ossimJpipMessageDecoder Class Reference

#include <ossimJpipMessageDecoder.h>

Inheritance diagram for ossimJpipMessageDecoder:

Public Member Functions
	ossimJpipMessageDecoder ()
ossimByteStreamBuffer &	inputStreamBuffer ()
std::istream &	inputStream () const
virtual ossimJpipMessage *	readMessage ()
Public Member Functions inherited from ossimReferenced
	ossimReferenced ()
	ossimReferenced (const ossimReferenced &)
ossimReferenced &	operator= (const ossimReferenced &)
void	ref () const
	increment the reference count by one, indicating that this object has another pointer which is referencing it. More...
void	unref () const
	decrement the reference count by one, indicating that a pointer to this object is referencing it. More...
void	unref_nodelete () const
	decrement the reference count by one, indicating that a pointer to this object is referencing it. More...
int	referenceCount () const

Protected Member Functions
ossim_int64	readVBAS ()
	Reads a Variable-length Byte-Aligned Segment. More...
ossimJpipMessage *	readEORMessage ()
Protected Member Functions inherited from ossimReferenced
virtual	~ossimReferenced ()

Protected Attributes
ossim_int32	m_lastClass
ossim_int32	m_lastCSn
	Contains the last CSn value. More...
ossim_int64	m_headerLength
	Indicates the length of the JPIP message header. More...
ossimByteStreamBuffer	m_streamBuffer
std::istream	m_inputStream

Detailed Description

Definition at line 9 of file ossimJpipMessageDecoder.h.

Constructor & Destructor Documentation

ossimJpipMessageDecoder()

ossimJpipMessageDecoder::ossimJpipMessageDecoder

(

)

Definition at line 3 of file ossimJpipMessageDecoder.cpp.

:m_lastClass(0),
m_lastCSn(0),
m_headerLength(0),
m_inputStream(&m_streamBuffer)
{
}

Member Function Documentation

inputStream()

std::istream& ossimJpipMessageDecoder::inputStream ( ) const

inline

Definition at line 14 of file ossimJpipMessageDecoder.h.

{return m_inputStream;}

inputStreamBuffer()

ossimByteStreamBuffer& ossimJpipMessageDecoder::inputStreamBuffer ( )

inline

Definition at line 13 of file ossimJpipMessageDecoder.h.

{return m_streamBuffer;}

readEORMessage()

ossimJpipMessage * ossimJpipMessageDecoder::readEORMessage ( )

protected

Definition at line 148 of file ossimJpipMessageDecoder.cpp.

References ossimJpipMessage::header(), ossimJpipMessageHeader::m_EORCode, m_headerLength, m_inputStream, ossimJpipMessageHeader::m_isEOR, ossimJpipMessageHeader::m_msgLength, ossimJpipMessage::messageBody(), readVBAS(), and ossimRefPtr< T >::release().

Referenced by readMessage().

{
    ossimRefPtr<ossimJpipMessage> jpipMessage; 
    
    jpipMessage = new ossimJpipMessage();           
    jpipMessage->header()->m_isEOR = true;
    
    // Read EOR code        
    jpipMessage->header()->m_EORCode = m_inputStream.get();
    m_headerLength++;
    
    // Read EOR body length
    int EORBodyLength = (int)readVBAS();
    jpipMessage->header()->m_msgLength = EORBodyLength;
    
    // Read EOR body
    if (EORBodyLength > 0 ) 
    {
        jpipMessage->messageBody().resize(EORBodyLength);
        m_inputStream.read((char*)&jpipMessage->messageBody().front(), EORBodyLength);
    }
    
    return jpipMessage.release();
}

readMessage()

ossimJpipMessage * ossimJpipMessageDecoder::readMessage ( )

virtual

Definition at line 12 of file ossimJpipMessageDecoder.cpp.

References ossimJpipMessage::header(), ossimJpipMessageHeader::m_aux, ossimJpipMessageHeader::m_classIdentifier, ossimJpipMessageHeader::m_CSn, m_headerLength, ossimJpipMessageHeader::m_inClassIdentifier, m_inputStream, ossimJpipMessageHeader::m_isLastByte, m_lastClass, m_lastCSn, ossimJpipMessageHeader::m_msgLength, ossimJpipMessageHeader::m_msgOffset, ossimJpipMessage::messageBody(), readEORMessage(), readVBAS(), ossimRefPtr< T >::release(), and ossimJpipMessage::setHeaderLength().

{
    ossim_int32 BinIDIndicator = 0;
    ossim_int64 inClassIdentifier = 0;
    bool completeDataBin = false;
    ossim_int64 tempByte = 0;
    
    // Initialization
    m_headerLength = 0;
    ossimRefPtr<ossimJpipMessage> jpipMessage = new ossimJpipMessage();
    
    //  Bin-ID
    tempByte = m_inputStream.get();
    m_headerLength++;
    
    if (tempByte == 0x00) 
    { // EOR is reached
        jpipMessage = readEORMessage();
        jpipMessage->setHeaderLength(m_headerLength);
        return jpipMessage.release();
    }
    
    // b bits
    BinIDIndicator = (tempByte >> 5) & 0x03;
    if ( (BinIDIndicator < 1) || (BinIDIndicator > 3) ) 
    {
        throw new ossimException("Wrong server response: impossible to decode it correctly");
    }
    
    // c bit
    completeDataBin = (tempByte & 0x10)==0 ? false : true;
    
    // d bits (In-Class ID)
    inClassIdentifier = tempByte & 0x0F;
    if ((tempByte >> 7) > 0 ) {
        int numBytesVBAS = 1;
        do {
            tempByte = m_inputStream.get();
            m_headerLength++;
            if (tempByte == -1) {
                throw new ossimException("There is not data available to read the VBAS");
            }
            inClassIdentifier = (inClassIdentifier << 7) | (ossim_int64)(tempByte & 0x7F);
            numBytesVBAS++;
            
            if (numBytesVBAS > 9) { // maximum long value is 2^63 - 1 => 9 bytes VBAS 
                throw new ossimException("VBAS length is larger than 63 bits (which is the maximum of long)");
            }
        } while ( (tempByte & 0x80) != 0 );
    }
    
    jpipMessage->header()->m_isLastByte = completeDataBin;
    jpipMessage->header()->m_inClassIdentifier = inClassIdentifier;
    
    // Class        
    if ( (BinIDIndicator == 2) || (BinIDIndicator == 3) )  
    {
        jpipMessage->header()->m_classIdentifier = (int)readVBAS();
        m_lastClass = jpipMessage->header()->m_classIdentifier;
        
    } 
    else 
    {
        jpipMessage->header()->m_classIdentifier = m_lastClass;
    }
    if ((jpipMessage->header()->m_classIdentifier < 0) || (jpipMessage->header()->m_classIdentifier > 8) )
        throw new ossimException("Wrong server response: invalid value for Class identifier)");
    
    // CSn              
    if ( BinIDIndicator == 3) 
    {
        jpipMessage->header()->m_CSn = (int)readVBAS();
        m_lastCSn = jpipMessage->header()->m_CSn;
        
    } 
    else 
    {
        jpipMessage->header()->m_CSn = m_lastCSn;
    }
    
    // Msg-Offset
    jpipMessage->header()->m_msgOffset = (int)readVBAS();
    
    // Msg-Length                       
    jpipMessage->header()->m_msgLength = (int)readVBAS();           
    
    // Aux
    if ( (jpipMessage->header()->m_classIdentifier % 2) == 1 ) 
    {
        jpipMessage->header()->m_aux = (int)readVBAS();
    }
    
    // Read jpip message body
    if (jpipMessage->header()->m_msgLength > 0) 
    {
        jpipMessage->messageBody().resize(jpipMessage->header()->m_msgLength);
        m_inputStream.read((char*)&jpipMessage->messageBody().front(), (int)jpipMessage->header()->m_msgLength);                    
    }
    
    jpipMessage->setHeaderLength(m_headerLength);
    
    return jpipMessage.release();
}

readVBAS()

ossim_int64 ossimJpipMessageDecoder::readVBAS ( )

protected

Reads a Variable-length Byte-Aligned Segment.

Returns

the value which has been read from the VBAS.

Exceptions

ossimException

if an I/O error occurs.

Definition at line 117 of file ossimJpipMessageDecoder.cpp.

References m_headerLength, and m_inputStream.

Referenced by readEORMessage(), and readMessage().

{
    ossim_int64 value = 0;
    ossim_int64 tempByte;
    ossim_int32 numBytesVBAS = 0;
    m_headerLength = 0;
    
    do 
    {           
        tempByte = m_inputStream.get();
        m_headerLength++;
        
        if(tempByte == -1) 
        {
            throw ossimException("There is not data available to read the VBAS");
        }
        
        value = (value << 7) | (long) (tempByte & 0x7F);
        numBytesVBAS++;
        
        if (numBytesVBAS > 9) 
        {   // maximum long value is 2^63 - 1 => 9 bytes VBAS 
            throw ossimException("VBAS length is larger than 63 bits (which is the maximum of long)");
        }
        
    } while ( (tempByte & 0x80) != 0 );                 
    
    return value;
}

Member Data Documentation

m_headerLength

ossim_int64 ossimJpipMessageDecoder::m_headerLength

protected

Indicates the length of the JPIP message header.

This attribute is useful for statistics.

Definition at line 45 of file ossimJpipMessageDecoder.h.

Referenced by readEORMessage(), readMessage(), and readVBAS().

m_inputStream

std::istream ossimJpipMessageDecoder::m_inputStream

mutableprotected

Definition at line 48 of file ossimJpipMessageDecoder.h.

Referenced by readEORMessage(), readMessage(), and readVBAS().

m_lastClass

ossim_int32 ossimJpipMessageDecoder::m_lastClass

protected

Definition at line 33 of file ossimJpipMessageDecoder.h.

Referenced by readMessage().

m_lastCSn

ossim_int32 ossimJpipMessageDecoder::m_lastCSn

protected

Contains the last CSn value.

It is a state variables used when dependent form is used.

Definition at line 39 of file ossimJpipMessageDecoder.h.

Referenced by readMessage().

m_streamBuffer

ossimByteStreamBuffer ossimJpipMessageDecoder::m_streamBuffer

mutableprotected

Definition at line 47 of file ossimJpipMessageDecoder.h.

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The documentation for this class was generated from the following files:

• ossimJpipMessageDecoder.h
• ossimJpipMessageDecoder.cpp