AMQPInnerFrame.java

/*
* This class represents an AMQP inner frame
* Class is never instantiated, but extended by other frame classes representing
* method-, header-, body- and hearthbeat frames
*/

public class AMQPInnerFrame {

  AMQPInnerFrame() {}
  AMQPInnerFrame(ByteArrayBuffer byteArrayBuffer) {}

  //Build an AMQPInnerFrame from a packet received on the wire
  //Expects one complete frame
  //This method consumes data from the ByteArrayBuffer, make sure to copy data
  //if you need to keep it for other purposes
  public static AMQPInnerFrame build(ByteArrayBuffer byteArrayBuffer, AMQPFrame.AMQPFrameType frameType, ALongUInt length, AShortUInt channel) throws InvalidFrameException {

    //Do we want to build a Method frame?
    if (frameType == AMQPFrame.AMQPFrameType.METHOD) {
      //System.out.println("AMQPInnerFrame building new Method frame from this buffer:");
      //System.out.println(byteArrayBuffer.toHexString());

      //Declare and set to null so compiler wont complain
      AShortUInt amqpClass = null;
      AShortUInt amqpMethod = null;

      //Read class and method
      try {
        amqpClass = new AShortUInt(byteArrayBuffer); //Pop 2 bytes
        amqpMethod = new AShortUInt(byteArrayBuffer); //Pop 2 bytes
      } catch (InvalidTypeException e) {
        throw new InvalidFrameException("Failed to read method frame class/method: " + e.toString());
      }

      AMQPMethodFrame amqpMethodFrame = null;

      //From now on, we need to start reading the method arguments
      //The structure of each argument list differs depending on which class
      //and method we're dealing with
      try {
        amqpMethodFrame = new AMQPMethodFrame(
        amqpClass,
        amqpMethod,
        byteArrayBuffer
        );
      } catch (InvalidTypeException e) {
        throw new InvalidFrameException("Failed to build method frame, invalid encoding: " + e.toString());
      }

      return amqpMethodFrame;
    }

    //Do we want to build a Header frame?
    if (frameType == AMQPFrame.AMQPFrameType.HEADER) {
      //To be created
      AMQPHeaderFrame amqpHeaderFrame = null;

      //Class ID
      AShortUInt amqpClass = null;

      //Read class ID
      try {
        amqpClass = new AShortUInt(byteArrayBuffer); //Pop 2 bytes
      } catch (InvalidTypeException e) {
        throw new InvalidFrameException("Failed to build header frame class ID: " + e.toString());
      }

      //Attempt to build the frame object
      try {
        amqpHeaderFrame = new AMQPHeaderFrame(
        amqpClass,
        byteArrayBuffer
        );
      } catch (InvalidTypeException e) {
        throw new InvalidFrameException("Failed to build header frame, invalid encoding: " + e.toString());
      }

      return amqpHeaderFrame;
    }

    //Do we want to build a Body frame?
    if (frameType == AMQPFrame.AMQPFrameType.BODY) {
      //System.err.println("Got a body frame:\n" + byteArrayBuffer.toHexString());
      AMQPBodyFrame amqpBodyFrame = null;

      //Attempt to build the body frame
      try {
        amqpBodyFrame = new AMQPBodyFrame(
        length,
        byteArrayBuffer
        );
      } catch (InvalidTypeException e) {
        throw new InvalidFrameException("Failed to build body frame, invalid encoding: " + e.toString());
      }

      return amqpBodyFrame;
    }

    //Build a Heartbeat frame?
    if (frameType == AMQPFrame.AMQPFrameType.HEARTBEAT) {
      //System.err.println("Got a body frame:\n" + byteArrayBuffer.toHexString());
      AMQPHeartbeatFrame amqpHeartbeatFrame = null;

      //Heartbeats MUST be received on channel 0
      if (channel.toInt() != 0) {
        throw new InvalidFrameException("Received heartbeat on channel other than 0");
      }

      //Attempt to build the Heartbeat frame
      try {
        amqpHeartbeatFrame = new AMQPHeartbeatFrame(
        length,
        byteArrayBuffer
        );
      } catch (InvalidTypeException e) {
        throw new InvalidFrameException("Failed to build Heartbeat frame, invalid encoding: " + e.toString());
      }

      return amqpHeartbeatFrame;
    }

    //Should never be reached, as all four possible frame types are created above
    throw new InvalidFrameException("Unknown frame type received (probably a bug in the tester code) : " + frameType.name());
  }

  //Output data to wire
  public ByteArrayBuffer toWire() {
    System.err.println("Override me");
    System.exit(1);
    return null;
  }
};