ucar.nc2.iosp
Interface IOServiceProvider

All Known Subinterfaces:

IOServiceProviderWriter

All Known Implementing Classes:

AbstractIOServiceProvider, AbstractLightningIOSP, AreaServiceProvider, Cinrad2IOServiceProvider, DMSPiosp, Doradeiosp, Fysatiosp, GempakGridServiceProvider, GempakSoundingIOSP, GempakStationFileIOSP, GempakSurfaceIOSP, Ghcnm, Ghcnm2, Giniiosp, GribGridServiceProvider, GridServiceProvider, GtopoIosp, H4iosp, H5iosp, JniIosp, McIDASGridServiceProvider, N3iosp, N3raf, NcStreamIosp, Nexrad2IOServiceProvider, Nidsiosp, Nldn, NmcObsLegacy, NOWRadiosp, SigmetIOServiceProvider, UAMIVServiceProvider, UFiosp, Uspln, Vis5DIosp

public interface IOServiceProvider

This is the service provider interface for the low-level I/O access classes (read only). This is only used by service implementors. The NetcdfFile class manages all registered IOServiceProvider classes. When NetcdfFile.open() is called:

1. the file is opened as a ucar.unidata.io.RandomAccessFile;
2. the file is handed to the isValidFile() method of each registered IOServiceProvider class (until one returns true, which means it can read the file).
3. the open() method on the resulting IOServiceProvider class is handed the file.

Author:

caron

See Also:

;

Method Summary

void	close() Close the file.
String	getDetailInfo() Show debug / underlying implementation details
String	getFileTypeDescription() Get a human-readable description for this file type.
String	getFileTypeId() Get a unique id for this file type.
String	getFileTypeVersion() Get the version of this file type.
StructureDataIterator	getStructureIterator(Structure s, int bufferSize)
boolean	isValidFile(RandomAccessFile raf) Check if this is a valid file for this IOServiceProvider.
void	open(RandomAccessFile raf, NetcdfFile ncfile, CancelTask cancelTask) Open existing file, and populate ncfile with it.
Array	readData(Variable v2, Section section) Read data from a top level Variable and return a memory resident Array.
Array	readSection(ParsedSectionSpec cer) Allows reading sections of nested variables
long	readToByteChannel(Variable v2, Section section, WritableByteChannel channel) Read data from a top level Variable and send data to a WritableByteChannel.
Object	sendIospMessage(Object message) A way to communicate arbitrary information to an iosp.
boolean	sync() Update the metadata in the NetcdfFile if the underlying dataset has changed.
boolean	syncExtend() Extend the NetcdfFile if the underlying dataset has changed in a way that is compatible with the current metadata.
String	toStringDebug(Object o) Debug info for this object.

Method Detail

isValidFile

boolean isValidFile(RandomAccessFile raf)
                    throws IOException

Check if this is a valid file for this IOServiceProvider. You must make this method thread safe, ie dont keep any state.

Parameters:

raf - RandomAccessFile

Returns:

true if valid.

Throws:

IOException - if read error

open

void open(RandomAccessFile raf,
          NetcdfFile ncfile,
          CancelTask cancelTask)
          throws IOException

Open existing file, and populate ncfile with it. This method is only called by the NetcdfFile constructor on itself. The provided NetcdfFile object will be empty except for the location String and the IOServiceProvider associated with this NetcdfFile object.

Parameters:

raf - the file to work on, it has already passed the isValidFile() test.

ncfile - add objects to this empty NetcdfFile

cancelTask - used to monitor user cancellation; may be null.

Throws:

IOException - if read error

readData

Array readData(Variable v2,
               Section section)
               throws IOException,
                      InvalidRangeException

Read data from a top level Variable and return a memory resident Array. This Array has the same element type as the Variable, and the requested shape.

Parameters:

v2 - a top-level Variable

section - the section of data to read. There must be a Range for each Dimension in the variable, in order. Note: no nulls allowed. IOSP may not modify.

Returns:

the requested data in a memory-resident Array

Throws:

IOException - if read error

InvalidRangeException - if invalid section

See Also:

Range

readToByteChannel

long readToByteChannel(Variable v2,
                       Section section,
                       WritableByteChannel channel)
                       throws IOException,
                              InvalidRangeException

Read data from a top level Variable and send data to a WritableByteChannel. Must be in big-endian order.

Parameters:

v2 - a top-level Variable

section - the section of data to read. There must be a Range for each Dimension in the variable, in order. Note: no nulls allowed. IOSP may not modify.

channel - write data to this WritableByteChannel

Returns:

the number of bytes written to the channel

Throws:

IOException - if read error

InvalidRangeException - if invalid section

readSection

Array readSection(ParsedSectionSpec cer)
                  throws IOException,
                         InvalidRangeException

Allows reading sections of nested variables

Parameters:

cer - section specification : what data is wanted

Returns:

requested data array

Throws:

IOException - on read error

InvalidRangeException - if section spec is invalid

getStructureIterator

StructureDataIterator getStructureIterator(Structure s,
                                           int bufferSize)
                                           throws IOException

Throws:

IOException

close

void close()
           throws IOException

Close the file. It is the IOServiceProvider's job to close the file (even though it didnt open it), and to free any other resources it has used.

Throws:

IOException - if read error

syncExtend

boolean syncExtend()
                   throws IOException

Extend the NetcdfFile if the underlying dataset has changed in a way that is compatible with the current metadata. For example, if the unlimited dimension has grown.

Returns:

true if the NetcdfFile was extended.

Throws:

IOException - if a read error occured when accessing the underlying dataset.

sync

boolean sync()
             throws IOException

Update the metadata in the NetcdfFile if the underlying dataset has changed.

Returns:

true if the NetcdfFile was changed.

Throws:

IOException - if a read error occured when accessing the underlying dataset.

sendIospMessage

Object sendIospMessage(Object message)

A way to communicate arbitrary information to an iosp.

Parameters:

message - opaque message.

Returns:

opaque return, may be null.

toStringDebug

String toStringDebug(Object o)

Debug info for this object.

Parameters:

o - which object

Returns:

debug info for this object

getDetailInfo

String getDetailInfo()

Show debug / underlying implementation details

Returns:

debug info

getFileTypeId

String getFileTypeId()

Get a unique id for this file type.

Returns:

registered id of the file type

See Also:

"http://www.unidata.ucar.edu/software/netcdf-java/formats/FileTypes.html"

getFileTypeVersion

String getFileTypeVersion()

Get the version of this file type.

Returns:

version of the file type

See Also:

"http://www.unidata.ucar.edu/software/netcdf-java/formats/FileTypes.html"

getFileTypeDescription

String getFileTypeDescription()

Get a human-readable description for this file type.

Returns:

description of the file type

See Also:

"http://www.unidata.ucar.edu/software/netcdf-java/formats/FileTypes.html"