java.lang.Object
- org.apache.derby.impl.drda.DDMReader

```
class DDMReader
extends java.lang.Object
```
The DDMReader is used to read DRDA protocol. DRDA Protocol is divided into three layers corresponding to the DDM three-tier architecture. For each layer, their is a DSS (Data Stream Structure) defined. Layer A Communications management services Layer B Agent services Layer C Data management services
At layer A are request, reply and data correlation, structure chaining, continuation or termination of chains when errors are detected, interleaving and multi-leaving request, reply, and data DSSs for multitasking environments. For TCP/IP, the format of the DDM envelope is 2 bytes Length of the data 1 byte 'D0' - indicates DDM data 1 byte DDM format byte(DSSFMT) - type of DSS(RQSDSS,RPYDSS), whether it is chained, information about the next chained DSS 2 bytes request correlation identifier
The correlation identifier ties together a request, the request data and the reply. In a chained DSS, each request has a correlation identifier which is higher than the previous request (all correlation identifiers must be greater than 0).
At layer B are object mapping, object validation and command routing. Layer B objects with data 5 bytes less than 32K bytes consist of 2 bytes Length 2 bytes Type of the object (code point) Object data Object data is either SCALAR or COLLECTION data. Scalar data consists of a string of bytes formatted as the class description of the object required. Collections consist of a set of objects in which the entries in the collection are nested within the length/ code point of the collection.
Layer B objects with data >=32763 bytes long format is 2 bytes Length - length of class, length, and extended total length fields (high order bit set, indicating >=32763) 2 bytes Type of the object (code point) n bytes Extended total length - length of the object (n = Length - 4) Object data
At layer C are services each class of DDM object provides. |-------------------------------------------| Layer C | Specific | Specific | Specific | | Commands | Replies | Scalars and | | and their | and their | Collections | |-------------------------------------------|----------------| Layer B | Commands | Reply | Scalars and | Communications | | | Messages | Collections | | |-----------|---------------|---------------|----------------| Layer A | RQSDSS | RPYDSS | OBJDSS | CMNDSS | | | | | Mapped Data | |-----------|---------------|---------------|----------------| | DDM Data Stream Structures | |------------------------------------------------------------| DSS's may be chained so that more than one can be transmitted at a time to improve performance. For more details, see DRDA Volume 3 (Distributed Data Management(DDM) Architecture (DDS definition)

Field Summary

Fields
Modifier and Type	Field	Description
`private static boolean`	`ADJUST_LENGTHS`
`private DRDAConnThread`	`agent`
`private byte[]`	`buffer`
`private CcsidManager`	`ccsidManager`
`private int`	`count`
`private long[]`	`ddmCollectionLenStack`
`private long`	`ddmScalarLen`
`private static int`	`DEFAULT_BUFFER_SIZE`
`private boolean`	`doingLayerBStreaming`
`private int`	`dssCorrelationID`
`private boolean`	`dssIsChainedWithDiffID`
`private boolean`	`dssIsChainedWithSameID`
`private boolean`	`dssIsContinued`
`private int`	`dssLength`
`private DssTrace`	`dssTrace`
`private EbcdicCcsidManager`	`ebcdicCcsidManager`
`private static int`	`EMPTY_STACK`
`private java.io.InputStream`	`inputStream`
`private static long`	`MAX_EXTDTA_SIZE`
`private static int`	`MAX_MARKS_NESTING`
`private static boolean`	`NO_ADJUST_LENGTHS`
`private static int`	`NO_CODEPOINT`
`private int`	`pos`
`private int`	`prevCorrelationID`
`private int`	`svrcod`
`private static int[][]`	`tenRadixMagnitude`
`private boolean`	`terminateChainOnErr`
`private int`	`topDdmCollectionStack`
`(package private) long`	`totalByteCount`
`private Utf8CcsidManager`	`utf8CcsidManager`

Constructor Summary

Constructors
Constructor	Description
`DDMReader(java.io.InputStream inputStream)`	This constructor is used for testing the protocol It is used by ProtocolTestAdapter to read the protocol returned by the server
`DDMReader(DRDAConnThread agent, DssTrace dssTrace)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`private void`	`adjustLengths(int length)`	Adjust remaining length
`protected void`	`clearBuffer()`
`private void`	`compressBLayerData(int continueDssHeaderCount)`	Compress B Layer data if extended total length is used by removing the continuation headers
`private int[]`	`computeMagnitude(int[] input)`	Compute the int array of magnitude from input value segments.
`protected java.lang.String`	`convertBytes(byte[] buf)`	Convert EBCDIC byte array to unicode string
`(package private) boolean`	`doingLayerBStreaming()`
`private void`	`ensureALayerDataInBuffer(int desiredDataSize)`	Make sure a certain amount of Layer A data is in the buffer.
`private void`	`ensureBLayerDataInBuffer(int desiredDataSize, boolean adjustLen)`	Make sure a certain amount of Layer B data is in the buffer.
`private void`	`ensureSpaceInBufferForFill(int desiredSpace)`	This method makes sure there is enough room in the buffer for a certain number of bytes.
`private void`	`fill(int minimumBytesNeeded)`	This method will attempt to read a minimum number of bytes from the underlying stream.
`private void`	`finishLayerBStreaming()`
`protected int`	`getCodePoint()`	Get the next CodePoint from a collection
`protected int`	`getCodePoint(int codePointCheck)`	Get the next CodePoint from a collection and check that it matches the specified CodePoint
`protected byte`	`getCurrChainState()`	Return chaining bit for current DSS.
`protected long`	`getDdmLength()`	Length of current DDM object
`(package private) byte[]`	`getExtData(long desiredLength, boolean checkNullability)`
`(package private) EXTDTAReaderInputStream`	`getEXTDTAReaderInputStream(boolean checkNullability)`	Creates an InputStream which can stream EXTDTA objects.
`protected void`	`initialize(DRDAConnThread agent, DssTrace dssTrace)`	Initialize values for this session, the reader is reused so we need to set null and 0 values
`protected boolean`	`isChainedWithDiffID()`	Next DSS has different correlator than current DSS
`protected boolean`	`isChainedWithSameID()`	Next DSS has same correlator as current DSS
`protected boolean`	`isCmd()`	Check for the command protocol
`private boolean`	`isEXTDTANull()`
`protected void`	`markCollection()`	Push DDM Length on to collection stack
`protected boolean`	`moreData()`	Is there more data in the buffer
`protected boolean`	`moreDdmData()`	Is there more in this DDM object
`protected boolean`	`moreDssData()`	Is there more in this DDS object
`private int`	`packedNybblesToInt(byte[] buffer, int offset, int startNybble, int numberOfNybbles)`	Convert a range of packed nybbles (up to 9 digits without overflow) to an int.
`private long`	`packedNybblesToLong(byte[] buffer, int offset, int startNybble, int numberOfNybbles)`	Convert a range of packed nybbles (up to 18 digits without overflow) to a long.
`protected java.math.BigDecimal`	`readBigDecimal(int precision, int scale)`	Read a BigDecimal value
`protected byte`	`readByte()`	Read byte value
`protected byte[]`	`readBytes()`	Read byte string value
`protected byte[]`	`readBytes(int length)`	Read byte string value
`protected java.lang.String`	`readCmdString()`	Read string value
`protected java.lang.String`	`readCmdString(int length)`	Read string value
`protected int`	`readCodePoint()`	Read the CodePoint
`protected double`	`readDouble(int byteOrder)`	Read platform double value
`private void`	`readDSSContinuationHeader()`
`protected int`	`readDssHeader()`	Read DSS header DSS Header format is 2 bytes - length 1 byte - 'D0' - indicates DDM data 1 byte - DSS format \|---\|---------\|----------\| \| 0 \| flags \| type \| \|---\|---------\|----------\| \| 0 \| 1 2 3 \| 4 5 6 7 \| \|---\|---------\|----------\| bit 0 - '0' bit 1 - '0' - unchained, '1' - chained bit 2 - '0' - do not continue on error, '1' - continue on error bit 3 - '0' - next DSS has different correlator, '1' - next DSS has same correlator type - 1 - Request DSS - 2 - Reply DSS - 3 - Object DSS - 4 - Communications DSS - 5 - Request DSS where no reply is expected 2 bytes - request correlation id
`protected java.lang.String`	`readEncryptedString(DecryptionManager decryptM, int securityMechanism, byte[] initVector, byte[] sourcePublicKey)`	Read encrypted string
`protected float`	`readFloat(int byteOrder)`	Read platform float value
`protected int`	`readInt(int byteOrder)`	Read platform int value
`protected java.lang.String`	`readLDStringData(java.lang.String encoding)`	Read length delimited string value in DDM data with default encoding
`protected int`	`readLengthAndCodePoint(boolean isLayerBStreamingPossible)`	Read the DDM Length and CodePoint
`private java.io.ByteArrayInputStream`	`readLOBChunk(boolean readHeader, long desiredLength)`	This method is used by EXTDTAReaderInputStream to read the next chunk of data.
`(package private) java.io.ByteArrayInputStream`	`readLOBContinuationStream()`	This method is used by EXTDTAReaderInputStream to read the next chunk of data.
`(package private) java.io.ByteArrayInputStream`	`readLOBContinuationStream(long desiredLength)`	This method is used by EXTDTAReaderInputStream to read the next chunk of data.
`(package private) java.io.ByteArrayInputStream`	`readLOBInitStream()`	This method is used by EXTDTAReaderInputStream to read the first chunk of data.
`(package private) java.io.ByteArrayInputStream`	`readLOBInitStream(long desiredLength)`	This method is used by EXTDTAReaderInputStream to read the first chunk of data.
`protected long`	`readLong(int byteOrder)`	Read platform long value
`protected int`	`readNetworkInt()`	Read network int value
`protected long`	`readNetworkLong()`	Read network long value
`protected int`	`readNetworkShort()`	Read network short value
`protected long`	`readNetworkSixByteLong()`	Read network six byte value and put it in a long v
`protected void`	`readReplyDss()`	Read Reply DSS This is used in testing the protocol.
`protected short`	`readShort(int byteOrder)`	Read platform short value
`protected int`	`readSignedNetworkShort()`	Read signed network short value
`protected java.lang.String`	`readString()`	Read string value
`protected java.lang.String`	`readString(int length)`	Read string value Strings in DRDA protocol are encoded in EBCDIC by default so we need to convert to UCS2
`protected java.lang.String`	`readString(int length, java.lang.String encoding)`	Read encoded string value
`protected void`	`readString(DRDAString dst, int size, boolean unpad)`	Read string value into a `DRDAString` object.
`protected java.lang.String`	`readStringData(int length)`	Read specified length of string value in DDM data with default encoding
`protected int`	`readUnsignedByte()`	Read byte value and mask out high order bytes before returning
`protected void`	`setEbcdicCcsid()`
`protected void`	`setUtf8Ccsid()`
`private void`	`shiftBuffer(byte[] destinationBuffer)`	This is a helper method which shifts the buffered bytes from wherever they are in the current buffer to the beginning of different buffer (note these buffers could be the same).
`protected void`	`skipBytes()`	Skip byte string value
`protected void`	`skipBytes(int length)`	Skip byte string value
`protected void`	`skipDss()`	Skip remaining DSS
`private void`	`startLayerBStreaming()`
`protected boolean`	`terminateChainOnErr()`
`private void`	`trace(java.lang.String msg)`	Print a internal trace message

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - DEFAULT_BUFFER_SIZE
```
private static final int DEFAULT_BUFFER_SIZE
```
    See Also:
    
    Constant Field Values
  - MAX_MARKS_NESTING
```
private static final int MAX_MARKS_NESTING
```
    See Also:
    
    Constant Field Values
  - NO_CODEPOINT
```
private static final int NO_CODEPOINT
```
    See Also:
    
    Constant Field Values
  - EMPTY_STACK
```
private static final int EMPTY_STACK
```
    See Also:
    
    Constant Field Values
  - ADJUST_LENGTHS
```
private static final boolean ADJUST_LENGTHS
```
    See Also:
    
    Constant Field Values
  - NO_ADJUST_LENGTHS
```
private static final boolean NO_ADJUST_LENGTHS
```
    See Also:
    
    Constant Field Values
  - MAX_EXTDTA_SIZE
```
private static final long MAX_EXTDTA_SIZE
```
    See Also:
    
    Constant Field Values
  - tenRadixMagnitude
```
private static final int[][] tenRadixMagnitude
```
  - agent
```
private DRDAConnThread agent
```
  - utf8CcsidManager
```
private Utf8CcsidManager utf8CcsidManager
```
  - ebcdicCcsidManager
```
private EbcdicCcsidManager ebcdicCcsidManager
```
  - ccsidManager
```
private CcsidManager ccsidManager
```
  - buffer
```
private byte[] buffer
```
  - pos
```
private int pos
```
  - count
```
private int count
```
  - topDdmCollectionStack
```
private int topDdmCollectionStack
```
  - ddmCollectionLenStack
```
private long[] ddmCollectionLenStack
```
  - ddmScalarLen
```
private long ddmScalarLen
```
  - dssLength
```
private int dssLength
```
  - dssIsContinued
```
private boolean dssIsContinued
```
  - terminateChainOnErr
```
private boolean terminateChainOnErr
```
  - dssIsChainedWithSameID
```
private boolean dssIsChainedWithSameID
```
  - dssIsChainedWithDiffID
```
private boolean dssIsChainedWithDiffID
```
  - dssCorrelationID
```
private int dssCorrelationID
```
  - prevCorrelationID
```
private int prevCorrelationID
```
  - svrcod
```
private int svrcod
```
  - dssTrace
```
private DssTrace dssTrace
```
  - inputStream
```
private java.io.InputStream inputStream
```
  - doingLayerBStreaming
```
private boolean doingLayerBStreaming
```
  - totalByteCount
```
volatile long totalByteCount
```
- Constructor Detail
  - DDMReader
```
DDMReader(DRDAConnThread agent,
          DssTrace dssTrace)
```
  - DDMReader
```
DDMReader(java.io.InputStream inputStream)
```
    This constructor is used for testing the protocol It is used by ProtocolTestAdapter to read the protocol returned by the server
- Method Detail
  - initialize
```
protected void initialize(DRDAConnThread agent,
                          DssTrace dssTrace)
```
    Initialize values for this session, the reader is reused so we need to set null and 0 values
  - setUtf8Ccsid
```
protected void setUtf8Ccsid()
```
  - setEbcdicCcsid
```
protected void setEbcdicCcsid()
```
  - terminateChainOnErr
```
protected boolean terminateChainOnErr()
```
  - isChainedWithSameID
```
protected boolean isChainedWithSameID()
```
    Next DSS has same correlator as current DSS
    
    Returns:
    
    true if next DSS has the same correlator as current DSS
  - isChainedWithDiffID
```
protected boolean isChainedWithDiffID()
```
    Next DSS has different correlator than current DSS
    
    Returns:
    
    true if next DSS has a different correlator than current DSS
  - getDdmLength
```
protected long getDdmLength()
```
    Length of current DDM object
    
    Returns:
    
    length of DDM object
  - moreDdmData
```
protected boolean moreDdmData()
```
    Is there more in this DDM object
    
    Returns:
    
    true if DDM length is > 0
  - moreDssData
```
protected boolean moreDssData()
```
    Is there more in this DDS object
    
    Returns:
    
    true if DDS length is > 0
  - moreData
```
protected boolean moreData()
```
    Is there more data in the buffer
    
    Returns:
    
    true if there is more data in the buffer
  - isCmd
```
protected boolean isCmd()
                 throws DRDAProtocolException,
                        java.io.UnsupportedEncodingException
```
    Check for the command protocol
    
    Returns:
    
    true if this is a command; false otherwise
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
    
    java.io.UnsupportedEncodingException
  - readDssHeader
```
protected int readDssHeader()
                     throws DRDAProtocolException
```
    Read DSS header DSS Header format is 2 bytes - length 1 byte - 'D0' - indicates DDM data 1 byte - DSS format |---|---------|----------| | 0 | flags | type | |---|---------|----------| | 0 | 1 2 3 | 4 5 6 7 | |---|---------|----------| bit 0 - '0' bit 1 - '0' - unchained, '1' - chained bit 2 - '0' - do not continue on error, '1' - continue on error bit 3 - '0' - next DSS has different correlator, '1' - next DSS has same correlator type - 1 - Request DSS - 2 - Reply DSS - 3 - Object DSS - 4 - Communications DSS - 5 - Request DSS where no reply is expected 2 bytes - request correlation id
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - readReplyDss
```
protected void readReplyDss()
                     throws DRDAProtocolException
```
    Read Reply DSS This is used in testing the protocol. We shouldn't see a reply DSS when we are servicing DRDA commands
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - readLengthAndCodePoint
```
protected int readLengthAndCodePoint(boolean isLayerBStreamingPossible)
                              throws DRDAProtocolException
```
    Read the DDM Length and CodePoint
    
    Parameters:
    
    isLayerBStreamingPossible - true only when layer B streaming is possible
    
    Returns:
    
    - returns codepoint
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - readCodePoint
```
protected int readCodePoint()
```
    Read the CodePoint
    
    Returns:
    
    - returns codepoint
  - markCollection
```
protected void markCollection()
```
    Push DDM Length on to collection stack
  - getCodePoint
```
protected int getCodePoint()
                    throws DRDAProtocolException
```
    Get the next CodePoint from a collection
    
    Returns:
    
    NO_CODEPOINT if collection stack is empty or remaining length is 0; otherwise, read length and code point
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - getCodePoint
```
protected int getCodePoint(int codePointCheck)
                    throws DRDAProtocolException
```
    Get the next CodePoint from a collection and check that it matches the specified CodePoint
    
    Parameters:
    
    codePointCheck - - codePoint to check against
    
    Returns:
    
    codePoint
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - readByte
```
protected byte readByte()
                 throws DRDAProtocolException
```
    Read byte value
    
    Returns:
    
    value
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - readUnsignedByte
```
protected int readUnsignedByte()
                        throws DRDAProtocolException
```
    Read byte value and mask out high order bytes before returning
    
    Returns:
    
    value
    
    Throws:
    
    DRDAProtocolException
  - readNetworkShort
```
protected int readNetworkShort()
                        throws DRDAProtocolException
```
    Read network short value
    
    Returns:
    
    value
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - readSignedNetworkShort
```
protected int readSignedNetworkShort()
                              throws DRDAProtocolException
```
    Read signed network short value
    
    Returns:
    
    value
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - readShort
```
protected short readShort(int byteOrder)
                   throws DRDAProtocolException
```
    Read platform short value
    
    Returns:
    
    value
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - readNetworkInt
```
protected int readNetworkInt()
                      throws DRDAProtocolException
```
    Read network int value
    
    Returns:
    
    value
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - readInt
```
protected int readInt(int byteOrder)
               throws DRDAProtocolException
```
    Read platform int value
    
    Returns:
    
    value
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - readNetworkLong
```
protected long readNetworkLong()
                        throws DRDAProtocolException
```
    Read network long value
    
    Returns:
    
    value
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - readNetworkSixByteLong
```
protected long readNetworkSixByteLong()
                               throws DRDAProtocolException
```
    Read network six byte value and put it in a long v
    
    Returns:
    
    value
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - readLong
```
protected long readLong(int byteOrder)
                 throws DRDAProtocolException
```
    Read platform long value
    
    Returns:
    
    value
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - readFloat
```
protected float readFloat(int byteOrder)
                   throws DRDAProtocolException
```
    Read platform float value
    
    Returns:
    
    value
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - readDouble
```
protected double readDouble(int byteOrder)
                     throws DRDAProtocolException
```
    Read platform double value
    
    Returns:
    
    value
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - readBigDecimal
```
protected java.math.BigDecimal readBigDecimal(int precision,
                                              int scale)
                                       throws DRDAProtocolException
```
    Read a BigDecimal value
    
    Parameters:
    
    precision - of the BigDecimal
    
    scale - of the BigDecimal
    
    Returns:
    
    value
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - getEXTDTAReaderInputStream
```
EXTDTAReaderInputStream getEXTDTAReaderInputStream(boolean checkNullability)
                                            throws DRDAProtocolException
```
    Creates an InputStream which can stream EXTDTA objects. The InputStream uses this DDMReader to read data from network. The DDMReader should not be used before all data in the stream has been read.
    
    Parameters:
    
    checkNullability - used to check if the stream is null. If it is null, this method returns null
    
    Returns:
    
    EXTDTAReaderInputStream object which can be passed to prepared statement as a binary stream.
    
    Throws:
    
    DRDAProtocolException - standard DRDA protocol exception
  - readLOBInitStream
```
java.io.ByteArrayInputStream readLOBInitStream()
                                        throws DRDAProtocolException
```
    This method is used by EXTDTAReaderInputStream to read the first chunk of data. This lengthless method must be called only when layer B streaming.
    
    Throws:
    
    DRDAProtocolException - standard DRDA protocol exception
  - readLOBInitStream
```
java.io.ByteArrayInputStream readLOBInitStream(long desiredLength)
                                        throws DRDAProtocolException
```
    This method is used by EXTDTAReaderInputStream to read the first chunk of data.
    
    Parameters:
    
    desiredLength - the desired length of chunk. This parameter is ignored when layerB Streaming is doing.
    
    Throws:
    
    DRDAProtocolException - standard DRDA protocol exception
  - readLOBContinuationStream
```
java.io.ByteArrayInputStream readLOBContinuationStream()
                                                throws java.io.IOException
```
    This method is used by EXTDTAReaderInputStream to read the next chunk of data. Calling this method finishes layer B streaming if continuation of DSS segment was finished. This lengthless method must be called only when layer B streaming.
    
    Throws:
    
    java.io.IOException - IOException
  - readLOBContinuationStream
```
java.io.ByteArrayInputStream readLOBContinuationStream(long desiredLength)
                                                throws java.io.IOException
```
    This method is used by EXTDTAReaderInputStream to read the next chunk of data. Furthermore, when Layer B streaming is carried out, calling this method finishes layer B streaming if continuation of DSS segment was finished.
    
    Parameters:
    
    desiredLength - the desired length of chunk. This parameter is ignored when layerB Streaming is doing.
    
    Throws:
    
    java.io.IOException - IOException
  - readLOBChunk
```
private java.io.ByteArrayInputStream readLOBChunk(boolean readHeader,
                                                  long desiredLength)
                                           throws DRDAProtocolException
```
    This method is used by EXTDTAReaderInputStream to read the next chunk of data. Furthermore, when Layer B streaming is carried out, calling this method may finish layer B streaming.
    
    Parameters:
    
    readHeader - set to true if the dss continuation should be read
    
    desiredLength - the desired length of chunk. This parameter is ignored when layerB Streaming is doing.
    
    Throws:
    
    DRDAProtocolException - standard DRDA protocol exception
  - getExtData
```
byte[] getExtData(long desiredLength,
                  boolean checkNullability)
           throws DRDAProtocolException
```
    Throws:
    
    DRDAProtocolException
  - readDSSContinuationHeader
```
private void readDSSContinuationHeader()
                                throws DRDAProtocolException
```
    Throws:
    
    DRDAProtocolException
  - isEXTDTANull
```
private boolean isEXTDTANull()
                      throws DRDAProtocolException
```
    Throws:
    
    DRDAProtocolException
  - packedNybblesToInt
```
private int packedNybblesToInt(byte[] buffer,
                               int offset,
                               int startNybble,
                               int numberOfNybbles)
```
    Convert a range of packed nybbles (up to 9 digits without overflow) to an int. Note that for performance purpose, it does not do array-out-of-bound checking.
    
    Parameters:
    
    buffer - buffer to read from
    
    offset - offset in the buffer
    
    startNybble - start nybble
    
    numberOfNybbles - number of nybbles
    
    Returns:
    
    an int value
  - packedNybblesToLong
```
private long packedNybblesToLong(byte[] buffer,
                                 int offset,
                                 int startNybble,
                                 int numberOfNybbles)
```
    Convert a range of packed nybbles (up to 18 digits without overflow) to a long. Note that for performance purpose, it does not do array-out-of-bound checking.
    
    Parameters:
    
    buffer - buffer to read from
    
    offset - offset in the buffer
    
    startNybble - start nybble
    
    numberOfNybbles - number of nybbles
    
    Returns:
    
    an long value
  - computeMagnitude
```
private int[] computeMagnitude(int[] input)
```
    Compute the int array of magnitude from input value segments.
    
    Parameters:
    
    input - value segments
    
    Returns:
    
    array of int magnitudes
  - readEncryptedString
```
protected java.lang.String readEncryptedString(DecryptionManager decryptM,
                                               int securityMechanism,
                                               byte[] initVector,
                                               byte[] sourcePublicKey)
                                        throws DRDAProtocolException,
                                               java.sql.SQLException
```
    Read encrypted string
    
    Parameters:
    
    decryptM - decryption manager
    
    securityMechanism - security mechanism
    
    initVector - initialization vector for cipher
    
    sourcePublicKey - public key (as in Deffie-Hellman algorithm) from source (encryptor)
    
    Returns:
    
    decrypted string
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
    
    java.sql.SQLException - wrapping any exception in decryption
  - readString
```
protected java.lang.String readString(int length)
                               throws DRDAProtocolException
```
    Read string value Strings in DRDA protocol are encoded in EBCDIC by default so we need to convert to UCS2
    
    Parameters:
    
    length - - length of string to read
    
    Returns:
    
    value
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - readString
```
protected void readString(DRDAString dst,
                          int size,
                          boolean unpad)
                   throws DRDAProtocolException
```
    Read string value into a DRDAString object.
    
    Parameters:
    
    dst - destination for the read string
    
    size - size (in bytes) of string to read
    
    unpad - if true, remove padding (trailing spaces)
    
    Throws:
    
    DRDAProtocolException
  - readString
```
protected java.lang.String readString(int length,
                                      java.lang.String encoding)
                               throws DRDAProtocolException
```
    Read encoded string value
    
    Parameters:
    
    length - - length of string to read
    
    Returns:
    
    value
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - readStringData
```
protected java.lang.String readStringData(int length)
                                   throws DRDAProtocolException
```
    Read specified length of string value in DDM data with default encoding
    
    Parameters:
    
    length - - length of string to read
    
    Returns:
    
    value
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - readLDStringData
```
protected java.lang.String readLDStringData(java.lang.String encoding)
                                     throws DRDAProtocolException
```
    Read length delimited string value in DDM data with default encoding
    
    Returns:
    
    value
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - readString
```
protected java.lang.String readString()
                               throws DRDAProtocolException
```
    Read string value
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - readBytes
```
protected byte[] readBytes(int length)
                    throws DRDAProtocolException
```
    Read byte string value
    
    Parameters:
    
    length - - length of string to read
    
    Returns:
    
    byte array
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - readBytes
```
protected byte[] readBytes()
                    throws DRDAProtocolException
```
    Read byte string value
    
    Returns:
    
    byte array
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - skipBytes
```
protected void skipBytes(int length)
                  throws DRDAProtocolException
```
    Skip byte string value
    
    Parameters:
    
    length - - length of string to skip
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - skipBytes
```
protected void skipBytes()
                  throws DRDAProtocolException
```
    Skip byte string value
    
    Throws:
    
    DRDAProtocolException
  - skipDss
```
protected void skipDss()
                throws DRDAProtocolException
```
    Skip remaining DSS
    
    Throws:
    
    DRDAProtocolException
  - clearBuffer
```
protected void clearBuffer()
                    throws DRDAProtocolException
```
    Throws:
    
    DRDAProtocolException
  - convertBytes
```
protected java.lang.String convertBytes(byte[] buf)
```
    Convert EBCDIC byte array to unicode string
    
    Parameters:
    
    buf - - byte array
    
    Returns:
    
    string
  - adjustLengths
```
private void adjustLengths(int length)
```
    Adjust remaining length
    
    Parameters:
    
    length - - adjustment length
  - readCmdString
```
protected java.lang.String readCmdString(int length)
                                  throws DRDAProtocolException,
                                         java.io.UnsupportedEncodingException
```
    Read string value
    
    Parameters:
    
    length - - length of string to read
    
    Returns:
    
    value
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
    
    java.io.UnsupportedEncodingException
  - readCmdString
```
protected java.lang.String readCmdString()
                                  throws DRDAProtocolException,
                                         java.io.UnsupportedEncodingException
```
    Read string value
    
    Returns:
    
    value
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
    
    java.io.UnsupportedEncodingException
  - ensureALayerDataInBuffer
```
private void ensureALayerDataInBuffer(int desiredDataSize)
                               throws DRDAProtocolException
```
    Make sure a certain amount of Layer A data is in the buffer. The data will be in the buffer after this method is called.
    
    Parameters:
    
    desiredDataSize - - amount of data we need
    
    Throws:
    
    DRDAProtocolException
  - ensureBLayerDataInBuffer
```
private void ensureBLayerDataInBuffer(int desiredDataSize,
                                      boolean adjustLen)
                               throws DRDAProtocolException
```
    Make sure a certain amount of Layer B data is in the buffer. The data will be in the buffer after this method is called.
    
    Parameters:
    
    desiredDataSize - - amount of data we need
    
    adjustLen - - whether to adjust the remaining lengths
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - compressBLayerData
```
private void compressBLayerData(int continueDssHeaderCount)
                         throws DRDAProtocolException
```
    Compress B Layer data if extended total length is used by removing the continuation headers
    
    Parameters:
    
    continueDssHeaderCount - - amount of data we need
    
    Throws:
    
    DRDAProtocolException
  - shiftBuffer
```
private void shiftBuffer(byte[] destinationBuffer)
```
    This is a helper method which shifts the buffered bytes from wherever they are in the current buffer to the beginning of different buffer (note these buffers could be the same). State information is updated as needed after the shift.
    
    Parameters:
    
    destinationBuffer - - buffer to shift data to
  - ensureSpaceInBufferForFill
```
private void ensureSpaceInBufferForFill(int desiredSpace)
```
    This method makes sure there is enough room in the buffer for a certain number of bytes. This method will allocate a new buffer if needed and shift the bytes in the current buffer to make ensure space is available for a fill. Right now this method will shift bytes as needed to make sure there is as much room as possible in the buffer before trying to do the read. The idea is to try to have space to get as much data as possible if we need to do a read on the socket's stream.
    
    Parameters:
    
    desiredSpace - - amount of data we need
  - fill
```
private void fill(int minimumBytesNeeded)
           throws DRDAProtocolException
```
    This method will attempt to read a minimum number of bytes from the underlying stream. This method will keep trying to read bytes until it has obtained at least the minimum number.
    
    Parameters:
    
    minimumBytesNeeded - - minimum required bytes
    
    Throws:
    
    DRDAProtocolException - if a protocol error is detected
  - trace
```
private void trace(java.lang.String msg)
```
    Print a internal trace message
  - getCurrChainState
```
protected byte getCurrChainState()
```
    Return chaining bit for current DSS.
  - startLayerBStreaming
```
private void startLayerBStreaming()
```
  - finishLayerBStreaming
```
private void finishLayerBStreaming()
```
  - doingLayerBStreaming
```
boolean doingLayerBStreaming()
```

Class DDMReader

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

DEFAULT_BUFFER_SIZE

MAX_MARKS_NESTING

NO_CODEPOINT

EMPTY_STACK

ADJUST_LENGTHS

NO_ADJUST_LENGTHS

MAX_EXTDTA_SIZE

tenRadixMagnitude

agent

utf8CcsidManager

ebcdicCcsidManager

ccsidManager

buffer

pos

count

topDdmCollectionStack

ddmCollectionLenStack

ddmScalarLen

dssLength

dssIsContinued

terminateChainOnErr

dssIsChainedWithSameID

dssIsChainedWithDiffID

dssCorrelationID

prevCorrelationID

svrcod

dssTrace

inputStream

doingLayerBStreaming

totalByteCount

Constructor Detail

DDMReader

DDMReader

Method Detail

initialize

setUtf8Ccsid

setEbcdicCcsid

terminateChainOnErr

isChainedWithSameID

isChainedWithDiffID

getDdmLength

moreDdmData

moreDssData

moreData

isCmd

readDssHeader

readReplyDss

readLengthAndCodePoint

readCodePoint

markCollection

getCodePoint

getCodePoint

readByte

readUnsignedByte

readNetworkShort

readSignedNetworkShort

readShort

readNetworkInt

readInt

readNetworkLong

readNetworkSixByteLong

readLong

readFloat

readDouble

readBigDecimal

getEXTDTAReaderInputStream

readLOBInitStream

readLOBInitStream

readLOBContinuationStream

readLOBContinuationStream

readLOBChunk

getExtData

readDSSContinuationHeader

isEXTDTANull