EDOBE XDOM PMML Manual de usuario descargar pdf (Pagina 89)

If the CNKProc has outputs, the execute() method may set the column

names and types of the output

CNKBuf objects if they are not set

already. This can be done easily by calling

CNKBuf::setUnknownColumnInfo.

3. Release data rows.

After reading from the inputs and writing to the outputs, the

execute() method must release the input data rows that it has been

reading (by calling

CNKBufReader::releaseRows), to prepare for

reading the next chunk of input data. It must also release the output

data rows it has been writing (by calling

CNKBufWriter::releaseRows), so that the output data can be read by

other components.

The

execute() method does not necessarily need to release all of its

input and output rows. If an input had access to 100 rows and the

execute method released 95, the last 5 rows would be available on the

input as the first 5 rows the next time that a chunk of rows was

requested. By repeatedly releasing less than all of the input rows, the

execute method would access a rolling, overlapping window over the

input data. There is less reason for releasing less than the full set of

output rows: once an output row has been written, there is little

reason to change it.

Along with releasing the rows, the

execute() method should perform

several other housekeeping chores: handling the

EOF flags, calling

setDone, and calling incrementRowsDone.

If an input buf has its

EOF flag set (accessed via getEOF()), this signals

the end of the input data. The

execute() method has to detect and

handle this situation. Note that even if the

EOF flag is set, the buf may

still contain data that the

CNKProc needs to process. Only when

(inbuf->getEOF() && inbuf->getRowsReady()==0) is true has all of

the input data been released.

The

execute() method has to handle the situation where the CNKProc

has processed all of its data, and it is "done". When this occurs, after

releasing all of its input and output rows, the

CNKProc should call

setEOF() on all of its outputs, and then call setDone(true) to signal

that it should not be executed again.

The

execute() method should also call incrementRowsDone(long

rows), to update the number of rows processed by the CNKProc

(accessed by

getRowsDone()).

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