.g., "OP_2")
   * @param oport the oplet output port index (0-based)
   * 
   * @return null if no StreamScope registered for that stream.
   */
  public static StreamScopeMXBean getStreamScope(String jobId, String opletId, int oport) {
    return getRgy().lookup(jobId, opletId, oport);
  }

  private static StreamScopeRegistryMXBean getRgy() {
    MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
    ObjectName objName = mkObjectName(StreamScopeRegistryMXBean.class, StreamScopeRegistryMXBean.TYPE);
    return JMX.newMXBeanProxy(mbs, objName, StreamScopeRegistryMXBean.class);
  }
  
  private static ObjectName mkObjectName(Class<?> klass, String beanType) {
    StringBuffer sbuf = new StringBuffer();
    try {
      sbuf.append("*:interface=");
      sbuf.append(ObjectName.quote(klass.getCanonicalName()));
      sbuf.append(",type=");
      sbuf.append(ObjectName.quote(beanType));
      return new ObjectName(sbuf.toString());
    }
    catch (MalformedObjectNameException e) {
      
      // TODO logger.error("Unable to create ObjectName for "+sbuf, e);
      
      throw new RuntimeException("Unable to create ObjectName for "+sbuf, e);
    }
  }
  
}