Package org.apache.derby.impl.drda

Class EXTDTAReaderInputStream

  • All Implemented Interfaces:
    java.io.Closeable, java.lang.AutoCloseable
    Direct Known Subclasses:
    LayerBStreamedEXTDTAReaderInputStream, StandardEXTDTAReaderInputStream
    abstract class EXTDTAReaderInputStream
extends java.io.InputStream
    Implementation of InputStream which get EXTDTA from the DDMReader.

    This class can be used to stream LOBs from Network client to the Network server.

    To be able to correctly stream data from the client without reading the while value up front, a trailing Derby-specific status byte was introduced (version 10.6). It is used by the client to tell the server if the data it received was valid, or if it detected an error while streaming the data. The DRDA protocol, or at least Derby's implementation of it, doesn't enable the client to inform the server about the error whilst streaming (there is a mechanism in DRDA to interrupt a running request, but it didn't seem like a feasible approach in this case).

    • Field Summary

      Fields 
      Modifier and Type Field Description
      protected boolean isLayerBStream
      Whether or not the subclass is a layer B stream.
      protected boolean readStatusByte
      Whether or not to read the trailing Derby-specific status byte.
      private byte status
      The status Derby-specific status byte, if any.
      private boolean statusSet
      Tells if the status byte has been set.
      private boolean suppressException
      Whether or not to suppress the exception when an error is indicated by the status byte.

    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      protected EXTDTAReaderInputStream​(boolean layerB, boolean readStatusByte)
      Initializes the class.

    • Method Summary

      All Methods Static Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method Description
      protected void checkStatus​(int clientStatus)
      Interprets the Derby-specific status byte, and throws an exception if an error condition has been detected on the client.
      byte getStatus()
      Returns the status byte.
      boolean isLayerBStream()  
      boolean isStatusSet()
      Returns whether the status has been set or not.
      protected abstract void onClientSideStreamingError()
      Performs necessary clean up when an error is signalled by the client.
      private void setStatus​(int status)
      Saves the status byte read off the wire.
      (package private) void setSuppressException​(boolean flag)
      Sets whether or not to suppress the exception when setting the status.
      (package private) static void throwEXTDTATransferException​(int status)
      Throws an exception as mandated by the EXTDTA status byte.

      • Methods inherited from class java.io.InputStream

        available, close, mark, markSupported, nullInputStream, read, read, read, readAllBytes, readNBytes, readNBytes, reset, skip, transferTo

      • Methods inherited from class java.lang.Object

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

    • Field Detail

      • isLayerBStream

        protected final boolean isLayerBStream
        Whether or not the subclass is a layer B stream.

      • readStatusByte

        protected final boolean readStatusByte
        Whether or not to read the trailing Derby-specific status byte.

      • statusSet

        private boolean statusSet
        Tells if the status byte has been set.
        See Also:
        checkStatus(int)

      • status

        private byte status
        The status Derby-specific status byte, if any.
        See Also:
        isStatusSet()

      • suppressException

        private boolean suppressException
        Whether or not to suppress the exception when an error is indicated by the status byte.

    • Constructor Detail

      • EXTDTAReaderInputStream

        protected EXTDTAReaderInputStream​(boolean layerB,
                                  boolean readStatusByte)
        Initializes the class.
        Parameters:
        layerB - whether or not DDM layer B streaming is being used
        readStatusByte - whether or not to read the trailing Derby-specific status byte

    • Method Detail

      • setStatus

        private void setStatus​(int status)
        Saves the status byte read off the wire.
        Parameters:
        status - the status
        See Also:
        DRDAConstants

      • isStatusSet

        public boolean isStatusSet()
        Returns whether the status has been set or not.
        Returns:
        true if set, false if not.

      • getStatus

        public byte getStatus()
        Returns the status byte.

        NOTE: Check if the status byte has been set by calling isStatusSet().

        Returns:
        The status byte.

      • setSuppressException

        void setSuppressException​(boolean flag)
        Sets whether or not to suppress the exception when setting the status.
        Parameters:
        flag - true to suppress, false to throw exception if an error condition is indicated by the status flag

      • isLayerBStream

        public boolean isLayerBStream()

      • checkStatus

        protected void checkStatus​(int clientStatus)
                    throws java.io.IOException
        Interprets the Derby-specific status byte, and throws an exception if an error condition has been detected on the client.
        Parameters:
        clientStatus - the status flag sent by the client
        Throws:
        java.io.IOException - if the status byte indicates an error condition

      • onClientSideStreamingError

        protected abstract void onClientSideStreamingError()
        Performs necessary clean up when an error is signalled by the client.

      • throwEXTDTATransferException

        static void throwEXTDTATransferException​(int status)
                                  throws java.io.IOException
        Throws an exception as mandated by the EXTDTA status byte.
        Parameters:
        status - the EXTDTA status byte received from the client, should not be DRDAConstants.STREAM_OK
        Throws:
        java.io.IOException - the exception generated based on the status byte