org.acplt.oncrpc
Class XdrUdpDecodingStream

java.lang.Object
  org.acplt.oncrpc.XdrDecodingStream
      org.acplt.oncrpc.XdrUdpDecodingStream

public class XdrUdpDecodingStream
extends XdrDecodingStream

The XdrUdpDecodingStream class provides the necessary functionality to XdrDecodingStream to receive XDR packets from the network using the datagram-oriented UDP/IP.

Field Summary

private byte[]	buffer The buffer which will be filled from the datagram socket and then be used to supply the information when decoding data.
private int	bufferHighmark Index of the last four byte word in the buffer, which has been read in from the datagram socket.
private int	bufferIndex The read pointer is an index into the buffer.
private java.net.InetAddress	senderAddress Sender's address of current buffer contents.
private int	senderPort The senders's port.
private java.net.DatagramSocket	socket The datagram socket to be used when receiving this XDR stream's buffer contents.

Constructor Summary

XdrUdpDecodingStream(java.net.DatagramSocket datagramSocket, int bufferSize)
Construct a new XdrUdpDecodingStream object and associate it with the given datagramSocket for UDP/IP-based communication.

Method Summary

void	beginDecoding() Initiates decoding of the next XDR record.
void	close() Closes this decoding XDR stream and releases any system resources associated with this stream.
void	endDecoding() End decoding of the current XDR record.
java.net.InetAddress	getSenderAddress() Returns the Internet address of the sender of the current XDR data.
int	getSenderPort() Returns the port number of the sender of the current XDR data.
int	xdrDecodeInt() Decodes (aka "deserializes") a "XDR int" value received from a XDR stream.
void	xdrDecodeOpaque(byte[] opaque, int offset, int length) Decodes (aka "deserializes") a XDR opaque value, which is represented by a vector of byte values, and starts at offset with a length of length.
byte[]	xdrDecodeOpaque(int length) Decodes (aka "deserializes") an opaque value, which is nothing more than a series of octets (or 8 bits wide bytes).

Methods inherited from class org.acplt.oncrpc.XdrDecodingStream

getCharacterEncoding, setCharacterEncoding, xdrDecodeBoolean, xdrDecodeBooleanFixedVector, xdrDecodeBooleanVector, xdrDecodeByte, xdrDecodeByteFixedVector, xdrDecodeByteVector, xdrDecodeDouble, xdrDecodeDoubleFixedVector, xdrDecodeDoubleVector, xdrDecodeDynamicOpaque, xdrDecodeFloat, xdrDecodeFloatFixedVector, xdrDecodeFloatVector, xdrDecodeIntFixedVector, xdrDecodeIntVector, xdrDecodeLong, xdrDecodeLongFixedVector, xdrDecodeLongVector, xdrDecodeOpaque, xdrDecodeShort, xdrDecodeShortFixedVector, xdrDecodeShortVector, xdrDecodeString, xdrDecodeStringFixedVector, xdrDecodeStringVector

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

socket

private java.net.DatagramSocket socket

The datagram socket to be used when receiving this XDR stream's buffer contents.

senderAddress

private java.net.InetAddress senderAddress

Sender's address of current buffer contents.

senderPort

private int senderPort

The senders's port.

buffer

private byte[] buffer

The buffer which will be filled from the datagram socket and then be used to supply the information when decoding data.

bufferIndex

private int bufferIndex

The read pointer is an index into the buffer.

bufferHighmark

private int bufferHighmark

Index of the last four byte word in the buffer, which has been read in from the datagram socket.

Constructor Detail

XdrUdpDecodingStream

public XdrUdpDecodingStream(java.net.DatagramSocket datagramSocket,
                            int bufferSize)

Construct a new XdrUdpDecodingStream object and associate it with the given datagramSocket for UDP/IP-based communication. This constructor is typically used when communicating with servers over UDP/IP using a "connected" datagram socket.

Parameters:

datagramSocket - Datagram socket from which XDR data is received.

bufferSize - Size of packet buffer for storing received XDR datagrams.

Method Detail

getSenderAddress

public java.net.InetAddress getSenderAddress()

Returns the Internet address of the sender of the current XDR data. This method should only be called after beginDecoding(), otherwise it might return stale information.

Specified by:

getSenderAddress in class XdrDecodingStream

Returns:

InetAddress of the sender of the current XDR data.

getSenderPort

public int getSenderPort()

Returns the port number of the sender of the current XDR data. This method should only be called after beginDecoding(), otherwise it might return stale information.

Specified by:

getSenderPort in class XdrDecodingStream

Returns:

Port number of the sender of the current XDR data.

beginDecoding

public void beginDecoding()
                   throws OncRpcException,
                          java.io.IOException

Initiates decoding of the next XDR record. For UDP-based XDR decoding streams this reads in the next datagram from the network socket.

Specified by:

beginDecoding in class XdrDecodingStream

Throws:

OncRpcException - if an ONC/RPC error occurs.

java.io.IOException - if an I/O error occurs.

endDecoding

public void endDecoding()
                 throws OncRpcException,
                        java.io.IOException

End decoding of the current XDR record. The general contract of endDecoding is that calling it is an indication that the current record is no more interesting to the caller and any allocated data for this record can be freed.

This method overrides XdrDecodingStream.endDecoding(). It does nothing more than resetting the buffer pointer (eeek! a pointer in Java!!!) back to the begin of an empty buffer, so attempts to decode data will fail until the buffer is filled again.

Overrides:

endDecoding in class XdrDecodingStream

Throws:

OncRpcException - if an ONC/RPC error occurs.

java.io.IOException - if an I/O error occurs.

close

public void close()
           throws OncRpcException,
                  java.io.IOException

Closes this decoding XDR stream and releases any system resources associated with this stream. A closed XDR stream cannot perform decoding operations and cannot be reopened.

This implementation frees the allocated buffer but does not close the associated datagram socket. It only throws away the reference to this socket.

Overrides:

close in class XdrDecodingStream

Throws:

OncRpcException - if an ONC/RPC error occurs.

java.io.IOException - if an I/O error occurs.

xdrDecodeInt

public int xdrDecodeInt()
                 throws OncRpcException,
                        java.io.IOException

Decodes (aka "deserializes") a "XDR int" value received from a XDR stream. A XDR int is 32 bits wide -- the same width Java's "int" data type has.

Specified by:

xdrDecodeInt in class XdrDecodingStream

Returns:

The decoded int value.

Throws:

OncRpcException - if an ONC/RPC error occurs.

java.io.IOException - if an I/O error occurs.

xdrDecodeOpaque

public byte[] xdrDecodeOpaque(int length)
                       throws OncRpcException,
                              java.io.IOException

Decodes (aka "deserializes") an opaque value, which is nothing more than a series of octets (or 8 bits wide bytes). Because the length of the opaque value is given, we don't need to retrieve it from the XDR stream. This is different from xdrDecodeOpaque(byte[], int, int) where first the length of the opaque value is retrieved from the XDR stream.

Specified by:

xdrDecodeOpaque in class XdrDecodingStream

Parameters:

length - Length of opaque data to decode.

Returns:

Opaque data as a byte vector.

Throws:

OncRpcException - if an ONC/RPC error occurs.

java.io.IOException - if an I/O error occurs.

xdrDecodeOpaque

public void xdrDecodeOpaque(byte[] opaque,
                            int offset,
                            int length)
                     throws OncRpcException,
                            java.io.IOException

Decodes (aka "deserializes") a XDR opaque value, which is represented by a vector of byte values, and starts at offset with a length of length. Only the opaque value is decoded, so the caller has to know how long the opaque value will be. The decoded data is always padded to be a multiple of four (because that's what the sender does).

Specified by:

xdrDecodeOpaque in class XdrDecodingStream

Parameters:

opaque - Byte vector which will receive the decoded opaque value.

offset - Start offset in the byte vector.

length - the number of bytes to decode.

Throws:

OncRpcException - if an ONC/RPC error occurs.

java.io.IOException - if an I/O error occurs.