Package org.apache.derby.impl.drda
Class EXTDTAReaderInputStream
java.lang.Object
java.io.InputStream
org.apache.derby.impl.drda.EXTDTAReaderInputStream
- All Implemented Interfaces:
Closeable
,AutoCloseable
- Direct Known Subclasses:
LayerBStreamedEXTDTAReaderInputStream
,StandardEXTDTAReaderInputStream
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).
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Field Summary
FieldsModifier and TypeFieldDescriptionprotected final boolean
Whether or not the subclass is a layer B stream.protected final boolean
Whether or not to read the trailing Derby-specific status byte.private byte
The status Derby-specific status byte, if any.private boolean
Tells if the status byte has been set.private boolean
Whether or not to suppress the exception when an error is indicated by the status byte. -
Constructor Summary
ConstructorsModifierConstructorDescriptionprotected
EXTDTAReaderInputStream
(boolean layerB, boolean readStatusByte) Initializes the class. -
Method Summary
Modifier and TypeMethodDescriptionprotected 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
Returns the status byte.boolean
boolean
Returns whether the status has been set or not.protected abstract void
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, skipNBytes, transferTo
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Field Details
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isLayerBStream
protected final boolean isLayerBStreamWhether or not the subclass is a layer B stream. -
readStatusByte
protected final boolean readStatusByteWhether or not to read the trailing Derby-specific status byte. -
statusSet
private boolean statusSetTells if the status byte has been set.- See Also:
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status
private byte statusThe status Derby-specific status byte, if any.- See Also:
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suppressException
private boolean suppressExceptionWhether or not to suppress the exception when an error is indicated by the status byte.
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Constructor Details
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EXTDTAReaderInputStream
protected EXTDTAReaderInputStream(boolean layerB, boolean readStatusByte) Initializes the class.- Parameters:
layerB
- whether or not DDM layer B streaming is being usedreadStatusByte
- whether or not to read the trailing Derby-specific status byte
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Method Details
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setStatus
private void setStatus(int status) Saves the status byte read off the wire.- Parameters:
status
- the status- See Also:
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isStatusSet
public boolean isStatusSet()Returns whether the status has been set or not.- Returns:
true
if set,false
if not.
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getStatus
public byte getStatus()Returns the status byte.NOTE: Check if the status byte has been set by calling isStatusSet().
- Returns:
- The status byte.
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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
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isLayerBStream
public boolean isLayerBStream() -
checkStatus
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:
IOException
- if the status byte indicates an error condition
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onClientSideStreamingError
protected abstract void onClientSideStreamingError()Performs necessary clean up when an error is signalled by the client. -
throwEXTDTATransferException
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:
IOException
- the exception generated based on the status byte
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