org.acplt.oncrpc
Class XdrTcpDecodingStream

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

public class XdrTcpDecodingStream
extends XdrDecodingStream

The XdrTcpDecodingStream class provides the necessary functionality to XdrDecodingStream to receive XDR records from the network using the stream-oriented TCP/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 int	fragmentLength Remaining number of bytes in this fragment -- and still to read.
private boolean	lastFragment Flag indicating that we've read the last fragment and thus reached the end of the record.
private java.net.Socket	socket The streaming socket to be used when receiving this XDR stream's buffer contents.
(package private) java.io.InputStream	stream The input stream used to pull the bytes off the network.

Constructor Summary

XdrTcpDecodingStream(java.net.Socket streamingSocket, int bufferSize)
Construct a new XdrTcpDecodingStream object and associate it with the given streamingSocket for TCP/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.
private void	fill() Fills the internal buffer with the next chunk of data.
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.
private void	readBuffer(java.io.InputStream stream, byte[] bytes, int bytesToRead) Read into buffer exactly the amound of bytes specified.
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.Socket socket

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

stream

java.io.InputStream stream

The input stream used to pull the bytes off the network.

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.

fragmentLength

private int fragmentLength

Remaining number of bytes in this fragment -- and still to read.

lastFragment

private boolean lastFragment

Flag indicating that we've read the last fragment and thus reached the end of the record.

Constructor Detail

XdrTcpDecodingStream

public XdrTcpDecodingStream(java.net.Socket streamingSocket,
                            int bufferSize)
                     throws java.io.IOException

Construct a new XdrTcpDecodingStream object and associate it with the given streamingSocket for TCP/IP-based communication.

Parameters:

streamingSocket - Socket from which XDR data is received.

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

Throws:

java.io.IOException

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 TCP-based XDR decoding streams this reads in the next chunk of data from the network socket (a chunk of data is not necessary the same as a fragment, just enough to fill the internal buffer or receive the remaining part of a fragment).

Read in the next bunch of bytes. This can be either a complete fragment, or if the fragments sent by the communication partner are too large for our buffer, only parts of fragments. In every case, this method ensures that there will be more data available in the buffer (or else an exception thrown).

Specified by:

beginDecoding in class XdrDecodingStream

Throws:

OncRpcException - if an ONC/RPC error occurs.

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

readBuffer

private void readBuffer(java.io.InputStream stream,
                        byte[] bytes,
                        int bytesToRead)
                 throws java.io.IOException,
                        OncRpcException

Read into buffer exactly the amound of bytes specified.

Parameters:

stream - Input stream to read byte data from.

bytes - buffer receiving data.

bytesToRead - number of bytes to read into buffer.

Throws:

OncRpcException - if EOF is reached before all bytes could be read.

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

fill

private void fill()
           throws OncRpcException,
                  java.io.IOException

Fills the internal buffer with the next chunk of data. The chunk is either as long as the buffer or as long as the remaining part of the current XDR fragment, whichever is smaller.

This method does not accept empty XDR record fragments with the only exception of a final trailing empty fragment. This special case is accepted as some ONC/RPC implementations emit such trailing empty fragments whenever the encoded data is a full multiple of their internal record buffer size.

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 reads in and throws away fragments until it reaches the last fragment.

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.